Tuesday, December 09, 2008

GPS -- a practical example

People keep talking about GPS -- an exciting gadget to have, while some do not understand what-the-hell is GPS and why would they ever need it. This might help them to understand and decide on it. While few people don't want to understand it, because they just dont want to get into hitech stuff -- this is not for those.. Let them live happily without it.

I knew about GPS since my college days (when GPS was not popular for consumer/commercial use -- atleast in India). I've been using GPS in my ASUS P320 phone for quite sometime and feel good about its use. GPS is specially useful when you go out on trip and you do not prior knowledge about the place. A realtime example will make you understand and appreciate the use of GPS.

I've a phone running on Windows mobile; so all that I talk about "software" here apply only to the Windows variants of GPS devices. The advantages of GPS remain the same anyways. Okay, after going thru a number of navigation software, I've finally boiled down to tracky and google maps as my preferences. Both have their own advantages so I need them both. I also have mapmyindia for navigation purposes.. Maybe I will compare the various software later in the blog.

We went to jungle resort and for a trip like this tracky is the way to go. I had downloaded all relevant maps (both road and satellite) onto my phone (at various zoom levels based on the need at various locations during the trip) and integrated with tracky (approx 2000 tiles covering the route from bangalore to that resort). That was a place where there is no mobile connectivity -- so offline maps was a must to have. It worked beautifullly...

To download the google maps for a given location, you need to definite the co-ordinates of the map first. Use mapcacher for this.
Then use gMapMaker to download the real tiles of the map you just configured.

Practical GPS:

* Tracky shows the speed of your vehicle.. pretty interesting to watch it go in tandem the vehicle speed.. I have tested this on train too :)

* I recorded the track of our travel. The route is not pretty clear as it has to go through villages -- so I wanted this track when I visit the place next time. Now next time all I need to do is, just load the track in tracky and just follow it (see my earlier post on this). Moreover, you can transfer the file (GPX) to your comp and load it in google earth and see the track in which the trip went..!! endless....

* When no one had any idea as to how long it is going to take or how many kilometers more to the resort -- hehe I had answer (rather my phone had an answer).. Set the target to where you want to go and tracky tells you the distance left and the approx time thats going to take (based on your current location and the average speed so far in the trip).

* Even better, If I had to walk from one place in resort to another place (eg., my logger hut to the ayurvedic massage center), I was able to measure the distance (being in any place) using tracky and tell people that it is not worth 2kms walk :)

* And to my surprise, I was running GPS continuously for 3 hours and at the end of the trip I still had 40% battery left in my phone.. And once I got the satellites locked, I didn't have to keep my phone facing the window or anything.. I just carried my phone (with gps and tracky on) on my pocket just like I normally do..

Aside from this trip,

* When I usually travel by train, I usually track my destination by GPS so I would know when to come down from my berth. This is specially useful when its dark outside and is difficult to guess the place from the upper berth.

* The trackyme feature of the tracky software is useful when you want someone else to track you as you travel. The software uploads the co-ordinates (in configurable intervals) to their server, and your location can be spotted through the internet (yes, it is username/password protected, so only people whom you want to track you can really track you). And this is optional feature to turn on -- for the privacy paranoid people like me.

This is just about the tracking part of GPS ; the navigational abilities that the software provide is of separate use (where is the nearest pizza corner and how do I reach there?) -- maybe its worth a separate post later.

All in all, it is a wonderful device to have. Believe me, it is useful if you know how to use it and if you have the right software for the moment.


  1. true. once we start using it, we would realize so many uses of it.

    However, I should admit that, at least as of today, GPS is not a must-have-gadget.

  2. "When I usually travel by train, ... specially useful when its dark outside and is difficult to guess the place from the upper berth."

    I wrote something very similar that uses cell tower information rather than GPS, primarily because my phone doesn't have GPS :).


  3. mm interesting. But I'm not sure if you are using the cell-broadcast information or the cell tower id. Depending on cell-broadcast information (btw which channel do u use?) is risky because it looks like the service providers are not bound to broadcast tower information. Once I saw vodafone publishing ads through cell broadcast in madurai network.

    Using the cell phone's tower-id obtained through the underlying OS APIs might be more practical; given that you want the user to give the name of the towers, it should be good enough.

    Are you aware of the google maps AGPS? where they provide an approximate geographical location based on your tower id? I use this when it is difficult to get the GPS signal inside closed areas (sometimes in train). They have a really huge database of the towerids mapping to geographic locations.

  4. I use cell broadcast information (channel 50). You're right, it's not very reliable (ads etc.) and the location names vary with the service provider. I was just too lazy to find how to read the tower id :)

    Using google's service would require internet connectivity - something that I didn't want to mandate.