[time-nuts] Computing GPS Distance Error in Time

Kasper Pedersen time-nuts at kasperkp.dk
Mon Nov 4 18:37:01 EST 2013


On 11/04/2013 06:30 PM, Bill Dailey wrote:
> The pps on that unit is good.  Compares favorably to the ublox6T. I can't say how favorably.  
> 
> I am working on quantifying its pps as compared to my 2 fury units and the ublox 6T.  

They are pretty good, being dirt cheap nav receivers. In this plot, it
is identical to the MC-1010 (same reference design, same firmware).

http://cm.kasperkp.dk/mc1010ga.png  (adev of various)
http://cm.kasperkp.dk/mc1010p.png   (phase, fei5680)

The MC-1010 is using the 3339 chipset, and is GPS-only.
The MC-1010-G has the 3333 chipset, and is GPS+GLONASS.

When testing, try fast temperature shifts; I found that it would shift
the PPS much more than I expected, as if there is a rather slow filter
driving the PPS output.


> 
> Have another trick up my sleeve but need a Linux kernel hacker.  I don't want to go down another rabbit hole if I can avoid it.
> 

I have stuck my fingers in the timekeeping code in the kernel, and
managed to get away unscathed.
If it is not too complicated, and interesting, shoot me a mail directly.
I reserve the right to decline, and the right to give up:-)


/Kasper Pedersen



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