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Author Topic: "RFID Devices" 13560 (?) 1559 UTC 3 FEB 2022  (Read 1561 times)

Offline Erik Mattson

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"RFID Devices" 13560 (?) 1559 UTC 3 FEB 2022
« on: February 03, 2022, 1620 UTC »
What sort of "RFID Devices" would I be picking up on 13560? Sounds like an off-balance, spin-cycling, washing machine.


Clip: https://www.dropbox.com/s/gkk2lqrvcko153l/SDRuno_20220203_105921_13560000HZ.wav?dl=0
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Offline Token

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Re: "RFID Devices" 13560 (?) 1559 UTC 3 FEB 2022
« Reply #1 on: February 04, 2022, 1711 UTC »
13560 kHz (+/- 7 kHz) is one of several ISM (Industrial, Scientific, and Medical) bands.  These are pieces of RF spectrum specifically set aside for intentional radiators that may not fall in the more traditional telecommunications or measurements realms, but still require RF emissions to do their tasking.  Not telcom, not radar, not point to point data, but still devices that must radiate energy to do their jobs.  If, for whatever reason, you cannot keep the RF levels low enough to qualify as Part 15 devices, to make them work right you need higher levels than that kind of regulation allows, then you typically design the item so that the RF falls in one of the ISM bands.

An example of an ISM device would be a microwave oven.  It must radiate energy to cook food, but it is not a more traditional RF source.  Most microwaves use a frequency of 2450 MHz (+/- 50 MHz), but there have been other frequencies used by Microwave ovens, such as 915 MHz.  Both of these frequencies fall in ISM bands.  Another example of an ISM device would be a key fob for a vehicle.  Another might be a high power laser power supply.  And yes, some RFID systems also use ISM bands.

Still another use would be the security monitoring system operated by some companies / entities with fiber or copper communications lines.  Some off these systems send pulses of RF down the cable or a shield on the fiber, unrelated to the cables / fibers primary task, to monitor for breaks or changes in the cable.  13560 kHz is a common frequency for these systems, and it can often be heard as a periodic (sometimes slow, sometimes fast) beep on that frequency.  This signal is pretty commonly heard, and while most ISM signals are shorter ranged, this one can often be heard for many miles, as the cable / fiber system associated can cover large areas.

The upshot of this is that there are thousands of possible signals that might be heard on 13560 kHz and other ISM bands.  It is often impossible to nail what is heard down to a specific type of signal, as so many of them are near identical and often highly variable.

So, not everything heard on 13560 kHz is an RFID system, in fact, while some do use that frequency, that is a minority of the type of signals heard there.  Your recoriding will not play for me, so I cannot ID the specific signal in your recording (and might not be able to even if it did play), but I doubt, just based on the shear number of other signals it might be, it is RFID.

T!
« Last Edit: February 04, 2022, 1713 UTC by Token »
T!
Mojave Desert, California USA

Offline Erik Mattson

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Re: "RFID Devices" 13560 (?) 1559 UTC 3 FEB 2022
« Reply #2 on: February 07, 2022, 1836 UTC »
Thanks, Token.
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Offline Josh

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Re: "RFID Devices" 13560 (?) 1559 UTC 3 FEB 2022
« Reply #3 on: February 09, 2022, 2220 UTC »
Mebbe lojack stuff uses that freq
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Offline NJQA

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Re: "RFID Devices" 13560 (?) 1559 UTC 3 FEB 2022
« Reply #4 on: February 23, 2022, 1403 UTC »
In the past, Lojack was on VHF high band.  The police cars with Lojack trackers all had 1/4 wave VHF whips in a group of four…probably a doppler df unit.  I imagine they are still on VHF.

 

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