Sunday, January 13, 2019

Radar 4980 kHz US East Coast (2)

Here is a small update on the HF radar signals which can be received on KiwiSDRs located in the US east-coast area
  • The center frequency seems to be close to 4900 kHz and the bandwidth is 50-60kHz
  • The signals are active every few minutes for about 40 seconds
  • Up to four trains of pulses can be seen. These pulses repeat every 0.01 sec but the autocorrelation function peaks at 0.02 sec indicating that the pulses are phase modulated
  • The phase of all pulses is flipped by 180 degrees in each 0.02 sec slot
  • Each pulse train consists of at least 5 pulses
  • The fast pulse repetition rate suggests this is a radar for fast-moving targets, as opposed to, e.g., CODAR


abs(IQ) in 0.02 sec frames


abs(IQ) in 0.02 sec frames (zoom)


pulse trains w.r.t. GPS time


pulse trains w.r.t. GPS time (zoom)



arg(IQ) zoom in 0.01 sec frames, ×2 resampling

abs(IQ) zoom in 0.01 sec frames, ×2 resampling

arg(IQ) for two consecutive 0.01 sec frames, ×2 resampling

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