Phase locked loop question

[George]

Just looking for a very quick ballpark indication, nothing accurate needed.

Is it easy and cheap to build a PLL with one degree resolution of a 30 kHz
sinusoidal signal input asuming low pre-detection noise (S/N > 50 dB) and
100 millisecond acquisition time?

Thanks, George

 

[Phil Hobbs]

Just looking for a very quick ballpark indication, nothing accurate needed.

Is it easy and cheap to build a PLL with one degree resolution of a 30 kHz
sinusoidal signal input asuming low pre-detection noise (S/N > 50 dB) and
100 millisecond acquisition time?

Thanks, George

50 dB SNR means an instantaneous phase uncertainty of
1/(sqrt(2)*10**2.5) radians, or about 0.13 degree, which is fine. If
you know that your signal is always near 30 kHz, you can make a VCO with
a restricted range, so that it will pull in very rapidly. (Simple PLLs
pull in nice and fast if the frequency offset is less than a few times
the loop BW.)

So something like a NE565 or MC14046 can do this, no problems. You'll
want to use an op amp in the feedback loop if you use a 565 or the XOR
phase detector of the '4046. If the sinusoid is nice and big, you can
use the frequency-phase detector in the 4046, which is even easier--no
op amp required, no limitation on pull-in range.

Cheers,

Phil Hobbs

(Do they even make 565s any more?)