BPM 5 MHz: new digital modulation?
edited January 2022 in Signals Received
Anyone else notice China HF time station BPM on 2.5 & 5 MHz now transmitting a new digital modulation? It almost sounds like a broken transmitter, but the pulses are absent during the CW and voice ID segments at the top and bottom of the hour. Youtube videos show the waveform was present in February 2021, but not June 2020. I checked closer to South Korea to make sure the signal wasn't HLA. Not present on 10 MHz.
Screenshot below from a Kiwi in Japan:
Modulation seems to be a 3-PSK sort of thing with subcarriers at +/- 0.9 1.0 1.1 kHz.
Good YT video: https://www.youtube.com/watch?v=SNHja_K1aA0