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Re: [TowerTalk] RF int makeup mirror

To: towertalk@contesting.com
Subject: Re: [TowerTalk] RF int makeup mirror
From: jimlux <jimlux@earthlink.net>
Date: Wed, 7 Mar 2018 10:38:47 -0800
List-post: <mailto:towertalk@contesting.com>
On 3/7/18 9:55 AM, David Gilbert wrote:

Yes ... they are basically a transmitter and the interfering RF is likely radiated, rather than solely conductive.  Not much he can do other than turn the bedroom/bathroom into a Faraday cage.   Or turn the ham shack into a Faraday cage, but even that wouldn't help if his antennas are close enough to pick up the signal.

For the mirror to be messing up multiple bands the oscillator must be generating something akin to a square wave.  If it were possible to access the circuitry maybe trying to filter it to something closer to a sine wave would cut down on the harmonics.



we stray from Towers here...but..

Modern touch sensors also use the change in amplitude of received 60 Hz line frequency - the problem is that they're cost driven, so basically, what they have is a broadband power detector, followed by a AC coupled thresholder. Your RF gets detected, making it think that there's an increase in signal level.

Or, they periodically send a burst of pulses to the sensing plate, and look for a change in impedance.



https://www.mouser.com/ds/2/268/40001948A-1145202.pdf
Microchip AT42QT1012


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