DMR message decode issue #231

Looking through this output, DSD-neo is detecting the DMR transmission and successfully reading the data header, but the actual message blocks are arriving corrupted.

The header says this is a confirmed Short Data message with nine 3/4-rate blocks and UTF-32 formatting. After that, nearly every R34C block reports:

(CRC ERR)

and the completed message ends with:

Multi Block PDU Message CRC32 ERR

Because the payload fails both the individual block checks and the final PDU CRC32 check, DSD-neo cannot safely display the text. Relaxing the CRC checks would not repair the message, it would most likely produce garbage.

The later output points to the same reception/input problem:

CACH/Burst FEC ERR FLCO FEC ERR Input Level LOW -40.8 dBFS

Voice can still sound acceptable while data messages fail because a multi-block data message needs every block to be received correctly.

A few things to check:

• Confirm the TCP producer is sending signed PCM16LE, mono, at 48 kHz.
• Raise the audio/source level in the SDR application; the incoming PCM level is currently low.
• Make sure the signal is accurately centered and the SDR’s frequency correction is right.
• Avoid an overly narrow NFM filter.
• Disable noise reduction, audio EQ, or other processing that may distort the DMR discriminator audio.
• Check RF gain and signal quality, but avoid turning the gain up far enough to overload the receiver.

--input-volume 2 can be tried as a quick test if the TCP audio itself is simply too quiet, but it will not improve RF SNR or repair distorted audio.

Could you also provide:

• The exact DSD-neo version
• Your complete command line
• The SDR application and its NFM bandwidth/audio settings
• A short, raw input recording covering one known test message

You can make the recording with something like:

dsd-neo.exe -fs -i tcp:127.0.0.2:25500 -6 dmr-test.wav
i am using dsd-neo VERSION 2.3.0,

image Audio File: [dmr-test.wav](https://github.com/user-attachments/files/30073556/dmr-test.wav) image

i send a message from DMR, "helo i am junior, its a text message".

Thanks, the screenshots help. The 48 kHz mono TCP output and no de-emphasis look right. One thing that jumps out is the 50 kHz NFM bandwidth... that’s much too wide for a 12.5 kHz DMR channel. Try around 12.5–15 kHz and retest.

The new output is still showing CRC errors on every R34C block plus the final PDU CRC32 error, so DSD-neo still isn’t receiving an intact message payload.

There’s also a separate limitation here: the radio is sending Defined Short Data as format 0x16 (UTF-32), which v2.3.0 doesn’t currently decode properly. So even after the reception errors are fixed, this particular text format will need some decoder work.

I tried downloading dmr-test.wav, but the attachment is returning a 404. Could you upload it again, maybe as a ZIP? Your -6 dmr-test.wav command is correct. Once I can replay it, I should be able to tell how much is reception-related versus the UTF-32 limitation.

Thanks, the screenshots help. The 48 kHz mono TCP output and no de-emphasis look right. One thing that jumps out is the 50 kHz NFM bandwidth... that’s much too wide for a 12.5 kHz DMR channel. Try around 12.5–15 kHz and retest.

The new output is still showing CRC errors on every R34C block plus the final PDU CRC32 error, so DSD-neo still isn’t receiving an intact message payload.

There’s also a separate limitation here: the radio is sending Defined Short Data as format 0x16 (UTF-32), which v2.3.0 doesn’t currently decode properly. So even after the reception errors are fixed, this particular text format will need some decoder work.

I tried downloading dmr-test.wav, but the attachment is returning a 404. Could you upload it again, maybe as a ZIP? Your -6 dmr-test.wav command is correct. Once I can replay it, I should be able to tell how much is reception-related versus the UTF-32 limitation.

well! i tried on 12.5 and 15k but still facing same issue. let me show you the files.
https://drive.google.com/file/d/1xobzbfLW7TujZdp8Y8TE1oHa4-YPrrBc/view?usp=sharing

i've uploaded the .rar file here. with all the files and Readme.text please review them. and you've mentioned that v2.3.0 doesn’t currently decode properly format 0x16 (UTF-32), then is there any other version or way from which i can achieve my requirement?

i implemented the decoder changes to support this, the latest nightly build has it: https://github.com/arancormonk/dsd-neo/releases/download/nightly/dsd-neo-msvc-x86_64-native-nightly.zip

Yes! Now i can see the text, currently i pulled the source code from your git, and i am trying to read it, i created .exe from that code, and using exe from release. please can you provide me the updated code or the file you've made changes, so that i can put it in the source folder? i am still learning many things and DSD is helping me alot.