real HF signal with doppler shift fc= 437.366 MHz
FT-736R with SDR-IQ (2nd IF), SpectraVue 655536 FFT/BLK Size, 3 dB/Div
20:40:00 UTC COMM A 20:40:35 UTC COMM A 20:41:25 UTC COMM B 20:42:05 UTC COMM B 20:42:45 UTC COMM B -- no beacon 20:44:10 UTC COMM B 20:44:50 UTC COMM B 20:46:13 UTC COMM A 20:46:55 UTC COMM A