[time-nuts] WWVB BPSK Receiver Project? (fwd)
lists at rtty.us
Fri Mar 16 16:36:40 UTC 2012
My main concern on short averages is the relatively long path from WWVB to
most of the target audience. The day / night phase shift is fairly
significant over a long path. That's something I would want to process out.
Since it (hopefully) is predictable, it's just another thing to feed into
the signal estimation side of the process.
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Poul-Henning Kamp
Sent: Friday, March 16, 2012 12:27 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] WWVB BPSK Receiver Project? (fwd)
In message <34C510BB3C6449B89AC4F7FBC20F46DA at vectron.com>, "Bob Camp"
>One assumption is that you will indeed be capturing / averaging for several
>days. I'd include some sort of model for sunrise / sunset shifts (might be
>just "ignore for the next hour").
Some of my best results had 8 buffers each used for 3 hours and
all timenuttery based on 24 hour differences from these buffers.
>Another assumption is that your local reference is close enough and stable
>enough to make a multi day average meaningful.
Well, the above technique got me a new offset estimate every three hours
and that did a pretty good job on both OCXO and Rb disciplining.
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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