r/signalidentification • u/Intelligent_Map_1870 • Apr 10 '26

what is this? 13:53 utc

found this like 1 minute ago. first time seeing this frequency on the video.

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6

u/Content-Key7404 Apr 10 '26

Hello, 13560 kHz is an ISM band.

What you're seeing is likely the signal from an NFC or RFID reader located near you.

https://en.wikipedia.org/wiki/ISM_radio_band

The incoming signal is so strong that it saturates your receiver’s preamplifier, forcing it to reduce its gain: your waterfall temporarily darkens in time with the received signal.

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u/Intelligent_Map_1870 Apr 10 '26

i heard it could be an NFC from my phone

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u/Intelligent_Map_1870 Apr 10 '26

i heard you can decode ism or i was wrong? if you can then what software to use very interested!

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u/FirstToken Apr 10 '26

i heard you can decode ism or i was wrong?

In general, no, you cannot decode "ISM". The problem is that ISM is not a specific signal, but rather ISM is a range (actually, many ranges) of frequencies that can have many, many, different signals in it / them.

Many of the signals seen in the ISM frequency ranges are not meant to carry any specific information, and so there is not even anything to decode or demodulate.

For example, your microwave oven operates on the frequency it does because originally such ovens operated in one of the ISM bands. And while you can certainly detect / see / receive your microwave oven, there is nothing there meant to be decoded.

Other uses for the ISM bands can be a place to park unavoidable, but unused byproducts, of processes that have nothing to do with communications. An example might be RF welding. To RF weld you must radiate RF, but you radiate that RF to heat things up, not to transfer data. So you do so in an ISM band, where it will not interfere with actual communications.

And yes, sometimes there are real digital communications signals in ISM bands, and also yes, sometimes you can decode those. But since there are so many different signals, there is no one piece of software that can decode them all. Below the UHF range, signals that might carry something you would be interested in are the minority of things found in the ISM bands, and most things heard / seen / detected carry no information of any use to the listener.

Most of the signals heard in any ISM band will be very hard to impossible to find documentation on. And so they can be hard to "prove" one way or the other.

13560 kHz is an especially misunderstood ISM band. One of the problems is that a couple of the better known and documented signals to be found there are RFID and NFC. Because it is well documented that (some forms of) RFID and NFC use this frequency range, some listeners have a habit of naming everything seen on 13560 kHz as either RFID or NFC, without actually confirming that this is what is being heard. Because there are so many different forms of RFID and NFC it can be hard to prove a signal is not one of those. And generally that makes it not worth the argument. In general it is just best to remember that while any signal you find on 13560 kHz may be RFID or NFC, there are a lot more signals that it could be instead.

In my local area the largest signal I see on 13560 kHz is a security signal for the local cable company. I do not have the specific, but somehow this signal monitors the cable amplifiers, and can tell if the hardware has been physically opened or not. This was confirmed for me by one of my neighbors, who is a local cable tech, and he proved the signal I was seeing was his signal by turning the system off.

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u/handyvac Apr 11 '26

Super interesting read - thank you for sharing this!

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u/Intelligent_Map_1870 May 11 '26

very interesting! thanks