Will PLL duplicate a weak signal at the output properly?

[electron_boy]

about pll

i have one doubt. in a project i ve to track a weak signal. for that ive planned to use a pll. but the doubt i have is will the pll will exactly duplicate the signal at the output. i.e. will the weak signal be unchanged in its amplitude.

 

[flatulent]

Re: about pll

The PLL will have the same frequency. To duplicate the amplitude, you have to use the PLL output to down convert the input signal to DC and use that to determine the amplitude. Most PLL circuits will lock on at 90 degrees phase shift. Multiplying this by the input signal will produce zero DC so you will have to do a further 90 degree phase shift on the PLL output before mixing it with the input signal.

 

[IanP]

Re: about pll

If you say tracking, what do you expect this tracking output to be: a dc voltage fed to VCO, signal of the same frequency as your weak signal (usually output from VCO is a square wave) or what?
You may need to buffer this weak in order to maintain its amplitude ..[/quote]

 

[electron_boy]

Re: about pll

actually im doing a robot for a competition where ive to constantly monitor a fixed freq sound source and ive to move towards it. so iam using 2 mics for stereo reception of the sound . for tracking the fixed freq sound i ve planned to use a pll. and also ive to monitor the gain from the two mics to identify the location of the sound source. will the pll replica the input or it will give out only the dc. im a bit confused.

 

[blue2lucy]

Re: about pll

Please understand how PLL works first before you go any further.