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[help]Digital Pll for decoding FSK signal

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bobcat1

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pll sourcecode

Hi

I have attached source code (c language) for digital pll who decode FSK signal
in the 1150 ~ 2150 Hz frequency range , I have 4 questions:

1) Can this source code be allterd to decode FSK signal with frequency range between 100 ~ 200 KHz

2) Whether the answer to question 1 is true - how do I re calculate the coefficient and sample frequency to work in the new frequency range

3) Whether the answer to question 1 and 2 are true - how many A2D samples neded (window size) in order to id a the 1 st and the 2nd frequency.

4) Can I use DFT insted of PLL to ID the requested frequency magnitud or is it a slower methode

Any answer will be appreciated

Thanks

Bobi
 

FvM

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digital pll

1) No, because it's far beyond the LPC213x speed capabilities.

The original code is performing it's sampled operation at an interrupt frequency of 8 kHz. It sounds illusional, to increase it by a factor higher than 5 or 10.

Also the maximum ADC sampling rate of about 400 kHz is basically too low. Nyquist rate isn't sufficient in this case.
 

bobcat1

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digital pll source code

Hi

The code attached was for referance only, I have no plan to impliment it on the LPC213x it is to slow for my project

regarding the samplerate the controller A2D I have plan to work with can sample up to 750KHz

all the best

bobi
 

FvM

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how to decode fsk

I wouldn't think about the implementation details unless it's clear, that the controller can perform the required amount of arithmetics at the sampling frequency.
 

bobcat1

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pll fsk decode

HI

Would this code work with 50KHz & 60KHz carrier frequency?(50KHz for F1 and 60KHz for F2)

What should be the sampling frequecy and the window size?

how do I make the calculation?

All the best

Bobi
 

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