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Tamper Alarm for remote TXers.

 
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Tamper Alarm for remote TXers.
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Medus
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Joined: 07 Jul 2006
Posts: 10

Post Tamper Alarm for remote TXers. Reply with quote
Mark,

Heres a simple suggestion for an optional module. It is a simple card with a set of N/O and N/C contacts which detect an alarm condition (Such as the TX being lifted or opened... or, perhaps, the rooftop access door being opened)

Upon tripping the alarm...

either:

- An audible alarm signal is injected/replaced into the audio for a second or two
- The RDS broadcasts the alarm on an unused code (Or, you could re-use the traffic switch)


Meanwhile...

Back in the studio a second module responds to either the RDS or the audio tone (PLL, DTMF Decoder or an off-the-shelf RDS decoder IC) and switches a load. The load could be an LED... a buzzer... anything to alert the operator that the Transmitter has been located/tampered and that the channel may soon go down.



The audio version is simple and cheap... it would simply insert into the audio chain. At the studio a standard radio receiver is interfaced to the audio detect circuitry via the headphone jack.

The RDS version would be suitable for those already using an RDS encoder... it could connect to the traffic-announce switch or, given a slight firmware modification, to a dedicated 'alarm' input.

Cost is minimal.



-Medus
Thu Aug 31, 2006 11:05 pm View user's profile Send private message
Pigmeat02
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Joined: 22 Oct 2006
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Post Reply with quote
It's not a bad idea,but how are you going to get there in time to stop someone from taking it? You'd have to be very close and if that's the case you're essentially w/ the transmitter,so how is it "remote"?

I've learned a little trick from hunting in tree stands. Very few people look up when walking in a wooded area? I've had dozens of people walk under me over the years w/ me at about 4-5 meters up? Never saw me and I'm not a small human being.

When I leave a transmitter alone it goes up a tree,w/the battery and audio source. I've never lost one yet. 3 meters up is good IMO. Makes the antenna harder to spot too. Black coax looks an awfully lot like a vine from any kind of distance.
Sun Oct 22, 2006 6:42 am View user's profile Send private message
pcs
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Joined: 18 Jan 2002
Posts: 3046
Location: Radio Land

Post Reply with quote
The simpler way to deal with it is to have tx detect the carrier from the studio,
that's the signal itself. If that signal isn't present, simply disable the transmitter
at remote location.

This is way more simple and cheap to do, receivers usually have some sort
of carrier strength measurement facility, just put a small comparator there
and feed the output to a switch, relay if you will.

_________________
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Marko - PCS Electronics
--------------------------------------------------------
Turn your PC into a FM radio station!
http://www.pcs-electronics.com
fax +386 4 2316 128
Sun Oct 22, 2006 10:23 am View user's profile Send private message Visit poster's website
pcs
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Joined: 18 Jan 2002
Posts: 3046
Location: Radio Land

Post Reply with quote
Regarding tamper alarm, we will soon start selling GSM remote control module. You will be able to check status of your transmitter via SMS. Also, there is an input for alarm so you can connect alarm system to this GSM remote control unit. If someone tries to break in a SMS will be sent to you.

Same happens in case of any other alarm triggering (Temperature, SWR etc).

GSM remote control plugs into RS232 at the back of your transmitter. You need a working SIM card, too.

_________________
Best regards,
Marko - PCS Electronics
--------------------------------------------------------
Turn your PC into a FM radio station!
http://www.pcs-electronics.com
fax +386 4 2316 128
Mon May 26, 2014 7:51 pm View user's profile Send private message Visit poster's website
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