radio frequency emmision

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gdodds@ctv.es - 16 Dec 2007 13:05 GMT

My Jeep Cherokee has begun to operate my automatic gates randomly.
This can occur with the vehicle switced off as well as with engine
running.
Other vehicles we own do notdo so.
Any ideas?!
George

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clifto - 16 Dec 2007 17:27 GMT

> My Jeep Cherokee has begun to operate my automatic gates randomly.
> This can occur with the vehicle switced off as well as with engine
> running.

How can you tell it's the Cherokee doing it?

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Dec. 6 (Bloomberg) -- Government officials and activists flying to Bali,
Indonesia, for the United Nations meeting on climate change will cause
as much pollution as 20,000 cars in a year.

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gdodds@ctv.es - 16 Dec 2007 17:53 GMT

> gdo...@ctv.es wrote:
> > My Jeep Cherokee has begun to operate my automatic gates randomly.
[quoted text clipped - 7 lines]
> Indonesia, for the United Nations meeting on climate change will cause
> as much pollution as 20,000 cars in a year.

Because I can "control" the gates by driving the car into and out of
range.
I have isolated many electric functions by removing fuses and relays.
None of my other cars do it
I have removed and swapped around the remote control from vehicle to
vehicle.
It is more predictable if the motor is running but not essential.
The common denominator is the Cherokee at normal remote control
distance from the gates - around 30 metres or less.
The emission is probably constant (or fairly constant) as it defeats
the remote - i.e. the remote does not function untill the jeep is out
of range.

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clifto - 16 Dec 2007 17:59 GMT

>> gdo...@ctv.es wrote:
>> > My Jeep Cherokee has begun to operate my automatic gates randomly.
[quoted text clipped - 5 lines]
> Because I can "control" the gates by driving the car into and out of
> range.

Is the Cherokee taller than the other vehicles you drive into and out of
range?

> The emission is probably constant (or fairly constant) as it defeats
> the remote - i.e. the remote does not function untill the jeep is out
> of range.

Have you lost any remotes in the past? Is there one jammed in the seat of
the Cherokee, transmitting continuously?

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Dec. 6 (Bloomberg) -- Government officials and activists flying to Bali,
Indonesia, for the United Nations meeting on climate change will cause
as much pollution as 20,000 cars in a year.

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Scott Dorsey - 17 Dec 2007 15:16 GMT

>Because I can "control" the gates by driving the car into and out of
>range.
[quoted text clipped - 8 lines]
>the remote - i.e. the remote does not function untill the jeep is out
>of range.

First, get the manual for the gate opener and find out what frequency
it operates at.

Then call your local amateur radio club and see if there is someone
with a spectrum analyzer who might want to come over and help you track
it down.
--scott

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"C'est un Nagra. C'est suisse, et tres, tres precis."

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Paul < - 17 Dec 2007 02:46 GMT

> My Jeep Cherokee has begun to operate my automatic gates randomly.
> This can occur with the vehicle switced off as well as with engine
> running.
> Other vehicles we own do notdo so.
> Any ideas?!
> George

Not enough info.
What are the freqs of the equipment?
Digital?
Analog?
What is the encoding scheme?
Channel hopping?
etc.

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John S. - 17 Dec 2007 16:20 GMT

On Dec 16, 8:05 am, gdo...@ctv.es wrote:

Some cars have a garage door opener control built-in. Does yours?

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gdodds@ctv.es - 18 Dec 2007 14:09 GMT

> On Dec 16, 8:05 am, gdo...@ctv.es wrote:
>
[quoted text clipped - 6 lines]
>
> Some cars have a garage door opener control built-in. Does yours?

Found it!! The spec. analizer idea was the trigger. No local club
(rural Spain!) Bought a new radio card for the gate system and set it
up with battery and LED.
Got erratic triggers from the XJ but statistically more when occupying
the passenger seat. Attenuated the Radio card by wrapping it in foil
with no antenna etc
Eventually centred off on right rear passenger foot area. Under the
carpet (removed during a radio fit) was a remote!! Only triggered (I
suppose) when floor/carpet deflected under weight of person sitting
near. All made more frustrating and inconsistant because the remote
switches off after 30 secs constant output and needs further 15 secs
before turning on (and then only if the button is momentarily
released). Before retiring I spent 30 years in the auto trade and we
always said "there's always a new one"!
My wife only admitted losing the remote when I found the damn thing!
Many thanks for responses
George

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