[ntp:questions] Windows time question.

Maarten Wiltink maarten at kittensandcats.net
Tue May 3 20:46:48 UTC 2011

"unruh" <unruh at wormhole.physics.ubc.ca> wrote in message
news:slrnis0nra.4on.unruh at wormhole.physics.ubc.ca...
> Unfortunately , AFAIK, usb is terrible for delivering a PPS-- ie no
> interrupt lines--

IIRC, USB is polled at 1000 Hz. That means that, if done well, it
should be able to gather PPS with an error of 0.5 ms at most. Probably
still a sight better than NTP over WAN.

I understand that the PPS from GPS units tends to come from a well-
chosen flank on a 10 MHz signal. Quite a difference in degree admittedly
(4 zeroes!), but not in kind.

Maarten Wiltink

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