At 7:21 AM +0000 2005-10-22, Bjorn Gabrielsson wrote:

        You may have been unlucky to get a GPS unit that is not
 well-suited to your desired task.

 IF the offset is fairly constant it may very well be a suitable
 receiver - for some low accuracy timing applications (like ntp).

On most consumer-grade GPS devices, the serial port communications get the lowest priority of anything on the device, and the manufacturers tend to cut as many corners as they possibly can. The result is that most of them don't support NMEA at all, and those few that do have such horribly bad jitter that they are virtually worthless as timekeeping devices.

There are a very few consumer-grade GPS devices (such as the Garmin GPS 18LVC) which do not fall into this situation, but they are very few and very far between.

--
Brad Knowles, <[EMAIL PROTECTED]>

"Those who would give up essential Liberty, to purchase a little
temporary Safety, deserve neither Liberty nor Safety."

    -- Benjamin Franklin (1706-1790), reply of the Pennsylvania
    Assembly to the Governor, November 11, 1755

  SAGE member since 1995.  See <http://www.sage.org/> for more info.
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