New Signal in NB

[Freemor]

Went to listen to my local P25 signals again and there is a new, mysterious, definitely not any P25 signal (that i know of) smack dab in the middle on the P25 range. I've seen it once before but that time it disappeared too quickly for me to get a screen cap. Does anyone know what this is? and/or how one would demodulate/decode it?

 

[Deziel0495]

Went to listen to my local P25 signals again and there is a new, mysterious, definitely not any P25 signal (that i know of) smack dab in the middle on the P25 range. I've seen it once before but that time it disappeared too quickly for me to get a screen cap. Does anyone know what this is? and/or how one would demodulate/decode it?


View attachment 182616

Hard to say without hearing it. What is the exact frequency it's on? Could do a search to see who/what it belongs to.

 

[Freemor]

Hard to say without hearing it. What is the exact frequency it's on? Could do a search to see who/what it belongs to.

I haven't figured out the center freq yet as it has nothing that looks like a carrier, just those blips spread over a fairly wide frequency spread. From the looks of it I'm guessing some type of MFSK. it is also intermittent which makes narrowing down the center frequency a bit more tricky. If I come up with a number I suspect is close I'll post it here. I may also post a baseband I/Q wav if enough people are interested.

 

[mciupa]

Looking at TAFL data for that frequency brings up this: TAFL Search Results
The emission shown on that license is

8K10F1W

P25 Phase II subscriber units (Harmonized Continuous Phase Modulation – H-CPM

Are you near any of the locations on the license?

 

[Freemor]

Looking at TAFL data for that frequency brings up this: TAFL Search Results
The emission shown on that license is

8K10F1W

P25 Phase II subscriber units (Harmonized Continuous Phase Modulation – H-CPM

Are you near any of the locations on the license?

I'm near a couple of those. but both the ones I am close to are way off frequency for this. they are both at 770.6ish, where the signal I'm seeing is in the 770.8ish. Also those licenses are for P25 and although this signal is in a P25 range, it looks nothing like P25. It doesn't even look like DMR.

I do not know if it is something they are testing or what. it is annoyingly intermittent. next time I see it I'll do a baseband recording if I have time before it winks out again.

 

[Freemor]

Watching it a bit more (hoping for a long enough run to do a base band recording) it looks a lot like what I'd expect to see on the ISM/SRD bands. Quick chirp style transmissions spread over 770.7M to 770.9M.

 

[dave3825]

If you have DSDPlus, you could try running it on that, and if its something DSDPlus supports, it should display what it is.

You could also poke around signal wiki to see if its listed there.

All Identified Signals - Signal Identification Wiki

www.sigidwiki.com

.

 

[Freemor]

If you have DSDPlus, you could try running it on that, and if its something DSDPlus supports, it should display what it is.

You could also poke around signal wiki to see if its listed there.

All Identified Signals - Signal Identification Wiki

www.sigidwiki.com

.

Don't have DSDPlus as I'm in Linux. I've already looked on the Sigidwiki but I wasn't thinking ISM/SDR type transmission at that point so I'll look again with that in mind. I may point rtl_433, which decodes ISM/SRD signals, at that part of the spectrum and see if it can decode anything.

 

[rhughes6]

Seeing as you’re in NB, have your electric meter changed to a smart meter recently? They use FHSS in the 902-928 mhz band, and with the poor filtering on some SDRs it might be possible that it’s showing up in a strange place, and with FHSS it might explain why it only shows up there intermittently. You could also check if there are any licenses for harmonic frequencies that might be data or telemetry of some kind.

 

[Freemor]

Seeing as you’re in NB, have your electric meter changed to a smart meter recently? They use FHSS in the 902-928 mhz band, and with the poor filtering on some SDRs it might be possible that it’s showing up in a strange place, and with FHSS it might explain why it only shows up there intermittently. You could also check if there are any licenses for harmonic frequencies that might be data or telemetry of some kind.

Interesting idea. Gave it a look. There is definitely chirp traffic on that band but much wider chips spread over the entire band. The signal in question is tiny chirps confined to a narrow segment of the band. So, probably not that. I'll play with the gain and panning to see if it might be harmonics from some other place.

 

[Freemor]

Finally managed to catch a run of more than a few blips. Here is the baseband recording. The signal seems to be centered on 770.8M or close to it. It is here

A longer run with more activity.

 

[Freemor]

There is currently a long and consistent run of this signal going on. I'm Just wondering if others in SW New Brunswick, or East Maine can pick it up. Closest cities would be St. Stephen in the Canadian side or Calais / East Port on the Maine side.

Also, wanted to add a bit of context for people that might be looking at those baseband recordings and trying to figure it out.
I live in a rural, coastal area (St. Andrews, NB) So there will be marine signal. I have a community trade college pretty much next door. So possibly stray signals from something there. But since I see the signal on weekends too I'm would think of that as a strong possibility.

My current thinking is that maybe someone close to me bought some radio/wireless doodad online and it is transmitting in a place it shouldn't be here in Canada. That's why I'm asking if others can see it. If it is just me then it's probably some extraneous local source not something related to the local P25 system that it is smack in the middle of.

I've tried to listen to the pulses FM, USB, AM But I can't hear any discernible structure. I suppose it could be some weird kind of QRM but if it is it a QRM pattern I've never seen before.