US Patent 9602974 Dead reconing system based on locally measured movement

A Global Navigation Satellite System (GNSS) chipset embedded within the cellular device is accessed. The GNSS chipset calculates raw pseudoranges. The raw pseudoranges are extracted from the GNSS chipset for processing elsewhere in the cellular device outside of the GNSS chipset. A position fix is calculated based on the raw pseudoranges. At a first point in time, a first image, and at a second point in time, a second image are obtained with an image capturing device that is in a known physical relationship with the cellular device. An estimate of a distance that the cellular device moved from the first point in time to the second point in time is calculated by processing image data collected from the first point in time to the second point in time. The position fix is processed based on the estimate of the distance.