[eagle] Re: PAVE PAWS EMI

Juan Rivera juan-rivera at sbcglobal.net
Tue Sep 4 19:55:02 PDT 2007


Lee,

I think you may be correct - my data may in obsolete.  I think we will be
able to determine if what I am seeing here is really PAVE PAWS by moving to
a mountain top that has line of sight to them, or moving into the local area
near the base.  I am going to try to make a stereo .wav file with my main
receiver on one channel and the sub receiver on the other.  By tuning the
two receivers to what appears to be two different PAVE PAWS channels I may
be able to see if the pops I hear are correlated across both or not.  If
they are not I think that strengthens my feeling that this probably is PAVE
PAWS.  Once we get up on a mountain we can tell with much more confidence,
but I can try this now.

I may have the original files, but I extracted everything that I thought was
pertinent and put it in the ATP already.

Once we get the CAN-Do module running again, and we see if there are guard
bands, then I can tune the 70 cm receiver into one to see if that improves
the situation.

I'll post my .wav file if I get it done this evening...

73,

Juan

-----Original Message-----
From: Lee McLamb [mailto:ku4os at cfl.rr.com] 
Sent: Tuesday, September 04, 2007 7:38 PM
To: eagle at amsat.org; juan-rivera at sbcglobal.net
Cc: 'Robert McGwier'; 'David Smith'; 'Dave Black (Work)'; 'Dave Black
(Home)'; 'Samsonoff at Mac. Com'; 'Juan.Rivera (Work)'
Subject: Re: [eagle] Re: PAVE PAWS EMI

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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