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Thread: Time Stamping [EE]
www.piclist.com/techref/timers.htm?key=time
picon face BY : Robert Rolf email (remove spam text)



Andy, to give you a good answer we need to know a bit more about
what kind of data rates you're using and what you define as 'accurate
time stamp'. All accuracy is relative. For Radio Astronomy, sub
nanosecond
is required if you're running a wide baseline interferometer.  For river
levels, minutes is sufficient.

GPS 1PPS will get you to +/- 30 nSec or so short term. 1E-10 to -12 with
a long term average and a disciplined clock. A tweaked and compensated
Dallas clock, a few seconds a month. A fine tuned PIC about the same.
Reference time is also available on GOES satellites (485Mhz or so).


What do you actually need? Absolute time, or relative? Battery backed
up, or can you survive a power outage and several minute recovery?
If you lock your sampling to an external clock you don't really need to
time stamp your samples. You just need to store the time stamp of the
first (or last) sample, and then compute the time based on sample
number.
Saves one heck of a lot of memory.

Ramana wrote:
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> {Original Message removed}
<3926174D.FB69293B@UAlberta.ca> 7bit

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