[time-nuts] Alternate frequency sources - second opinions

J. Forster jfor at quik.com
Sun Nov 22 23:10:55 UTC 2009


> Hockey puck (or mouse) type GPS receivers are available for under $100.
>
> What can I get in that price range that doesn't depend on GPS?  I'm
> interested in millisecond accuracy as well as nanosecond.
>
> Has anybody built a WWVB-DO?  (Time to dust off my WWVB toys.)
>
> Is there some good WWV setup?

I have an HP 117A and loop. It works much of the time, but has diurnal
night/day shifts of a good fraction of a 60 KHz cycle. It really takes
continuous monitoring for several days to get good numbers.

> Somebody mentioned TV and radio stations recently.  (I think it was part
> of the North discussion.)
>
> What sort of frequency source is at the root of the local TV or radio
> stations?
>
> Is the sync timing for TV stations derived from the same source as the
> carrier?  Or are there two separate clocks to discuss?  How about the
> color-burst frequency?

NTSC is gone w/ analog TV. No color burst any more.

> What do radio/TV stations do for backups?  If there was a hurricane or
> earthquake that broke the main transmitter are they likely to switch to a
> backup with a different timing source?

I'm not sure, but when satellite links go down, the picture freezes. That
implies a frame store which is likely bad news for timing.

FWIW,
-John

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