[time-nuts] Russian GPSDO
SAIDJACK at aol.com
SAIDJACK at aol.com
Wed Oct 19 18:20:48 UTC 2011
>I am very eager to see lab reports of low-cost combined
>GPS+GLONASS receivers. I bet Said has good info on
>the u-blox 4T vs. 5T vs. 6T but now that he's selling to us
>instead of sharing with us, you've noticed how quiet he
>is about all this.
Sorry, haven't posted as much info as I used to some time ago, I got
burned by a jealous competitor going after one of our customers and feeding
them nonsense about us. Some folks will desperately use any information they
can to try to make themselves look better than they are.. And our baby is
taking all of my spare time now :)
I can safely say that the 6T works much better than 5T, much faster lock
(~35s versus ~50s typically), significantly lower power consumption, higher
sensitivity (a couple of dB), and some other intricate electrical
advantages that I cannot detail unfortunately. Timing stability has not improved
that much, the 5T is already quite excellent. A larger timing stability
difference is visible in the non-timing, mobile receivers for 5S versus 6S for
example. We support both versions moving forward (for legacy customers who do
not want to change over). Using a timing receiver improves stability quite
remarkably in static conditions, on good CSAC boards we see standard
deviation as reported by GPSCon go down from say 11ns to less than 4ns when
enabling Position Hold mode and with the antenna below foliage.
Motorola M12M and M12+ are still the king of the hill unfortunately, even
with 6T being available. But uBlox works wonderfully well in moving
platforms when configured properly. They even support both Carrier Phase AND
Doppler tracking, depending on the dynamic mode settings, which in our software
can be selected automatically, or through simple SCPI commands. WAAS/EGNOS
improves horizontal accuracy to typically better than 0.8 meters typically,
even while moving in an airplane. Better horizontal accuracy means better
timing accuracy of course, as one is essentially the reciprocal of the
Will report on the Glonass enabled parts when we have that information.
It's too early for now.
>(Hey, no harm meant, but don't forget
>where you came from).
Lastly, I can happily say that we are actively working on solutions that
will appeal to Time Nuts, Hams, and others who are concerned about low cost
but want great performance. More on this later this year..
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