domenica 11 aprile 2010

Mapper and N900 battery life

In this lovely sunny Sunday I decided to pick up my bike for the first time after the winter hibernation and go for a trip around the Seurasaari bay, just next to Helsinki centre. Of course I took my N900 with Mapper with me, to make it record the GPS track into a GPX file which I will then use to geotag the photos I took with my film camera (which is a rather advanced model capable of storing the time of the pictures in its internal memory), and to visualize my track in some sports tracking website. While it will take quite some time before I'll be able to show you the pictures I took (I've just started this film roll, and I don't use this camera often), I can show you how the Mapper-generated GPX track looks like in, a sports tracking website where one can upload his own GPS tracks and get them analyzed and put into different charts:
As a geek, watching these data is enough to stimulate me to do some sports. :-)

In the screenshot posted to the right, you can see my development version of Mapper with portrait mode support (mostly useful when walking or cycling) with the track shown in red. I fully charged my N900 just fifteen minutes before starting the trip, so here you can see how the battery level looks like after about 1 hour and half (the trip itself lasted 1 hour and 18 minutes, as shown in the small info panel on the upper right of the map); from such a quick test it's hard to say how many hours the device would last, but I was positively surprised that the battery was still in a good shape.
The reason why I was expecting the battery level to be lower is that (besides running a version of Mapper with all optimizations disabled) so far I didn't take power consumption into much consideration during the development; there is a lot of room for improvements I'm aware of, namely:
  • Avoid drawing while the screen is off
  • Use longer intervals on the GPS device
...and probably many more I'm not aware of. While the first item is quite easy to implement and unlikely to cause any evil side-effects, the second can be tricky because it also alters the quality of the generated GPX track, so it probably needs to be a user configurable setting. On the other hand, I assume that forcing GPS updates to happen no often than every 10 seconds while the screen is off is reasonable — and it might actually improve the quality of the GPX track, whose charts in now appear very jagged. In any case, it's something that needs to be tested on the field.

And to conclude with good news, turn-by-turn navigation with visual and voice announcements is coming soon on your favourite Mapper. :-)

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13 Commenti:

Blogger Gökhan Sever ha detto...

Too much teasing :) How to get the Mapper app working without having the PR1.2 firmware? It complains about missing dependencies when I try to install using the app-manager.

11 aprile 2010 19:10  
Blogger Mardy ha detto...

He he :-)
Unfortunately the fremantle builder in is targeting the PR1.2 release, so the packages it produces cannot be run on the N900.

And I intentionally removed Mapper from the Extras repository some time ago, because of stability problems in PR1.1:

I could post the packages built by myself, but I think that waiting is wiser! :-)

11 aprile 2010 19:45  
Anonymous Anonimo ha detto...

Can't wait for the Mapper release!

11 aprile 2010 20:06  
Blogger Gökhan Sever ha detto...

Not fair ;) I will pick the wiser solution for the time-being. I use the raw GPS data viewer --GPSJinni :) Are you doing building right within N900 or from your desktop Linux?

11 aprile 2010 20:56  
Blogger Mardy ha detto...

@Gökhan: I'm building from my Linux PC, using the maemo SDK.

11 aprile 2010 21:00  
Blogger Gökhan Sever ha detto...

I use Fedora 12. Is there any advantage doing the development using a Debian Linux? I am thinking to make a local Debian or Ubuntu installation instead of using Vbox? Do you have any recommendation of what to use?

11 aprile 2010 21:36  
Blogger Mardy ha detto...

I guess that Fedora can be used too; it's just that all the instructions I've seen are for Ubuntu.
You'd better ask in, I'm sure there are developers using Fedora too.

11 aprile 2010 21:47  
Blogger Slodge ha detto...

Good job - looks really nice! I've had some experience of some of the problems you've seen - e.g. the jagged lines are now in navmi too - I'm definitely changing navmi to sample only once every 5 or 10 seconds - or to find a good smoothing algorithm (I think this is what Garmin does). If you'd like to talk techy with runsat at any point - about either upload of action or download of routes - then please come find me! Mainly though wanted to say - Good job! Looks beautiful :)

11 aprile 2010 22:36  
Anonymous Christoph Eckert ha detto...

For openstreetmap, 10Hz is way too less. OTOH, some smoothing algorithm was great. Doesn't liblocation do some autosmoothing via the changed signal?

11 aprile 2010 23:06  
Blogger Slodge ha detto...

I agree with Mardy's user configurable suggestion - the required frequency and smoothing depends on what you want to use the data for. Walking up a mountain at 2kph and are using the app to record your route, is very different to driving along at 80kph and using the app for live turn-by-turn instructions. I'll have a play with some test data and settings on navmi.

12 aprile 2010 18:54  
Blogger Gökhan Sever ha detto...


This virtual Ubuntu 8.10 Desktop with Maemo dev tools [1] provided a good start for me. I like the ESBox environment and the N900 emulator. I will yet to figure installing PyQt4 set into the scratchbox.


13 aprile 2010 00:45  
Blogger Gökhan Sever ha detto...

Hey Mardy,

How did you add time data into your logged coordinates? Are you outputting to KML?

16 aprile 2010 05:37  
Blogger Mardy ha detto...

I'm using the element of the GPX format.

No KML output.

16 aprile 2010 09:01  

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