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MSK demodulation using PLL

Started by Unknown August 10, 2006
Can I implement a MSK demodulator using PLL? Basically I want to
demodulate MSK using FM demodulator IC. The IC uses a PLL for FM
demodulation.

What are the drawbacks in using PLL ( if I can use one ) as compared to
coherent demodulator with carrier recovery?

Thanks

~ Kaushal

kaushalparikh@yahoo.com wrote:

> Can I implement a MSK demodulator using PLL? Basically I want to > demodulate MSK using FM demodulator IC. The IC uses a PLL for FM > demodulation.
If you can do FM demodulation then you can probably do MSK -- you'd really want a chip that is designed for FSK demodulation, but as long as you can recover DC from your PLL you'll be all right as far as it goes.
> > What are the drawbacks in using PLL ( if I can use one ) as compared to > coherent demodulator with carrier recovery? >
Noncoherent demodulation of MSK loses you a whole bunch of effective power. Just how much you'd lose probably depends on the error rate that you're aiming for and how you implement your detector. For a realistic system with Gaussian noise I'll bet that you couldn't do better than 6dB loss; in something that's just thrown together the loss could easily be as bad as 20dB. For information on coherent detection of MSK see my Master's thesis: http://www.wescottdesign.com/articles/MSK/mskTop.html. It probably isn't the best possible exposition on MSK, but it's the best one I can point to on the web (other links would be welcome). -- Tim Wescott Wescott Design Services http://www.wescottdesign.com Posting from Google? See http://cfaj.freeshell.org/google/ "Applied Control Theory for Embedded Systems" came out in April. See details at http://www.wescottdesign.com/actfes/actfes.html