On 2020-07-08 03:05 AM, Per Jessen wrote:
As long as it receives the time signal, the precision will be that of the WWVB time code.
That would be the clock accuracy, not the display precision. Precision refers to how accurately you can read something. That doesn't mean the clock is accurate, as it could be off but you, but you can read it precisely. One example I recall from years ago would be 2 rulers. One has coarse divisions, but they are extremely accurate. The other has fine divisions, but the entire ruler is the wrong length. With the first, you could accurately measure things that are close to the coarse divisions, but with the other, you'd be wrong, no matter how many divisions there were, if you didn't know about the error. Astronomers considered something called "rate". It is the known error in a clock and they would include it in their calculations. This reminds me of something at work many years ago. I used to work for a telecom company. In the network mangement centre, there was a large digital clock. I asked one of the guys how accurate it was. He said it was very accurate because it was driven by the same clock as the entire network, which was derived from LORAN C. However, that only provided an extremely accurate time base, not time of day. The actual displayed time was set by hand. This was back in the days before the Internet became popular, so NTP wasn't an option. I know ntp can be accurate within milliseconds, but that's an entirely separate issue from how accurate the display is in relation to it.
It will probably depend on where it is displayed, but if you do a gettimeofday(), the result is returned with precision in microseconds.
You'd have to be connected to an appropriate stratum 0 source for that. Stratum 1 will only be within milliseconds. Incidentally, I read a book about time & frequency, etc. It's a free download from the NIST: https://nvlpubs.nist.gov/nistpubs/Legacy/MONO/nistmonograph155e1999.pdf https://en.wikipedia.org/wiki/Network_time_protocol https://en.wikipedia.org/wiki/Loran-C -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org