An integrated global navigation satellite system and inertial navigation system

A cell phone (1) or similar portable device includes a global navigation satellite subsystem (5) and an inertial navigation subsystem (7) responsive to an inertial sensor (6). The inertial sensor (6) is used in a navigation mode discrimination routine to sample the frequency of inertial disturbances of the device and the sampled frequencies are processed to determine if the device is being carried by a pedestrian or carried in a vehicle. By reliably determining the mode of transport, erroneous navigation can be avoided.