Patent ID: 8301366

Claim:
A portable navigation device displaying map information and navigation instructions for use in a vehicle, the portable navigation device comprising: a memory; a display for displaying the map information and navigation instructions; a microphone for inputting sound signals to the portable navigation device; and a processor for controlling operation of the portable navigation device, the processor receiving the sound signals input by the microphone, analyzing the sound signals, determining a speed at which the vehicle is moving according to characteristics of the analyzed received sound signals when not receiving Global Positioning System (GPS) signals with the portable navigation device, and estimating a current location of the vehicle based on the determined speed of the vehicle, wherein analyzing the sound signals is performed by comparing the sound signals to a data model containing sound information related to a particular make and model of the vehicle, the speed at which the vehicle is moving being determined according to the comparison between the sound signals and sound information contained in the data model.