[time-nuts] WWV / WWVH / WWVB
Tom Van Baak
tvb at LeapSecond.com
Wed Jan 14 15:58:14 EST 2009
> Kind of a shame they didn't use the unused bits in the WWVB stream for some
> kind of checksum or error correcting code.
Not really. At just 1 baud and with questionable reception in
many parts of the country, checksum bits aren't the answer.
The usual WWVB trick is to collect as many minutes of data
as you want in order to increase confidence in your decoded
result. It allows you to pull a very weak signal out of the noise.
This might be as little as 1 or 2 minutes; or depending on time
and location, it might be 5 or 10 or more minutes. With this
level of patient oversampling there are a number of software
tricks one can employ to pull out an error-free timecode from
incredibly weak or noisy signals.
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