15 January 2015

Smartphone as GPS

For quite some time I had wanted to get a GPS to log my rides, plan routes and navigate on recce rides. Although I had briefly considered getting a dedicated GPS unit like a Garmin or Magellan, I found the value of a generic smartphone hard to beat. In Aug 2012 I bought an entry level smartphone - the Karbonn A5, then a newly launched Indian mobile phone. That phone was great value for the price (Rs 5000) at the time - the GPS worked great (especially with AGPS), it had a fast CPU and loads of storage. Based on the experience, here are the reasons I'd prefer a (smart)phone over a GPS.

1. GPS Functionality:
Platforms like Android and Apple today have a wide variety of apps, a little searching will get you the app(s) that serve your purpose best. You can even use separate apps for various functions - e.g. one app each making GPS tracks, one for navigation, one for maps, etc. On a dedicated GPS, the firmware/software is unmodifiable, and likely will never be updated. Also, the UI on smartphone platforms is way better than anything I've seen on a standalone GPS.

2. Replacability:
Since the UI / apps are fairly independent of the underlying hardware, you can get practically the same functionality irrespective of what hardware you are using. When you have a little cash you can always upgrade to  a better smartphone (perhaps even bought second hand). Just install the same apps, set up your OS and you are done

3. Battery life / runtime:
A smartphone is far less energy efficient precisely because it is not optimised as a standalone GPS. Unlike phones, GPS units can run on AAs, which you can carry or purchase anywhere. However, it is just as easy to find AA powered USB chargers. Lithium battery powered USB chargers (mobile power banks) are inexpensive and readily available as well.
A few simple tricks will extend the battery life on your phone when using it as a GPS tracker
(a) Download GPS assistance data over WiFi or mobile data before starting out, to ensure faster GPX locks.
(b) Disable cellular radios, WiFi and bluetooth.
(c) If keeping radios on, turn off automatic network selection to reduce power spent in cell-hops as you travel.
(d) Select an appropriate GPX logging interval. If too short, the GPS will burn too much power consistently. If too long, the GPS will lose lock each time and waste power trying to reacquire GPS lock.

4. Offline (stored) maps, tracks and data:
Offline maps for GPS devices used to be a royal pain. On the other hand, most mapping apps for Android support offline maps with varying degrees of detail. Moreover the maps can even be copied over WiFi using SFTP or SCP.
Similarly, recorded tracks can be uploaded/backed up/shared directly from a smartphone, whereas a GPS typically requires a compatible computer for this.

There are, however, some caveats to be noted:

1. Accuracy:
Smartphones typically cannot match the lock speed and accuracy of standalone devices. I find the error insignificant for my purposes, but you should evaluate based on your requirements.

2. Altimetry:
The GPS system is notoriously inaccurate for altitude measurement. Unlike GPS units, smartphones do not have barometric altimeters, and the altitude numbers are not to be believed. Services like Strava and Endomondo calculate elevation gain using different algorithms anyway, so the numbers you finally see can be pretty much anything.

3. Ruggedness / Waterproofing:
GPS units are typically  IPx7 rated - dust, water and weather proof, and can easily withstand bumps or drops. A zip lock bag can be crude but effective waterproof case for a phone, but if you drop your phone...

4. Social
Can you stand the peer pressure of not owning a Garmin Edge when everyone else has one for their carbon bikes?

And finally, here's a short list of apps that are worth a look:

1. OSMAnd: Do-it-all Mapping and GPS app. Supports offline maps, routing, GPS logging, even route creation. For older devices, older versions of the app may be installed from the archives. OSMAnd Version 1.7.5-175 is the newest that works on a HTC Pico Jellybean version.

2. GPS Status apps: GPS Status and GPS Test are both simple, light and work well.

3. GPX Logger is a simple, light app which does a fantastic job.

4. Google Maps comes pre installed on most Android platforms, and now supports offline data as well. I prefer to use web based maps and satellite imagery (Google, Bing and OSM) more for route planning and 'homework' than on the actual ride itself.

5. Google Fit: is an interesting app that tracks activity, especially cycling and running, fairly well with minimal inputs from the user.

6. There are a bunch of sport tracking apps - Strava, Endomondo, MapMyRide, Runkeeper, etc. Choose one if you want. Services like Tapiriik allow automatic updating of data across such apps.

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