"unruh" <un...@wormhole.physics.ubc.ca> wrote in message
news:slrnis2psa.6vn.un...@wormhole.physics.ubc.ca...
[]
Jitter and accuracy are not the same thing. It would be interesting to
attach the PPS to a real interrupt (ie one which can be serviced on the
1usec level) and see what the offset of the usb pps actually is.
From what I read, the usb interrupts have a minimum latency of 125us but
more likely much larger ( but less than 100ms).
Bill, I would not be able to see offsets on 125 microseconds on the
arrangement I have, only hundreds of microseconds. I don't have the time
for the tests you propose, either, sorry. But from the graphs, it's
obvious that the offset is well under 500 microseconds in the test
configuration, at least.
Cheers,
David
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