> : You may not know the answer to this, but it's worth a shot. Wht kind of
> : accuracy can we expect using 'cheap' off-the-shelf GPS receivers?
>
> We're getting, with ntp4 on a 3.x kernel, about +- 4uSec with a cheap
> gps receiver + atomic clock on a i486 class machine.
I've got the cheap gps receiver (Garmin 12XL), but what do you mean by
an 'atomic clock'? Should the GPS receiver's NMEA messages be adequate
enough to do the job? However, all I need is ms accuracy, so anything
below 500us is good enough for me.
> The clock
> doesn't want to sync more closely than that, likely due to the large
> jitter in the 8254 timing device, so the atomic clock is a bit of a
> waste for this part of our application (there are others it is needed
> for). With a pentium class machine and w/o the atomic clock
> "backing", I'd say you could easily get into the sub-micro second
> range.
I've got a 486, although running the antenna to an outside window might
get exciting. :)
Nate
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