[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [gpsd-dev] Time autonomy
From: |
Gary E. Miller |
Subject: |
Re: [gpsd-dev] Time autonomy |
Date: |
Tue, 24 Feb 2015 12:41:04 -0800 |
Yo Eric!
On Tue, 24 Feb 2015 14:58:57 -0500 (EST)
address@hidden (Eric S. Raymond) wrote:
> This will yield nearly correct time provided either (a) you trust the
> system clock, or (b) the device is on continuously from a date during
> its build era (e.g. before the first rollover after BUILD_EPOCH), and
> gets at least one valid fix per week. (There are optimistic scenarios
> in which fix frequency can drop to once per *era* without worrying
> edge cases.)
Not the case on a RasPi. No battery back clock, and often a lot
of downtime.
> 6. If you had to increment saved_epoch in step 3, write it
> /var/run/gps-epoch at shutdown time.
But only if you knwo the gps-epoch to save is good.
RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97701
address@hidden Tel:+1(541)382-8588