Matthew,

It is common practice to use GPS data in conjunction with dead-reckoning data (compass and odometry) for a more robust navigation solution. GPS fails in tunnels, parking garages and deep urban canyons (think Manhatten or even San Francisco) where a line-of-sight view of the satellites is obstructed and dead-reckoning drifts over time (think KAL 007, an inertial navigation system is a very sophisticated form of dead-reckoning). Either sensor alone will leave something to be desired. Your needs will somewhat depend on the terrain where you will be navigating.

Lynn
[Go Bears ]