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

Joe nss at mwt.net
Tue Feb 8 16:01:57 PST 2011

a doppler fox hunt antenna system would get the direction also.


The Original Rolling Ball Clock
Idle Tyme

On 2/8/2011 5:49 PM, Bob Bruninga wrote:
>> 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?)
> Bob, WB4APR
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