1) The auto-correlation has peaks at multiples of 405/20250Hz = 0.02 sec = 1/50Hz:
2) Plotting abs(IQ) in frames of 1/50Hz reveals a pair of pulses, each apparently consisting of three separate sub-pulses:
|abs(IQ) in terms of 1/50Hz frames|
3) TDoA analysis locates this is a real signal somewhere in upstate NY (and demonstrates that it is not local QRM):
|KiwiSDR TDoA 4980 kHz|
If anyone knows what kind of HF radar signal this is I would be grateful to know.