[time-nuts] ublox NEO-M8T improved by insulated chamber?

Gary E. Miller gem at rellim.com
Wed Nov 8 13:55:27 EST 2017


Yo Chris!

On Wed, 8 Nov 2017 11:47:05 -0600
"Chris Caudle" <chris at chriscaudle.org> wrote:

> On Wed, November 8, 2017 10:45 am, Gary E. Miller wrote:
> > No one here has yet bothered to address the issues I raise
> > in Section 3.3.4.  
> 
> Sure they did.  Why are you referencing the old version instead of the
> newer version that Leo Bodner provided the link to?

Because that was sent last night after I stopped reading email.

I knew about the errata, I left out that detail to see when someone
actually read my citation.  Leo actually did, but not got to his email
yet, I read email in reverse chrono order.

> https://www.gps.gov/technical/icwg/IRN-IS-200H-001+002+003_rollup.pdf

What I said is correct, IS-GPS-200H is STILL the latest version of
the GPS standard.  Leo's link, which I found Monday, is to a copy of
IS-GPS-200H with the errata applied.  So not technically an update to
IS-GPS-200H.

> "The NAV data contains the requisite data for relating GPS time to
> UTC. The accuracy of this data during the transmission interval shall
> be such that it relates GPS time (maintained by the MCS of the CS) to
> UTC (USNO) within 20 nanoseconds (one sigma). "

So yes, UTC from a GPS is now 20 ns (one sigama).  What I said about
+/- 13 ns being noise relative to the spec still applies.

Do you now see how measured GPS time/location can be very precise, but
UTC from a GPS less so?  Have you read the entire 3.3.4?

RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
	gem at rellim.com  Tel:+1 541 382 8588

	    Veritas liberabit vos. -- Quid est veritas?
    "If you can’t measure it, you can’t improve it." - Lord Kelvin
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