Hi With anything like this a very real question is “what am I trying to do?”. Generally it involves getting time from device A to device B. The next layer of the onion is “how accurate is device A?” and “how good does device B need to be?”. If the source is only good to 0.1 seconds, there isn’t any way the destination will be any better than that. Once the link is 10X better than the source, making it any better does not significantly improve the destination’s idea of what time it is.
You can do pretty well with serial streams that have a definition of which point in the string is the “time mark”. That assumes your gear has a good way to link that point in the string to your local source clock (at the origin) or the flywheel clock (at the destination). This may not be as easy to do as one might hope. Often the packaged solution that already worked out all this mess wins out. Bob > On Aug 7, 2019, at 8:13 AM, Ralph Aichinger > <ausserirdischesindges...@gmail.com> wrote: > > Hi everybody! > > > I am a newbie and am wondering what options there are for exchanging time > > on a more basic level than NTP or PTP (that is for situations when a > > full network stack is too complex). > > > For now I have found: > > > NMEA (probably ZDA only) > > IRIG timecode (this is rather complex, I would rather have a > > full network stack than IRIG?) > > SMPTE timecode (this too?) > > > Are there any other obvious candidates I missed? How did e.g. > > HP atomic clocks tell their time to connected devices before > > there was the NTP protocol? Did they output NMEA or something > > else? Did they emit IRIG directly? > > > I want to create an Arduino based clock that tells time to a computer > > it is linked too. For exact seconds alignment I want to use a PPS signal, > > but I need a means to tell the computer about second numbers, hours etc. > > too. > > > Of course I could invent a serial protocol, but I suppose if I invented a > > text based serial protocol, it would probably end up looking very > > similar in structure to NMEA ZDA sentences. > > > *Is* NMEA the most practical time protocol at the 1 second level > > (that is when a PPS pulse takes care of second alignment?) or should > > I use something else if I am free to design stuff clean slate? > > > TIA > > /ralph > > -- > > ----------------------------------------------------------------------------- > > > https://aisg.at > > ausserirdische sind > gesund > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
