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+--- Thread: GPS Offset question (/showthread.php?tid=158)
GPS Offset question - kf5tfj - 01-05-2014
What is the correct method to determine the value to enter into the Offset box when using GPS? My GPS reports both GPS and UTC in the NMEA messages.
Re: GPS Offset question - iz2bkt - 01-06-2014
kf5tfj Wrote:What is the correct method to determine the value to enter into the Offset box when using GPS? My GPS reports both GPS and UTC in the NMEA messages.
Hi,
the field offset is used to correct a possible error given by the delay of GPS signal reception
Re: GPS Offset question - kf5tfj - 01-10-2014
That's what I guessed. What I do not know is how to determine if an offset may be needed and its magnitude and direction.
Thanks,
KF5TFJ
Re: GPS Offset question - iz2bkt - 01-10-2014
The easiest way is to use a reliable time source like a radio controlled clock.
Re: GPS Offset question - kf5tfj - 01-11-2014
Using a radio controlled clock is a big step backwards; GPS time is super accurate whereas radio time (WWVB in the USA) is really not that accurate due to propagation issues. I'll search for another way to determine the offset and if successful, I'll post the solution here.
I'm not sure how accurate time is from pool.ntp.org except that errors will average out somewhat due to the shear number of randomly selected time servers used.
Great little program Murio.
KF5TFJ / Jon
Re: GPS Offset question - kf5tfj - 01-11-2014
Sorry I misspelled your name. My bad...
Re: GPS Offset question - iz2bkt - 01-11-2014
No problem for the name,
thanks for your test, the program BktTimeSync was born to properly use the JT65 transmission and the error can be safely tolerated up to 1 second, however, your study is interesting.
I await any developments.