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General Scanning Discussion - For general questions not specific to a model of scanner or general discussion of use of a scanner. Manufacturer specific posts should be directed to the appropriate forums below and location specific posts should go in the appropriate regional forum..

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Old 03-11-2018, 3:37 PM
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Default Is this a digital transmission, data, or something else?

Does anybody know what this noise is on my local PD's tactical frequency? I have been hearing this off and on for months now. It doesn't happen everyday which leads me to believe its some sort of digital transmission or data? I have a digital scanner capable of P25, and DMR and it didn't decode it. I had the scanner set to Tone search, and it didn't have a Ctcss tone or NAC while this was transmitting. The PD usually uses a Ctcss tone of 173.8 on this frequency.

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Old 03-11-2018, 3:41 PM
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I've heard the same thing in a fire frequency in the next county over from me. I think it may be DMR or NXDN, but I really don't know. Or it could be icom iDAS


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Old 03-11-2018, 3:46 PM
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I've heard the same thing in a fire frequency in the next county over from me. I think it may be DMR or NXDN, but I really don't know. Or it could be icom iDAS


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Hmm. I don't think its DMR since my scanner decodes DMR. Maybe ill try and decode it with my SDR sometime if I can catch it.
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Old 03-11-2018, 3:49 PM
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Yeah this signal always really baffles me! I've never heard anything like it before...it could be DMR tier 3 but I doubt it. Do you know what type of radios your local police uses? Also, are they still using analog, or is this on full time and no analog traffic?


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Old 03-11-2018, 4:02 PM
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Yeah this signal always really baffles me! I've never heard anything like it before...it could be DMR tier 3 but I doubt it. Do you know what type of radios your local police uses? Also, are they still using analog, or is this on full time and no analog traffic?


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They still use analog. even on this frequency except for whatever this is. I would have thought if its some sort of digital voice transmission they would use it when they are conducting tactical operations because they even broadcast analog in the clear when they are doing stuff like that. I have heard encryption on this frequency once before in the past, about 5 years ago, but never again since. After doing a bit of searching I found a document that mentioned them using NX700 radios as mobiles, which are NXDN capable radios I think, so this might be NXDN.
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Old 03-11-2018, 4:04 PM
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They still use analog. even on this frequency except for whatever this is. I would have thought if its some sort of digital voice transmission they would use it when they are conducting tactical operations because they even broadcast analog in the clear when they are doing stuff like that. I have heard encryption on this frequency once before in the past, about 5 years ago, but never again since. After doing a bit of searching I found a document that mentioned them using NX700 radios as mobiles, which are NXDN capable radios I think, so this might be NXDN.


Yep I bet that's what it is. The same thing is going on in the county next to me, and I definitely think it's NXDN


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Old 03-11-2018, 4:07 PM
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Yep I bet that's what it is. The same thing is going on in the county next to me, and I definitely think it's NXDN


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I guess they also use the TK-5710 which is a p25 radio so I wonder why they use NXDN.
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Old 03-11-2018, 4:40 PM
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Just sounds like some form of digital voice or data to me -- can't really tell what type. If it's data, your radio won't decode it regardless.
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Old 03-11-2018, 4:41 PM
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does DMR -CAP - LNC - ENC - or some other code show up?
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Old 03-11-2018, 5:52 PM
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Just sounds like some form of digital voice or data to me -- can't really tell what type. If it's data, your radio won't decode it regardless.
I know if its data I cant decode it. I was just curious what it is.
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Old 03-11-2018, 5:53 PM
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does DMR -CAP - LNC - ENC - or some other code show up?
No, nothing shows up, so its probably NXDN or something my scanner does not recognize.
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Old 03-11-2018, 9:36 PM
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You need to get a $20 RTL SDR dongle and DSD+, it will tell you in about 30 seconds whether you've got a monitorable protocol or not.
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Old 03-11-2018, 11:45 PM
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You need to get a $20 RTL SDR dongle and DSD+, it will tell you in about 30 seconds whether you've got a monitorable protocol or not.
I have both. It's just a matter of catching it with the SDR and DSD when this pops up. It happens at random times, and usually doesn't last long.
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Old 03-12-2018, 1:57 AM
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NXDN9600, RAN4, group calls, 15 bit NXDN encryption.

RID 1 [Det Spare]

RID 2 [Radio-2]

Last edited by slicerwizard; 03-12-2018 at 2:46 AM..
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Old 03-12-2018, 1:26 PM
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NXDN9600, RAN4, group calls, 15 bit NXDN encryption.

RID 1 [Det Spare]

RID 2 [Radio-2]
Did you use DSD to find that information out?
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Old 03-12-2018, 3:57 PM
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DSD doesn't display that sort of information. I used DSDPlus.
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Old 03-12-2018, 5:10 PM
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Default one of the ones on here maybe

Digital*Modes*Samples
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Old 03-13-2018, 2:43 PM
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Sounds like a data control channel.....
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Old 03-13-2018, 4:31 PM
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Quote:
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Sounds like a data control channel.....
Eh? It's already been identified.
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