Originally Posted by
AdamDZ
Also people keep forgetting that iPhone uses assisted GPS: GPS signal plus cellular tower triangulation. The GPS antenna is weak and without cellular signal assistance it becomes pretty useless as a GPS device. Plus its compass is ridiculously sensitive to electromagnetic interference. Save your money towards are real GPS receiver.
Adam
I hope you don't mind if I fling a pile of techy questions at you. Just tell me if I'm barking up the wrong tree.
Is the tower info just there to handle satellite shadowing and the resulting "urban canyons" issue? Or is it necessary under open access conditions?
Is the inertial navigation system (INS, for a compass and a multi-axis accelerometer) based on a MEMS chip? or what? Some automotive INS developments are finding COTS MEMS to be inadequate. Path prediction software based on INS and GPS makes it a lot more accurate and robust.
How does the EMI sensitivity manifest itself?
Some of this sounds like design issues rather than basic technology inadequacy. Hopefully Apple will do more product improvement (AND ATT will cut the price!).