Poul-Henning Kamp wrote: > In message <[EMAIL PROTECTED]>, Bruce Griffiths writes: > >> Poul-Henning Kamp wrote: >> > > >> Since USB and Firewire ports may persist a little longer, is it possible >> to use similar techniques with these interfaces? >> > > For talking to the timestamping device: certainly. For signalling > the computers time-edge: no way, they're serial protocols. > > >> Do you mean that the PCI66XX boards could be used to implement the >> multichannel timestamp function? >> > > Yes, they have counter and latches that I belive a suitable for > at least two signals, but I'm not sure there were any usable > prescalers. It was a long time ago. > > My understanding is that the prescalers are only useful for dividing the clock frequency down to a frequency that is sufficiently low for the counters. These boards are now available in 2, 4 and 8 channel versions. Their industrial counter timer boards have a maximum external clock frequency of 400Khz and a minimum pulse width of 1us, so thes may be less suitable. > I'm not sure what kind of flanks plastic fibers (as used for instance > from CD-players) have, I might go that route to get complete > electrical separation. > > I have 3 HP (now Avago technologies) 5 Mbaud glass fibre transmitter/receiver evaluation kits, I must get around to measuring their jitter and delay tempcos. However for low resolution time stamping (10ns resolution) they (and their plastic fibre cousins) should be perfectly adequate. Jitter may be a little high (for some purposes) when the timestamp resolution is 100ps or so. > I saw a HP eval kit with 3' of plastic fiber and transmitter and > receiver that would work great. > > > Bruce
_______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.