Military radio signal jams garage doors

snipped-for-privacy@ipal.net wrote:


When I was young, I hooked up a 5 wattt mobile CB directly to the antenna inputs of a portable B&W TV. Ended up frying the sucker (the TV, not the radio. :)
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| | snipped-for-privacy@ipal.net wrote: |> | |> BTW, I've actually overloaded a couple GFCI receptacles with my 2 meter |> hand held ham radio transmitter running at 5 watts to a rubber duck |> antenna at a distance of 10 feet. Those things really freak out when |> that happens. It could have been a resonance in the wiring. |> | | When I was young, I hooked up a 5 wattt mobile CB directly to the | antenna inputs of a | portable B&W TV. Ended up frying the sucker (the TV, not the radio. :)
I would expect. Gotta learn those lessons young :-)
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snipped-for-privacy@ipal.net wrote:

All the garage door units I've ever examined had regenerative receivers. Those, of course, overload quite easily, and selectivity is seldom better than a few percent, e.g. a 5-10MHz bandpass @ 300MHz. Can't be more selective than that anyhow--the regenerative detector drifts about that much all by itself.
Best, James Arthur
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hob wrote:

I wonder if they sell garage door openers and remotes that use challenge-response. It wouldn't be that expensivge to do.
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I have problems with steel doors, and walls that use metal mesh for the stucco, so my range is crap.
I'v been considering some kind of IR replacement. Any available commercially?
...Jim Thompson
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In alt.engineering.electrical Jim Thompson
| |> |>hob wrote: |> |>> 1) If the military signals are interfering with those digital commands, then |>> the signal must be overwhelming the receivers - they surely are not sending |>> simultaneous multiple sets of "trains" of pulses that fool all those |>> receivers' security, weak as it is. |> |> I wonder if they sell garage door openers and remotes that use |>challenge-response. It wouldn't be that expensivge to do. | | I have problems with steel doors, and walls that use metal mesh for | the stucco, so my range is crap. | | I'v been considering some kind of IR replacement. Any available | commercially?
Try coax through the wall to an external antenna.
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| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
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On 5 Dec 2006 18:24:20 GMT, snipped-for-privacy@ipal.net wrote:

Brings to mind the cell phone extender gimmick... external antenna capacitively-coupled thru the rear vehicle window, then another antenna inside
...Jim Thompson
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hob wrote:

I wonder if they sell garage door openers and remotes that use challenge-response. It wouldn't be that expensive to do.
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Igor The Terrible wrote:

This story is from Denver, Colorado but is applicable to Alaska since we have so many military installations, the new missile defense project
at Ft. Greely not being the least. The ionospheric heaters located near Glenn Allan and the BMEWS radar located at Clear both have caused massive radio frequency interferences in the past. Just ask any pilot that has flown into the radar signal or long time residents of Glenn Allan. I live between Ft. Wainwright and Eielson AFB and often experience strange signals on my cell phone and through my upstairs TV.
During my time in the US Army I worked at a frequency monitoring station at Ft. Huachuca, Arizona where we attempted to find interference among the many military signals that operated during war time exercises. It was a futile attempt to say the least. Radio signal interference from the military's many transmissions can come from harmonic signals generated by two or more signals. These harmonic
signals are difficult to detect and correct.
What is not known is the long term health risks associated with the barrage of radio frequency signals that penetrate our body every day. Millions of these transmissions come from earth and satellite transmitters and grow in number. No one knows what the end result will
be.
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snipped-for-privacy@electrician2.com wrote:

I haven't seen Ft. Greely since I left the US Army in 1974. Are you working on the project, or just living near the old base?
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On 3 Dec 2006 07:47:06 -0800, "Igor The Terrible"

Garage-door openers are some of the worst RF gear around. Receiver selectivity and overload tolerance is crap. If they want to operate near military bands with garbage receivers, they shouldn't complain about being blanked.
John
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