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Re: [gpsd-users] Power saving
From: |
Ed W |
Subject: |
Re: [gpsd-users] Power saving |
Date: |
Tue, 27 Mar 2012 18:25:41 +0100 |
User-agent: |
Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:11.0) Gecko/20120313 Thunderbird/11.0 |
Hi
I found the power consumption of GPS antenna is too high for my
specification. It is OK however to turn it on occasionally to
re-caliber the system time, e.g. once per hour, in order to system
system power.
I am wondering if gpsd and automatically handle that while still
working with NTPd. For example, if I only turn on gps power for every
power, will GPSd still be able to correct the NTPd time during that
small time window?
Dunno, but some things which might help:
Try chrony - it has additional features that assist with "disconnected"
operation, in particular you can mark network based sources "offline"
and "online" - quite possibly you can do the same with gps based
sources. The "online" can causes chrony to become aware of a source
becoming available and with suitable tweaking of burst/iburst you could
take best advantage of a small time sync window...
Chrony is *probably* also going to do better with occasionally available
sources due to the way it averages previous observations.
I don't see any fundamental reason though why you can't *do* what you
ask. Just whether it meets your accuracy requirements.
Simple suggestion:
- Recent gpsd comes with a command line gpsdctl utility, so scripting is
trivial
- Using cron, periodically wake up gps,
- add it to gpsd
- wake up chrony and tell it we are online
- pause as long as you can justify....
- reverse the above, take down chrony, remove the device from gpsd, turn
off the device
None of the above is particularly dangerous or tricky or misusing a
feature...
Good luck - would be interested to hear your results
Ed W