Re: Car alarm that goes off when in a certain distance

[Frank Olson <Use_the_email_links@xxxxxxxxxxxxxxxxxxxxxx>]

mikey wrote:
> "Frank Olson" <Use_the_email_links@xxxxxxxxxxxxxxxxxxxxxx> wrote in message
> news:VQ3Mf.71399$B94.11984@xxxxxxxxxxx
>
>>hiding@xxxxxxxxxx wrote:
>>
>>>  Hi,
>>>Hope someone can help with this.
>>>I would like to be able to set up a alarm on a car. It would only go
>>>off if the car got in certain distance of some point, say 100 feet.
>>>
>>>In other words if the car drove up to where I work my alarm would
>>>sound that the car is nearby.
>>>
>>>I looked a bit for proximity alarms and really couldn't find much what
>>>I was looking for. Any websites, adivce you could provide would help.
>>>Thank you
>>
>>
>>That's easy if you have an Ademco or DSC wireless system that
>>annunciates "trouble" for a missing transmitter.  You'd have to program
>>a transmitter into your system, set up a relay correlation to either
>>turn on a light or start a local buzzer when it's actually "present" in
>>the system, and place the transmitter on the car you wanted to monitor.
>>  If it's within 200 feet of the receiver, the light/buzzer would turn
>>"on".  If it's out of range (or the battery's dead), the light/buzzer
>>would be "off".  The down side is that your system would also display
>>"trouble" for the missing transmitter, but I think if you set it up on a
>>different partition you could get around that.
>>
>>Frank Olson
>>http://www.yoursecuritysource.com
>
>
> Not that easy. You've got the concept but it's not that fast, Frank. It
> depends on the window.
> My guess is the systems you mention are probably at least an hour, the car
> has
> come and gone by then :-)


Yeah...  You'd need something that transmitted continuously which would
mean you'ld have to either hard wire the sucker to the vehicle's
electrical system (can a 9 volt transmitter work on 14 volts??  I don't
think so), or trip some sort of relay...  easy enough to do if wire it
to the ignition.  Turning the engine off would energize the relay and
open the contacts to the transmitter (it would transmit the open)
instantly and accomplish two things...  It would "log" back on to the
security system and show an open zone.  Starting the car would have the
effect of "closing" the zone.  The problem I see is that it sounds like
the OP won't have that kind of access to the vehicle.  A more
clandestine approach is required.  Like one of those card transmitters
from HID.  The reader for that guy's expensive though...  and you'd need
a head end unit to power it as well...