The DelfiC3 project is described here and the purpose of this experiment was to see whether a 3 element Yagi for 2 meter is sufficient to catch the signal. With the airspy, and the yagi shown below and sdrshap we found an SNR of approximately 10dB. You need to stay a few meter away from the notebook that records the data to avoid radio frequency interference.
This was the passage on 27-feb-2018 at 9:40 at the campus of the TU Delft. The elevation was approximately 30 degrees, and the ground track was eastwards. Mind that the satellite transmit power is no more than approximately 2 Watt and that the distance to the transmitter is some 2000 km.
PE4WJ added: the TX power is 10dB under the total power consumption, which is 2.4W. So 2.4 Watt minus 10dB = 0.24 Watt, or 23.8 dBm.
The Antarctic WSPR station on Neumayer station heard my 500 mW signal on 40m. I was in WSPR transmit mode.
What matters in radio propagation is power spectral density, the bandwidth is really small, (6 Hz) and the power is roughly that what you put in a flashlight. More about station Neumayer can be found here.
Screenshot of what I did last night on 40m with up to 16 receive frequencies in the waterfall. Good to have the software mute when I use the FT991A to transmit on a nearby wire antenna, the airspy hf+ is on a separate active antenna. My only wish is CAT control to this rig via MK2.