"Percival P. Cassidy" wrote in message
...
On 03/08/08 12:40 pm mm wrote:

Today on the news I heard that a big bunch of electronic garage door
openers weren't working in Churchville Maryland because the govt. at
the Aberdeen Proving Grounds was doing something with a satellite or
something. Tomorrow their going to do the same thing around Aberdeen.

People are paying techs to change the freqs, but some may have paid
for other repairs by mistake, one would assume. Someone in charge admits
he didn't get the word out well enough.

1) Don't they assign frequency ranges to things so that this sort of
thing doesn't happen?

2) How could the use of a frequency mess up the garage door openers?
Even if the govt. signal was stronger, why wouldn't the opener still
work? If the govt. signal was picked up by the opener, how come the
doors didn't open or shut. (Apparently they didn't since they would
surely have mentioned that.)

Garage door openers (and a bunch of other household electronic devices
(e.g., cordless phones, computers, wireless networking systems, wireless
remote temperature/humidity sensors) are unlicensed devices governed by
Part 15 of the FCC regs. They must not interfere with licensed services
but must put up with any interference from licensed services. So if your
garage door opener interferes with your ham-radio neighbor's
communications, it's your responsibility to fix the problem (e.g., by
replacing or refraining from using the offending device). Similarly, as
long as your ham-radio neighbor is operating within the terms of his/her
license and you keep hearing him/her in your cordless phone, that again is
your problem -- although he/she ought to be willing to assist you in
finding a solution to the problem (but is under no obligation to actually
fix the problem or pay for somebody else to fix the problem).

Perce
This is the same sort of problem that some Chrysler cars had in the 90s. If
you drove by a powerful radar installation, and the beam hit your car, it
would stall due to interference with the electronic ignition/computer
components in the car. The car manufacturer had to come up with a
modification to harden the engine's controls to the radar signal.