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!GPS_Time
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1997-08-01
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1KB
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32 lines
!GPS_Time Reset Acorn CMOS Clock from GPS Date: 1997 Jun 08
-------------------------------
This program resets the computer's clock from a GPS receiver.
The receiver should be plugged into the computer's serial port. Only
RXData is needed.
ASCII plaintext messages scanned are $GPRMC and $GPGGA, typically:
$GPRMC,203409,A,5212.4600,N,00003.5436,E,0.174,296.8,060697,3.8,W*6B
$GPGGA,203410,5212.4585,N,00003.5379,E,1,08,1.00,7.9,M,47.0,M,,*72
|----|
^---- time, hhmmss
Only time is reset; the computer's date is assumed correct.
You may find that your GPS set's time differs from true UTC by a second or
two. Change the variable "SECoffset" in !RunImage to add or subtract a
correction (in seconds) to GPS time.
The GPS is also assumed to be displaying a valid time; that is, the $GPRMC
validity flag (A or V) is not checked for either state.
These is no indication that this program is running unless you bring up the
Task Manager window (click on the Acorn). Then you will see an entry "UTC from
GPS v1.01". If the GPS set is working, this will disappear almost immediately
with a beep. Otherwise it will persist for 10 seconds, and then Quit silently.
James Miller g3ruh@amsat.org
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