FSK Demodulation with ADAU 1701

Hello Lama,

You found the right post with two different ways to demodulate. So you want to mute the audio output when FSK is detected correct? 

Well, the first approach in the post you found is showing a way to do it. The output of the two filters are going through a peak envelop generator. That output can be summed and tested with a threshold level stored in a DC cell using an ABCD block like KJBob did. Then with that signal you invert it and use that to control a volume control. Most of the pieces are there. 

So what are you not able to get working? The FSK or the muting?

Feel free to attach your project. It usually saves time so we are not guessing. 

Dave T

Also tried the PLL variant, but get no signal on GPIO. However, audio seems to filter the FSK signal much better.

Design_Demodulation_PLL_V0.1.dspproj.zip

Got the sample PLL working. It shows a perfect signal at 50 Hz and is working fine up to 200Hz.

I adopted the sample to my frequencies and even the 50 Hz signal does not show fine:

However I need to achieve 1200 Baud. Is this a kind of magic feedback and filter configuration, or do I want too much from the little 1701 on 48 kHz sampling? 

Design_Demodulation_PLL_V0.2.dspproj

Got the sample PLL working. It shows a perfect signal at 50 Hz and is working fine up to 200Hz.

I adopted the sample to my frequencies and even the 50 Hz signal does not show fine:

However I need to achieve 1200 Baud. Is this a kind of magic feedback and filter configuration, or do I want too much from the little 1701 on 48 kHz sampling? 

Design_Demodulation_PLL_V0.2.dspproj