Global Positioning System (GPS) and Doppler Augmentation (GDAUG) and Space Location Inertial Navigation Geopositioning System (SPACELINGS)

A method for determining a global position of a receiver, the method comprising:

• receiving, at the receiver, transponded signals from at least one relay satellite, wherein the relay satellite is configured to receive downlink signals from a high altitude satellite and generate the transponded signals from the downlink signals;
• detecting, at the receiver, a first Doppler shift for the transponded signals received from the relay satellite, the first Doppler shift being from the high altitude satellite to the relay satellite;
• detecting, at the receiver, a second Doppler shift for the transponded signals received from the relay satellite, the second Doppler shift being from the relay satellite to the receiver,
• determining, at the receiver, an aggregate range between the high altitude satellite and the relay satellite using a time of signal flight between the high altitude satellite and the receiver, wherein the aggregate range includes a first range between the high altitude satellite and the relay satellite and a second range between the relay satellite and the receiver;
• and
• determining, at the receiver, the global position of the receiver based on the aggregate range between the high altitude satellite and the relay satellite, the first Doppler shift for the transponded signals and the second Doppler shift for the transponded signals.

A receiver operable to determine a global position, the receiver comprising:

• a transponded signal receiver operable to receive transponded pseudo-random noise (PRN) signals from at least one relay satellite, wherein the relay satellite is configured to receive downlink PRN signals from a high altitude satellite and generate the transponded PRN signals from the downlink PRN signals;
• a Doppler shift module operable to:
• detect a first Doppler shift for the transponded PRN signals received from the relay satellite, the first Doppler shift being from the high altitude satellite to the relay satellite;
• detect a second Doppler shift for the transponded PRN signals received from the relay satellite, the second Doppler shift being from the relay satellite to the receiver;
• a range estimator operable to determine an aggregate range between the high altitude satellite and the relay satellite based on a time of signal flight between the high altitude satellite and the receiver, wherein the aggregate range includes a first range between the high altitude satellite and the relay satellite and a second range between the relay satellite and the receiver;
• and
• a receiver location estimator operable to determine the global position of the receiver based on the aggregate range between the high altitude satellite and the relay satellite, the first Doppler shift for the transponded PRN signals and the second Doppler shift for the transponded PRN signals.

A relay satellite operable to facilitate position determination for a receiver, the relay satellite comprising:

• a signal receiver operable to receive downlink signals from a high altitude satellite, wherein the downlink signals received from the high altitude satellite include two downlink signals on at least two distinct carrier frequencies that are previously known;
• a frequency shifter operable to shift a frequency for the downlink signals and combine the downlink signals to a common frequency, thereby generating transponded signals;
• and
• a transponded signal transmitter operable to send the transponded signals to the receiver,
• wherein the receiver is operable to determine a global position of the receiver based on a first Doppler shift of the transponded signals from the high altitude satellite to the relay satellite, a second Doppler shift of the transponded signals from the relay satellite to the receiver, and an aggregate range between the receiver and the high altitude satellite.