[TowerTalk] RF int makeup mirror

[jimlux]

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