Lowpower Mode

wjrs5 · Posted: Sat Jul 17, 2004 7:13 am Post subject: Lowpower Mode

Does anybody know what extra battery life you will get on the Emtac if you switch it into Low Power mode using the CruxView utility? Also, on this screen in Cruxview, what is the meaning of "On Time (ms)"?

lbendlin · Posted: Sat Jul 17, 2004 4:12 pm Post subject:

The standard NMEA refresh cycle is 1 second (1000 milliseconds).

Every second the receiver gets a fix, sends the required NMEA sequences and then waits for the next second

In normal mode the receiver stays switched on for the whole cycle.

In Trickle Mode (low power) the receiver can be put to sleep after it finished all its business. This is where you specify the On Time. I found that a value as low as 200 ms is sufficient for it to keep its position, with only a slight degradation in signal. Don't try to go below that.

The battery life will not expand linearly, but you can expect up to 30% more in 200 ms trickle mode. I had the Emtac running for 8 straight hours, where it normally would last only 5 to 6 hours.
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wjrs5 · Posted: Sat Jul 17, 2004 4:24 pm Post subject: Walking Settings

So for maximum battery time when out walking, the best settings would be:
Update rate (sec) 2
On time (ms) 200

Or would it be best to have the update rate set at 1?

Brandon · Posted: Wed Jul 21, 2004 5:15 am Post subject:

It depends on your use for walking. If you wanted to trace your position, I would probably suggest the trickle power mode. However if you wanted to check your position about once every 15 or 30 minutes I would probably suggest turning the reciever off until you want to check your next location.

sjs · Occasional Visitor Joined: Aug 19, 2004 Posts: 10

so we lower the on time to 200ms....but what is a good number for the update time? would it still work if i told it to update every 15 or 30 seconds or even a minute? that would be good enough for me if i was walking...

lbendlin · Posted: Sat Aug 21, 2004 7:40 pm Post subject:

very good question. I haven't tried that yet. But from what I understand the farther away the wake periods are the more time the circuits will need to lock onto the sats.

So if you would leave it at 200 ms On-time and set the interval to 15 seconds the receiver might not be able to maintain the fix. I say "might" because I haven't tested that yet. Somebody with lots of time and a scientific background could actually produce a X/Y chart with the x axis being the on-time and the Y-axis being the interval, and then determine the filed of success versus the field of failure...
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sjs · Occasional Visitor Joined: Aug 19, 2004 Posts: 10

yes, neat idea...if i ever get a trine...
is this feature precisely what is known as "trickle" in the first place?

lbendlin · Posted: Tue Aug 24, 2004 11:16 pm Post subject:

yes. trickle in itself means that full power is not always supplied to the device. There are periods of full power interchanging with sleep mode power.

But as far as I know so far trickle has always assumed that a full cycle would take just one second - and nobody is really sure what happens when you go beyond that.
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sjs · Occasional Visitor Joined: Aug 19, 2004 Posts: 10

ok thanks...now is trickle part of the spec of Sirf or optional? are there freeware utilities to tweak the trickle or must you use an OEM supplied app of some kind?

lbendlin · Posted: Wed Aug 25, 2004 9:58 pm Post subject:

I think it is part of some SiRF chipsets. I normally use Crux_View to set this mode, but haven't been successful to do so with all the SiRF based devices I tested. You don't break anything by trying, though.
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sjs · Occasional Visitor Joined: Aug 19, 2004 Posts: 10

great, thanks :-)

hogbreath · Posted: Sun Aug 07, 2005 3:46 pm Post subject:

[b]lbendlin

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