[time-nuts] GPSDO simulation tool

Poul-Henning Kamp phk at phk.freebsd.dk
Wed Mar 26 18:47:57 EDT 2014


In message <5333314D.5090202 at rubidium.dyndns.org>, Magnus Danielson writes:

>Did some home-work on third-degree PLL parameters, so now I know why I 
>failed, as I never tried to do it right.

Once you get to third-order PLLs you need to start paying serious
attention to rounding errors.

In most cases using a "double" floating point format will do, but you
have to make sure you don't loose precision to normalisation in
your additions.

I've had varying degress of success myself, and overall I'm not
sure it really makes sense to fight the battles, unless you need
really long hold-over times.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.


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