FMP24 connection with RTL-SDR Error

[mtindor]

Yes now i got the data, but unable to hear decoded voice, also tell me how can i record its iq?
View attachment 193701

DSDPLUS --> OUTPUT --> SPEAKERS (and make sure your speakers are on)
- you should hear your decoded audio coming from DSDPlus

Look in my previous email regarding .IQ recording.

 

[mtindor]

And, if you went into the DSDPlus menu and started adjusting things that for which you did not know what they did, you probably screwed it up.

OUTPUT --> Synthesize All Digital Voice (make sure this is selected)

 

[mtindor]

NOTE: FMP24 can only play back FMP24-sourced IQ files.

So, that may mean that the IQ file that is produced by FMP24 is not compatible with other SDR applications.

Mike

 

[Saqib]

from DSDPlus --> Input --> Start Source Audio Recording, i recorded a raw audio file, 1R-DSDPlus-Raw-Input_2025-12-11@090458.wav when i playback the same file it doesn't decode completely it gives error why? it misses alot of audio data.

Once you have FMP24 <--> DSDPlus talking to each other, are tuned to an active DMR ffrequency, and can see DMR information at the bottom of the main DSD EVent window, then you can proceed to messing with recording IQ.

You record IQ via FMP24. In the command prompt window that corresponds to FMP24 (there is a command window associated with FMP24 and one associated with DSDPlus), do this:

1. open the command window for fmp24 so that you ccan see it
2. mouse-focus on FMP24 app
3. hit ?
4. Look at the command window for help
4. press R
5. Look at the bottom of the command window

I will indicating that recording to .WAV and .IQ has started and the top of FMP24 will say "RECORDING"

6. press R again to stop the recording

 

[mtindor]

from DSDPlus --> Input --> Start Source Audio Recording, i recorded a raw audio file, 1R-DSDPlus-Raw-Input_2025-12-11@090458.wav when i playback the same file it doesn't decode completely it gives error why? it misses alot of audio data.

bad input signal? If you are running a transmitter right besideyou, you're probably overloading the dongle receiver frontend. If it's not a site nearby you, it might be a weaker site. You need approx 20 db of signal for a good decode.

There is a saying -- "you can't polish a turd". And that applies to bad input signals.

Mike

 

[Saqib]

bad input signal? If you are running a transmitter right besideyou, you're probably overloading the dongle receiver frontend. If it's not a site nearby you, it might be a weaker site. You need approx 20 db of signal for a good decode.

There is a saying -- "you can't polish a turd". And that applies to bad input signals.

Mike

aaaa i'm sitting on my seat infront of my PC where dongle is connected and also i've DMR in my hand where i'm speaking. i think the DMR is only 1 feet away form dongle.

 

[mtindor]

aaaa i'm sitting on my seat infront of my PC where dongle is connected and also i've DMR in my hand where i'm speaking. i think the DMR is only 1 feet away form dongle.

you're probably overloading the front end of the cheap RTL dongle with the radio being so close.

Decrease power / decrease gain in FMP24 until it's only about 20-30 db.

 

[Saqib]

Ohkz now i understood the whole scenario, let me try again n again. well thank you so much for help and your time. #appriciated.

you're probably overloading the front end of the cheap RTL dongle with the radio being so close.

Decrease power / decrease gain in FMP24 until it's only about 20-30

 

[Saqib]

you're probably overloading the front end of the cheap RTL dongle with the radio being so close.

Decrease power / decrease gain in FMP24 until it's only about 20-30 db.

I've recorded files on different Db, from 5,10,15,20,25 upto 49, but on every file its still same, when i run those recording files it doesn't give clear audio. let me attach my output files, you can check them. i've also added my decoded file you can check that as well.

RecordedAudios.zip

drive.google.com

 

[dave3825]

On the raw input wav files, you have a signal issue. Error in each line and displaying different cc (color code) for each frame.

Please post a pic of FMP24 when you are receiving the signal from the radio.





On 1R-DSDPlus_DecodedAudio.wav we hear you counting and the audio is able to be understood.

 

[mtindor]

Ohkz now i understood the whole scenario, let me try again n again. well thank you so much for help and your time. #appriciated.

I've recorded files on different Db, from 5,10,15,20,25 upto 49, but on every file its still same, when i run those recording files it doesn't give clear audio. let me attach my output files, you can check them. i've also added my decoded file you can check that as well.

RecordedAudios.zip

drive.google.com

0458 sounds great.
3443 sounds great.
3855 sounds almost perfect.
4037 sounds almost perfect.

Some of the .wavs have no decoded audio. Most of the wavs have a couple of errors. Two of them sound perfect.

It's likely just an issue with the handheld being so close. I know you tested with different gains. But the energy from the radio transmitting may still be too much at times for the dongle right next to it to deal with.

Sounds to me like it's performing as I would expect it to perform.

Mike

 

[cg]

Also, best bandwidth for DMR is 7.6. The first screen shot has 7.6, the second has 12.5. Use "b" to adjust
Your SDR could use a touch of PPM adjustment but not a huge amount. Use "P/p" to adjust

 

[Saqib]

On the raw input wav files, you have a signal issue. Error in each line and displaying different cc (color code) for each frame.

Please post a pic of FMP24 when you are receiving the signal from the radio.


View attachment 193712


On 1R-DSDPlus_DecodedAudio.wav we hear you counting and the audio is able to be understood.

here is the screen record and screen short. please check.

DMRRecordingSS.rar

drive.google.com

 

[Saqib]

when i run those files, it gives this! it missed frames, didn't give full audio data.

0458 sounds great.
3443 sounds great.
3855 sounds almost perfect.
4037 sounds almost perfect.

Some of the .wavs have no decoded audio. Most of the wavs have a couple of errors. Two of them sound perfect.

It's likely just an issue with the handheld being so close. I know you tested with different gains. But the energy from the radio transmitting may still be too much at times for the dongle right next to it to deal with.

Sounds to me like it's performing as I would expect it to perform.

Mike

 

[mtindor]

when i run those files, it gives this! it missed frames, didn't give full audio data.
View attachment 193759

Then stop looking at the frames Nothing is perfect. No matter how you set things, there is probably some issue with running the radio right next to the dongle, no matter how lower the power is set or how low the gain is set.

And as @cg mentioned, you should make sure you are running a 7.6 BW using 'b' and that you're PPM is adjusted (using P / p) , both in FMP24.

 

[Saqib]

Then stop looking at the frames Nothing is perfect. No matter how you set things, there is probably some issue with running the radio right next to the dongle, no matter how lower the power is set or how low the gain is set.

And as @cg mentioned, you should make sure you are running a 7.6 BW using 'b' and that you're PPM is adjusted (using P / p) , both in FMP24.

i'm trying to improve the mistakes, so now i tried on different gain and BW, and now i'm using DMR from aprox 20 meter far. not nearby the dongle.