Sensormatic AM system ?

dave3825

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Abercrombie shipped me a pair of pants for my son and left this on. Reading about it it says 58Khz. Do these things transmit? I dont have my spyverter at the moment.

 

belvdr

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Almost positive they are passive. The door sensors activate them, like an RFID tag.
 

mmckenna

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The only emit RF when they are excited by an external trigger.
Usually in a retail store, they'll have some sort of loop near the door, usually on either side, it contains a loop that is transmitting on a specific frequency. When the tag passes through that RF field, it emits a signal that gets picked up and then sets off the alarm.
 

dave3825

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emit RF when they are excited by an external trigger.
Emits something when excited? Sounds kinda kinky.


So if the loop by the door excites it, it then tx 58 khz. Does the tag need power for that to happen?


And at home, is there a way that I could excite it, to make it tx?
 

mmckenna

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Emits something when excited? Sounds kinda kinky.

Hey man, whatever floats your boat. We don't judge here….
So if the loop by the door excites it, it then tx 58 khz. Does the tag need power for that to happen?

The loops at the door energize a coil in the device. That powers the tag briefly.

And at home, is there a way that I could excite it, to make it tx?

You'd need a way to induce enough energy into the tag to energize it.
Then you'd need a way to receive whatever frequency the tag generates (58KHz).
 

RFI-EMI-GUY

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Emits something when excited? Sounds kinda kinky.


So if the loop by the door excites it, it then tx 58 khz. Does the tag need power for that to happen?


And at home, is there a way that I could excite it, to make it tx?
You might want to check the patents of Sensormatic. Some of the old tags worked by generating two signals in one of the ISM radio bands and receiving on a third mathematically derived from an intermodulation mix (IMD), like 2A-B=C . The tags having a resonating coil and diode mixer. The check point being a fixed non linear junction detector (NLJD).
 

N9JIG

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Many years ago I had a friend who owned a video store. They had a system where they embedded specific length metal strips (that had double-stick tape on one side) in the VHS cases that would activate the security system at the door. This same system was also used at the area public libraries. He gave me a few of the strips and I stuck them on the inside of several friends' belts, including my then girlfriend. Every time they would go to a video store or library they would set off the alarm. This went on for weeks before they caught on. Needless to say they were a little ticked off!

All that said, I presume these worked in a similar fashion except that the metal strips were totally passive, no electronics in them at all. I assume the door sensor sent out a signal and waited for a return on a resonant frequency from the strip. I have no idea what frequency they used as I really wasn't concerned with that kind of thing at the time.
 

dave3825

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Hey man, whatever floats your boat. We don't judge here….
I tried to LOL but the like button does not seem to be in this forum.

You'd need a way to induce enough energy into the tag to energize it.
Then you'd need a way to receive whatever frequency the tag generates (58KHz).
I know zero about how to do that but would like to learn because I find this stuff interesting.


I stuck them on the inside of several friends' belts, including my then girlfriend.

When I was much younger, I have a brief job at Caldor. They used these square stickers for their anti theft. I was very tight with a few people in asset protection and whenever someone rubbed me the wrong way, they got a sticker either on them or their cart. Of course they would set off door alarm so in advance my AP friends knew who I stuck and would thoroughly inspect every item at the door holding them up.



I may try to dissect this thing to see thats inside and if it can be manually excited to tx that 58 khz..
 
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