Mixing signals for optical Link

[Mr CCE]

Hi everyone,

I'm currently working on an experiment that involves an AM and FM modulated signal being mixed together someway so I can transmit the mixed signal through an optical Link ( IR led,fiber optic,photoTransistor ).

On the Rx side the two signals will be separated and each one properly demodulated.

My question is: How can I mix these two signals and consequently how can I "Un-mix" them?

thx very much for any help in advance,

best regards

 

[carbonzit]

Would probably help to know the frequencies of these signals.

 

[crutschow]

If the two signal carriers are far enough apart in frequency then you could linearly sum them together, and use that to linear amplitude modulate the optical link transmitter. At the receive end you would linearly recover the signal and send it through two narrow filters to separate the two signals back into their respective individual signals. These can then be demodulated using the respective AM and FM demodulators.

 

[Mr RB]

I would consider using a microcontroller doing 2 channel ADC and sending digital data, then using another micro to decode the digital data and produce 2 DAC or 2 PWM etc as needed.

You might even be able to get some of the common ADC/DAC chips they use to send 2 channed digital audio over optical link, that's a pretty standard task these days and many appliances have optical connetors.