FM down converter in LabView. How?

[ACiDuser]

Hello NI Developers!

I have Frequency Modulated (FM) Signal, with carrier frequency 1000Hz and message signal frequency 20Hz. I want to downconvert FM signal frequency to 200Hz. I searched through the forum and google and didn't find anything where would be at least algorithms or Math equations. How to downconvert FM signal?

The aim is down convert signal to low frequencies where it is easier to filter from noise.

Thank you in advance! 

[Vivek_N]

Hello,

You could try using the Scale Delta t VI (Functions >> Programming >> Waveform). As the help says, "Multiplies the delta t component of the waveform by the specified scale factor. Generally, this lengthens or shortens the sample rate of the waveform." 

You could also take a look at the  Resample Waveforms (continuous) VI (Functions >> Signal Processing >> Waveform Conditioning. 

I hope this helps.

[ACiDuser]

I needed to shift signal spectrum in frequency domain - to DC. Not changing sampling rate.

I already solved this problem - simply by multiplying Signal with COS(w0t);   where w0 - Signal carrier frequency.

[ACiDuser · Accepted solution]

This is my problem solution. An example of Digital Down-Converter for FM Signal. Note: That any other signals can be downconverted too.