DSDPlus FMPx Noise Filters with DSDPlus

[EI9BAB]

I uses DSDPlus with FMP24 and FMPA and there is a big improvement in decoding quality when I switch on the Noise Filter (NF2 specifically) in FMPx. However, if I want to take audio from something else like a discriminator tap or an audio file I would like to be understand what exactly the FMP noise filter does please. Is it filtering out specific audio frequencies with some form of audio equalisation or notch filtering or does it remove certain patterns of sounds or what? Is it possible to replicate this with something else before feeding audio into DSDPlus?
Thanks

 

[DaveNF2G]

If you are using a discriminator tap, then FMPx is not doing anything. Its job is to control the SDR dongle.

 

[EI9BAB]

Sorry if I wasn't clear on my question. I'm trying to work out how to clean up the audio if it is NOT coming from FMPx. I'd just like to understand what the noise filter does so I can try and replicate that processing outside off FMPx if possible.

 

[mtindor]

If you are using a discriminator tap, then FMPx is not doing anything. Its job is to control the SDR dongle.

Not what he is asking. he is asking what the noise filters are actually doing so that perhaps he may be able to duplicate the efforts of the noise filters when running a discriminator tap [such as piping that discriminator tapped signal through SDR software and modifying filtering).

 

[slicerwizard]

Sorry if I wasn't clear on my question. I'm trying to work out how to clean up the audio if it is NOT coming from FMPx. I'd just like to understand what the noise filter does so I can try and replicate that processing outside off FMPx if possible.

It's going to be some sort of low pass filter that sharply attenuates audio frequencies (i.e. the noise) above some threshold (somewhere around 2 kHz, give or take)

 

[EI9BAB]

Thanks @slicerwizard
Maybe there is an audio filter that I can apply to the stream before I send it then. I've used a couple of tools to do something similar before so I might have a play with those again.