Garmin 12 power save

tadpole

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Joined
2 Aug 2001
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West Dorset
Am I daft or what? My new Garmin 12 has three operating modes, normal, simulator and power save. I can't find anything in the manual about power save. Please tell me I'm not losing my marbles.
 
G

Guest

Guest
Hope this helps.

From :- http://celia.mehaffey.com/dale/user.htm

Normal - This is the highest performance mode and is used for navigation.

The simulation setting is only used when you do not actually need to track satellites and offers battery savings since the receiver portion is shut down. On some units this is called in-doors, gps off, or demo mode. It will be turned-off each time you power off the unit to avoid accidently confusing the user on the next startup. Simulation mode has many extra features which are covered the the simulation chapter. You may be able to set this mode from the status screen also.

Some machines and software versions also include a battery-save mode, also known as power save. Battery-save mode is remembered when you power off the unit. It works by noticing whether the unit is doing something unusual. If it was able to predict what will appear on the next sample from the satellites then it could have saved on batteries by not performing this sample. In battery-save mode the gps decides how often to sample data based on its ability to predict the next sample. If you are standing still or moving in a straight line at a set speed then there is no need to sample data from the satellite as often since the gps can predict what the answer is. If the gps detects that something unusual is happening then it samples every second as in normal mode. Of course there can be a slight lag before the unit figures out that conditions have changed but this method works surprising well and under some conditions it can offer 50% greater battery life. Something changing means a change in direction or a significant change in speed and is similar in concept to the automatic tracklog detection.
On newer 12 channel units the battery save mode, also known as power save, will also limit the number of satellites being tracked. This is done by changing the mask angle to limit the unit from attempting to track satellites that are close to the horizon. (Older multiplex units do this in all modes.) Solutions depending on these low lying satellites are generally less accurate due to tropospheric delays. With a clear sky view battery-save mode can offer a significantly longer battery life with little degradation in service. In forest regions the accuracy suffers much more, particularly when traveling in vehicles. Waiting 5 seconds (3 seconds in older units) between fixes can cause a loss of lock in some cases and contribute to even longer excursions offtrack than a momentary loss in normal mode. If you are experiencing long straight tracks with sharp bends when traveling on a winding road the battery-save mode should be discontinued to maintain best accuracy.
 

Plum

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Joined
6 Jun 2001
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3,754
Location
UK East Coast
Re: Garmin told me something slightly different

I too have a Garmin 12 and I asked Garmin the same question (they obviously still have not updated their instruction books). They said that in Power Save mode the GPS still uses all the available satelites and still calculates your position to the same level of accuracy. However, if the GPS detects that you are not moving or if you are moving at a constant speed in the same direction, then the GPS use dead-reconning and recalculated your position less frequently. The result is that the batteries will, they say, last 3 to 4 hours longer than in Normal mode.

I have been using my GPS 12 for 6 months now in Power Save mode and have never noticed a problem with accuracy.
 

Paul_T

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Joined
29 Sep 2004
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1
So does that mean...

that 'power save' comes on and off automatically?
My Garmin 48 manual talks of 'power save' but doesn't mention anything about switching it on & off.
 
G

Guest

Guest
Re: So does that mean...

No, what it means is that the version of firmware in your 48 isn't the latest. On the Garmin website you will find the following:-

Changes made from version 4.57 to 4.58:

When receiving a waypoint from NMEA input, initializes the waypoint symbol to a simple dot.
Updated magnetic variation tables based on the new IGRF 2000 model.
Corrected Loran TD position format secondary station "W - Whisky" for chain number GRI-9960.

Changes made from version 4.56 to 4.57:

Enhanced unit battery life with Power Saver mode.
Added track area calculation feature.


So if you already have a serial cable for your PC then download the latest firmware 4.58 and load it and hey presto you will have a Power Save mode. It will also add the extra features listed above.

Firmware for the 48 is available from:-

http://www.garmin.com/products/gps48/download.html

Anyone else with Garmins should check to see if they have the latest firmware. If they are anything like most IT companies there will be bug fixes in there as well although they won't admit to it unless necessary!

Cheers
 

Plum

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Joined
6 Jun 2001
Messages
3,754
Location
UK East Coast
Re: yes.....

I can only speak for the Garmin 12, but yes, all is automatic. I leave mine constantly on "power Save" function.
 
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