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@gmail.com] Sent: Monday, September 03, 2007 10:58 AM To: Robert McGwier Cc: juan-rivera@sbcglobal.net; David Smith; Dave Black (Work); Dave Black (Home); eagle@amsat.org; Samsonoff@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@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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