[amsat-bb] Re: Strange Signal - 436Mhz - (sample provided)

Bob Bruninga bruninga at usna.edu
Tue Feb 8 15:49:52 PST 2011

> Has anybody else heard this --
> http://mysite.verizon.net/vzeqe0l7/Signal_436MHz.wav
> The signal strength is not constant - 
> and peaks about every 10 seconds - -
> A new radar perhaps?

The 10 sec rotation rate nails it as an E6C Radar plane.  Probably operating
off the East Coast.  I have been hearing it periodically for years, and
getting ready for a satellite receive lab this week, it would have
completely spoiled the lab.  So I spent over an hour on the web and on the
phone and finally got in touch with the right folks and when I said "10
seconds" they didn't need any more.  That nailed it to an E6.

They are not supposed to operate on the UHF channel that overlaps the
400-420 MHz band anywhere near land, but it is unclear what the guidance is
for the band 430-450 where HAMS ARE SECONDARY.

The above is my understanding, might not be exact.

To locate it would be hard... Swinging the beam doesn't help much, because
the radar is rotating at the same time and giving all kinds of fluctuations
per second... which would mask your attempts at peaking on it.  

My best guess to locate it would be to get two hams on the phone separated
by several hundred miles and to TIME the difference between the peak.  That
would establish an angle from the radar between the two hams.  Then both
hams compare signal strengths to an OMNI antenna (must be omni) and both
must be calibrated for equal S meter readings.  The difference in peak
signal strength would get an idea of range ratio between the two stations.
That and the angle (and ignoring the mirror solution over land) would get
you a good idea where he is operating.  (Maybe?)


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