[time-nuts] M12+T First Light

Brooke Clarke brooke at pacific.net
Fri Apr 15 19:23:17 EDT 2005


To use an astronomical term "First Light" meaning my first use of the M12+T GPS Timing receiver.  WOW!!!!

The manual description of the @@Hn command shows -128 to +127 ns as the range for the sawtooth error.  On the 8 channel unit I think the actual sawtooth error was around + and - 50 ns.

I looked at the @@Hn data stream in TAC32 and saw numbers in the mid teens, much lower than the 8 chan sawtooth error.  I'm not sure if this is typical, or maybe I was just lucky.  I have the El mask set to 50 degrees and Time RAIM turned off.

I've made a small number of measurements against the Cesium source whose C field I haven't touched for a month or two and the standard deviation for 5,000 1 PPS measurements ranges from 14 to 27 ns, whereas the 8 channel unit was typically in the mid 30 ns range with excursions much higher.

So the way timing is being handled in the M12+T is far better than the old 8 channel units, i.e. it's not just more channels.

Having Fun,

Brooke Clarke, N6GCE
w/Java http://www.PRC68.com
w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml

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