Location - GPS back off and Cell towers

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kevwal
Posts: 5
Joined: Sun Aug 21, 2011 6:34 pm

Location - GPS back off and Cell towers

Post by kevwal »

Hi

I have just started running the app and it looks very promising. I want to leave the application running for a week at a time whilst I am traveling, and I generally also have infrequent access to power during that time so battery life is important to me.

Currently when I go indoors it seems to put the gps on for 2 mins every 4 mins as it cant get a fix (ie 50% cycle time). Compared to 10 seconds every 10 mins when outdoors that uses a lot of battery power!

So, some feature requests:

Can the back off time be adjustable within the application please and maybe some type of increasing back off interval (noting that it might not have gps reception for 12 hours over night, so should never go over the 'send interval'.

Can the GPS accuracy limit be defined in 'real terms', ie I assume you are using HDOP values mapped to poor, good, etc - just state the values

Lastly, how about the use of cell tower based location mapping when GPS isnt available?

Thanks very much
Kevin
admin
Site Admin
Posts: 3127
Joined: Tue Feb 06, 2007 12:36 pm

Re: Location - GPS back off and Cell towers

Post by admin »

Hi kevwal,

Thanks for your posting. When I designed this app I was thinking about the same what you are thinking now so let's discuss these points.
Can the back off time be adjustable within the application please and maybe some type of increasing back off interval (noting that it might not have gps reception for 12 hours over night
I thought a lot about the optimal intervals between GPS retries. I decided to let the intervals grow from 10 seconds at begin until 2 minutes. If the interval is too long the phone will notice very late that you are outside and GPS signal is back. I want to keep the app simple because I don't want to discourage newbies.
I will think about making that value configurable. But at the same I'm wondering why you don't shut down the tracker if you stay inside of buildings for a longer time. This definitely would save battery. Another problem is that you would have 3G to be turned on all the time. I hardly believe that your battery would last for one week if 3G were enabled all the time. What's your opinion?
so should never go over the 'send interval'.
Do you mean it should never be bigger or smaller that the 'send interval'?

Can the GPS accuracy limit be defined in 'real terms', ie I assume you are using HDOP values mapped to poor, good, etc - just state the values
The terms 'good', 'poor', etc. are mapped to the GPS accuracy in meters reported by the phone. Again, I wanted to keep the app simple and understandable for newbies. So I preferred this term to numeric values. But I can post the mapping between accuracy in meters and these terms if you wish.

Lastly, how about the use of cell tower based location mapping when GPS isnt available?
I was also thinking about that from time to time. So far I haven't added this feature because actually my app is designed to track exact locations in short intervals (the application name gives a hint to that ). If the app accepted cell tower locations it would be difficult to draw trails for example. So don't expect this feature in the close future. But if I find a proper solution I will add it.
kevwal
Posts: 5
Joined: Sun Aug 21, 2011 6:34 pm

Re: Location - GPS back off and Cell towers

Post by kevwal »

Hi

Thanks for the reply.
admin wrote:Hi kevwal,

Thanks for your posting. When I designed this app I was thinking about the same what you are thinking now so let's discuss these points.
Can the back off time be adjustable within the application please and maybe some type of increasing back off interval (noting that it might not have gps reception for 12 hours over night
I thought a lot about the optimal intervals between GPS retries. I decided to let the intervals grow from 10 seconds at begin until 2 minutes. If the interval is too long the phone will notice very late that you are outside and GPS signal is back. I want to keep the app simple because I don't want to discourage newbies.
I will think about making that value configurable. But at the same I'm wondering why you don't shut down the tracker if you stay inside of buildings for a longer time. This definitely would save battery. Another problem is that you would have 3G to be turned on all the time. I hardly believe that your battery would last for one week if 3G were enabled all the time. What's your opinion?

KW You could always create an 'advanced' config section to keep the basic stuff basic - I do understand the keep it simple thinking for the main settings. Re shutting it down - because I will forget to start it again I was not suggesting the battery would last for a week, but anything we can do to increase battery life is a good thing. How does the Send Interval interact with that 2 min back off? FYI I am considering looking at send intervals around 900 seconds.
so should never go over the 'send interval'.
Do you mean it should never be bigger or smaller that the 'send interval'?

KW I mean the back off time, should never be bigger than the send interval - ie if I have a send interval of 900 seconds, then the app should always try and get a GPS signal every 900 seconds.
Can the GPS accuracy limit be defined in 'real terms', ie I assume you are using HDOP values mapped to poor, good, etc - just state the values
The terms 'good', 'poor', etc. are mapped to the GPS accuracy in meters reported by the phone. Again, I wanted to keep the app simple and understandable for newbies. So I preferred this term to numeric values. But I can post the mapping between accuracy in meters and these terms if you wish.

KW That would be great, Out of interest is the source code public?
Lastly, how about the use of cell tower based location mapping when GPS isnt available?
I was also thinking about that from time to time. So far I haven't added this feature because actually my app is designed to track exact locations in short intervals (the application name gives a hint to that ). If the app accepted cell tower locations it would be difficult to draw trails for example. So don't expect this feature in the close future. But if I find a proper solution I will add it.
Thanks
Kevin
admin
Site Admin
Posts: 3127
Joined: Tue Feb 06, 2007 12:36 pm

Re: Location - GPS back off and Cell towers

Post by admin »

True, I could create an advanced section. This is exactly what I'm going to do if the complexity keeps growing.

The back off interval is not influenced by the send interval. If I would set it equal to the (possibly large) send interval this could result in a behavior only the expert users understand. Most people would ask "why the app does not send my location?". So I decided to let back off time grow continuously but to set a limit of five minutes. I will consider to make that limit configurable because now I know some users prefer that.

This is a private project so there is no public source code. Nevertheless here is the mapping:

Excellent: <= 15 m
Good: <= 34 m
Sufficient: <= 50 m
Poor: <= 120 m
Very Poor > 120 m
kevwal
Posts: 5
Joined: Sun Aug 21, 2011 6:34 pm

Re: Location - GPS back off and Cell towers

Post by kevwal »

Thanks, so >120 basically means any fix of whatever acuracy?

A confiurable back off would be great.

Also, would you consider linking to any other web mapping sites - like mapmytracks for example?

thanks
Kev
admin
Site Admin
Posts: 3127
Joined: Tue Feb 06, 2007 12:36 pm

Re: Location - GPS back off and Cell towers

Post by admin »

Yes, if you choose "Very poor" every GPS fix will be accepted. Accuracy will have no influence in this case.
Back off time will be configurable in next release.
Right now I'm not planning to support external web portals. But who knows, maybe I will think different at some point in future.
admin
Site Admin
Posts: 3127
Joined: Tue Feb 06, 2007 12:36 pm

Re: Location - GPS back off and Cell towers

Post by admin »

New version including configurable back off time is already available in Market . On the first three GPS timeouts the back off time is 10 seconds. Afterwards the configured value will be used.
kevwal
Posts: 5
Joined: Sun Aug 21, 2011 6:34 pm

Re: Location - GPS back off and Cell towers

Post by kevwal »

Thanks very much. As well as send interval could we have minimum distance between points sent? ie if the change in position is less than x meters?

THANKS
Kev
admin
Site Admin
Posts: 3127
Joined: Tue Feb 06, 2007 12:36 pm

Re: Location - GPS back off and Cell towers

Post by admin »

Hi,

There is already a minimum distance option available in the sections. Do you mean something different?
kevwal
Posts: 5
Joined: Sun Aug 21, 2011 6:34 pm

Re: Location - GPS back off and Cell towers

Post by kevwal »

admin wrote:Hi,

There is already a minimum distance option available in the sections. Do you mean something different?
Hi

Just got my 3g access back so can carry on testing now, doh!

I thought I had seen something about minimum distance too in the GPS Config section of Settings, but in the new version it doesn't seem to be there?

I also couldn't find a version number to quote you to show which version I am running...

Thanks very much
Kevin
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