[eagle] Re: PAVE PAWS EMI

Lee McLamb ku4os at cfl.rr.com
Mon Sep 3 16:42:49 PDT 2007


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?

73,
Lee-KU4OS


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 noise
> 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,
> > TAPR, Packrats, NJQRP, QRP ARCI, QCWA, FRC. ARRL SDR WG Chair
> > "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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