No-outage GPS/commercial RF positioning system

A position location system operating in combination with a GPS system wherein a plurality of satellites transmit time and location data over radio frequency signals to enable a mobile GPS receiver station on the ground to determine its position, and a cellular telephone carried with said mobile GPS receiver, and wherein there are a plurality of conventional ground based commercial RF broadcast transmitters for transmitting commercial broadcast signals, characterized by:

• 1) each mobile GPS receiver station including phase detection means for (1) simultaneously receiving a predetermined number of said commercial broadcast signals, and (2) measuring the changes in phase of each of said commercial broadcast signals as said mobile GPS receiver travels, and deriving therefrom a further position signal, and
• 2) means to detect GPS outage or black-out and providing said further position signal as an indication of position of said mobile GPS receiver station.

A location finding navigation system for operating in an environment of GPS satellite signals and commercial radio wave (CR) broadcast signals and wherein from time-to-time said navigation system is in an obstructed GPS signal area, comprising:

• first receiver means for receiving a predetermined number of GPS satellite signals and producing a GPS location signal,
• second receiver means for receiving a predetermined number of said CR broadcast signals and producing a CR location signal,
• means connected to receive said GPS and CR location signal and selecting the most reliable of said location signals and presenting the most reliable location signal to a utilization device.