iPhone 4 GPS performance

[bldn10]

The "Compatibility" page still says that iPhones "3 upward" need external GPS assistance. Is that true of the iPhone 4 or 4S? From what I understand the 4 is still 3g but the 4S is 4g - does that make any difference?
Alternatively, can I add the Emprum to an iPhone 3 and get performance equivalent to the 4S? Or better?

I know nothing of all this - I just want a good track day lap timer and need to know what phone to get.

Bill/Memphis/USA

[Harry]

Description is "The iPhone 3G upwards comes with an internal GPS sensor and can be used standalone." Not sure if this is misleading. The meaning should be that iPhones starting at 3G had a GPS chip included - opposed to the iPhone 1st gen. Between the iPhone3G and 4 there was a major improvement of GPS quality. While the 3G and 3GS were pretty weak, the iPhone4 (and 4S) are good enough for most situations. The TomTom, and the XGPS159 have still some advantages, the UltiMate GPS is clearly better as it features 5Hz.

Adding an UltiMate GPS to an iPhone3G will produce better timing / recording results than the iPhone4 without. It certainly suffers from the lower processing power and lower resolution. Furthermore, I may need to stop support for old devices some time.

- Harry

[bldn10]

Thanks, Harry. Coupled w/ the recommendation to use an external GPS device if you want accuracy (and don't we all?), I read that to mean that you can maybe "get by" w/ a 3 alone. I have a buddy who was not satisfied w/ the performance w/ his 3 but is delighted w/ it w/ his 4. Sounds like the basic iPhone 4 is sufficient. You can tell Apple that your app is selling the phone and not vice versa.

Bill/Memphis/USA