[time-nuts] GPS clock to RT-Linux for pulsar machine
dforbes at dakotacom.net
Fri Jul 1 16:45:04 EDT 2005
As part of my radioastronomy job, I'm being asked to devise a low-cost
pulsar detection machine for very high frequencies (~80 GHz), which
requires many tens of hours of integration time staring at the pulsar
while maintaining absolute timing accuracy of ~50 microseconds.
I have GPS time and a maser available for absolute and relative timing
respectively. I expect to be taking the data via a low-cost A/D card
clocked by the maser at about 100 us per sample. I plan to use RTLinux
unless I can be convinced there's a better way, as I already use
RT-Linux successfully for our various spectrometers.
My question is: What's a good way to synchronize the RT-Linux OS clock
to the GPS clock? I am considering the use of the A/D card's interrupt
with the 1PPS from GPS. I expect to use NTP to get the correct second.
Does NTP provide a way to tie an interrupt from some user-provided
hardware to sync up the fast clock to ~50 microsecond accuracy, or is
there some other method?
Thanks in advance for any help.
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