Fw: [MilCom] Military Remote Garage Door Jamming Frequency?

[Ken]

---- Original Message ----- 
From: Duane Mantick 
To: Ken 
Sent: Sunday, December 03, 2006 5:47 PM
Subject: Re: [MilCom] Military Remote Garage Door Jamming Frequency?


You might want to post this out to the list.........I'm having some difficulty with that 
right now......

I can confirm that this is VERY possible.  I used to work for a large national retail
company as an In-Home Service Tech and Garage Door Openers was one of the things
that I did.  Had a number of occasions where the receiver/logic boards were getting
jammed (these were virtually all either 315 or 390 MHz, I am pretty sure).  One was as
simple a source as the charger for a cordless phone that happened to be emitting on
the receiver frequency.  The receiver could not pick up the hand-held transmitter signal
any further than about 10 feet unobstructed until the charger was unplugged.  Verified that 
it wasn't the phone itself by removing the phone to the other side of the house but
leaving the charger plugged in, interference was still there.  Our Tech Support people
told me that they had similar reports from all over the country, sources everything from
electric fence chargers to cable/satellite boxes and stuff you might never imagine.  Given
the rather small transmitters that probably fell under Part 15 Low Power Devices FCC rules,
those receivers had to have been pretty sensitive as I saw them operate reliably a couple 
hundred feet or more away when no interference was present.  I have no doubt in my mind 
that RF signals in their passband could "swamp out" the receivers and cause them to 
not operate.

Duane
WB9OMC


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