Tuesday, November 18, 2014

Return of the "Russian Woodpecker"?


The Duga-3 was a Soviet-era long-range over-the-horizon anti-ballistic missile early warning radar.  With a roughly 10 Hz. knocking tone (when AM demodulated), it was nicknamed the "Russian Woodpecker."  The spectrum of its signal looked something like these three samples:


From left to right, the two pronounced peaks are (probably) ham SSB signals.  The flat-topped broadband signal near the middle (green bar in the waterfall plots) is the one of interest.  Finally, the strong peak on the right is (probably) a shortwave broadcast station.

Now, the odd thing is that these were all recorded in the last week.  Hrm.

For what it's worth, the Fourier transform of this boxcar frequency spectrum is a nice sharp pulse:
Nice, easy to handle.  Gives good localization.

Wonder who's feeling the need to switch on this sort of early warning radar.  We shall see.

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