DSD questions or Suggestions

[SDR_USER]

this is my first topic so I hope I am in the correct place. I have been using SDRAngel for some time. I have uploaded the most recent and I am not getting the best performance from the DSD. It receives and I show no errors on the log but I have noticed that the Output frequency response is muffled like there is to much low frequency output below 500 hertz. On viewing the output of the DSD on the spectrum analyzer I find that to be the issue. Frequencies about 2000 Hz fall off rapidly. I added a equalizer (audio) and cut frequencies below 500 to -60db. It appears to clean it up and is more readable. Is the digital samples less than 8 bit? Is it possible to add to SDRAngel a E.Q. connects to the out of DSD and compensates for the issue? Maybe I am doing something wrong? Suggestions would be appreciated. Thank you so much for your hard work. I really love this thing and it is so versatile. Thanks again , Kurt.

[andyrs]

In principle AMBE software decoding is known to be rather poor in terms of audio quality. It is not like TETRA's ACELP codec for example. I think that quality also differs by format (DMR, Fusion etc), but really not sure about that...

Other than using hardware AMBE dongle, did you switch on hipass filter in settings? See A.10 on the help page.

[Sebbi]

this is my first topic so I hope I am in the correct place. I have been using SDRAngel for some time. I have uploaded the most recent and I am not getting the best performance from the DSD. It receives and I show no errors on the log but I have noticed that the Output frequency response is muffled like there is to much low frequency output below 500 hertz. On viewing the output of the DSD on the spectrum analyzer I find that to be the issue. Frequencies about 2000 Hz fall off rapidly. I added a equalizer (audio) and cut frequencies below 500 to -60db. It appears to clean it up and is more readable. Is the digital samples less than 8 bit? Is it possible to add to SDRAngel a E.Q. connects to the out of DSD and compensates for the issue? Maybe I am doing something wrong? Suggestions would be appreciated. Thank you so much for your hard work. I really love this thing and it is so versatile. Thanks again , Kurt.

The muffled sound could be due to the DSD output or settings. The digital samples are 16-bit, not 8-bit. Adding an EQ was a good move. I’d suggest checking for any audio settings in SDRAngel to see if you can adjust the frequency response further.