All,

I live in an apartment and we have a radio controlled garage door
opener. Every once in a while someone's remote gets stuck on and
the door remains open until the battery dies (there are about 40
cars in the garage). I looked at my remote and its a Linear Corp.
Digital Transmitter Model DTD which transmits on 310Mhz.

What I'd like to do is find a cheap receiver of some kind that would
allow me to detect which car has the stuck remote. I was thinking
that maybe an X10 product might be easily adaptable to my purpose
since they use 310Mhz frequency. What I would like is a hand-held,
battery operated device that would beep or indicate when it was near
a remote that was active so I could walk through the garage and find
out who needed to be contacted to fix their remote. Any suggestion?

Alternative solutions are welcome (other than moving ;-)

Regards,
David

"DMF" wrote:

}...
}What I'd like to do is find a cheap receiver of some kind that would
}allow me to detect which car has the stuck remote.

A cheap filed strength meter would probalby suffice.

See: http://www.alphalink.com.au/~parkerp/noapr97.htm

or google for more circuits.

Stan.

DMF wrote:

All,

I live in an apartment and we have a radio controlled garage door
opener. Every once in a while someone's remote gets stuck on and
the door remains open until the battery dies (there are about 40
cars in the garage). I looked at my remote and its a Linear Corp.
Digital Transmitter Model DTD which transmits on 310Mhz.

What I'd like to do is find a cheap receiver of some kind that would
allow me to detect which car has the stuck remote. I was thinking
that maybe an X10 product might be easily adaptable to my purpose
since they use 310Mhz frequency. What I would like is a hand-held,
battery operated device that would beep or indicate when it was near
a remote that was active so I could walk through the garage and find
out who needed to be contacted to fix their remote. Any suggestion?

Alternative solutions are welcome (other than moving ;-)

Regards,
David


I'm no radio expert but...
You may need more than a receiver. The signal may reflect off the
walls and cars in the garage and bounce around. You might need complex,
sensitive equipment to "triangulate" where the signal is coming from.
This would be a very expensive system using three antennae and receivers
to sense from which direction the signal is strongest. Since these
openers sometimes operate for 50 to 100 feet away from the receiver the
signal would be bouncing all over the place and make it very difficult
to find the source within the garage.
Someone more experienced in radio frequency equipment may have a better
or much simpler answer for you.

The observation (below) is quite good, and to eliminate the confusion you
need
to attenuate the signal and use a horizontal dipole or short yagi to find
directional
bearings. This would essentially become a "fox hunt". Using sensitive
equipment
may actually become counterproductive, especially in a reflective enclosure.
If I'm not mistaken, the digital pulses from openers are difficult todetect,
as they
are bursts in msec ranges, not nice constant AM/FM transmissions. Metering
this
would be frustrating.
Perhaps the interference is from some outside source, not even one of the
tenants.
What if you attenuate the receiver sensitivity. Afterall, the door neednot
sense
a command unless the car is within 15 feet of the door. And a car with a
"stuck
key" parked 30 feet away will not play havoc with the system.
Sounds like an easier solution...........

Les KA9GLW
"Jumpster Jiver" wrote in message
news:ir7lf.4707$6Z5.721@trndny02...
DMF wrote:

All,

I live in an apartment and we have a radio controlled garage door
opener. Every once in a while someone's remote gets stuck on and
the door remains open until the battery dies (there are about 40
cars in the garage). I looked at my remote and its a Linear Corp.
Digital Transmitter Model DTD which transmits on 310Mhz.

What I'd like to do is find a cheap receiver of some kind that would
allow me to detect which car has the stuck remote. I was thinking
that maybe an X10 product might be easily adaptable to my purpose
since they use 310Mhz frequency. What I would like is a hand-held,
battery operated device that would beep or indicate when it was near
a remote that was active so I could walk through the garage and find
out who needed to be contacted to fix their remote. Any suggestion?

Alternative solutions are welcome (other than moving ;-)

Regards,
David


I'm no radio expert but...
You may need more than a receiver. The signal may reflect off the
walls and cars in the garage and bounce around. You might need complex,
sensitive equipment to "triangulate" where the signal is coming from.
This would be a very expensive system using three antennae and receivers
to sense from which direction the signal is strongest. Since these
openers sometimes operate for 50 to 100 feet away from the receiver the
signal would be bouncing all over the place and make it very difficult
to find the source within the garage.
Someone more experienced in radio frequency equipment may have a better
or much simpler answer for you.

"Les" wrote in message
The observation (below) is quite good, and to eliminate the
confusion you need to attenuate the signal and use a horizontal
dipole or short yagi to find directional bearings. This would
essentially become a "fox hunt". Using sensitive equipment
may actually become counterproductive, especially in a reflective
enclosure. If I'm not mistaken, the digital pulses from openers are
difficult to detect, as they are bursts in msec ranges, not nice
constant AM/FM transmissions. Metering this would be frustrating.
Perhaps the interference is from some outside source, not even one
of the tenants. What if you attenuate the receiver sensitivity. Afterall,
the door need not sense a command unless the car is within 15 feet
of the door. And a car with a "stuck key" parked 30 feet away will
not play havoc with the system. Sounds like an easier solution.

Thanks to everyone who replied. I am looking into a cheap Field
Strength Meter as suggested by Stan.

These remotes work from about 100ft since I can open the door
from about that distance. I think that as long as the FSM has a
sensitivity adjustment I can reduce the sensitivity until it can only
detect from about 10ft. That should allow me to zero in on the car
in the lot with the stuck remote. Also, even though the output from
the remote is pulsed if the button is stuck on its probably sending
out enough sequential pulses at the 310Mhz frequency for me to
detect with the FSM... I hope... right now the only way for the
landlord to deal with this is to post signs to get the other tenants to
check their remotes and/or wait until the battery dies, so the door
stays open for days.

Regards,
David

you probably want a FSM with audio out,,, you'll be able to hear the
pulses and when they get louder you are getting closer...


hmmm portable TV set tuned to UHF Ch 39 = 620 MHz which is the second
harmonic,,, you may be able to see some lines on snow when you get
close....

may need to get very close as the second harmonic should be much
weaker

Mark

"Mark" wrote:

}hmmm portable TV set tuned to UHF Ch 39 = 620 MHz which is the second
}harmonic,,, you may be able to see some lines on snow when you get
}close....

hmmm...also, if you have a portable cable-ready tv, cable channel 38
would show the 310 mhz signal in the video.

Stan.

Stan...

cable ready TV..... great idea...!

Mark