This is one of the spectrograms that I have made the last couple of days, but no idea if it is from prospero. We will try again the next couple of days. Downlink frequentie 137.560 MHz and PCM modulated signal.
There is a possible explanation for the signals that I receive and can be seen in the spectrogram. This are probably signals that are transmitted by ORBCOMM. The 57k6 broadcasts of the ORBCOMM satellites. The frequency 137.560 was received by the ORBCOMM organisation after Prospero was no longer active on that frequentie.