[Milsurplus] Garage door openers

[Dick]

In that case, I suspect the probldem is a very high power UHF SATCOM signal; 
probably either
high priority traffic, satellite control, or both.

Dick

----- Original Message ----- 
From: Ralph Cameron
To: Dick
Sent: 03 December, 2006 14:22
Subject: Re: [Milsurplus] Garage door openers


Dick:

This was a case of fundamental overload. In this case changing codes doesn't
work. Front end selectivity is required.

Thanks

Ralph
----- Original Message ----- 
From: "Dick" <rertman at ix.netcom.com>
To: "Ralph Cameron" <ramcam at magma.ca>
Sent: Sunday, December 03, 2006 3:04 PM
Subject: Re: [Milsurplus] Garage door openers


> The milkitary are the primary users of the 225-400 MHz spectrum.  They use 
> it for air/air and air/ground communications, along with some channels 
> dedicated to UHF SATCOM.  The UHF SATCOM XMTRs typically put 100 W on the 
> air and can be either continuous or burst, depending on the SATCOM mode in 
> use.  The aircraft UHF voice radios typically put 10-20 W on the air. 
> Glide slope XMTRS used in airport instrument landing systems (ILS) also 
> operate in this band.
>
> Out of curiosity, I fired up a spectrum analyzer and looked at the signal 
> from the key chain keyless entry XMTR for my Dodge pickup truck.  It was 
> close to 349 MHz.  Keyless entry and garage door gadgets must meet FCC 
> Rules Part 15, which says they cannot cause interference and  must accept 
> any interference they suffer.
>
> So, try changing the codes on your garage door openers.
>
> Dick
>
>
> This reminds me of the very strong garage door jammer that operated in 
> downtown Ottawa last year. With all the government sophisticated DF 
> equipment they couldn't locate the source but every garage door opener for 
> 20 miles radius was knocked out. Even the local embassies had trouble and 
> there are quite a few here.
>
> That frequency range has military as primary use in Canada but it is 
> shared with other users.
>
> After all the excitement died down it was attributed to a ,"...new U.S. 
> military system" but failed to elaborate.
>
> Didn't Pres. Nixon's Air Force One cause similar problems when he flew 
> home to Calif.  All the neighbours knew he was coming because their garage 
> doors operated. Sort of a distant early warning system.
>
>
> 73
>
> Ralph Cameron
> VE3BBM