On Mon, Mar 19, 2012 at 3:06 PM, unruh <un...@invalid.ca> wrote: > On 2012-03-19, Chris Albertson <albertson.ch...@gmail.com> wrote: > > On Mon, Mar 19, 2012 at 10:25 AM, Alby VA <alb...@empire.org> wrote: > > > >> On Mar 19, 12:12 pm, unruh <un...@invalid.ca> wrote: > >> > >> > The actual PPS signal at the PPS pin has a rise time of about 10ns, > and > >> > the Sure has a normal sawtooth timing signal, so that would indicate a > >> > few 10s of ns accuracy from the Sure, but the conversion to RS232 > washes > >> > that out > > > > > > Does the conversion to rs232 add uncertainty or simply a fixed delay. I > > can't believe the conversion is so noisy. it can be done with a single > > 2n2222 transistor or if you care about speed find a faster RF transistor > > that works at UHF. > > Probably delays, but also noise. If the signal ramps up very slowly, > then the slightest noise on the line will cause the transition to occur > early or late ( and there is always noise.) >
That's true, but the raise time is about 10 nanoseconds. I'd think that even with noise the transition would occur some time within the 10ns raising edge. Chris Albertson Redondo Beach, California _______________________________________________ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
