# Translate signals amplitude into frequency

I have a sinusoidal signal at 50 Hz, that varies in amplitude, with no offset. The amplitude goes from 0 to 5 V (peak to peak), and the amplitude contains all the information I need. This signal will change abruptly (in amplitude) but not very frequently, by that I mean for example that it could be at 2Vpp for an hour and then suddenly change to 3Vpp.

What I want to do is transmit that information using FM. For that to work I will need to transform the signal into something which gives me the same information but now related to it's frequency. For example map the 0 to 5 V range into some frequency range so then I can modulate using a VCO. I would also need to demodulate this at the receptor, and will probably need to remap from frequency to voltage ater the signal is received. This I don't know how to do, so I'm asking for help here.

I don't know if I explained myself correctly, so I'll edit my question if needed. I know that FM may not be the best way to go here, but I have all the components I would need and I don't have the money to buy for some other option.

• May we know why you would like to do this? You should be using a peak detector. If you're clever, you can even make it reset on zero crossings. Nov 11, 2013 at 23:41
• I'm using a hall effect current sensor which gives me the current as the signal I described. Yes, I can use a peak detector, and now how to implement it. The issue is that then I will have a DC signal which I don't know how to transmit using FM. That's why I'm asking about translating the amplitude information (or the DC signal from the peak detection) into frequency. Nov 12, 2013 at 0:17
• I think it is often buffered and used to bias a varicap diode in an oscillator circuit. I also think this means you require a superheterodyne receiver on the other end. My knowledge of FM isn't as handy as it could be Nov 12, 2013 at 0:45