DMR not decoded - BCD536HP

[ASAD]

Hello. There is DMR activity in my area on VHF Hi. Some of the channels are decoded successfully but on certain channels I only hear raw data noise. Please know that I have purchased both DMR and NXDN licenses for my scanner and are activated. Why do I hear raw data noise on a DMR channel? Please see the screen shot attached.

 

[Saint]

Is it raw data or is it a someone using encryption

 

[ASAD]

Is it raw data or is it a someone using encryption

No ENC on this channel. There are some encrypted channels but I know those (they sound different). I have heard DMR and NXDN noises on analog channels. It sounds to be the same noise. I’m wondering why my scanner is not decoding if it’s DMR or NXDN.

 

[626hawkeye]

I've noticed at times while using "search for" or "custom search" I'd have tune down then back up using the scroll knob to get it to decode. Sometimes I'd have to do it a couple times. However once programmed in a favorites list it seems to decode just fine. It happens on both my 436 and 536. Don't get me started pin the 325p2 decoding.

 

[buddrousa]

Disregard

 

[ASAD]

I've noticed at times while using "search for" or "custom search" I'd have tune down then back up using the scroll knob to get it to decode. Sometimes I'd have to do it a couple times. However once programmed in a favorites list it seems to decode just fine. It happens on both my 436 and 536. Don't get me started pin the 325p2 decoding.

I have tuned up and down several times but the noise on certain frequencies (e.g.,160.2250) is continuous. I even saved it to favorites. It's still not decoded. Could it be a trunking control channel?

 

[kevino]

Are you positive that it's DMR or NXDN? If so, and seeing that it transmits continuously, a control channel would be my first guess. But the 536 should decode it if it's DMR, NXDN or even P25, so maybe it is some other data format.

 

[slicerwizard]

Why do I hear raw data noise on a DMR channel?

How do you know it's DMR and not something else, like dPMR?

 

[IAmSixNine]

There are other digital signals out there.

 

[Ubbe]

Could you set the scanner to record and post the file here so we can have a listen. We might be able to determine what kind of signal it is from listening to the audio recording.

/Ubbe

 

[ASAD]

Could you set the scanner to record and post the file here so we can have a listen. We might be able to determine what kind of signal it is from listening to the audio recording.

/Ubbe

Here is the recording from 2 different channels. I am getting 5 of these channels on VHF Hi.

 

[ASAD]

Are you positive that it's DMR or NXDN? If so, and seeing that it transmits continuously, a control channel would be my first guess. But the 536 should decode it if it's DMR, NXDN or even P25, so maybe it is some other data format.

I can't tell. It's a different part of the world. I didn't expect anything else here other than analog and DMR. May be it's one of these radios https://www.nrtc.com.pk/pdfs/LMR Encrypted Base Station.pdf

 

[slicerwizard]

That's not flat audio and it's recorded at a very low sampling rate. Not good.

 

[Ubbe]

Here is the recording from 2 different channels. I am getting 5 of these channels on VHF Hi.

It sure sounds like DMR. Strange that it doesn't trigger a DMR decode and mutes the digital audio.

Check again that those channels actually are set the same way as the ones that do decode the DMR signal. Try to set Threshold to manual and 8.
If you push the "channel" button to stop scan and then enter the frequency and then hit "channel" again it should decode DMR. The threshold setting for that mode are in the menu for Srch/CloCall Opt.

I know that I have problem with super narrow FM modulation that some ships are using, that are more narrow than FM and NFM. The audio level are too low to start to decode in the 536. Do Fn+CHANNEL and continue to push "CHANNEL" until you come to NFM and use that mode.
The most sensitive setting for threshold are 5 so try that as well, but it will also be the setting that creates the most false decodes but are good way to try and see if the signals modulation are too weak for a normal threshold setting, usually the one that auto will end up with after a few seconds.

/Ubbe

 

[ASAD]

It sure sounds like DMR. Strange that it doesn't trigger a DMR decode and mutes the digital audio.

Check again that those channels actually are set the same way as the ones that do decode the DMR signal. Try to set Threshold to manual and 8.
If you push the "channel" button to stop scan and then enter the frequency and then hit "channel" again it should decode DMR. The threshold setting for that mode are in the menu for Srch/CloCall Opt.

I know that I have problem with super narrow FM modulation that some ships are using, that are more narrow than FM and NFM. The audio level are too low to start to decode in the 536. Do Fn+CHANNEL and continue to push "CHANNEL" until you come to NFM and use that mode.
The most sensitive setting for threshold are 5 so try that as well, but it will also be the setting that creates the most false decodes but are good way to try and see if the signals modulation are too weak for a normal threshold setting, usually the one that auto will end up with after a few seconds.

/Ubbe

I added color codes to the favorite list. It worked. I used Quick Search instead of Custom Search, it helps me find new DMR channels. Thanks to everybody for his input.

 

[buddrousa]

Thanks for posting the answer it may help someone else down the road.

 

[Ubbe]

I used Quick Search instead of Custom Search, it helps me find new DMR channels.

Yes, that channel+freq+channel quick search mode has everything on auto so you can't screw up any settings that you might have programmed incorrectly at other places and are a good way to check new frequencies, and will even start to decode encryption but not decrypt of course.

/Ubbe