Hi The gotcha is that the NEMA string has a poorly defined transit due to the USB stack. The jitter is still there. On a loaded system it can be fairly large.
The next layer to the onion is that the location of the PPS within the NEMA string is also poorly defined on a lot of the cheap(er) hardware out there. There are some devices where it's off by a large fraction of a second. Better to figure out a way to get a "real" pps into the box. Bob On Nov 8, 2010, at 8:14 PM, jim s wrote: > This is probably the thousandth time this was asked, but I googled and didn't > get a direct answer. > > I want to do a crude (as in to the second or so) time server inhouse to add > into a group of high accuracy servers. This is so that I can go off grid and > still get updates. > > I see that there is a way to get a feed called PPS or with PPS via RS232. > The discussions of using USB instead are concerned with having too much > jitter. > > since USB by its nature won't have an accurate exact dedicated line to let > the GPS toggle to do a time hack to the software, I can see why RS232 is > preferable with the hardware signal lines they have. > > If I just go with the NEMA stream as it gets to me via an USB HID Com port, I > assume that there will be some jitter baring a way to send in the physical > time hack. > > Any pointers to reading or comment on this would be appreciated. I am > probably asking the query before I should, as far as research, and appreciate > any replies. > > Jim > > _______________________________________________ > 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. _______________________________________________ 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.
