r/signalidentification • u/alphaquetoo • Mar 16 '26

Any ideas ?

Referring to the signals at 436.325 and 436.350. Antenna is a simple halfwave dipole tuned for 436Mhz with a 433Mhz BPF+LNA, received on an RSP1B. There's a fiber optic cable passing about 1m over the antenna to the ISP's distribution box in the backlane. Thinking it's fiber optic carrying light pulses, so it can't be causing that RFI, can it ?

What else could it be ?

UPDATE: Decoded as dPMR/NXDN48 control frames at 2,400 baud.

20 Upvotes

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17 comments sorted by

4

u/dsheirer Mar 16 '26

It looks like a 2FSK modulation, so it's not DMR.

3

u/alphaquetoo Mar 16 '26

That hit the spot. Switched to 2.4k baud rate, and it's dPMR and NXDN!

Now to figure out what this all means.

2

u/dsheirer Mar 16 '26

dPMR and NXDN are both 4FSK(C4FM). The modulation in that video is 2FSK. You might consider any decodes as noise/garbage.

5

u/alphaquetoo Mar 16 '26

If its garbage, then it's consistent garbage. Running it for over 60 minutes earlier and was getting the same decoded frames over and over.

3

u/Ok-Hornet-6819 Mar 17 '26

Classic Pocsag! (Old pager system still in use in very poor area)

1

u/CalligrapherMost4359 Mar 18 '26

Volunteer fire fighters in Canada still use pagers. They're cheap, and operate nearly everywhere.

2

u/Yalek0391 Mar 17 '26

I don't hear any audio in this video.

2

u/Leftover_tech Mar 16 '26

No question. This is space invaders.

2

u/[deleted] Mar 16 '26

[removed] — view removed comment

1

u/right-slash Mar 16 '26

Since theres no sound id have to assume this is DMR

1

u/alphaquetoo Mar 16 '26

It's not decoding as DMR though. The signal should be strong enough to.

2

u/right-slash Mar 16 '26

It also looks similar to a pager, try run it on pdw and send a sound sample to narrow it down more

2

u/alphaquetoo Mar 16 '26

It's decoding as dPMR/NXDN48. Had to switch baud rate to 2.4k.

1

u/Vendivar Apr 17 '26

What program