On Nov 8, 2010, at 10:58 PM, jimlux wrote: > 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. > > I would think that USB is not inherently worse than a hardware RS232. Both > have some interrupt latency, but it's small in both cases. USB has to handle > audio reliably at no worse than 8kHz sampling rate.
And as an audio nut as well as a time nut I can say that USB and Firewire both do this poorly (under certain conditions). I often have to restart encodings of multi-track audio if I don't shut absolutely everything down on what should be a well powered system because USB and Firewire both are unable to keep up. -- Mike _______________________________________________ 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.
