[time-nuts] PLL performance?

David Scott Coburn scotttt at optonline.net
Tue Mar 21 21:26:37 EDT 2017


The loop filter does have a very low bandwidth, of the order you mentioned.

The lock time is surprisingly quick, but one man's pocket change may be another man's fortune....

I use a lag-lead filter with the PC2 comparator.  It begins to 'track' after a minute or so.

>From a cold start there is one large overshoot with the VCO frequency starting too low and then going high.  On the scope  you can then watch the VCO  0.5 Hz signal slowly sidle up to the reference 0.5 Hz signal over the course of a few more minutes.

It does take 10 or 15 minutes for it to settle to where the jitter is down into the 5th or 6th digit on my frequency counter though.

Scott

On Tuesday, March 21, 2017 12:14:15 PM EDT M. Simon via time-nuts wrote:up to
> To get your loop to lock and keep phase noise down the loop filter would
> need a bandwidth of .05 Hz or less. That would mean long lock times. Very
> long lock times. Engineering is the art of making what you want from what
> you can get at a profit. I like Polywell Fusion.
> 
> 
>     On Tuesday, March 21, 2017 2:01 AM, David Scott Coburn
> <scotttt at optonline.net> wrote:
> 

<snip>

> 
> 
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