[time-nuts] adafruit $40 GPS
Kasper Pedersen
time-nuts at kasperkp.dk
Tue May 14 18:58:47 UTC 2013
On 05/14/2013 07:57 PM, George Lu wrote:
> According to the documentation at
> http://www.adafruit.com/datasheets/GlobalTop-FGPMMOPA6H-Datasheet-V0A.pdf:
>
> High accuracy 1-PPS timing support for Timing Appli
> cations (10ns jitter)
>
> George
Here, have some data.
I am testing a few MT3339 modules at the moment; They all seem to have
the same firmware. The (live, updates every minute) plots of one are at
http://cm.kasperkp.dk/mc1010p.png (phase)
http://cm.kasperkp.dk/mc1010a.png (adev of this and others)
http://cm.kasperkp.dk/mc1010p.txt (pps phase in seconds)
It is far better than others cheap navigation receivers I have tested,
but it does peculiar things sometimes, such as the 60ns excursion at
2500 seconds.
And I am looking for a navigation receiver at the moment, not a timing
one, so this is just because I can.
/Kasper Pedersen
Note:
The receiver is fed off of a splitter from an external antenna.
The counter is one of my homebrew ones with ~250ps-ish resolution, and
the FEI-5680A in it was turned on 15 mins before starting the run, so
it's still settling.
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