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Discussion of precise time and frequency measurement

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Re: [time-nuts] GPS World Article on PRN-32

HM
Hal Murray
Thu, Mar 13, 2008 6:32 PM

I'll let the battery die (and hopefully lose the ephemera data) and
restart and see what happens.

How often is the data in the satellites updated by the ground stations?

How often do normal GPS units grab a new copy from the satellites?

--
These are my opinions, not necessarily my employer's.  I hate spam.

> I'll let the battery die (and hopefully lose the ephemera data) and > restart and see what happens. How often is the data in the satellites updated by the ground stations? How often do normal GPS units grab a new copy from the satellites? -- These are my opinions, not necessarily my employer's. I hate spam.
CK
Chris Kuethe
Thu, Mar 13, 2008 7:06 PM

On Thu, Mar 13, 2008 at 11:32 AM, Hal Murray hmurray@megapathdsl.net wrote:

I'll let the battery die (and hopefully lose the ephemera data) and
restart and see what happens.

How often is the data in the satellites updated by the ground stations?

I'll have to dig for the reference, but ISTR 3x daily

How often do normal GPS units grab a new copy from the satellites?

A number of my receivers try to refresh the ephemeris every 2hrs, just
in case it might've changed. Tomtoms (among others) have some form of
"Extended Ephemeris" feature whereby they can load a precomputed
ephemeris for a week. Certain builds of SiRF, Global Locate/Broadcom
and possibly uBlox firmware can do this. Perhaps doing a software
update to fetch the lastest QuickFix data might help.

CK

--
GDB has a 'break' feature; why doesn't it have 'fix' too?

On Thu, Mar 13, 2008 at 11:32 AM, Hal Murray <hmurray@megapathdsl.net> wrote: > > > I'll let the battery die (and hopefully lose the ephemera data) and > > restart and see what happens. > > How often is the data in the satellites updated by the ground stations? I'll have to dig for the reference, but ISTR 3x daily > How often do normal GPS units grab a new copy from the satellites? A number of my receivers try to refresh the ephemeris every 2hrs, just in case it might've changed. Tomtoms (among others) have some form of "Extended Ephemeris" feature whereby they can load a precomputed ephemeris for a week. Certain builds of SiRF, Global Locate/Broadcom and possibly uBlox firmware can do this. Perhaps doing a software update to fetch the lastest QuickFix data might help. CK -- GDB has a 'break' feature; why doesn't it have 'fix' too?