Garmin Forerunners are arguably the most practical GPS (Global Positioning System) solutions for runners albeit comes at a premium price.  That premium fortunately gives room for alternative solutions but aside from competing brands, an option that is getting more prevalent are devices with embedded A-GPS (Assisted GPS).

A-GPS is a system which can improve startup performance of a GPS satellite-based positioning system by having GPS computations handled by third parties like cellular network towers.  The result is less processing power required on the device, less power consumption, and faster location acquisition—at least on paper.

A-GPS is now widely available in a variety of consumer products from digital cameras to laptops but more commonly on mobile phones.  A-GPS is a sensible alternative to Garmins because of its availability and relatively lower cost, but are they really good enough?

The Test

For this test we’ll need the following:

• A device with A-GPS
• A software to track the A-GPS readouts
• The great outdoors

For this test I’ll be using Nokia 5800 ExpressMusic, currently situated in the middle tier of the price range.  All settings are set to defaults except that network support (Wi-Fi, HSDPA, 3G, Edge, or GSM) is disabled effectively disabling the “A” (assistance) in the A-GPS and focusing on its GPS capabilities.

I opted to disable network assistance for practical reasons: the cost of bandwidth (typically P10 per 30 minutes of usage which is the minimum) and availability of network (Wi-Fi and 3G isn’t always available all the time everywhere).

Utilizing the device’s A-GPS is Sports Tracker 3.01 for Symbian Series 60 by Sports Tracking Technologies, available for free download via Nokia Ovi.  Alternative tracking software is also available for various devices and platforms but I chose this software as it is specifically designed for Nokia Series 60 devices.

I’ve had my Nokia 5800 for quite a while now but wasn’t really able to successfully track a run because of A-GPS’s major drawback—time to first fix (TTFF), or is the time it takes for your location to be pinpointed.  When we run we usually are eager to start our run as soon as possible so we’d rather start running than stand by for the device to have a “fix.”  Fortunately though, during New Balance Trail Adventure Run, I had enough patience to wait for that fix while waiting for the gunstart.  Of course I still had my Garmin Forerunner 405 to validate the results my Nokia 5800 would track.

Nokia 5800s aren’t the handiest devices around (111 × 51.7 × 15.5 mm) so I had to place it in one of the pockets of my hydration belt for convenience.  The drawback was that I had to start it earlier before gunstart because of accessibility issues and when the race was over I actually forgot about it and was able to end the track after a while resulting in a slightly longer distance.  Running with a device that really isn’t designed for such activities are manageable but can be a bit cumbersome and may take some time to get used to.

The Results

At the end of the day I was finally able to compare the GPS readings between my GF405 and Nokia 5800.  The result: practically the same! I was really surprised that both readings are almost exact copies each other.  At this point we can easily say that the GPS in A-GPS devices do complement more expensive dedicated GPS devices.

Here are my assessments:

Good:

• A-GPS devices works practically the same as dedicated GPS devices
• A-GPS devices are relatively cheaper than dedicated GPS devices
• “Real-time” plot of your route depending on your software

Bad:

• TTFF is very, very long without assistance (significantly more than 10 minutes)
• The accuracy of A-GPS devices (at least as far as my Nokia 5800 is concerned) are very low compared to dedicated GPS devices (normally at 30 meters compared to a typical 5 meters for GF405)
• Activating assistance (even through Wi-Fi) doesn’t guarantee a faster “fix”
• Activating assistance is costly unless you have unlimited data plans
• A-GPS devices aren’t always portable
• A-GPS devices’ tracking capabilities are software dependent (normally third party software)
• Uploading your GPS tracks online is trivial

Conclusion

Tracking-wise A-GPS devices work the same way as dedicated GPS devices although at a much lower accuracy but the difference is practically negligible as far as tracking your route, distance, and pace is concerned.  Depending on your software you may even see your actual route in “real-time,” a feature that isn’t always available in dedicated GPS devices (like GF405).  Typically A-GPS devices are much cheaper than dedicated GPS devices (my Nokia 5800 is much cheaper than my GF405) but despite all of these I still don’t see it as a serious alternative.  Its biggest drawback, the very long TTFF, is enough to turn most users off especially if they have experienced dedicated GPS devices like Garmins.  I remember being furious when my GF405 didn’t lock within five minutes but even in an ideal situation I never saw my Nokia 5800 lock within 10 minutes, even in the presence of Wi-Fi!  (I think 3G is the preferred medium of assistance for A-GPS.)  In fact the first time I used A-GPS on my 5800 it took 30 minutes before it was able to have a GPS lock.

To summarize, if you have A-GPS feature with your portable devices and have enough time to wait for it to “fix” it is a viable alternative to dedicated GPS devices like Garmins, but if you can afford it nothing beats a “dedicated” device.  At the current state of technology it isn’t good enough yet to replace dedicated devices but is good enough to complement it.  With all the “overheads” I had to consider for it to work I’d say I learned to love more the convenience my GF405 gave me.  In this case you really get your money’s worth.  With the rate of improvements in technology who knows maybe one of these days an A-GPS device will come out matching the “dedication” of Garmins, but until then Garmins still rule!

Suggested read:

• Garmin Forerunner® 405 Review
• GPS vs. aGPS