[eagle] Re: PAVE PAWS EMI

Juan Rivera juan-rivera at sbcglobal.net
Mon Sep 3 16:52:57 PDT 2007


That's possible.  In a few weeks we'll gather up our equipment and head for
the top of a local mountain where we'll have a much better shot at the PAVE
PAWS site.  Right now we're not completely sure we're really looking at PAVE
PAWS.  It may be that our data from old environmental impact statements is
obsolete.  We know something has changed or the Department of Defense
wouldn't be clearing out all the local ham repeaters.

Juan - WA6HTP

-----Original Message-----
From: Lee McLamb [mailto:ku4os at cfl.rr.com] 
Sent: Monday, September 03, 2007 4:43 PM
To: eagle at amsat.org; juan-rivera at sbcglobal.net
Cc: 'Dave hartzell'; 'Robert McGwier'; 'David Smith'; 'Dave Black (Work)';
'Dave Black (Home)'; 'Samsonoff at Mac. Com'; 'Juan.Rivera (Work)'
Subject: Re: [eagle] Re: PAVE PAWS EMI

This reminds me of a briefing we got at work from a UHF receiver vendor 
regarding their receiver's susceptibility to radar.  In it they demonstrated

how a strong enough RF pulse would actually cause a bias shift on the first 
stage resulting in a 'blanking effect' until the RF induced voltage decayed 
off.  Perhaps we're seeing something similar here?


On Monday 03 September 2007 14:32:05 Juan Rivera wrote:
> Dave,
> The noise blanker is off and when you think about it, it doesn't matter
> anyway since I'm pulling the 10.7 MHz 3rd IF out of the TS-2000.  The
> blanker is implemented in DSP farther downstream.  I'm not sure what is
> causing that.  I'll have to scratch my head some more...
> Juan
> -----Original Message-----
> From: Dave hartzell [mailto:hartzell at gmail.com]
> Sent: Monday, September 03, 2007 10:58 AM
> To: Robert McGwier
> Cc: juan-rivera at sbcglobal.net; 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
> Attached is a Matlab plot of Juan's SDR-IQ PAVE PAWS capture...
> In the plot, you can really see the noise-blanker suppression after
> each spike...
> Dave
> On 9/3/07, Robert McGwier <rwmcgwier at gmail.com> wrote:
> > 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
> >
> > --
> > AMSAT Director and VP Engineering. Member: ARRL, AMSAT-DL,
> > "If you're going to be crazy, you have to get paid for it or
> > else you're going to be locked up." Hunter S. Thompson
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