Is this DMR ?

TA2ISO
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Is this DMR ?

Post by TA2ISO » Wed Mar 18, 2020 11:05 pm

OpenGD77 decodes some talk groups and ids but there is no audio.
gqrx_20200318_224223_425300000.zip
(232.58 KiB) Downloaded 23 times
It looks like some kind of a trunking control channel. DSD also sees it as DMR.

VK3KYY
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Re: Is this DMR ?

Post by VK3KYY » Thu Mar 19, 2020 12:04 am

It doesn't sound like DMR to me.

Open the file in Audacity and you'll see 2 distinct packet types.
There is a short burst and a long burst.

I don't know what this is typical of.

Try using a SDR dongle and DSD, it auto detects most modes

kt4lh
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Re: Is this DMR ?

Post by kt4lh » Thu Mar 19, 2020 12:34 pm

Maybe it's Tier 3? Encrypted?

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EB3AM
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Re: Is this DMR ?

Post by EB3AM » Thu Mar 19, 2020 11:39 pm

TA2ISO wrote:
Wed Mar 18, 2020 11:05 pm
OpenGD77 decodes some talk groups and ids but there is no audio.gqrx_20200318_224223_425300000.zip

It looks like some kind of a trunking control channel. DSD also sees it as DMR.
Maybe Tetra?
Is constant? or is like a talk transmission? Tetra make a constant TX on the BSU...
Jordi, EB3AM, Talarn JN02ke, Catalonia.

TA2ISO
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Location: Istanbul

Re: Is this DMR ?

Post by TA2ISO » Thu Mar 19, 2020 11:52 pm

dsd3.png
dsd3.png (270.94 KiB) Viewed 383 times
dsd4.png
dsd4.png (249.59 KiB) Viewed 383 times
gqrx_20200319_233419_425300000.zip
(505.23 KiB) Downloaded 9 times
This is the longer version with a different burst at the end.

TA2ISO
Posts: 18
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Location: Istanbul

Re: Is this DMR ?

Post by TA2ISO » Fri Mar 20, 2020 12:13 am

EB3AM wrote:
Thu Mar 19, 2020 11:39 pm
TA2ISO wrote:
Wed Mar 18, 2020 11:05 pm
OpenGD77 decodes some talk groups and ids but there is no audio.gqrx_20200318_224223_425300000.zip

It looks like some kind of a trunking control channel. DSD also sees it as DMR.
Maybe Tetra?
Is constant? or is like a talk transmission? Tetra make a constant TX on the BSU...
Have`t tried decoding it with tetra, going to try with telive. i have never listened to a tetra frequency sounding like this one though.

VK3KYY
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Re: Is this DMR ?

Post by VK3KYY » Fri Mar 20, 2020 1:14 am

Probably encrypted audio

G4EML
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Re: Is this DMR ?

Post by G4EML » Fri Mar 20, 2020 9:39 am

Doesn’t sound like DMR. But even if it is don’t forget that DMR is not only used for voice traffic. Many systems use it just for digital data or telemetry. As previously mentioned tier 3 is trunked and so also has a control channel.

VK3KYY
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Re: Is this DMR ?

Post by VK3KYY » Fri Mar 20, 2020 9:52 am

There is around 10ms of audio, then a gap of around 10mS, then there is 30mS of audio then another gap of 10ms

I'm not sure what DMR looks like, does it have gaps in it?

waveform.png
waveform.png (5.61 KiB) Viewed 349 times

G4EML
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Re: Is this DMR ?

Post by G4EML » Fri Mar 20, 2020 11:28 am

DMR from a repeater is constant, no gaps. You can hear changes in the tone when speech or data start but they are quite subtle.

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