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
What are the drawbacks in using PLL ( if I can use one ) as compared to
coherent demodulator with carrier recovery?
Reply by Tim Wescott●August 10, 20062006-08-10
> 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
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).
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