[Discuss-gnuradio] RFC: A generic 'Loop Filter' for PLL type blocks (Work with Freq and Time synch)

[Colby Boyer]

Hi All,

Recently, I've gone down the road of timing synchronization and ended
up learning basics for PLLs and such. So far in GNURadio, it seems
that the loop filters used in the existing GNURadio synch blocks are
only first order. From what I understand, increasing the filter order
of the PLL can help it to lock in the presence of noise, for both
timing and frequency. Any else care to comment on the performance
gains for higher orders?

I propose to come up with a block that can cascade a series of
integrators and gains to form a loop filter. The total order and gains
of the filter can perhaps be defined in the block constructor. The
idea is make the block generic enough so that you can drop it in with
an outside NCO and phase error detector.

Thoughts, questions or concerns?

Colby