FM demodulation Sound card

[IRserial]

Hi,

I am using a VCO (Voltage Controlled Oscillator) to convert an input signal (pulse: lengh=0.1ms DutyCycle=2%)  in  tones and acquire it with my sound card (mono 16 bit 44,1kHz). My goal is to demodulate the signal obtained by the VCO to retrieve the amplitude voltage of the input pulse and sum these voltage with a loop that iterate at each pulse event. Obviously, the problem is the time to aquire tones and demodulate it (each iteration must take less than 5ms). Does anybody have an idea???

Thank you
François

[Jarrod_S.]

If your only problem is loop iteration times, then I would recommend splitting up this process (acquisition and analysis) into two parallel loops. This way you can have one loop dedicated to acquiring data quickly and pass the data to the other loop that would analyze the data accordingly. An application design pattern along these lines might help you get started. Also look into other design patterns such as the Producer Consumer that transfer buffered data from one loop to the other using Queues. Hope this helps!

[AnalogKid2DigitalMan]

Any reason not to use a DAQ card with analog inputs? Seems like a more accurate way to sample. But yes, it does cost more.

[Jarrod_S.]

It's true, that's a great idea. With a DAQ card you'd have hardware dedicated to performing the analog acquisition in real-time. It would automatically use a buffering technique for a continuous acquisition which would allow you some breathing-room in your application with regards to loop times.