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Re: [RFI] mystery noise

To: rfi@contesting.com
Subject: Re: [RFI] mystery noise
From: Jim Brown <jim@audiosystemsgroup.com>
Reply-to: jim@audiosystemsgroup.com
Date: Wed, 12 Jan 2011 14:06:19 -0800
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
On 1/12/2011 11:50 AM, Pete Smith wrote:
> Does the description or the periodicity suggest a source that I can look
> for?

YES!  Anything with this sort of signature is almost certain to be some 
sort of oscillator, either as part of a microprocessor, other digital 
equipment, a switching power supply, or motor controller.  One of the 
great reasons for owning a panadapter is to identify them on the ham 
bands, where each harmonic appears as a patch of noise a few kHz wide 
(carriers modulated by noise). Most are either free-running or dithered 
(randomly varying in frequency), although those associated with 
microprocessors are crystal controlled.  One of the effects of the 
dither is that they drift several kHz around their center frequency.

73, Jim Brown K9YC
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