Mike, Attila is trying to explain that the leading edge is not what we are concerned about in this thread (its subject to discussion in other email threads), it is the effect of what follows after that leading edge, and propagates down the power supplies to cause side effects that is being discussed here. Tom mentioned he can measure this as 10's of Watts of increased power consumption spikes on the AC line when the 1PPS goes high. This won't happen with short pulses, only with long ones that are end-terminated. In a message dated 5/15/2012 13:51:43 Pacific Daylight Time, mi...@flatsurface.com writes:
On 5/15/2012 4:19 PM, Attila Kinali wrote: > If the > PPS pulse is short, it contains very little energy, which means > the energy can be supplied by the small capacitors at the output > driver. The longer the pulse gets, the more energy it needs. The pulse is meaningless. It's only the leading edge that matters. I understand how shorter pulses may make for marginally cheaper electronics. > Which might have a negative effect on their performance. I might win the lotto. The question is exactly _how_ does it effect their performance, especially if they're synchronizing to the PPS signal. > it's no use of having a fast > rising edge, if the pulse colapses a couple ns later. Huh? If ns is too short, and ms is too long, what makes us just right? And why are there so many timing receivers that only output on the order of 20 us, when there are so many inputs which may require a few ms? PPS is edge triggered, not level triggered. Once the leading edge is transmitted (and it by necessity has a very fast rise time, so it looks to capacitors, transformers, etc. as a high frequency signal), the shape of the pulse really doesn't matter much. Some devices need more than a minimum above some threshold, but what ones need less than a maximum? If it doesn't look like a flat topped pulse, so what? As long as the decay is basically monotonic, and the receiver has some hysteresis (reasonable assumptions), it makes no difference. _______________________________________________ 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.