Transmitting a simple sine wave in gnuradio using the USRP - and measuring it's power
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.
|The gnuradio flowchart consists of a Signal Source block and a UHD: USRP Sink block. Sliders are added to adjust the amplitude and frequency.|
|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.|
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?
had a negligible impact on the circuit. So it comes down to which dummy load we are using.