Post by dave on Nov 4, 2008 7:29:59 GMT -5
Hello everyone!
My question (actually more than one) to the forum is:
Is it possible to create a PLL which can lock to signals in the audio band (say 20..10KHz)? The problem I can see is that say we have an input of 40Hz and a VCO output of 43Hz (instantaneously) so we have 3Hz and 83Hz components. Am I correct in thinking that this would be a little disastrous since it wouldn't be possible to filter out the sum component without limiting the bandwidth to such an extent that it wouldn't be able to lock to signals over the full range?
Is the operation of PLLs in the classic 2nd order analysis dependent on the assumed absence of the sum component generated by the phase detector i.e. by the loop filter?
Would I have to heterodyne the audio signal first to get it out into a higher frequency spectrum for success?
Kind regards,
Dave.
My question (actually more than one) to the forum is:
Is it possible to create a PLL which can lock to signals in the audio band (say 20..10KHz)? The problem I can see is that say we have an input of 40Hz and a VCO output of 43Hz (instantaneously) so we have 3Hz and 83Hz components. Am I correct in thinking that this would be a little disastrous since it wouldn't be possible to filter out the sum component without limiting the bandwidth to such an extent that it wouldn't be able to lock to signals over the full range?
Is the operation of PLLs in the classic 2nd order analysis dependent on the assumed absence of the sum component generated by the phase detector i.e. by the loop filter?
Would I have to heterodyne the audio signal first to get it out into a higher frequency spectrum for success?
Kind regards,
Dave.