[ntp:questions] NMEA driver clk_fault - OK. Thanks

Frank Hage fhage at oberon.rap.ucar.edu
Thu Sep 11 18:00:43 UTC 2003


RE: NMEA driver clk_fault.  Please Help.

Sorry folks about the shrill tone of my message. I was able to find your kind
replies today. 

Thanks to Steven, Allen and others, I'm now on the right track.

The problems started when someone in the control tower moved the antenna
closer to the window sill.  The Garmin GPS 16 is a magnetic mount 'pod,'
with an internal antenna. I have them sitting on the window sills, with
a clear view of the sky through huge windows. I'm testing a duplicate in
my office, which has a much smaller view of the sky through a window.

1. Idiot me thought V = "Valid"  in the GPRMC output.  A=Valid, V=Invalid
2. There's a 30-60 sec delay in change of receiver status after moving.
3. Clamping it to the side of my filing cabinets that faces the window
   really helps reception over sitting directly on the aluminum window
   sill, even though it has a smaller view of the sky.

In summary, I've learned to:

1. Use Kermit (etc) to setup the unit and pick a good antenna spot.
    
	# Turn off all output:
	$PGRMO,,2<cr><lf>
	# Turn on GPRMC
	$PGRMO,GPRMC,1<cr><lf>
	# Turn on PPS
	$PGRMC,,,,,,,,,,,,2<cr><lf>

	Watch the output:
	# GOOD:
	$GPRMC,171021,A,4002.2677,N,10514.5021,W,000.0,279.8,110903,010.2,E*68
	# BAD: - Don't be fooled that the time fields are still available.
	$GPRMC,171102,V,4002.2706,N,10514.4973,W,,,110903,010.2,E*73

2. Running 'ntpd -d -d -d' Shows enough output to see if the messages
   are valid when the daemon requires valid output.

3. Use 'ntpq -p'  And look in the 'reach' column to see if the driver
   is consistently getting a good signal.

4. Thank the good folk who produce and support the NTP Software. 


Thanks again. 

-- 
Frank Hage  fhage at ucar.edu
National Center for Atmospheric Research




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