[time-nuts] Msg to N.Z. time nuts

[Russell Rezaian]

At 12:58 PM -0700 2009/05/19, Hal Murray wrote:
>USB has a bad reputation, but I think it's way way overblown.  Yes, it's
>polled, but that polling is done in hardware and the time scale is 1 ms.  If
>you are satisfied with an accuracy of a few 10s of ms, USB works fine.  The
>problem is the GPS unit.

And I can confirm that for my very un-scientific experiments I do get 
a pretty consistent time sync around 1 MS plus or minus mark from a 
USB serial port adapter in best case conditions.  That's with no 
special work on a pretty stock consumer grade computer with an off 
the shelf USB to serial port.

Even my worst case machine where I expect horrible USB performance 
(busy USB 1.x port with other devices, and a CPU that runs at 100% 
busy for extended periods of time) I find I things never seem to go 
worse than +-50 ms.  Not great, but much better than I was expecting 
based on some of the things I had read.

All my tests done with a time oriented GPS receiver.
--
Russell