On 03/01/14 15:05, David J Taylor wrote:
There seems to be a mis-perception that folk might estimate a fixed delay and somehow use the data as a source of time. That was certainly never my thinking, but simply to observe the delays, and see what values might be obtained. I've contributed one, rather uncertain, data point. It would be interesting to know whether there is any timing data in the various digital streams we get, either via terrestrial or via satellite sources.
There are several potential time-signals, but I would say it would be a bit hard to verify their traceability, which makes the exercise difficult.
The MPEG-2 Transport Stream have PID timestamps for every channel. However, there is really no good TAI/UTC traceability in them. Also, re-stamping is used to cover up for delay variations.
VITC might be present, and might provide local time, but for NTSC countries there is a frequency error only partly covered in the drop-frame compensation which causes a deviating display-time from actual local time.
Caption can also carry time, but there is no guarantee it has a sane source. Cheers, Magnus _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
