[eagle] Re: PAVE PAWS EMI

Lee McLamb ku4os at cfl.rr.com
Tue Sep 4 19:37:33 PDT 2007


Another source you could be seeing is the airborne AN/APS-145 UHF radar 
although it typically has a fairly distinctive 6 second pattern looking in 
the time domain due to the antenna rotation rate.

The web site cited in the ATP has been taken down.  Did you save the original 
files?  I know there was an upgrade done at Beal so it is now known as having 
both the original EWR and the UEWR modes.  I'm wondering if perhaps the 
frequencies in Table D-2 are for the EWR.  Also with the 1 MHz 
chirp, "channel 11" will be creeping into the satellite sub-band as well.

Another thought that comes to mind is that we might be well served to try to 
pick our uplink passband in the guard bands if we can determine what they 
are.  AO-40's 70cm analog uplink was 435.550 - 435.800 MHz.  That gave it an 
almost perfect worst case frequency alignment with channel 13.   We'd 
probably need to check all three sites, Beale,  Cape Cod and perhaps 
Flyindales, UK to feel sure we had a good handle on the spectrum.  Another 
advantage to putting ourselves in the 'quiet zones' is that our Users might 
avoid some of the problems the repeater owners are now having higher in the 
band.  ARRL is reporting that some repeaters are being asked to reduce their 
output by 7 to 54 dB.

73,
Lee-KU4OS


On Monday 03 September 2007 21:47:00 Juan Rivera wrote:
> Bob,
>
> We spent the afternoon trying to characterize the pulses that I see here
> with my antenna pointed north.  See my last plot for details:
>
> http://www.juanr.com/pages/hobbies/ham_radio/Eagle/PAVE_PAWS.htm
>
> You'll see several evenly spaced areas showing many hits over about a 30
> minute span.  They are too evenly spaced to be random but they don't
> conform to the PAVE PAWS band plan that I pulled from environmental impact
> reports from years ago.  Because of the recent push to clear ham repeaters
> off of the air anywhere in the vicinity of a PAVE PAWS site, we know
> something has changed, but what?
>
> To resolve all of our questions we'll need to move to an unobstructed
> location atop a local mountain and try again.  That will take a few weeks.
> Until then I would be cautious about using my .wav file.  It might be the
> neighbor driving around the block on his Harley.
>
> 73, Juan
>
>
> -----Original Message-----
> From: Robert McGwier [mailto:rwmcgwier at gmail.com]
> Sent: Monday, September 03, 2007 10:11 AM
> To: juan-rivera at sbcglobal.net
> Cc: 'Dave hartzell'; 'David Smith'; 'Dave Black (Work)'; 'Dave Black
> (Home)'; eagle at amsat.org; 'Samsonoff at Mac. Com'; 'Juan.Rivera (Work)'
> Subject: Re: [eagle] Re: PAVE PAWS EMI
>
> Juan Rivera wrote:
> > Hi Dave,
> >
> > I noticed that too.  I killed the AGC but didn't think of the noise
>
> blanker.
>
> > I'll take a look and try again if it was on.  Right now I can't
>
> communicate
>
> > with the CAN-Do module or I would switch to the 70 cm prototype receiver
>
> and
>
> > repeat the test.
> >
> > Juan
>
> Yes, please.  I have some interesting noise blanker stuff I want to work
> on to eliminate PAVE PAWS pulses on board the SDX transponder.  This is
> the PERFECT set of signal collection (SDR-IQ of IF) for doing that work.
>
> Thank you very much once again Juan for your extremely valuable
> contributions and your unbridled enthusiasm.  It is very welcome indeed.
>
> Bob




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