tag:blogger.com,1999:blog-33841115235859325402024-03-14T07:16:56.699+01:00SeiðrSpace physics, Experiments, Inverse problems - Daily Reports (seiðr). Writings about various topics in plasma physics, radio science, space physics, rockets, radars, aurora, remote sensing, geophysics, radio astronomy, inverse problems, outdoors activities, electronics, and software defined radio. The web page of the radio science group at University of Tromsø. Juha Vierinenhttp://www.blogger.com/profile/05315784473428964695noreply@blogger.comBlogger208125tag:blogger.com,1999:blog-3384111523585932540.post-63543171480286656332022-11-17T11:38:00.005+01:002022-11-17T11:38:52.217+01:00CZ-6A Rocket Body breakup The 18th Space Defence Squadron tweeted on November 13th that a breakup associated with a recent launch of a Chinese satellite had occurred on the early morning hours of November 12th. This breakup was associated with the upper stage rocket body CZ-6A R/B with NORAD ID #54236 and COSPAR ID 2022-151. We scheduled a 4 hour beam park observation using the 930 MHz EISCAT UHF radar to characterize the debris cloud size, adding another valuable measurement to the unique catalogue debris clouds produced by fragmentation events.
It appears that this recent event is not as bad as the anti-satellite events, or the Iridium-Cosmos collision. But we did observe a small cluster of new objects appearing on the orbital ring of the parent object.
<div class="separator" style="clear: both;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjZKA_m0zZURDi0r_LLxSaRQZLRIo20vqj_hbzsX_I0oScD_e-LrbAZTDSE4pR9k4fp78VtuhY3RFUL9y6F4nRVnUTHHCO71fo4YxZG6N853lLw9SXv50il3XX1J1lrRU7fWHVSMaZqI1lxvJ3qcy61MV-4GxzAubEwXQ24g5YQAK5fv3Msv5knPtLu/s1962/IMG_8723.PNG" style="display: block; padding: 1em 0; text-align: center; "><img alt="" border="0" width="400" data-original-height="906" data-original-width="1962" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjZKA_m0zZURDi0r_LLxSaRQZLRIo20vqj_hbzsX_I0oScD_e-LrbAZTDSE4pR9k4fp78VtuhY3RFUL9y6F4nRVnUTHHCO71fo4YxZG6N853lLw9SXv50il3XX1J1lrRU7fWHVSMaZqI1lxvJ3qcy61MV-4GxzAubEwXQ24g5YQAK5fv3Msv5knPtLu/s400/IMG_8723.PNG"/></a></div>Juha Vierinenhttp://www.blogger.com/profile/05315784473428964695noreply@blogger.com0tag:blogger.com,1999:blog-3384111523585932540.post-85905081322559877142021-12-14T10:26:00.003+01:002021-12-14T10:26:16.390+01:00Meteor trail and comet<div class="separator" style="clear: both;"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEiwO5QtgK0JjyOCDBjpnR4K9gePJxLyrhnETc8Kgcmjz3O19iXO-azjT0Mcu7WSvBrlDuxeNU-dixQB26TZib3wL5XvanC8W59Pdv3wBr73_cYgtIwkQ3ZlLjqa3AWuiiXTNp5yppAYhyCbkHJ24iteWJLag0i2ZY4IWqb21uOQ1GOvvXzE5w2AUIW-=s900" style="display: block; padding: 1em 0px; text-align: center;"><img alt="" border="0" data-original-height="616" data-original-width="900" src="https://blogger.googleusercontent.com/img/a/AVvXsEiwO5QtgK0JjyOCDBjpnR4K9gePJxLyrhnETc8Kgcmjz3O19iXO-azjT0Mcu7WSvBrlDuxeNU-dixQB26TZib3wL5XvanC8W59Pdv3wBr73_cYgtIwkQ3ZlLjqa3AWuiiXTNp5yppAYhyCbkHJ24iteWJLag0i2ZY4IWqb21uOQ1GOvvXzE5w2AUIW-=s320" width="320" /></a></div>
Tom Masterson and Terry Hancock and the <a href="GrandMesaObservatory.com">Grand Mesa Observatory</a>, Purdy Mesa, Colorado recent took a stunning image of a meteor trail, which shared the field of view with comet C/2021 A1 (Leonard) and Globular Cluster M3. You can nicely see the mesospheric wind shears breaking tearing apart the meteor trail, traced by the chemiluminescent glow of the meteoric matter. <div><br /></div><div>Copyright Tom Masterson and Terry Hancock. Original picture can be found <a href="https://www.transientastronomer.com/solar-system?pgid=jaexa0ge-a247878d-8816-421d-85fe-27be3ce720cf">here</a></div>Juha Vierinenhttp://www.blogger.com/profile/05315784473428964695noreply@blogger.com2tag:blogger.com,1999:blog-3384111523585932540.post-5436197359778703562021-07-27T23:06:00.004+02:002021-07-28T07:39:13.820+02:00SIMONe Piura: MLT dynamics in between the Geographic and Magnetic Equator<p><span face="Calibri, sans-serif" style="font-size: 10pt;"><a href="https://www.peru.travel/en/destinations/piura" target="_blank">Piura</a>, located in the most western part of the South America, is one of the most sensitive regions in the World to El Niño phenomena. Actually the "<a href="https://en.wikipedia.org/wiki/El_Niño" target="_blank">El Niño</a>" name was coined in Piura. The mesosphere and lower thermosphere (MLT) altitudes, where terrestrial weather meets the <a href="https://www.spaceweather.com" target="_blank">space weathe</a>r, is interesting over Piura since it is close to the geographic equator and slightly outside the influence of <a href="https://en.wikipedia.org/wiki/Equatorial_electrojet" target="_blank">equatorial electrojet</a> region.</span><span face="Calibri, sans-serif" style="font-size: 10pt;"> </span><span face="Calibri, sans-serif" style="font-size: 10pt;"> </span><span face="Calibri, sans-serif" style="font-size: 10pt;">Studies of MLT dynamics on this region will contribute to improve our understanding of planetary waves and tides at low latitudes, and also to the understand the influence of neutral winds on equatorial electrodynamics and plasma irregularities.</span><span face="Calibri, sans-serif" style="font-size: 10pt;"> </span></p><p class="MsoNormal" style="font-family: Calibri, sans-serif; font-size: 10pt; margin: 0in 0in 0.0001pt;"><o:p></o:p></p><p class="MsoNormal" style="font-family: Calibri, sans-serif; font-size: 10pt; margin: 0in 0in 0.0001pt;"><o:p> </o:p></p><p class="MsoNormal" style="font-family: Calibri, sans-serif; font-size: 10pt; margin: 0in 0in 0.0001pt;">In June-July 2021, we have installed a new multistatic specular meteor radar system called SIMONe Piura. General details about SIMONe, which uses a mix of MIMO, spread-spectrum, compressed sensing modern concepts in radar, can be found in <a href="https://www.atmos-meas-tech.net/9/829/2016/" target="_blank">Vierinen et al. (2016)</a>, <a href="https://www.atmos-meas-tech.net/12/2113/2019/" target="_blank">Chau et al. (2019)</a>, <a href="https://ieeexplore.ieee.org/document/8802292">Urco et al. (2019)</a>. A description of the operational SIMONe can be found in <a href="https://doi.org/10.1029/2020EA001293 " target="_blank">Chau et al. (2021)</a>. Contrary to previous SIMONe systems, SIMONe Piura uses 6 antennas with 6 different codes on transmission, and will have six receiver stations. Figure 2 shows the initial configuration of SIMONe Piura. The final location of the receivers will be decided in the next few weeks, depending on the performance.</p><p class="MsoNormal" style="font-family: Calibri, sans-serif; font-size: 10pt; margin: 0in 0in 0.0001pt;"><br /></p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhiOsl-VBeHBeA_PMwTQourocJUdxK2Fv0jlVrlnj3ynDCPKFeMlul_t55hhtrikE8ujXibdlAB1_wGeJOgwMenDLwsGNCxo34FjjnCvmcOH9lIAjdXek8NpmHr12zPHYh8YaS-_uZditOm/s2048/simone_piura_stations.png" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="2008" data-original-width="2048" height="389" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhiOsl-VBeHBeA_PMwTQourocJUdxK2Fv0jlVrlnj3ynDCPKFeMlul_t55hhtrikE8ujXibdlAB1_wGeJOgwMenDLwsGNCxo34FjjnCvmcOH9lIAjdXek8NpmHr12zPHYh8YaS-_uZditOm/w396-h389/simone_piura_stations.png" width="396" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;"><p class="MsoCaption" style="color: #44546a; font-family: Calibri, sans-serif; font-size: 9pt; font-style: italic; margin: 0in 0in 10pt;">Figure 1. SIMONe Piura antennas: (a) transmitting array (red) at <a href="https://udep.edu.pe" target="_blank">Universidad de Piura</a> (UDEP), (b) receiving arrays within 50 km from the transmitter (green), and (c) receivers within 50-100 km from the transmitter.</p></td></tr></tbody></table><p class="MsoNormal" style="font-family: Calibri, sans-serif; font-size: 10pt; margin: 0in 0in 0.0001pt;"><br /></p><p class="MsoNormal" style="font-family: Calibri, sans-serif; font-size: 10pt; margin: 0in 0in 0.0001pt;">SIMONe Piura is the most recent addition to the multistatic family of specular meteor radars. Previously we have reported about SIMONe Germany, <a href="https://doi.org/10.1029/2020EA001293 " target="_blank">SIMONe Peru</a> and <a href="https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020EA001356" target="_blank">SIMONe Argentina</a>. Besides the low-latitude planetary-scale MLT dynamics and the connection of MLT neutral dynamics with the equatorial ionosphere, given its multistatic geometry SIMONe Piura will also contribute to the studies of gravity waves and stratified turbulence in South America at different latitudes around the Andes. Figure 2 shows the locations of the other multistatic specular meteor radars in South America.<o:p></o:p></p><p class="MsoNormal" style="font-family: Calibri, sans-serif; font-size: 10pt; margin: 0in 0in 0.0001pt;"><br /></p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiLvPwIT_NJPOTpo2Sm4niG9p9j8Grh2s-Oom2gRj6bQ1eZw80MibjMtURVtg7EOy_yiirEMfNOowY-rqdv9FrveaDuqFWHYC_9j5FAZ0mpMrTOP_ECReazr0iUwOWWfNWD7zZVJwalB9c7/s687/multistatic_south_america.png" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="687" data-original-width="406" height="591" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiLvPwIT_NJPOTpo2Sm4niG9p9j8Grh2s-Oom2gRj6bQ1eZw80MibjMtURVtg7EOy_yiirEMfNOowY-rqdv9FrveaDuqFWHYC_9j5FAZ0mpMrTOP_ECReazr0iUwOWWfNWD7zZVJwalB9c7/w349-h591/multistatic_south_america.png" width="349" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;"><span face="Calibri, sans-serif" style="font-size: 10pt; text-align: start;"><i>Figure 2</i></span><span face="Calibri, sans-serif" style="font-size: 10pt; text-align: start;"><i>. Multistatic meteor radar installations in South America. For top to bottom: (a) SIMONe Piura (5<sup>o</sup>S), (b) <a href="https://doi.org/10.1029/2020EA001293 " target="_blank">SIMONe Jicamarca</a> (12<sup>o</sup>S), (c) <a href="http://lidar.erau.edu/instrument/mr/index.php" target="_blank">CONDOR</a> (30<sup>o</sup>S), (d) <a href="https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020EA001356">SIMONe Argentina</a> (49<sup>o</sup>S), (e) MMARIA-SAAMER (54<sup>o</sup>S)</i><br /></span><span style="text-align: start;"></span></td></tr></tbody></table><div><br /></div><br /><p class="MsoNormal" style="font-family: Calibri, sans-serif; font-size: 10pt; margin: 0in 0in 0.0001pt;"><br /></p><p class="MsoNormal" style="font-family: Calibri, sans-serif; font-size: 10pt; margin: 0in 0in 0.0001pt;"><br /></p><br /><p class="MsoNormal" style="font-family: Calibri, sans-serif; font-size: 10pt; margin: 0in 0in 0.0001pt;"><br /></p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhSYYm-V8ZdvaxlqIENEiLpGx1prkYgLLTzyOArOAyTh6BgsmsPENwQiOR6dEXNanfgLu486EfwAkdV2VYsTt4v66nr_nruN-KPLWpulSJZw7fX5ACxjB_4PgOPSWk8l_3-x6D_hjqhyphenhyphenpWx/s1600/simone-peru2_overview.png" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="900" data-original-width="1600" height="389" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhSYYm-V8ZdvaxlqIENEiLpGx1prkYgLLTzyOArOAyTh6BgsmsPENwQiOR6dEXNanfgLu486EfwAkdV2VYsTt4v66nr_nruN-KPLWpulSJZw7fX5ACxjB_4PgOPSWk8l_3-x6D_hjqhyphenhyphenpWx/w691-h389/simone-peru2_overview.png" width="691" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;"><p class="MsoCaption" style="color: #44546a; font-family: Calibri, sans-serif; font-size: 9pt; font-style: italic; margin: 0in 0in 10pt; text-align: center;">Figure 3.. Summary plot of SIMONE Piura initial MLT winds. Note that the notorious oscillations in the winds are dominated by waves with 24 hour periods (courtesy of Mathias Clahsen).<o:p></o:p></p></td></tr></tbody></table><br /><div><p class="MsoNormal" style="font-family: Calibri, sans-serif; font-size: 10pt; margin: 0in 0in 0.0001pt;">The installation, led by Dr. Rodolfo Rodriguez from Universidad de Piura (UDEP), was performed by Christian Mauricio, Pool Nolasco and Jefferson Llacsahuanga from UDEP; and Rommel Yaya, Americo Coronado and Jose Suclupe from <a href="http://jro.igp.gob.pe/english/" target="_blank">Jicamarca Radio Observatory</a> (JRO). Online support was provided by Karim Kuyeng from JRO, and Nico Pfeffer and Matthias Clahsen from the <a href="https://www.iap-kborn.de/en/home/" target="_blank">Leibniz Institute of Atmospheric Physics</a> (IAP). Below we show some pictures of the installations.<o:p></o:p></p><p class="MsoNormal" style="font-family: Calibri, sans-serif; font-size: 10pt; margin: 0in 0in 0.0001pt;"><br /></p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgWPbpdtMU7jACd4CALxMjgD1vV-nDGrHau5gz2ui0TaFtwf5kl5pRtZ-wHRbzeup1OQYfK6L3kVplUAm8xo-IzJrKbJEXKAlV3dRXbO4Z6BzsLAtQyDtB90f6P4rmvf76QP53vXWbDSk2r/s950/tx.png" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="534" data-original-width="950" height="348" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgWPbpdtMU7jACd4CALxMjgD1vV-nDGrHau5gz2ui0TaFtwf5kl5pRtZ-wHRbzeup1OQYfK6L3kVplUAm8xo-IzJrKbJEXKAlV3dRXbO4Z6BzsLAtQyDtB90f6P4rmvf76QP53vXWbDSk2r/w620-h348/tx.png" width="620" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;"><p class="MsoCaption" style="color: #44546a; font-family: Calibri, sans-serif; font-size: 9pt; font-style: italic; margin: 0in 0in 10pt; text-align: center;">Figure 4. Transmitter installation at Universidad de Piura.<o:p></o:p></p></td></tr></tbody></table><br /><p class="MsoNormal" style="font-family: Calibri, sans-serif; font-size: 10pt; margin: 0in 0in 0.0001pt;"><br /></p></div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhkXH6gRqaisPfJJ-7eYkYvp24KZZXEiHn450W1slPuQ9JtFKqJ8Xm82RBJqETFlSD6YSIdCZ9AZHeoVO6XAH4QNeTl2k846fQ2gRYwaEp4VQRjG7_f76JNubY-we3D_3ugIJYZ_wG9d4G0/s950/rx.png" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="534" data-original-width="950" height="348" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhkXH6gRqaisPfJJ-7eYkYvp24KZZXEiHn450W1slPuQ9JtFKqJ8Xm82RBJqETFlSD6YSIdCZ9AZHeoVO6XAH4QNeTl2k846fQ2gRYwaEp4VQRjG7_f76JNubY-we3D_3ugIJYZ_wG9d4G0/w618-h348/rx.png" width="618" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;"><span face="Calibri, sans-serif" style="font-size: 10pt; text-align: start;">Figure </span><span face="Calibri, sans-serif" style="font-size: 10pt; text-align: start;">5</span><span face="Calibri, sans-serif" style="font-size: 10pt; text-align: start;">. Receiving antennas at: (a) Colan, (b) San Carlos, (c) Sajino, (d) Piedritas, (e) Chulucanas, (f) Potrerillo.<br /></span><span style="text-align: start;"></span></td></tr></tbody></table><div><br /></div><style class="WebKit-mso-list-quirks-style">
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</style><p class="MsoNormal">The selected sites are located at interesting places in the Piura region. For example, the transmitter array is located at UDEP's campus (see Figure 4), where wild life can be freely moving. The receiver sites (see Figure 5) are at:</p><p class="MsoNormal"></p><ul style="text-align: left;"><li><a href="https://www.youtube.com/watch?v=b2iJPnkVQaw" style="text-indent: -0.25in;" target="_blank">Colan</a><span style="text-indent: -0.25in;"> is a beach resort where there is a Church dating back to 1536;</span></li><li><span style="text-indent: -0.25in;">San Carlos is in rich agriculture area of the low basin of Piura river where the ancient pre-inca Tallan culture was settled,</span></li><li><span style="text-indent: -0.25in;">Sajino is in the basin of Chipillico river another rich agriculture area close to the </span><a href="https://en.wikipedia.org/wiki/Andes" style="text-indent: -0.25in;" target="_blank">Andes</a>.</li><li><span style="font-family: "Times New Roman"; font-size: 7pt; font-stretch: normal; line-height: normal; text-indent: -0.25in;"> </span><!--[endif]--><span style="text-indent: -0.25in;">Piedritas is in </span><a href="https://en.wikipedia.org/wiki/Talara" style="text-indent: -0.25in;" target="_blank">Talara</a><span style="text-indent: -0.25in;"> province a well know area of Petroleum production and beautiful beaches.</span></li><li><span style="font-family: "Times New Roman"; font-size: 7pt; font-stretch: normal; line-height: normal; text-indent: -0.25in;"> </span><!--[endif]--><a href="https://en.wikipedia.org/wiki/Chulucanas" style="text-indent: -0.25in;" target="_blank">Chulucanas</a><span style="text-indent: -0.25in;"> is a placed well-known for its ceramic of ancient practice.</span></li><li><span style="text-indent: -0.25in;">Potrerillo antenna is solar-powered and its surrounded by Brahma-Cebu cattle near to in the </span><a href="https://en.wikipedia.org/wiki/Sechura_Desert" style="text-indent: -0.25in;" target="_blank">Sechura desert</a><span style="text-indent: -0.25in;"> area.</span></li></ul><p></p><p class="MsoListParagraphCxSpFirst" style="mso-list: l0 level1 lfo1; text-indent: -0.25in;"><!--[if !supportLists]--><o:p></o:p></p><p class="MsoListParagraphCxSpMiddle" style="mso-list: l0 level1 lfo1; text-indent: -0.25in;"><!--[if !supportLists]--><o:p></o:p></p><p class="MsoListParagraphCxSpMiddle" style="mso-list: l0 level1 lfo1; text-indent: -0.25in;"><!--[if !supportLists]--><o:p></o:p></p><p class="MsoListParagraphCxSpMiddle" style="mso-list: l0 level1 lfo1; text-indent: -0.25in;"><!--[if !supportLists]--><o:p></o:p></p><p class="MsoListParagraphCxSpMiddle" style="mso-list: l0 level1 lfo1; text-indent: -0.25in;"><!--[if !supportLists]--><o:p></o:p></p><p class="MsoListParagraphCxSpLast" style="mso-list: l0 level1 lfo1; text-indent: -0.25in;"><!--[if !supportLists]--><o:p></o:p></p><p class="MsoNormal"><o:p> </o:p></p><p class="MsoNormal">The installation has benefit from the kindly support from our local hosts: Luis Urteaga (Colan), Jose Garcia (Chulucanas), Baldemar Ocampos (Sajino), Sergio Chinga (Piedritas), Luis Chunga (San Carlos), and Emilio Hilbck, Rolando Montalve and Pedro Litano (Potrerillo) (see Figure 6).</p><p class="MsoNormal"><o:p></o:p></p><p class="MsoNormal"><br /></p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiwwqOy1Afhzw33SydFMASYxxsMzg_MdqM4HyBkaWrX0HLlnvomvCtmW1vKyyNqv_DEMGuhusdfp-M43bwSgZiuZNsaCs06iE7rdvtVUP_q9T8niB7kjaCXxDNmxEh722R_KLEXZsaXH5fI/s795/people.png" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="532" data-original-width="795" height="406" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiwwqOy1Afhzw33SydFMASYxxsMzg_MdqM4HyBkaWrX0HLlnvomvCtmW1vKyyNqv_DEMGuhusdfp-M43bwSgZiuZNsaCs06iE7rdvtVUP_q9T8niB7kjaCXxDNmxEh722R_KLEXZsaXH5fI/w607-h406/people.png" width="607" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;"><p class="MsoCaption" style="color: #44546a; font-family: Calibri, sans-serif; font-size: 9pt; font-style: italic; margin: 0in 0in 10pt; text-align: center;">Figure 6. UDEP and JRO personnel as well as collaborators at selected sites.</p></td></tr></tbody></table><p class="MsoNormal"><o:p><br /></o:p></p><p class="MsoNormal">SIMONe Piura is an international effort led by IAP (Germany) in collaboration with the Universidad de Piura (Peru), the Jicamarca Radio Observatory- <a href="https://www.gob.pe/igp" target="_blank">Instituto Geofísico del Perú</a> (Peru), the <a href="https://en.uit.no/ansatte/juha-pekka.vierinen" target="_blank">Arctic University of Norway</a> and the <a href="https://www.haystack.mit.edu" target="_blank">Haystack Observatory</a> at MIT (USA). <o:p></o:p></p><p class="MsoNormal"><o:p> </o:p></p><p class="MsoNormal">Well done Rodolfo et al.!<o:p></o:p></p><p class="MsoNormal"><o:p> </o:p></p>Koki Chauhttp://www.blogger.com/profile/14953766039432938744noreply@blogger.com0tag:blogger.com,1999:blog-3384111523585932540.post-81159085435840029812021-06-17T10:43:00.000+02:002021-06-17T10:43:04.904+02:00Polar Eclipse UpdateNow that the eclipse is over, here is an update on what we observed.
The trans polar HF propagation didn't seem to be effected very much. One would expect a reduction in bottom side electron density. How this is seen in a small incidence angle radio wave propagation is not entirely obvious.
Here is a plot of the signal-to-noise ratio as a function of time for two days before the eclipse, and the day of the eclipse. I have marked the time of the Eclipse with a red vertical line. While there is a brief period with lower signal after the eclipse, it doesn't look extraordinary. Transpolar propagation is periodically disrupted by energetic precipitation related absorption,
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj4yVDFztSgO5C1wXbYvoViy4gvYeckPVBftqH9cHzX0fqz-WSHp-KL_Vz89RY0hfKOP2DhrCwOvlogKldywnBkZwaBdlijE7tc1kj0UBKw2n8iDZRJgbVcXhAU28PgZPSHKYMVslJRiss/s977/eclipse_hf.png" style="display: block; margin-left: auto; margin-right: auto; padding: 1em 0px; text-align: center;"><img alt="" border="0" data-original-height="977" data-original-width="800" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj4yVDFztSgO5C1wXbYvoViy4gvYeckPVBftqH9cHzX0fqz-WSHp-KL_Vz89RY0hfKOP2DhrCwOvlogKldywnBkZwaBdlijE7tc1kj0UBKw2n8iDZRJgbVcXhAU28PgZPSHKYMVslJRiss/s400/eclipse_hf.png" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Signal-to-noise ratio as a function of time and frequency for the transpolar HAARP-Skibotn propagation path. Nothing extraordinary appears to happen. This is probably due to the very small incidence angle of propagation. The time of the eclipse is shown with a vertical red line.</td><td class="tr-caption" style="text-align: center;"> </td><td class="tr-caption" style="text-align: center;"> </td><td class="tr-caption" style="text-align: center;"><br /></td></tr></tbody></table>
The EISCAT radars in Svalbard and Tromsø did observe clear effects, such as a decrease in bottom-side electron density and electron temperature. Juha Vierinenhttp://www.blogger.com/profile/05315784473428964695noreply@blogger.com1tag:blogger.com,1999:blog-3384111523585932540.post-48539620669083434712021-06-09T15:09:00.006+02:002021-06-10T13:38:48.861+02:002021 Eclipse<p>There will be a <a href="https://en.wikipedia.org/wiki/Solar_eclipse_of_June_10,_2021">polar annular solar eclipse tomorrow (Thursday 2021-06-10 08:00-13:30 UTC)</a>. The maximum eclipse is going to be experienced in Tromsø around 11:15 UTC, with about 50 % of the solar disc eclipsed by the Moon. </p><p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="http://kaira.uit.no/juha/ec.gif" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="320" data-original-width="800" height="256" src="http://kaira.uit.no/juha/ec.gif" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">The fraction of the sun visible at 300 km altitude. The red line
indicates the great circle path between HAARP and Skibotn Norway, which
is sounded by a 100 W 2-20 MHz ionosonde setup by Naval Research
Laboratories. <br /></td></tr></tbody></table><br /> </p><div>This event presents a serendipitous observation opportunity for studying how a solar eclipse affects trans-polar HF radio propagation, as Paul Bernhardt and colleagues from the Naval Research Laboratories have setup a FMCW chirp sounder (ionosonde) at HAARP, Alaska. Northern Norway happens to be nearly perfectly situated on the other side of the geographic North pole. This allows us to listen to oblique ionograms that will probe the ionosphere through the eclipsed region. The path of the radio wave and the eclipsed fraction of the Sun is shown in the figure above. </div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEie8dwuraweGn-710pzvoHuHfaK25tFdqnbvEwb_N4RmiSuOSlqjACtPmg78n9xwKpJyItq7mT9DLUv0UKJ7vhekXjpor9EgmtTMOlBUh_aXAhyphenhyphenKLFDUxE9aW0EVeWiEibMvwvRrjdhz04/s1200/lfm_ionogram-002-1623207220.02.png" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="900" data-original-width="1200" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEie8dwuraweGn-710pzvoHuHfaK25tFdqnbvEwb_N4RmiSuOSlqjACtPmg78n9xwKpJyItq7mT9DLUv0UKJ7vhekXjpor9EgmtTMOlBUh_aXAhyphenhyphenKLFDUxE9aW0EVeWiEibMvwvRrjdhz04/w400-h300/lfm_ionogram-002-1623207220.02.png" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Example oblique ionogram HAARP-Skibotn<br /></td></tr></tbody></table><br /><div><br /></div><div>The ionosonde is operating with a regular schedule every 6 minutes and it can be observed using the <a href="https://github.com/jvierine/chirpsounder2">GNU Chirp Sounder program that I have written</a>. The plot shown above is an example ionogram observed in Skibotn today. Note that the propagation distance between Alaska and Northern Norway is 5000-6000 km, which means that the oblique ionogram will be very blurry. It will be very interesting to see what effects we'll have tomorrow. </div><div><br /></div><div>I've tried to make real-time plots of the HAARP-Skitbotn path ionogram here:</div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="http://kaira.uit.no/juha/latest-haarp.png" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="600" data-original-width="800" height="300" src="http://kaira.uit.no/juha/latest-haarp.png" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Latest HAARP-Skibotn oblique ionogram<br /></td></tr></tbody></table><p> </p><p>I am also recording another path, which is the Sodankylä-Skibotn path. This won't be as much affected by the eclipse. </p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="http://kaira.uit.no/juha/latest-sgo.png" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="600" data-original-width="800" height="300" src="http://kaira.uit.no/juha/latest-sgo.png" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Latest Sodankylä-Skibotn oblique ionogram<br /></td></tr></tbody></table><br /><p><br /></p><div><br /></div><div><br /></div>
<p>The EISCAT Tromsø and Svalbard radars are also observing the eclipse. You can follow the analysis for the EISCAT <a href="https://portal.eiscat.se/rtg/gup.cgi?U">UHF</a> and <a href="https://portal.eiscat.se/rtg/gup.cgi?E">Svalbard</a> radars.
</p>Juha Vierinenhttp://www.blogger.com/profile/05315784473428964695noreply@blogger.com0tag:blogger.com,1999:blog-3384111523585932540.post-59623549772043033012020-12-10T07:29:00.014+01:002020-12-23T02:59:30.837+01:00Fireball observed over Northern Finland and Sweden on 2020-12-04 13:30:37 UTC<p>We've recently installed a meteor camera system in Skibotn with the help of Ketil Vegum, Steinar Midskogen, and Torsten Aslaksen. This meteor camera uses software developed by Steinar Midskogen and is connected to the <a href="http://norskmeteornettverk.no/wordpress/">Norwegian meteor network.</a> This meteor camera was commissioned on the night of Thursday 2020-12-03. </p><p>Already on the very next day, we observed a spectacular fireball. This meteor was observed in daylight and it was approximately -13 apparent magnitude (very rough estimate) -- i.e., about as bright as the full Moon [<a href="http://norskmeteornettverk.no/wordpress/?p=3202">see Steinar's write-up</a>]. There were many eyewitness reports of this event as well. Because there is another meteor camera station operated by Ketil Vegum in Sørreisa, a triangulation of the trajectory was possible. Here's a video of the event captured with both cameras:<br /></p><p></p><div class="separator" style="clear: both; text-align: center;"><iframe allowfullscreen="" class="BLOG_video_class" height="420" src="https://www.youtube.com/embed/6ZDEO75mR8w" width="506" youtube-src-id="6ZDEO75mR8w"></iframe> </div><div class="separator" style="clear: both; text-align: center;">Video credits: Steinar Midskogen, University of Tromsø, and Ketil Vegum. <br /></div> <p></p><p>The fireball was associated the the <a href="https://en.wikipedia.org/wiki/Taurids">Northern Taurids</a> meteor shower. Based on the entry velocity (30 km/s) and brightness, a size estimate between 1-100 kg can be made. Based on video camera observations, the meteor completely burned up in the atmosphere. No rumbling sounds were reported by the eyewitnesses either, which probably means that no rocks made it down to the ground. <br /></p><p>It has been recently proposed that the <a href="https://en.wikipedia.org/wiki/Taurids">Northern Taurids</a> shower is associated with <a href="https://en.wikipedia.org/wiki/2004_TG10">2004 TG10</a>, which is a near Earth object that is approximately 1 km in diameter. This near Earth object has also been suggested to be a fragment of a larger comet that broke up a long time ago. <a href="https://en.wikipedia.org/wiki/Comet_Encke">Comet Encke</a> is also proposed to have once been part of the same parent object as 2004TG10. All of this is much speculation, but a good story nevertheless. <br /><br /></p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://upload.wikimedia.org/wikipedia/commons/thumb/a/a1/Comet_Encke.jpg/450px-Comet_Encke.jpg" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="450" data-original-width="450" height="425" src="https://upload.wikimedia.org/wikipedia/commons/thumb/a/a1/Comet_Encke.jpg/450px-Comet_Encke.jpg" title="This is an image of short-period comet Encke obtained by Jim Scotti on 1994 January 5 while using the 0.91-meter Spacewatch Telescope on Kitt Peak. The image is 9.18 arcminutes square with north on the right and east at top. The integration time is 150 seconds." width="425" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">"This is an image of short-period <a class="extiw" href="https://en.wikipedia.org/wiki/Comet_Encke" title="en:Comet Encke">comet Encke</a> obtained by <a class="extiw" href="https://en.wikipedia.org/wiki/James_V._Scotti" title="en:James V. Scotti">Jim Scotti</a> on 1994 January 5 while using the 0.91-meter <a class="extiw" href="https://en.wikipedia.org/wiki/Spacewatch" title="en:Spacewatch">Spacewatch</a> Telescope on <a class="extiw" href="https://en.wikipedia.org/wiki/Kitt_Peak_National_Observatory" title="en:Kitt Peak National Observatory">Kitt Peak</a>. The image is 9.18 arcminutes square with north on the right and east at top. The integration time is 150 seconds." (From <a href="https://en.wikipedia.org/wiki/Comet_Encke">Wikipedia</a>)<br /></td></tr></tbody></table><p>This fireball provides us a good opportunity to study how meteors interact with the Earth's atmosphere. There are five meteor radars that observed the fireball. The Sodankylä meteor radar even was able to observe the head echo of the ball of plasma surrounding the meteoroid as it was burning up in the atmosphere.</p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgBEB-V12fVn6iyih9AgO-D2IbC1NSvrXRxtqlGGwMF0CijNZKULcc7fpBfhf2ufr_g5iv0eHtsQeUqTeq5Rt4Kyn3UnLFHHKfDuaEV0CaMo6-8Ei8ub5dTZhD9HkK-QVKYXH_TuOdO93o/s640/paj_head.png" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="480" data-original-width="640" height="333" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgBEB-V12fVn6iyih9AgO-D2IbC1NSvrXRxtqlGGwMF0CijNZKULcc7fpBfhf2ufr_g5iv0eHtsQeUqTeq5Rt4Kyn3UnLFHHKfDuaEV0CaMo6-8Ei8ub5dTZhD9HkK-QVKYXH_TuOdO93o/w444-h333/paj_head.png" width="444" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">The head echo observed with the Sodankylä 36.9 MHz meteor radar.<br /></td></tr></tbody></table><p></p><p>The turbulent dusty plasma trail was also observed with the meteor radar and was visible for about six minutes, until diffusion and recombination reduced the plasma density to a point at which the echo from the trail no longer was visible. <br /></p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjSd68zVuSkkAtMMyicNjYIrzkg3CYpBxOUOwQsn-hCCIqAAWU7NREM7KfpgYhxt2Ab9JVUFJeZtaoP0S67aNSDmpTWot51fVaYsKYPv9b8dLMGnKOaUmt3WfWeKGQzrFVb1w9DvlKv-eA/s1668/paj_trail.png" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="705" data-original-width="1668" height="282" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjSd68zVuSkkAtMMyicNjYIrzkg3CYpBxOUOwQsn-hCCIqAAWU7NREM7KfpgYhxt2Ab9JVUFJeZtaoP0S67aNSDmpTWot51fVaYsKYPv9b8dLMGnKOaUmt3WfWeKGQzrFVb1w9DvlKv-eA/w668-h282/paj_trail.png" width="668" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">The trail echo of the plasma created by the fireball as measured by the Sodankylä meteor radar. The color represent signal power in dB.</td><td class="tr-caption" style="text-align: center;"><br /></td><td class="tr-caption" style="text-align: center;"><br /></td></tr></tbody></table><p></p><p></p><p>The Sodankylä meteor radar is an interferometric radar, with seven receiver antennas, similar to the five antenna radar antenna shown below. This allows us to determine the angle of arrival of radar echoes. Together with range, this allows determining the 3d position in space for each portion of the echo. In order to study where the trail plasma echoes come from, we performed interferometric positions of each range-Doppler bin of the radar measurement.<br /></p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://www.iap-kborn.de/fileadmin/_processed_/0/b/csm_skiymet-antenne_14edff6a92.gif" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="600" data-original-width="457" height="470" src="https://www.iap-kborn.de/fileadmin/_processed_/0/b/csm_skiymet-antenne_14edff6a92.gif" width="358" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">The antennas of a specular meteor radar. Receiver antennas are shown in green and the transmitter antenna is shown in red. Figure:<a href="https://www.iap-kborn.de/forschung/abteilung-radarsondierungen/instrumente/meteorradare/andenes-meteor-radar/"> IAP Kühlungsborn.</a><br /></td></tr></tbody></table><p></p><p>Here is a point cloud that maps the trail echo into 3d space as a function of latitude, longitude, height, and SNR.<br /></p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjXTQ-pduqMlQQpOE6aeAOmtsKR2FY6bpyFOD0EXATLm_joZjrEQqFceiE6UrGHqTtFup1EP0FKxqQHjwRAGOmm9_wAek7vlGErBBG1WxT-vS2BD2618QtzUrjta5E5aTjRb-D8g0b0-LY/s1786/paj_trail_loc.png" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="677" data-original-width="1786" height="295" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjXTQ-pduqMlQQpOE6aeAOmtsKR2FY6bpyFOD0EXATLm_joZjrEQqFceiE6UrGHqTtFup1EP0FKxqQHjwRAGOmm9_wAek7vlGErBBG1WxT-vS2BD2618QtzUrjta5E5aTjRb-D8g0b0-LY/w781-h295/paj_trail_loc.png" width="781" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Locations of the echoes obtained using interferometry with the Sodankylä meteor radar data using a custom processing scheme. </td></tr></tbody></table><p> </p><p>Here is a short video of the location of the plasma trail overlayed on a map. Right after entry, the plasma trail is observed in the path of the meteoroid. The trail then diffuses away and is transported by the neutral wind in the mesosphere, which deforms the original linear shape.</p><div class="separator" style="clear: both; text-align: center;"></div><div class="separator" style="clear: both; text-align: center;"></div><div class="separator" style="clear: both; text-align: center;"></div><div class="separator" style="clear: both; text-align: center;"></div><div class="separator" style="clear: both; text-align: center;"><iframe allowfullscreen="" class="BLOG_video_class" height="411" src="https://www.youtube.com/embed/M1Mq0zqYzN8" width="494" youtube-src-id="M1Mq0zqYzN8"></iframe></div><p></p><p style="text-align: center;">Observations of meteor trail plasma for the fireball using the Sodankylä Geophysical Observatory meteor radar.<br /></p><p>We were also able to observe plasma effects with an oblique ionosonde receiver located in Skibotn that is listening to the Sodankylä ionosonde that conducts a sounding every minute. The reflection point for this oblique path is by random chance approximately right where the fireball trail was located. On the oblique ionosonde receiver, a E-region enhancement in plasma denisty was observed for up to one hour. <br /></p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgjQhyCZZ1pRNthjb4ddU8rmneCgBnQdhAcLY95fIr5JeZ9Mlq323bsA68gi1otSVijzivCURB-buRxzCzCl6wBkgzAr6f_ZrmJy7Fvxywvlc_Nd2yEI3DuHwRoSYsB2JkSCwPXAjaKc3s/s1022/paj_iono_e_snr.png" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="528" data-original-width="1022" height="304" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgjQhyCZZ1pRNthjb4ddU8rmneCgBnQdhAcLY95fIr5JeZ9Mlq323bsA68gi1otSVijzivCURB-buRxzCzCl6wBkgzAr6f_ZrmJy7Fvxywvlc_Nd2yEI3DuHwRoSYsB2JkSCwPXAjaKc3s/w586-h304/paj_iono_e_snr.png" width="586" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Time-frequency-intensity plot of the E-region plasma density in the region between Sodankylä and Skitbotn, the region where the fireball trail was created.<br /></td></tr></tbody></table><br /><br /><br />Here is a an example of the oblique ionogram observed immediately after the fireball occurred. The horizontal line shows the E-region trace that is due to the enhanced plasma density due to the fireball. <br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhYtrQWpKqEEVDv3osEuoQVVlqFxR8BukJZEd9nH8HCE-14eVBSMnR0dT-2FUz7zhVw8VTnxQeNG2vaOF6hJ_WPmvzRjYjZC1QViKvZSdHXi9TgYWN_1DPOhQZtyeClBh2Svxdr64HPJYo/s1129/sod_ski.png" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="892" data-original-width="1129" height="412" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhYtrQWpKqEEVDv3osEuoQVVlqFxR8BukJZEd9nH8HCE-14eVBSMnR0dT-2FUz7zhVw8VTnxQeNG2vaOF6hJ_WPmvzRjYjZC1QViKvZSdHXi9TgYWN_1DPOhQZtyeClBh2Svxdr64HPJYo/w521-h412/sod_ski.png" width="521" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">The Sodankylä Geophysical Observatory Alphawolf ionosonde transmission received in Skibotn using<a href="https://github.com/jvierine/chirpsounder2"> GNU Chirp sounder. </a><br /></td></tr></tbody></table><br /><p><br /></p><p><br /></p><br /><br />Juha Vierinenhttp://www.blogger.com/profile/05315784473428964695noreply@blogger.com1tag:blogger.com,1999:blog-3384111523585932540.post-85130657837945823242020-05-12T02:12:00.000+02:002020-05-12T02:36:57.854+02:00Using the UHD Python API to control USRPs: Spectrum analyzer example<div dir="ltr" style="text-align: left;" trbidi="on">
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjHTZgRRaxC_GYnbKwcbVtqZwLc46SAk0UqL_hsRcES-_L7HpJ0Inv-G6StcsqFzeMG0Rf3nnk-RcnXVh9-27E9wlPgn5zvWuRp5zoPgLqBuC1F-fj8ywXaDOjZAYIy-lBvC9-HwHy-aeo/s1600/license.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="318" data-original-width="1600" height="124" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjHTZgRRaxC_GYnbKwcbVtqZwLc46SAk0UqL_hsRcES-_L7HpJ0Inv-G6StcsqFzeMG0Rf3nnk-RcnXVh9-27E9wlPgn5zvWuRp5zoPgLqBuC1F-fj8ywXaDOjZAYIy-lBvC9-HwHy-aeo/s640/license.png" width="640" /></a></div>
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I recently discovered the UHD Python API for controlling USRPs. It is really nice, and the performance isn't too shabby, when you use numpy for signal processing. You have nearly all of the UHD C API available on Python, and some additional high level calls, such as recv_num_samples.<br />
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We're currently in the process of implementing an open source software defined ionosonde using just the UHD Python API. Stay tuned.<br />
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Here's a simple example, which implements a spectrum analyzer. We've been using this to test that our system meets the frequency licensing requirements:<br />
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<code>
#!/usr/bin/env python3<br />
import numpy as n<br />
import uhd<br />
import scipy.signal as ss<br />
import time<br />
import matplotlib.pyplot as plt<br />
import h5py<br />
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def acquire_spectrum(freq=12.5e6,</code><br />
<code> sample_rate=25e6,</code><br />
<code> N=250000, </code><br />
<code> N_windows=10000, </code><br />
<code> subdev="A:A",<br /> ofname="spec.h5"):</code><br />
<code><br /> usrp = uhd.usrp.MultiUSRP("recv_buff_size=500000000")<br /> subdev_spec=uhd.usrp.SubdevSpec(subdev)<br /> usrp.set_rx_subdev_spec(subdev_spec)<br />
<br /> # 100 Hz frequency resolution<br /> N=250000<br /> w=ss.blackmanharris(N)<br /> freqv=n.fft.fftshift(n.fft.fftfreq(N,d=1/25e6))+freq<br /> S=n.zeros(N)<br /> Nw=N_windows<br /> for i in range(Nw):<br /> print("%d/%d"%(i,Nw))<br /> samps = usrp.recv_num_samps(N, freq, 25000000, [0], 0)<br />
<br /> if len(samps[0]) == N:<br /> z=samps[0]<br /> z=z-n.mean(z)<br /> S+=n.abs(n.fft.fftshift(n.fft.fft(z*w)))**2.0<br /> else:<br /> print(len(samps[0]))<br />
<br /> h=h5py.File(ofname,"w")<br /> h["spec"]=S<br /> h["freq"]=freqv<br /> h.close()<br /> plt.plot(freqv/1e6,10.0*n.log10(S))<br /> plt.show()<br />
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if __name__ == "__main__":<br /> acquire_spectrum()<br />
</code></div>
Juha Vierinenhttp://www.blogger.com/profile/05315784473428964695noreply@blogger.com0tag:blogger.com,1999:blog-3384111523585932540.post-32746818131894748892020-05-06T13:41:00.001+02:002020-05-27T16:32:38.623+02:00SIMONe Argentina: Exploring the MLT dynamics over southern Patagonia<div dir="ltr" style="text-align: left;" trbidi="on">
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<tr><td class="tr-caption" style="text-align: center;">Figure 1. A Google Earth sketch of SIMONe Argentina sites and <br />
how it works (courtesy of Miguel Urco)</td></tr>
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At mesosphere and lower thermosphere (MLT) altitudes (60-110 km), terrestrial weather meets the space weather. From stratospheric observations, strong gravity wave activity over the southern part of Argentina is known to occur. On our search for understanding atmospheric coupling processes under different conditions, a few months ago we installed a new and novel multistatic specular meteor radar system in southern Patagonia, that we called SIMONe Argentina. About SIMONe, we have already reported the preliminary results over <a href="http://www.radio-science.net/2018/11/simone-campaign-2018.html">northern Germany</a> (see also <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019EA000570">Vierinen et al., 2019</a>) and more recently over Peru. As in the case of <a href="http://www.radio-science.net/2020/05/simone-peru-after-6-months-of-operations.html">SIMONe Peru</a>, the system consists of one transmitter site with 5 transmitting antennas arranged in a Pentagon configuration, and 5 different receiving sites with one dual-polarization Yagi antenna each (see Figure 1 for a sketch of the installation and how it works).<o:p></o:p></div>
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SIMONe Argentina was installed, after a long customs process, in September 2019. Since then it has been operating with very few interruptions. In Figure 2 we can see a summary for February 2020. Here we show: the zonal and meridional winds from 75 to 105 km, the spatial distribution of the meteor detections (altitude, latitude and longitude), and the hourly counts for each of the links. Note that the link with most counts is Tres Lagos – El Calafate. As we say among us “<a href="https://en.wikipedia.org/wiki/El_Calafate">El Calafate</a> rocks!!!”.<o:p></o:p></div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjxwL3fQkY7DuB7LGc2cgb5zeqJKGBe2rhsVRAySQ6xW70EvERatpX56UTWOGanVbFOy-KEXeIgZYJZB-hvz861M_nL04N0c_bWDbPv8s02qrOn5F8xKtB2zRW6P0NPoX0BOE2FgNqm_tOF/s1600/simone_argentina_2020_02.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="645" data-original-width="1128" height="364" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjxwL3fQkY7DuB7LGc2cgb5zeqJKGBe2rhsVRAySQ6xW70EvERatpX56UTWOGanVbFOy-KEXeIgZYJZB-hvz861M_nL04N0c_bWDbPv8s02qrOn5F8xKtB2zRW6P0NPoX0BOE2FgNqm_tOF/s640/simone_argentina_2020_02.png" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Figure 2. <span style="font-family: "calibri" , sans-serif; font-size: 10pt;">Summary plot of SIMONE Argentina multilink measurements. Note that the notorious oscillations in the winds are dominated by waves with 12-hour periods (courtesy of Mathias Clahsen).</span></td></tr>
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Specific technical details about SIMONe, which uses a mix of <a href="https://en.wikipedia.org/wiki/MIMO_radar">MIMO</a>, <a href="https://en.wikipedia.org/wiki/Spread_spectrum">spread-spectrum</a>, <a href="https://en.wikipedia.org/wiki/Compressed_sensing">compressed sensing</a> modern concepts in radar, can be found in <a href="https://www.atmos-meas-tech.net/9/829/2016/">Vierinen et al. (2016)</a>, <a href="https://www.atmos-meas-tech.net/12/2113/2019/">Chau et al. (2019)</a>, <a href="https://ieeexplore.ieee.org/document/8802292">Urco et al. (2019)</a>.<o:p></o:p></div>
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Once the equipment was out of customs, the installation of all 6 sites (1 for transmission and 5 for reception), was done in 2 weeks by a team led by Ralph Latteck and Jacobo Salvador. Below you can find a couple of composite pictures of antennas at most sites (Figure 3), as well as installation moments (Figure 4). </div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhyd02YC66QyH4pE3URUWtfRpC-DTUweqxRZdAbYfnLKI7DulcYHbGuPxvrNm18yByZIRllH29jA5FC6XXFdudFSWmraWGEyCult9ARdK27wt7WukeN3habIuzawetDlWT182Qs_sDmxunO/s1600/sites.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="830" data-original-width="1600" height="332" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhyd02YC66QyH4pE3URUWtfRpC-DTUweqxRZdAbYfnLKI7DulcYHbGuPxvrNm18yByZIRllH29jA5FC6XXFdudFSWmraWGEyCult9ARdK27wt7WukeN3habIuzawetDlWT182Qs_sDmxunO/s640/sites.png" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Figure 3. <span style="font-family: "calibri" , sans-serif; font-size: 10pt;">Receiving sites at (a) <a href="https://en.wikipedia.org/wiki/R%C3%ADo_Gallegos,_Santa_Cruz">Rio Gallegos</a>, (b) El Chalten, (c) <a href="http://www.estancialaestela.com.ar/home.html">La Estela</a>, and (d) Gobernador Gregores. The transmitter site (e) was installed at Tres Lagos.</span></td></tr>
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Figure 4. Examples of installations by personnel from the <a href="https://www.iap-kborn.de/en/home/">Leibniz Institute of Atmospheric Physics</a> (IAP): (a) Thomas Barth and Jens Wedrich enjoying the terrain at <a href="https://es.wikipedia.org/wiki/Tres_Lagos">Tres Lagos</a>, (b) Nico Pfeffer and Fede Conte tuning an antenna and sun bathing, and (c) Fede Conte doing some sports while working.</div>
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The preliminary results are exciting. Not only we are able to provide characteristics of large-scale processes, but with this system we expect to explore the poorly understood mesoscale MLT dynamics over this region. The latter effort is being led by Fede Conte at IAP. An important not scientific point to stress, it is the time it took us to do the installation as well as the performance of the system. We have installed, essentially, the equivalent to five monostatic systems in 2 weeks!!! Well done Ralph et al.!<o:p></o:p></div>
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The installation was done mainly by IAP personnel with the help of Jacobo Salvador, Nahuel Díaz, and Jonathan Quiroga. Besides the on-site staff, Juha Vierinen, Matthias Clahsen, Miguel Urco and myself contributed remotely. The support from our different hosts is really appreciated.<o:p></o:p></div>
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<tr><td class="tr-caption" style="text-align: center;">Figure 5. <style class="WebKit-mso-list-quirks-style">
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<!--[if !supportLists]-->(a)<span style="font-family: "times new roman"; font-size: 7pt; font-stretch: normal; line-height: normal;"> </span><!--[endif]-->Thomas Barth, Nico Pfeffer, Jens Wedrich, Ralph Latteck, Fede Conte evaluating the possibility of a receiving site close to the glacier “<a href="https://en.wikipedia.org/wiki/Perito_Moreno_Glacier">El Perito Moreno</a>”, (b) Fede Conte and Jacobo Salvador inspecting the IAP container at the transmitter site, and (c) Jacobo, Ralph, Fede and Nahuel Díaz on their way to <a href="https://en.wikipedia.org/wiki/El_Chalt%C3%A9n">El Chalten</a> with a nice view of the peaks of “<a href="https://en.wikipedia.org/wiki/Cerro_Torre">Cerro Torre</a>” and “<a href="https://en.wikipedia.org/wiki/Fitz_Roy">Mount Fitz Roy</a>”. NB: "El Perito Moreno" ice field <span style="font-size: x-small;"><span style="background-color: white; caret-color: rgb(32, 33, 34); color: #202122; font-family: sans-serif; text-align: start; text-indent: 0px;">is the world's third largest reserve of fresh water.</span></span></div>
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SIMONe Argentina is an international effort lead by <a href="https://www.iap-kborn.de/en/home/">IAP</a> in collaboration with the <a href="https://www.ecured.cu/Universidad_Nacional_de_la_Patagonia_Austral_(Argentina)">Universidad Nacional de la Patagonia Austral</a> (Argentina), the <a href="https://en.uit.no/startsida">Arctic University of Norway</a> and the <a href="https://www.haystack.mit.edu/">MIT Haystack Observatory </a> (USA).<br />
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<span style="caret-color: rgb(255, 255, 255); font-family: Calibri, sans-serif; font-size: x-small;">We would like to sincerely thank Jacobo Salvador, Jonathan Quiroga and Nahuel Díaz (at UNPA, Río Gallegos); Darío Godoy and Facundo Olivares (at Tres Lagos); Pablo Quiroz (at La Estela); Martín “el griego” Palopoli y la gente de Parques Nacionales (at El Chaltén), and the Concejo Agrario de la Provincia de Santa Cruz (at Gob. Gregores and El Calafate). </span><span style="caret-color: rgb(255, 255, 255); font-family: Calibri, sans-serif; font-size: x-small;">Without you guys SIMONe Argentina would not have been possible.</span></div>
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Koki Chauhttp://www.blogger.com/profile/14953766039432938744noreply@blogger.com0tag:blogger.com,1999:blog-3384111523585932540.post-41400183769030928742020-05-01T12:21:00.001+02:002020-05-01T14:04:46.789+02:00SIMONe Peru: After 6 months of operations.<div dir="ltr" style="text-align: left;" trbidi="on">
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjqtP9rTsjbHMyUbxF9Yr31GOlx6Fop3M4rdPuuZXE1yyq22wNRnZFNVNg9EeUhviZ9FIkBtKA5bcBUcZP3uMxADoS16AOrUeRFz_JeMUNS4ePH2r6IKJMDHpwxstvwlMi1jbhazLIGoXKg/s1600/simone_peru_map.png" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="814" data-original-width="1248" height="208" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjqtP9rTsjbHMyUbxF9Yr31GOlx6Fop3M4rdPuuZXE1yyq22wNRnZFNVNg9EeUhviZ9FIkBtKA5bcBUcZP3uMxADoS16AOrUeRFz_JeMUNS4ePH2r6IKJMDHpwxstvwlMi1jbhazLIGoXKg/s320/simone_peru_map.png" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">SIMONe Peru Stations</td></tr>
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<span style="font-size: 10pt;">By the end of September 2019 a new Spread Spectrum Interferometric Multistatic meteor radar Observing Network (SIMONe) started operations in the central coast of Peru, with its transmitter located at the <a href="http://jro.igp.gob.pe/english/">Jicamarca Radio Observatory</a> (JRO), where the largest antenna for ionospheric studies exist. The system consists of 5 antennas on transmission forming a Pentagon interferometer located at JRO, and 5 dual-polarized single antennas located between 40 and 180 km from Jicamarca. The location of the operating (blue dots) and tested for some time (gray dot) receiving sites are indicated in this map</span></div>
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The main purpose of the system is to measure the winds in the mesosphere and lower mesosphere (between 70 and 110 km in altitude), by measuring the Doppler shift and location of meteor trails. In this figure we show an example of mean winds obtained during three continuous days December 2019 with five working multistatic links. In addition to the winds (middle two panels), the number of counts for each link (bottom panel), and other quality control parameters are shown on the figure (courtesy of Mathias Clahsen).<o:p></o:p></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEih5s0JsMQ5UjzxjVD8dOLK-0FIWptZnx-p0RsAfiUiq89k7ly2qKm9rAcKEDQ9ijMP5jSX8ZfVYrbPcqMTabwDMKV35-0h8cjnUrXz8jiV-uo08D1TyL-mdTAmhpwIlkHx689wXwdWvVwg/s1600/simone_peru_december.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="645" data-original-width="1128" height="363" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEih5s0JsMQ5UjzxjVD8dOLK-0FIWptZnx-p0RsAfiUiq89k7ly2qKm9rAcKEDQ9ijMP5jSX8ZfVYrbPcqMTabwDMKV35-0h8cjnUrXz8jiV-uo08D1TyL-mdTAmhpwIlkHx689wXwdWvVwg/s640/simone_peru_december.png" width="640" /></a></div>
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<span style="font-family: "calibri" , sans-serif;">The SIMONe concept since uses MIMO and spread spectrum on transmission (<a href="https://www.atmos-meas-tech.net/9/829/2016/">Vierinen et.al., 2016</a>) is easier to implement and to augment the number of receiver stations, when compare to traditional systems (e.g., </span><a href="https://www.atmos-meas-tech.net/12/2113/2019/" style="font-family: Calibri, sans-serif;">Chau et al., 2019</a><span style="font-family: "calibri" , sans-serif;"> and </span><a href="https://ieeexplore.ieee.org/document/8802292" style="font-family: Calibri, sans-serif;">Urco et al., 2019</a><span style="font-family: "calibri" , sans-serif;">). Previously, Juha Vierinen reported the successful </span><a href="http://www.radio-science.net/2018/11/simone-campaign-2018.html" style="font-family: Calibri, sans-serif;">SIMONe 2018</a><span style="font-family: "calibri" , sans-serif;"> campaign, that we conducted in northern Germany. One can get an idea of how easy is to implement the concept by reading that blog posting. Below you find some examples of our antenna installations in Peru.</span></div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgP3Z8ngcf-0dTUHbhXAs3wDEEvBYwTa2zp6t4A5zneqZK6ShWrIzjsSPe0HcwVQhkQYhT9Mhoy558FGvWBq5QI9tb83cnoUrNQK5-JwzcI0zDwzAsztzGuemszejlnZkig2jrVWhwGxh2S/s1600/Huancayo.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="469" data-original-width="554" height="267" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgP3Z8ngcf-0dTUHbhXAs3wDEEvBYwTa2zp6t4A5zneqZK6ShWrIzjsSPe0HcwVQhkQYhT9Mhoy558FGvWBq5QI9tb83cnoUrNQK5-JwzcI0zDwzAsztzGuemszejlnZkig2jrVWhwGxh2S/s320/Huancayo.jpg" width="320" /></a></td></tr>
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Huancayo Receiver. <span style="font-family: "calibri" , sans-serif; font-size: 10pt;">Receiving antenna </span><span style="font-family: "calibri" , sans-serif; font-size: 10pt;">installed by </span><span style="font-family: "calibri" , sans-serif; font-size: 10pt;">Miguel Urco et al. at the famous</span><a href="https://www.intermagnet.org/imos/imos-list/imos-details-eng.php?iaga_code=HUA" style="font-family: Calibri, sans-serif; font-size: 10pt;"> Huancayo Observatory</a><span style="font-family: "calibri" , sans-serif; font-size: 10pt;">, </span><span style="font-family: "calibri" , sans-serif; font-size: 10pt;">where the <a href="https://en.wikipedia.org/wiki/Equatorial_electrojet">equatorial electrojet</a> was </span><span style="font-family: "calibri" , sans-serif; font-size: 10pt;">discovered in the early 1920s.</span></div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh76OhCAFNQoQ7LTEuQ4y8VORL2GPEbcaxq4YhKcCPMLFPn27GC618RJMdFI782sRawpS3DNQ20ZwKEOAHMBy4-P-16Ma0LXM5ctDuIhmBDrKvL1DErl5TKuawPIi2lD7sxZfOOIkV-Z-ml/s1600/azpitia.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="555" data-original-width="641" height="276" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh76OhCAFNQoQ7LTEuQ4y8VORL2GPEbcaxq4YhKcCPMLFPn27GC618RJMdFI782sRawpS3DNQ20ZwKEOAHMBy4-P-16Ma0LXM5ctDuIhmBDrKvL1DErl5TKuawPIi2lD7sxZfOOIkV-Z-ml/s320/azpitia.jpg" width="320" /></a></td></tr>
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Azpitia Receiver. Antenna installed by Rommel Yaya at a field of banana plants in Azpitia (<a href="https://www.apec2016.pe/azpitia-the-skys-balcony/">The Sky's Balcony</a>).<o:p></o:p></div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi3N1tgermWkc-9UbnrUj4vzTA4cZMUFjU-VQc3KDSQhgirGOr-5_VxIC_dZGwF2Sw-yo7tNbW6KY1cnNjHvXwaOHvS978GyfZuB0CaLhJ7vzmtX586ZDPWLeffWpqfEQWNDuc8zmaBrJlj/s1600/sta_rosa.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="917" data-original-width="912" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi3N1tgermWkc-9UbnrUj4vzTA4cZMUFjU-VQc3KDSQhgirGOr-5_VxIC_dZGwF2Sw-yo7tNbW6KY1cnNjHvXwaOHvS978GyfZuB0CaLhJ7vzmtX586ZDPWLeffWpqfEQWNDuc8zmaBrJlj/s320/sta_rosa.jpg" width="318" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-family: "calibri" , sans-serif; font-size: 13.333333015441895px;">Santa Rosa Receiver. Antenna installed by Karim Kuyeng et al. in the roof of building in Santa Rosa de Quives. In this town was born the first American Roman Catholic saint (<a href="https://en.wikipedia.org/wiki/Rose_of_Lima">Rose of Lima</a>).</span></td></tr>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjZrmMX3K9MXAjbyiGptxXuHHPo8BJxTN4Z1mJQGjPvZszoHalFef56lnlBR0QucKLJoZbGyy-EvdO7wNPrzsiQ2PuhP7Z49grcQNzPePxXrN9AchEZH8X3VMmu6XmLBcgm68pYtrHEU4ib/s1600/La_Cantuta.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1200" data-original-width="1600" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjZrmMX3K9MXAjbyiGptxXuHHPo8BJxTN4Z1mJQGjPvZszoHalFef56lnlBR0QucKLJoZbGyy-EvdO7wNPrzsiQ2PuhP7Z49grcQNzPePxXrN9AchEZH8X3VMmu6XmLBcgm68pYtrHEU4ib/s320/La_Cantuta.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">La Cantuta receiving site.</td></tr>
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The next receiving antenna will be installed close <a href="https://www.crl.pe/categoria/filial-la-cantuta">La Cantuta branch of Club Regatas Lima</a>. We have already conducted successfully a four-day campaign. We hope that as soon as the lockdown restrictions in Peru due <a href="https://en.wikipedia.org/wiki/Coronavirus_disease_2019">COVID-19</a> stop, our JRO colleagues will be able to install it.<o:p></o:p></div>
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As mentioned above the transmitting antenna has been installed at JRO. Here is a view of three of the five antennas. Don’t get confused, it is not the Moon, it is planet Earth!<o:p></o:p></div>
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<tr><td class="tr-caption" style="text-align: center;">Transmitter antennas at JRO.</td></tr>
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Besides the mean winds shown above, the multistatic configuration will allow us to measure the winds inside an area of less than 400 km diameter at MLT heights, at horizontal resolutions less than 50 km diameter, i.e., 4D (x,y,z,t) winds, for example using a first-order <a href="https://en.wikipedia.org/wiki/Taylor_series">Taylor expansion</a> or gradient method (<a href="https://agupubs.onlinelibrary.wiley.com/doi/10.1002/2016RS006225">Chau et al., 2017</a>). Similarly, making use of line of sight velocity second order statistics (e.g., <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019EA000570">Vierinen et al., 2019</a>), we should also be able to measure 4D correlation, structure and spectra functions of the wind components, when the quality of multilink data is good.<o:p></o:p></div>
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A few days ago, Juha Vierinen wrote about a <a href="http://www.radio-science.net/2020/04/april-16th-2020-bolide.html">Bolide that was observed in Peru with SIMONe Peru</a>, showing that the system could be also used for bolide detection and identification, either from the trail left behind or the echo in front of the bolide (head echo). SIMONE Peru is also capable go getting echoes from airplanes and from plasma irregularities, like those related to the equatorial electrojet and non-specular meteor echoes.<o:p></o:p></div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg-94vErHJ7rII31ajzc2c1HF7weAJkjvEJoM1rWhe_VXqdpsgeIM9zB8PM_LBXSG6kuClRss99bFXhfRTFhjoZqmOI8Hh6TZJzPnF2xGHp7NWbOlerqSWcVhHUyzdR4svM7vXiGoonVTIj/s1600/simone_jro.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="312" data-original-width="413" height="241" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg-94vErHJ7rII31ajzc2c1HF7weAJkjvEJoM1rWhe_VXqdpsgeIM9zB8PM_LBXSG6kuClRss99bFXhfRTFhjoZqmOI8Hh6TZJzPnF2xGHp7NWbOlerqSWcVhHUyzdR4svM7vXiGoonVTIj/s320/simone_jro.png" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">On-site installation group at JRO. From left to right: <br />
Marco Milla, Juan Carlos Espinoza, Koki Chau, <br />
Karim Kuyeng, and Miguel Urco.</td></tr>
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<span style="font-family: "calibri" , sans-serif; font-size: 10pt;">SIMONe Peru is an international effort lead by the <a href="https://www.iap-kborn.de/en/home/">Leibniz Institute of Atmospheric Physics</a> (Germany) in collaboration with the <a href="https://www.gob.pe/igp">Instituto Geofisico del Peru</a>, Ciencia Internacional (Peru), the Arctic University of Norway, and the<a href="https://www.haystack.mit.edu/"> MIT-Haystack Observatory</a> (USA).</span><span style="font-family: "calibri" , sans-serif; font-size: 10pt;"> </span><span style="font-family: "calibri" , sans-serif;">The installation was done with the help of JRO staff in close coordination with Marco Milla, JRO Director. More than 16 people under the supervision of Karim Kuyeng and Juan Carlos Espinoza, as well as Miguel Urco and myself, participated in person, while Nico Pfeffer, Matthias Clahsen and Juha Vierinen participated remotely. </span></div>
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Koki Chauhttp://www.blogger.com/profile/14953766039432938744noreply@blogger.com0tag:blogger.com,1999:blog-3384111523585932540.post-81406970959165962592020-04-28T14:16:00.001+02:002020-04-28T16:44:36.955+02:00April 16th 2020 bolide in Peru<div dir="ltr" style="text-align: left;" trbidi="on">
Around 2020-04-16T01:02:10 UTC a bolide was sighted in Peru. The good news is that the SIMONe Peru meteor radar network at the <a href="http://jro.igp.gob.pe/english/">Jicamarca Radio Observatory</a> was operational. The team at<a href="https://www.iap-kborn.de/home/"> IAP Kühlungsborn</a> are trying to figure out the trajectory for this bolide.<br />
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So far, we have been able to detect trail echoes corresponding this bolide in the data for three receiver stations and an approximate location for the atmospheric entry point for the bolide has been determined from the trail echo.<br />
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I have been helping out with the IAP effort by writing some new analysis software, which allows head echoes to be detected in the coded continuous-wave meteor radar data. I ran the data for one of the transmit-receive links (Jicamarca Radio Observatory -> Azpitia), and was able to detect the range and Doppler shift of the bolide! I'm now working on the other links. You can find my code here: <a href="https://github.com/jvierine/meteor_head_cwradar/">https://github.com/jvierine/meteor_head_cwradar/</a><br />
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Let's hope we can piece together a trajectory and hopefully then we can recover some meteoric rocks!<br />
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Here are some videos I found on social media. One can definitely see the meteor fragment towards the end of some videos. I unfortunately was not able to determine who shot these videos, so I can't give proper credit.<br />
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Here is a determination of the position of the trail echo of the bolide, which was made by Carsten Schult at IAP.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjcB36hZAG5lZNCbxUOEIyxxfs3g6fpkSkqjDlD1OwMnkRbuFliMrl3ETz3pmnnDK0-p8RGIj_g3aTV_RDOxpauO1zQs5rAPyZjDlPB1oNCGOtw3nv-1ap4-M2udVHo8bH2B24xo4mD-3s/s1600/unnamed.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="774" data-original-width="874" height="283" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjcB36hZAG5lZNCbxUOEIyxxfs3g6fpkSkqjDlD1OwMnkRbuFliMrl3ETz3pmnnDK0-p8RGIj_g3aTV_RDOxpauO1zQs5rAPyZjDlPB1oNCGOtw3nv-1ap4-M2udVHo8bH2B24xo4mD-3s/s320/unnamed.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The locations of the radar receivers are shown in blue. The transmitter is shown in red. (Figure: Carsten Schult)</td></tr>
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Here are some measurements of the trail echo at Huancayo and Azpitia made by Miguel Urco. The transmitter in Jicamarca is a MIMO transmitter, with five spaced antennas, each transmitting a different pseudorandom code. This allows us to localize the echo in space using phase and time delay, just using one receiver. This is somewhat similar to how GPS works, except that in this case, we have five radar transmitters located Jicamarca Radio Observatory, instead of GPS satellites flying in space.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi-NrY09BH0ZjGERx1nEF8djPvge6irtr_2iUCqsJagawibmMkco-ktWikp1CWj4raU5_4NtCe9Yc7ngriikM-GSWsDn3RFNdXCphKXnEw9XHj9KXzoV1T1FX5ZGwSK39V7g2hSeEQueYw/s1600/81c99fee-db79-4008-a577-a2fdabceb66d.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="600" data-original-width="1000" height="192" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi-NrY09BH0ZjGERx1nEF8djPvge6irtr_2iUCqsJagawibmMkco-ktWikp1CWj4raU5_4NtCe9Yc7ngriikM-GSWsDn3RFNdXCphKXnEw9XHj9KXzoV1T1FX5ZGwSK39V7g2hSeEQueYw/s320/81c99fee-db79-4008-a577-a2fdabceb66d.JPG" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Range-Time-Intensity plot of echo power measured at Huancayo. The range corresponds to total range between Jicamarca and Huancayo. The echo lasts for about one minute! (Figure: Miguel Urco)</td></tr>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiGICwm36k4BB53kDXGBysp2lAlHdx7gr8L3YJ7S5tJzAeA62IHZjSvzLUGH6jvhCMo0bjsK4eUR-YNmKPiSSLqusP9ArYk4qL0R6-Fe0tBlK4OR_rvp0LpEn5srTy5uUXIw6V_uuMh6Yc/s1600/unnamed+%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1200" data-original-width="1000" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiGICwm36k4BB53kDXGBysp2lAlHdx7gr8L3YJ7S5tJzAeA62IHZjSvzLUGH6jvhCMo0bjsK4eUR-YNmKPiSSLqusP9ArYk4qL0R6-Fe0tBlK4OR_rvp0LpEn5srTy5uUXIw6V_uuMh6Yc/s320/unnamed+%25281%2529.jpg" width="266" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Here are phase differences measured between transmit antennas. This is in the case of the Jicamarca-Azpitia path. The uniform phase means that the echo is coming from a certain direction, and the phase difference is determined by the locations of the transmit antennas and the location of the meteor trail. (Figure: Miguel Urco)</td></tr>
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Here is a range-time-intensity radar measurement of the same bolide, showing a head and trail echo. With the head echo, it may be possible to determine an accurate trajectory, assuming that we can get<br />
a similar head echo from at least three links.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi4XHWR2FJrvzLvoxcjn9BgjbnofqudWZ3oKNg5W7nU9fMKKa-xYCKzsOqyYay1W_cvV9yi3b1qtdlVCX_tt23UyNufmrzPZSgOACbjD8lKc9Gu5LjdRDtzxccAmdfjURuvCqkfK55wsMw/s1600/azpitia_rti.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="584" data-original-width="1105" height="211" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi4XHWR2FJrvzLvoxcjn9BgjbnofqudWZ3oKNg5W7nU9fMKKa-xYCKzsOqyYay1W_cvV9yi3b1qtdlVCX_tt23UyNufmrzPZSgOACbjD8lKc9Gu5LjdRDtzxccAmdfjURuvCqkfK55wsMw/s400/azpitia_rti.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Range-time-intensity of radar echoes corresponding to the April 16th bolide. The head echo is the weak echo, which is traveling down in range. The trail echo is the strong echo that follows the head echo, which is caused by the turbulent plasma wake left behind the meteor as it burns up in the atmosphere.</td></tr>
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Here is an example of the range-Doppler spectrum with a head echo and a trail echo:<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgZgTERr0vTfvUdjuQLIwAbf7sahRlVpPYlfaPJs4R9AzUA1mEXFlY-AzaHsV68dVD-DcPHZvCn4fHQouf4pLf0O4NiQjugs9Q6_bn47gDc6bugFBckEJ9XsnKxupxR0l_YWzMrf4q3XVo/s1600/rd-158699893109000.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1200" data-original-width="1600" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgZgTERr0vTfvUdjuQLIwAbf7sahRlVpPYlfaPJs4R9AzUA1mEXFlY-AzaHsV68dVD-DcPHZvCn4fHQouf4pLf0O4NiQjugs9Q6_bn47gDc6bugFBckEJ9XsnKxupxR0l_YWzMrf4q3XVo/s320/rd-158699893109000.png" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Range-Doppler spectrum estimate containing a head echo (left) and a trail echo (right). This is for the Jicamarca-Azpitia link.</td></tr>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiRV09f-OFhUnzxSmzkYXJdQ43W9wZe2Tt9Bl5s1RLMH-zGEmBQ4HWA5Rm_j5rWeBkrJZHjc3ec05_Af4de782e-qvkGuImkNn4cVL5F4omp21qfq-a5jNz1S7eryujeokp_8WneCiRC24/s1600/azpitia_rd.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="601" data-original-width="1090" height="220" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiRV09f-OFhUnzxSmzkYXJdQ43W9wZe2Tt9Bl5s1RLMH-zGEmBQ4HWA5Rm_j5rWeBkrJZHjc3ec05_Af4de782e-qvkGuImkNn4cVL5F4omp21qfq-a5jNz1S7eryujeokp_8WneCiRC24/s400/azpitia_rd.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Detected range and Doppler shift. This corresponds to total radio propagation distance (km) and Doppler shift (Hz) for the transmit-receive path between Jicamarca Radio Observatory and Azpitia.</td></tr>
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Juha Vierinenhttp://www.blogger.com/profile/05315784473428964695noreply@blogger.com0tag:blogger.com,1999:blog-3384111523585932540.post-44921730504761162502020-04-27T12:20:00.001+02:002020-04-27T12:20:35.416+02:00Incoherent scatter radar measurement techniques - Part 2<div dir="ltr" style="text-align: left;" trbidi="on">
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The next part in the series of lectures on radar measurement techniques discusses the following topics: range-time diagram, bandwidth and range resolution, deconvolution of a transmit signal in the case of coherent targets to estimate the amplitude of scattered complex as a function of range, range-Doppler dilemma, range-Doppler overspread targets, techniques for deconvolving the autocorrelation function of scattered complex voltage as a function of range.</div>
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Juha Vierinenhttp://www.blogger.com/profile/05315784473428964695noreply@blogger.com2tag:blogger.com,1999:blog-3384111523585932540.post-89614376186454696652020-04-20T02:25:00.000+02:002020-04-20T02:25:41.254+02:00Incoherent scatter radar measurement techniques - Part 1 <div dir="ltr" style="text-align: left;" trbidi="on">
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Here is the next video in my series of youtube lectures for the AGF 304 course on incoherent scatter radar measurement techniques. This one covers the radar equation for ionospheric plasma, as well as different factors that determine signal-to-noise ratio. </div>
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Juha Vierinenhttp://www.blogger.com/profile/05315784473428964695noreply@blogger.com1tag:blogger.com,1999:blog-3384111523585932540.post-24784960658172604632020-04-17T17:29:00.003+02:002020-04-17T17:29:50.405+02:00Statistics of incoherent scatter radar signals<div dir="ltr" style="text-align: left;" trbidi="on">
Because of the situation we're currently in, lectures are now on-line lectures. I only have a few lectures this semester, so I thought I'd take the extra effort to make my lectures available for everyone on youtube. Here's my first ever on-line lecture. It covers statistical aspects of incoherent scatter radar signals. That is radar scattering from volume filling targets. Examples of such targets include: ionospheric plasma, weather radar observations of rain droplets, atmospheric turbulence, and even planetary surfaces. Since my target audience is not familiar with complex base band signals, I've also added a short introduction to this topic.<br />
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Juha Vierinenhttp://www.blogger.com/profile/05315784473428964695noreply@blogger.com1tag:blogger.com,1999:blog-3384111523585932540.post-24001527846021683722020-02-03T15:56:00.000+01:002020-02-03T15:56:03.350+01:00WindySvalbard is generally a windy place. The video is from December when UNIS got hold of a bus for the students living outside of town for safety reasons. In the picture can be seen the youth-club entrance after the storm had worn off.<div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgFzxDx42CGpAZ4wNNHjzy7bUYjL-fgOi4P1yQkja5uns4yVn7DJeligApVkjRq8Q8TDZBwK_hwha9DOzs1FENoxS_UrLI5GjJjpfxhMGJKPBmO9xymquPJeAixmNQU7SUOkn2ghSBJq78/s1600/klubb.jpeg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1600" data-original-width="1200" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgFzxDx42CGpAZ4wNNHjzy7bUYjL-fgOi4P1yQkja5uns4yVn7DJeligApVkjRq8Q8TDZBwK_hwha9DOzs1FENoxS_UrLI5GjJjpfxhMGJKPBmO9xymquPJeAixmNQU7SUOkn2ghSBJq78/s320/klubb.jpeg" width="240" /></a></div>
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Markus Floerhttp://www.blogger.com/profile/14935058314718905020noreply@blogger.com1tag:blogger.com,1999:blog-3384111523585932540.post-70104783811149368352020-01-29T15:43:00.000+01:002020-01-29T15:45:29.360+01:00Polar bear and dogsleddingWhile out dogsledding in the valley below The Kjell Henriksen Observatory we came by the tracks of the polar bear that recently visited the area. According to reports it had a few days earlier been in a close encounter with a party of dogsledding tourists where the guide luckily managed to chase it away <a href="https://www.nrk.no/troms/marcel-fikk-naerkontakt-med-isbjorn_-matte-sla-dyret-pa-snuten-for-a-skremme-det-vekk-1.14861977" target="_blank">with a rope</a>. Before we ventured out the local authorities had reported the bear being chased by helicopter across a glacier over to a neighboring valley.<br />
<br />
With the polar night still dominating most of the day, travelling out and about means a lot less overview of your surroundings and any encounter with a bear will by default be a close one.<br />
One therefore have to take the necessary precautions in terms of equipment and have a plan for any unforeseen events that may occur.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgZq5oHnk-8xDGngOAmz25LoXXFW884WqHAg5ia1-Ia-pgUMRvi0yNSNnBvlrLndGRphOnAvKeNAjw894d5jpH8AnJAD-iVv4YvDUKrsW19wmoh85tD-PgnZUfxWFvZReI0nRnB4jIQcBs/s1600/tracks.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1600" data-original-width="900" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgZq5oHnk-8xDGngOAmz25LoXXFW884WqHAg5ia1-Ia-pgUMRvi0yNSNnBvlrLndGRphOnAvKeNAjw894d5jpH8AnJAD-iVv4YvDUKrsW19wmoh85tD-PgnZUfxWFvZReI0nRnB4jIQcBs/s320/tracks.jpg" width="180" /></a></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiU3BHCtlSyzIZaKEFP76N8zFhTwUcre_ANHDJGmunELsXBeGKhCwO0RKGj_eUAngtIcVhjku5jOa6epYVZWWWtXS-Gc4iL8sgZ_pxgM2WNow6wuKW10VmTcxnP-o-zuRL-Nl0-7DSbGIo/s1600/sledding.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="900" data-original-width="1600" height="180" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiU3BHCtlSyzIZaKEFP76N8zFhTwUcre_ANHDJGmunELsXBeGKhCwO0RKGj_eUAngtIcVhjku5jOa6epYVZWWWtXS-Gc4iL8sgZ_pxgM2WNow6wuKW10VmTcxnP-o-zuRL-Nl0-7DSbGIo/s320/sledding.jpg" width="320" /></a></div>
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We are currently in full preparation for the annual darkseason dograce stretching 150km through the lands. Getting in the necessary training is key if we are to have any chance of competing with the bigger dog-yards.Markus Floerhttp://www.blogger.com/profile/14935058314718905020noreply@blogger.com0Longyearbyen, Svalbard og Jan Mayen78.223172200000008 15.62672290000000478.1713282 15.303999400000004 78.27501620000001 15.949446400000005tag:blogger.com,1999:blog-3384111523585932540.post-21897980386291939972019-09-06T16:58:00.002+02:002019-09-06T16:58:39.166+02:00Transmitting a simple sine wave in gnuradio using the USRP - and measuring it's power<br />
Transmitting a sine wave with the USRP is a simple matter of connecting your USRP to the computer and running an equivalent gnuradio flowchart as displayed below.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhbCpKJfutKFsSYzIhf1igxmaYvRVQ-nRp7vnYTXyydDwoNOeauwbnzt697DVpVN_y9mbcSsjpy8-fwjQoh6d0PwZfp2rLP_5yYGXNWXtYmCPZHve_kjqmyjK3CGLhe_PHsYO0fghmTlgg/s1600/Screenshot+from+2019-09-05+15-34-28.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="388" data-original-width="699" height="353" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhbCpKJfutKFsSYzIhf1igxmaYvRVQ-nRp7vnYTXyydDwoNOeauwbnzt697DVpVN_y9mbcSsjpy8-fwjQoh6d0PwZfp2rLP_5yYGXNWXtYmCPZHve_kjqmyjK3CGLhe_PHsYO0fghmTlgg/s640/Screenshot+from+2019-09-05+15-34-28.png" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The gnuradio flowchart consists of a Signal Source block and a UHD: USRP Sink block. Sliders are added to adjust the amplitude and frequency.</td></tr>
</tbody></table>
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<div>
The signal source is set to zero frequency with an amplitude of 1 - this serves as the baseband signal. The signal is then modulated by the UHD: USRP sink block with a center frequency set by the user. The center frequency represents the carrier frequency that up-converts the baseband signal. The gain is set to "normalized" with the maximum value of 1. This ensures that the USRP is always transmitting at it's highest power. </div>
<div>
The reason for setting our baseband/signal source frequency to zero is that we only measure the actual output power of the USRP at it's center frequency, avoiding any modulation effects. </div>
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<div>
Now that your script is ready, all you need is a transmission line/antenna to connect to one of the RF-channels of the USRP. Our setup looked like this:</div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjIAz0amGwF07dEVqCrXPHyTDF8vJS85iH6Q6qi3YgryEh7pjDId5TVNajaX3UpfkaHMz7id8TjcMYpDg0AQMqh1ZV5aLyC1J-1ZxQbyJJgHeiDH6qLxlZcd0GWynmzYhfsMxTdxfPvAUs/s1600/69457441_2651336298221225_5625360976741138432_n.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="901" data-original-width="1600" height="360" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjIAz0amGwF07dEVqCrXPHyTDF8vJS85iH6Q6qi3YgryEh7pjDId5TVNajaX3UpfkaHMz7id8TjcMYpDg0AQMqh1ZV5aLyC1J-1ZxQbyJJgHeiDH6qLxlZcd0GWynmzYhfsMxTdxfPvAUs/s640/69457441_2651336298221225_5625360976741138432_n.jpg" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">3D system diagram. The output of the USRP is fed into a T-piece with a 50 Ohm dummy load at the one end and a high-impedance oscilloscope probe at the other. </td></tr>
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<div>
The version seen on the picture is a USRP2 with an LFTX daughterboard mounted inside. As the script is running we can observe and do measurements on the transmitted waveform using the picoscope. Making sure that the probe is correctly compensated, and that we observe the actual true waveform by tweaking the settings of the digital oscilloscope accordingly, we measure the peak-voltage over a range of frequencies whilst keeping the amplitude at maximum.</div>
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<div>
The power in dBm (P<span style="font-size: x-small;">dBm</span>) is related to the peak voltage (V<span style="font-size: x-small;">p</span>) by the formula:</div>
<div>
</div>
<div>
P<span style="font-size: x-small;">dBm</span> = 10 + 20 log<span style="font-size: xx-small;">10</span>(V<span style="font-size: x-small;">p</span>)</div>
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<div>
Measuring over the HF-spectrum resulted in the following output from the LFTX daughterboard:</div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhxPRVSG4TDOu0WIVrsu-HDXoqx8aSafotuT8NRorMPBW8yvbnZzCRJHU1AXnVNfvYruQaXQ8s16uXLUWbE-VOsUCeuUjG-jKHxeBDuagJxGMLGiSw1Q9YfzbDcIXKoneIxak5-31sSk7s/s1600/Figure_1.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="530" data-original-width="1301" height="260" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhxPRVSG4TDOu0WIVrsu-HDXoqx8aSafotuT8NRorMPBW8yvbnZzCRJHU1AXnVNfvYruQaXQ8s16uXLUWbE-VOsUCeuUjG-jKHxeBDuagJxGMLGiSw1Q9YfzbDcIXKoneIxak5-31sSk7s/s640/Figure_1.png" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The figure on the left displays the output power as measured when using the setup shown above, reaching 4.1 dBm at 1MHz. When adding an additional adjustable attenuator between the USRP and the T-piece, and using a 300W capable, 50 Ohm dummy load instead of the small one seen in the picture above, we get power reaching up to 4.9 dBm at 1MHz.</td></tr>
</tbody></table>
<br />The first run of measurements peaked at 4.1 dBm. When including the adjustable attenuator and using a heavy-duty dummy load, the LFTX peaks at 4.9 dBm. Why the discrepancy? can it be that the added components adds up to a slightly higher impedance? </div>
<div>
The same measurements were conducted again, this time using the adjustable attenuator with the small black dummy load. These measurements showed that the attenuator (set to 0 attenuation)<br />had a negligible impact on the circuit. So it comes down to which dummy load we are using. </div>
<div>
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<div>
Based on these measurements we can guesstimate that the maximum output power of the LFTX lies somewhere in the range between 3 and 5 dBm. </div>
<div>
RF circuits assume a 50 Ohm impedance along the whole transmission line. The discrepancy we observed are for for the time being believed to be caused by some impedance mismatching between the dummy loads.</div>
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Note: The input impedance of the oscilloscope was 220k.</div>
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Markus Floerhttp://www.blogger.com/profile/14935058314718905020noreply@blogger.com0tag:blogger.com,1999:blog-3384111523585932540.post-88819151822934514022019-05-29T11:23:00.000+02:002019-05-31T16:40:11.275+02:00Towards A 21st Century Understanding of Earth's Upper Atmosphere<div dir="ltr" style="text-align: left;" trbidi="on">
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Dr Philip J. Erickson, from the MIT Haystack Observatory gave a talk last September to the HAM radio community at the TAPR conference about measuring the Earth's upper atmosphere with radio waves. The talk contains a nice overview of space physics, space weather, and radio remote sensing of ionospheric plasma. The talk is available on youtube.</div>
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<iframe allowfullscreen="" class="YOUTUBE-iframe-video" data-thumbnail-src="https://i.ytimg.com/vi/vDmEEEmQ9WE/0.jpg" frameborder="0" height="266" src="https://www.youtube.com/embed/vDmEEEmQ9WE?feature=player_embedded" width="320"></iframe></div>
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Juha Vierinenhttp://www.blogger.com/profile/05315784473428964695noreply@blogger.com0tag:blogger.com,1999:blog-3384111523585932540.post-85978076393829604262019-04-16T10:06:00.000+02:002019-04-16T10:06:05.694+02:00Oblique ionograms between Sodankylä and Longyearbyen<div dir="ltr" style="text-align: left;" trbidi="on">
As we don't yet have a license for the HF radar in Longyearbyen, I've setup the antenna to receive transmissions from the Sodankylä Geophysical Observatory ionosonde, which is about 1250 km away from Longyearbyen. The SGO ionosonde is a fairly straightforward FMCW system, which sweeps between 0.5 and 16 MHz with approximately a 500 kHz/s chirp rate.<br />
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Here's an example oblique ionogram.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEirv5FynoR2WzB_JzxsvXfcPydU7ZuQK2TCYOcZjJJvvpvnNzfoaR9__Yl0YH2kv39GuB0dnldRUZlwAxIiMk3e6ZI29ZN9IdjRqUDt-0hyUj2uVDOqPqEtRwGrZ3b1ReavqUX-2AYy5H8/s1600/latest2.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="900" data-original-width="1200" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEirv5FynoR2WzB_JzxsvXfcPydU7ZuQK2TCYOcZjJJvvpvnNzfoaR9__Yl0YH2kv39GuB0dnldRUZlwAxIiMk3e6ZI29ZN9IdjRqUDt-0hyUj2uVDOqPqEtRwGrZ3b1ReavqUX-2AYy5H8/s400/latest2.png" width="400" /></a></div>
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While installing the GNU Chirp Sounder, I made some updates to the software. It still compiles with relative ease with GNURadio 3.7, which was a huge relief. Just make sure you have cmake, swig, and all the relevant libraries installed. The new release can be downloaded here: <a href="http://kaira.uit.no/juha/gr-juha-1.25.tar.gz">gr-juha-1.25.tar.gz</a><br />
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I've even setup a real-time ionogram here:<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://kaira.uit.no/juha/latest.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="http://kaira.uit.no/juha/latest.png" data-original-height="600" data-original-width="800" height="300" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Real-time oblique ionogram, which shows radio propagation between Sodankylä and Longyearbyen.</td></tr>
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Juha Vierinenhttp://www.blogger.com/profile/05315784473428964695noreply@blogger.com1tag:blogger.com,1999:blog-3384111523585932540.post-11761893288056995082019-04-15T11:27:00.001+02:002019-04-15T11:27:46.581+02:00USRP BasicTX and LFTX - what is the maximum transmit power?Let's say this first: if you really want to know what the transmit power in your setup is, you will need to measure it yourself. Don't rely on whatever you might find in the net.<br />
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Having said that, Juha and I were searching the net with little success. We wanted to know the maximum TX power output levels that the USRP-boxes we had on our desk could produce. The various pieces of information we found were either confusing, not relevant for our hardware or simply conflicting.
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Practically all RF power amplifiers (PA) expect a nice 50-ohm load such as a properly impedance-matched antenna for the frequency range in question. If there is a problem with the antenna (matching), the reflected power can destroy the amplifier's final stage unless you take precautions. When prototyping, you have the responsibility and there are at least three ways to engineer this:<br />
<ol>
<li>Use a sufficiently rugged system that survives any load</li>
<li>Isolate the reflected power so that it does not go back to amplifier but gets dumped elsewhere</li>
<li>Monitor the reflected power and adjust the gain of the PA to avoid bad things happening.</li>
</ol>
Our choice was #1 mostly because it is a simple approach that would still provide a sufficient power level at the output. The advice from the Mini-Circuits technical support revealed that if we can keep the input level to ZX60-100VH+ less than -5dBm, the amplifier should survive anything Svalbard can offer. Our most likely failure case would be open load i.e. the antenna is gone with the wind or a broken feedline. We already had to repair one antenna cable when testing the HF setup at Svalbard, so things like this do happen.<br />
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So, what is the output from the USRP? Do we need to add an attenuator a.k.a. "pad" to limit the input to the PA or not?<br />
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The measurement setup was simple: a 50-ohm dummy load was connected to the USRP and an oscilloscope was used to measure the output peak-to-peak voltage. A simple flowchart in GNU Radio Companion produced a sinusoidal wave with adjustable frequency and amplitude. We had two different daughterboards, BasicTX and LFTX. We set the amplitude to maximum and measured the power levels at several frequencies.<br />
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<table style="width:50%;text-align:center;border:2px solid black">
<tr><th>f (MHz)</th><th>BasicTX (dBm)</th><th>LFTX (dBm)</th></tr>
<tr><td>1</td><td>-1.7</td><td>4.7</td></tr>
<tr><td>2</td><td>-1.6</td><td>4.7</td></tr>
<tr><td>3</td><td>-1.6</td><td>4.7</td></tr>
<tr><td>4</td><td>-1.6</td><td>4.6</td></tr>
<tr><td>5</td><td>-1.6</td><td>4.5</td></tr>
<tr><td>6</td><td>-1.6</td><td>4.5</td></tr>
<tr><td>7</td><td>-1.6</td><td>4.4</td></tr>
<tr><td>8</td><td>-1.6</td><td>4.2</td></tr>
<tr><td>9</td><td>-1.6</td><td>4.2</td></tr>
<tr><td>10</td><td>-1.6</td><td>4.0</td></tr>
<tr><td>11</td><td>-1.6</td><td>3.9</td></tr>
<tr><td>12</td><td>-1.6</td><td>3.8</td></tr>
<tr><td>13</td><td>-1.6</td><td>3.5</td></tr>
<tr><td>14</td><td>-1.7</td><td>3.4</td></tr>
<tr><td>15</td><td>-1.7</td><td>3.2</td></tr>
<tr><td>16</td><td>-1.7</td><td>3.0</td></tr>
</table>
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So, the BasicTX outputs a maximum of about -1.6dBm while the LFTX can reach 4.7dBm. We also did a quick measurement to see what we get when adjusting the amplitude. We did this test at 3MHz.
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<table style="width:50%;text-align:center;border:2px solid black">
<tr><th>Level @ 3MHz</th><th>Measured (dBm)</th><th>Nominal (dBm)</th><th>Delta (dB)</th></tr>
<tr><td>1</td><td>-1.7</td><td>-</td><td>-</td></tr>
<tr><td>0.9</td><td>-2.5</td><td>-2.6</td><td>0.1</td></tr>
<tr><td>0.8</td><td>-3.5</td><td>-3.6</td><td>0.1</td></tr>
<tr><td>0.7</td><td>-4.6</td><td>-4.8</td><td>0.1</td></tr>
<tr><td>0.6</td><td>-5.9</td><td>-6.1</td><td>0.2</td></tr>
<tr><td>0.5</td><td>-7.4</td><td>-7.7</td><td>0.3</td></tr>
<tr><td>0.4</td><td>-9.3</td><td>-9.6</td><td>0.4</td></tr>
<tr><td>0.3</td><td>-11.5</td><td>-12.1</td><td>0.6</td></tr>
<tr><td>0.2</td><td>-14.7</td><td>-15.6</td><td>1.0</td></tr>
<tr><td>0.1</td><td>-19.5</td><td>-21.7</td><td>2.2</td></tr>
</table>
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The amplitude changes pretty much in a way you'd expect. The comparison to theoretical values shows that at larger amplitudes things are ok. We did not spend too much time wondering about the large differences at small amplitudes: the measurement setup simply could not provide the accuracy to say much more. Measuring small things is difficult and requires great(er) care.
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<br>
Our measurements were done in a quick-n-dirty style in order to select correct system components before continuing with testing the HF radar prototype in field. One always expects to destroy a few components when developing stuff, but a few quick checks can save a lot of money/time. To be on the safe side, we need a 4dB pad for BasicTX while the LFTX would need a 10dB pad. Of course, we did not have any 4dB pads and used a 6dB model. And then measured the PA output and adjusted the BasicTX output level to minimise harmonics, but that's another story.
<br />Mikkohttp://www.blogger.com/profile/08193185789507543791noreply@blogger.com1tag:blogger.com,1999:blog-3384111523585932540.post-90003392745698904012019-04-12T23:19:00.003+02:002019-04-12T23:28:58.718+02:00Studying the polar cap ionosphere with HF radar<div dir="ltr" style="text-align: left;" trbidi="on">
Mikko and I have been building a little HF radar this week in Svalbard. The idea is to make radar range-Doppler resolved measurements of the polar cap ionosphere with low frequencies, build a prototype of a low cost open source ionospheric research radar, and to get some fresh air. The radar is the type of a spread spectrum radar, which <a href="http://kaira.uit.no/juha/sdiono.pdf">we've used in the past for meteor radars, and also ionospheric radars at Jicamarc</a>a. Our long term goal is to expand this radar into an ionosonde.<br />
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We're now in the process of acquiring a transmit license for a wider range of frequencies to try this radar as an ionosonde.<br />
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The radar uses a single antenna for transmission with about 100 mW. We also use a single active magnetic loop antenna for receive.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgLahihdfURmWTwje1sWPoS-_yIZFCOmJ7pxGAE8tNefxWX2xOW7DKpfqJoszxkJlKJYUZyRhHIFOb9E2Ry0R_XllVFAA08IWySNZn9iMSlNk8v7TIFlj-HGxDsuh8Hi3KoSGgrB3MqltE/s1600/IMG_1117.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="990" data-original-width="1320" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgLahihdfURmWTwje1sWPoS-_yIZFCOmJ7pxGAE8tNefxWX2xOW7DKpfqJoszxkJlKJYUZyRhHIFOb9E2Ry0R_XllVFAA08IWySNZn9iMSlNk8v7TIFlj-HGxDsuh8Hi3KoSGgrB3MqltE/s320/IMG_1117.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Here's the transmit antenna. A very basic broad band resistively loaded Diamond WD-330 folded dipole. We're using the location of the SuperDARN radar antenna as a temporary site for testing. Let's hope we don't get another ice storm.</td></tr>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhfIWN2QQozqabJX2tXNJ10DW9E0R43U3rnHWTrqTObssAG_gIJHBkI3KMzoIRiZcFPR0BBFtf1H6hW0IliVvUUYxNJnkBTPM8o8Y9YZpEl5rxo14vOdlCVkh9wwf2r2xT6uIPSW0wxpoc/s1600/IMG_1088.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="940" data-original-width="1254" height="239" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhfIWN2QQozqabJX2tXNJ10DW9E0R43U3rnHWTrqTObssAG_gIJHBkI3KMzoIRiZcFPR0BBFtf1H6hW0IliVvUUYxNJnkBTPM8o8Y9YZpEl5rxo14vOdlCVkh9wwf2r2xT6uIPSW0wxpoc/s320/IMG_1088.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The sun is starting to shine bright in the polar spring. On the right, you can see the receive antenna, and the transmit antenna in the distance. Lot's of snow to remove, just to open the container.</td></tr>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhEBnhZo9flS5T07f_sfxw9nWuRA5A1EY32whJjoNuzbdXuKrY8Wu4L-2106pOYuC8F9Yr6xGd1jJinDkFZy7FKswHX7DZge8L1kT2c0FEF0897yn7o-f8J-StsQ-QW74LIN9-wUybYAaU/s1600/IMG_1111.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="940" data-original-width="1254" height="239" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhEBnhZo9flS5T07f_sfxw9nWuRA5A1EY32whJjoNuzbdXuKrY8Wu4L-2106pOYuC8F9Yr6xGd1jJinDkFZy7FKswHX7DZge8L1kT2c0FEF0897yn7o-f8J-StsQ-QW74LIN9-wUybYAaU/s320/IMG_1111.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Another picture from when we were setting up the transmit antenna.</td></tr>
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After a few trips, we got all the hardware setup. The last remaining battle was RFI on the receive antenna. We're not really sure what the problem was even after we got rid of the RFI. The UPS was creating a lot of noise, and so was the laptop we used with the software defined radio receiver.<br />
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We tried locating the receiver antenna further away, with a modest improvement, which allowed us to see the first echoes. We then moved the code from the laptop to a PC, and even more of the RFI was removed. We're still not sure what the problem is, but we suspect grounding issues. We still haven't solved the interference problem completely, so any suggestions are welcome. We're thinking of changing the active loop antenna to a broad band dipole similar to the transmit antenna also on receive. Our transmit antenna works perfectly fine as a receiver, with very little RFI.<br />
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Anyway, here are some first light results from the radar. We only transmitted on a very narrow bandwidth (5 kHz), which limits our range resolution quite a bit. But things seem to work nicely. The polar cap ionosphere is extremely dynamic, involving convection of patchy plasma, with plenty of ionospheric irregularities on the wavelength scale. We even saw some overhead E-region echoes with a broad range of Doppler shifts in our test.<br />
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Juha Vierinenhttp://www.blogger.com/profile/05315784473428964695noreply@blogger.com0tag:blogger.com,1999:blog-3384111523585932540.post-88948285712791386822019-04-05T19:27:00.000+02:002019-04-05T19:27:04.453+02:00One more pass of the anti-satellite debris cloud<div dir="ltr" style="text-align: left;" trbidi="on">
Today we made one more observation of the debris cloud today between 8 and 12 UTC. This time we pointed the radar East 45 degrees above the horizon to get a better sensitivity for low altitude debris. All I can say is that the cloud of debris is very clearly visible. <div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhS1uONJigBl0rgZuDmMuxbLPWl5OQnl-c_TUv4A60Y3Q8qG8wAnookGRONOnMePx2Lax7rHyDI601vqLrGRXdV7P0vIUwAVZdk2SxUPXY_Fvm0clK8RMKNilKLfnH1OBmGEVW3xwQIMDA/s1600/coll_debris2.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="889" data-original-width="1600" height="354" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhS1uONJigBl0rgZuDmMuxbLPWl5OQnl-c_TUv4A60Y3Q8qG8wAnookGRONOnMePx2Lax7rHyDI601vqLrGRXdV7P0vIUwAVZdk2SxUPXY_Fvm0clK8RMKNilKLfnH1OBmGEVW3xwQIMDA/s640/coll_debris2.png" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Left: Time (seconds since experiment start) vs Range (km), color coding for Doppler shift. Right: Time histogram (counts per 30 minutes). </td></tr>
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Here's a similar plot for the previous run.</div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgoeD2AHDbCs8760ROKvU404HGW6wKLLKoyiA6S0oXxoMMuaaMPEhGksctAcdGQzXqKCoTz-89-k1xpmm4xSrsCq0QByvv4_LPprlvhvpDS1GEiwsMpsbcAOmIQMfIVt31wvO13DY3A7Bk/s1600/coll_debris.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="899" data-original-width="1586" height="362" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgoeD2AHDbCs8760ROKvU404HGW6wKLLKoyiA6S0oXxoMMuaaMPEhGksctAcdGQzXqKCoTz-89-k1xpmm4xSrsCq0QByvv4_LPprlvhvpDS1GEiwsMpsbcAOmIQMfIVt31wvO13DY3A7Bk/s640/coll_debris.png" width="640" /></a></td></tr>
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<tr><td class="tr-caption" style="font-size: 12.8px;">Left: Time (seconds since experiment start) vs Range (km), color coding for Doppler shift. Right: Time histogram (counts per 30 minutes).<br /></td></tr>
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Juha Vierinenhttp://www.blogger.com/profile/05315784473428964695noreply@blogger.com0tag:blogger.com,1999:blog-3384111523585932540.post-27742688462280537122019-04-03T22:25:00.001+02:002019-04-04T00:51:12.120+02:00Indian anti-satellite debris measured with the EISCAT Tromsø Radar<div dir="ltr" style="text-align: left;" trbidi="on">
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During the last few days, we've been scrambling to make a beam park measurement of the debris produced by the Indian anti-satellite experiment conducted on March 27th 2019. A beam park measurement is a type of a radar measurement, which points into a fixed direction (in our case East, 70 degrees above the horizon) for a 24 hour period of time, and records every detection of a space object that crosses the radar beam. This type of an experiment cannot provide precise information about the orbital elements of objects, but can provide a statistical sample of debris in orbit at the time of the experiment. Some information about orbital parameters and object size can be inferred from the recorded signal power, Doppler shift, and time of day. Such information is invaluable for modeling of the space debris population, assessing the the probability of collisions between space objects, and determining the evolution of the space object population.</div>
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Right after we heard the news about the anti-satellite experiment, we made an urgent scheduling request to EISCAT to conduct a measurement with the<a href="https://en.wikipedia.org/wiki/EISCAT"> Tromsø UHF radar</a> (shown in Figure 4), so that we could determine the amount of debris produced. Today we concluded a 24 hour statistical survey measurement of the debris in orbit now. Figures 2-4 show preliminary results analyzed by Jussi Markkanen from EISCAT. The experiment was carried out jointly by <a href="https://www.uit.no/startsida">University of Tromsø</a> (Norway), <a href="https://www.irf.se/sv/start/">Institute of Space Physics</a>, Kiruna (Sweden), and the <a href="http://eiscat.se/">EISCAT Scientific Association</a>.</div>
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There is a large increase of debris produced by the Indian anti-satellite experiment, which is evident when comparing the post anti-satellite experiment beam park measurement with a similar measurement that <a href="https://conference.sdo.esoc.esa.int/proceedings/neosst1/paper/480/NEOSST1-paper480.pdf">we made one year earlier</a> (Figures 1 and 2). The debris count doubles at the time when the debris cloud passes the EISCAT Tromsø site. You can see this in the time-range detections (Figure 2), time of day histogram (Figure 3), and time - Doppler velocity (Figure 4) plots very clearly between 21 and 0 UTC and 7 to 11 UTC. The cloud seems to extend up to ranges of 1500 km, which shows that also debris with relatively large eccentricities are produced by the explosion. The measurement also indicates that the target of the anti-satellite experiment was Microsat-R. These measurements will be important for determining the amount of and the orbital distribution of space debris produced by the anti-satellite experiment. </div>
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The results are still preliminary. We are investigating the possibility for making more experiments in the near future to obtain better statistics. An effort is also underway to determine if the measurements fit with a model of an explosion of Microsat-R. </div>
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Thanks to <a href="http://eiscat.se/">EISCAT</a> for conducting this experiment on such a short notice and such a fast turn around time!</div>
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Contact information:</div>
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<a href="https://en.uit.no/om/enhet/ansatte/person?p_document_id=478217&p_dimension_id=88136">Associate Professor Juha Vierinen</a> (juha-pekka.vierinen@uit.no)</div>
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University of Tromsø, The Arctic University of Norway</div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg91UMDy6XybeDMNj3xebv6_8AML0uqpB1hq9YNA4gK4J1oAhBGCG4VGi0fp6FME-2UBHSzAaO7dOVZdV2FNr6Y5DuaYQ2Rk80HB2jOjhFyRPdzqep7xMcOYuczIXYjnLFGwGu0HW_lI8o/s1600/before.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="724" data-original-width="1239" height="186" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg91UMDy6XybeDMNj3xebv6_8AML0uqpB1hq9YNA4gK4J1oAhBGCG4VGi0fp6FME-2UBHSzAaO7dOVZdV2FNr6Y5DuaYQ2Rk80HB2jOjhFyRPdzqep7xMcOYuczIXYjnLFGwGu0HW_lI8o/s320/before.png" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Figure 1. <a href="https://conference.sdo.esoc.esa.int/proceedings/neosst1/paper/480/NEOSST1-paper480.pdf">Beam park measurements of space debris objects BEFORE the anti-satellite experiment</a> on January 4th, 2018. Detections as a function of time and range (Analysis: Jussi Markkanen, EISCAT)<br />
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<tr><td class="tr-caption" style="font-size: 12.8px;">Figure 2. Space object detections as a function of time and range after the antisatellite experiment measured 2-3 April 2019. (Analysis: Jussi Markkanen, EISCAT)<br />
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<tr><td class="tr-caption" style="font-size: 12.8px;">Figure 3. Histogram of space object detections as a function of time (Analysis: Jussi Markkanen, EISCAT)</td></tr>
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<tr><td class="tr-caption" style="font-size: 12.8px;">Figure 4. Space object detections as a function of time and Doppler velocity (Analysis: Jussi Markkanen, EISCAT)</td></tr>
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<tr><td class="tr-caption" style="text-align: center;">Figure 5. EISCAT Tromsø UHF radar, operating at 930 MHz with 2 MW of peak power. (Photo: Derek McKay).</td></tr>
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Juha Vierinenhttp://www.blogger.com/profile/05315784473428964695noreply@blogger.com0tag:blogger.com,1999:blog-3384111523585932540.post-24303090184377645232019-03-04T23:02:00.001+01:002019-03-04T23:02:16.029+01:00<div class="separator" style="clear: both; text-align: center;">
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Sometimes the aurora is "a bit more dynamic than usual" as during the afternoon on December 3rd 2005, when we could observe flickering aurora on and off for a long period, in the video above we show 70 s of flickering aurora observed with the Odin imager, that was pointing towards magnetic zenith with a field-of-view of 10-by-16 degrees. The swirling and rotating structures you can see have intensity-variations of approximately 10 per cent and at frequencies between 5 and 12 Hz. Investigating such dynamic aurora is one of the main objectives with the EISCAT 3D project - but making IS-radar measurements with time-resolution good enough to follow these variations will still be challenging. Our best chance to get forward will be to combine observations with the EISCAT 3D radar and optical instrumentation.BjornGhttp://www.blogger.com/profile/00651053522876797670noreply@blogger.com0tag:blogger.com,1999:blog-3384111523585932540.post-72906886429463798402019-02-10T10:40:00.000+01:002019-02-11T01:45:50.700+01:00Exploring an ice cave<div class="separator" style="clear: both; text-align: center;">
Being a student at the university centre in Svalbard carries with it certain perks, one of them being able to venture into the wast icy expanse of Svalbard after lectures. Roughly 60% of these lands are covered by glaciers, and 3 of these glaciers are located just south of Longyearbyen. The most easily available is Longyear-glacier, just west of Sarkofagen, a looming peak named by it's shape of a sarcophagus.</div>
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This glacier serves as a highway for the snowmobiles travelling south, so getting there requires little effort. The glacier is also a land-based glacier, with little movement going on, so crevasses on this glacier are a little harder to come by compared to the more active ones heading into the sea. Still, being on the safe side, we probed the route when venturing out of the track to avoid falling into possible melt-water channels flowing along the glaciers. </div>
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Locating these caves can be quite the challenge in the dark, and they also move between the seasons, so we were not sure if we would find one. After a few hours though, we eventually found one, to the delight of everyone's cold feet. The temperature outside was about -22 degrees celsius, but inside the cave it felt alot warmer. </div>
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Lacking in proper gear for cave-exploring, we restricted ourselves to exploring the first 20 meters of the cave. These caves follow the bottom of the glacier and can reach length's into the 100's of meters.</div>
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<tr><td class="tr-caption" style="text-align: center;">The entrance</td></tr>
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<i>No draugr, wampas or polar bears were sighted in the cave, though a foul stench filled the motionless air as we ventured further. Will have to check back later to investigate further the whereabouts of the stone tablet the shopkeeper in town wanted me to find...</i><br />
<br />Markus Floerhttp://www.blogger.com/profile/14935058314718905020noreply@blogger.com0Longyearbyen, Svalbard og Jan Mayen78.223172200000008 15.62672290000000478.1713282 15.303999400000004 78.27501620000001 15.949446400000005tag:blogger.com,1999:blog-3384111523585932540.post-85479407195373877332019-02-09T21:34:00.003+01:002019-02-09T21:34:57.811+01:00Shoveling snow under the aurora<div class="separator" style="clear: both; text-align: center;">
Late in january me and 3 other students joined Mikko on a trip up to the field station at Breinosa; the site of the Kjell Henriksen Observatory and the EISCAT Svalbard radar. We were tasked with digging up the field station itself since it was covered in snow up to the ceiling.</div>
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The whole ordeal took about 4 hours, as the snow was hard-packed from the icy winds of Svalbard. At these latitudes, the sun won't come back over the horizon until mid-february, so it was completely dark for the most part. Bad for the polar bear-guard, very good for the northern lights-enthusiasts!</div>
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<tr><td class="tr-caption" style="text-align: center;">The EISCAT Svalbard 42m field-aligned dish to the left and the 32m dish set to "tourist mode" with the southern sky in the background.</td></tr>
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<tr><td class="tr-caption" style="text-align: center;">Shoveling snow under the aurora</td></tr>
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<tr><td class="tr-caption" style="text-align: center;">Radio science paraphernalia that were buried by the snow</td></tr>
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<tr><td class="tr-caption" style="text-align: center;">Happy students Aurora & Erlend with head engineer Mikko in the back</td></tr>
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<br />Markus Floerhttp://www.blogger.com/profile/14935058314718905020noreply@blogger.com0Svalbard, Svalbard og Jan Mayen78.153419340644 16.08677125938879778.146900840644008 16.046430759388798 78.159937840644 16.127111759388796