Reverse-ephemeris lunar navigation system for long-distance route determination
View Patent ↗The disclosed system and method transmit a signal from the surface (or surroundings) of a celestial object to a satellite (for which you know the orbital elements) that re-transmits the signal back to a transceiver on the surface of the celestial object from which a time delay to obtain a range measurement and a Doppler shift to obtain the range-rate can be measured. With knowledge of the satellite's orbital elements and the range and range-rate, a location of the transceiver can be determined.
1. A system configured to determine a location of a transceiver, the system comprising:
a non-transitory computer-readable medium comprising computer-executable instructions that when executed by a processor, cause the processor to perform at least, including at least:
receive a beacon signal at a transceiver in operative communication with the processor, the beacon signal being received from at least one satellite orbiting a celestial object, wherein the beacon signal is in a predetermined frequency band;
transmit an uplink signal to the at least one satellite on an uplink channel;
transmit by a transponder of the at least one satellite in response to receiving the first signal, a downlink signal on a downlink channel;
receive the downlink signal at the transceiver and determining a range measurement and a range rate measurement therefrom; and
calculate a location of the transceiver using the range measurement, the range rate measurement, and a known orbital location of the at least one satellite.
2. The system according to claim 1 , wherein as part of calculating the location of the transceiver, the computer-readable medium further comprises instructions that when executed by the processor, cause the processor to at least:
generate a first conic section of possible transceiver locations and a second conic section of possible transceiver locations, wherein the first and second conic sections intersect at two points; and
eliminate one of the two points as the location of the transceiver on the celestial object using prior data.
3. The system according to claim 1 , wherein the predetermined frequency band is the S-band.
4. The system according to claim 1 , the system further comprises the transceiver, and wherein the transceiver is handheld.
5. The system according to claim 4 , wherein the transceiver includes a helical antenna.
6. The system according to claim 1 , wherein the transceiver is configured to operate in a first operating mode in which it communicates with at least one satellite in a frozen elliptical orbit around the space object.
7. The system according to claim 4 , wherein the transceiver operating power is equal to or below 10 Watts.
8. The system according to claim 1 , wherein as part of determining the range rate measurement, the computer-readable medium includes computer-executable instructions that when executed by the processor, cause the processor to at least:
calculate a Doppler shift between the uplink and downlink signals.
9. The system according to claim 1 , wherein as part of determining a range measurement, the computer-readable medium includes computer-executable instructions that when executed by the processor, cause the processor to at least:
calculate a time delay between transmission of the uplink signal by the transceiver and receipt of the downlink signal by the transceiver.
10. A system configured to determine a location of a transceiver, the system comprising:
a transceiver configured to transmit and receive signals in a predetermined frequency band;
a processor;
a non-transitory computer-readable medium comprising computer-executable instructions that when executed by the processor cause the processor to at least:
obtain a known orbital location for at least one satellite operating in a frozen elliptical orbit around a celestial body;
receive one or more signals from a transponder of the one or more satellites;
determine a range measurement and a range rate measurement based, at least in part, on the one or more signals received from the transponder of the one or more satellites; and
calculate a location of the transceiver using at least the range measurement, the range rate measurement, and the orbital location of the at least one satellite.
11. The system according to claim 10 , wherein to calculate the location of the transceiver, the computer-readable medium further includes computer-readable instructions that when executed by the processor cause the processor to at least:
generate a first conic section of possible transceiver locations and a second conic section of possible transceiver locations, wherein the first and second conic sections intersect at two points; and
eliminate one of the two points as the location of the transceiver on the celestial object using prior data.
12. The system according to claim 10 , wherein the predetermined frequency band is the S-band.
13. The system according to claim 10 , wherein the transceiver is handheld.
14. The system according to claim 13 , wherein the transceiver includes a helical antenna.
15. The system according to claim 13 , wherein the transceiver operating power is equal to or below 10 Watts.
16. The system according to claim 10 , wherein the computer-readable medium includes computer-executable instructions that when executed by the processor causes the processor to determine the range rate measurement by calculating a Doppler shift between signals passed between the transceiver and the transponder.
17. The system according to claim 10 , wherein the computer-readable medium includes computer-executable instructions then when executed by the processor cause the processor to determine a range measurement by calculating a time delay between transmission of an uplink signal by the transceiver and receipt of a downlink signal from the transponder by the transceiver.
18. The system according to claim 10 , wherein the at least one satellite is a constellation of three satellites, in which the transceiver is configurable to be in within communication proximity of at least one of the satellites at all times while in a first operating mode.
19. A system for determining location of an asset, the system comprising:
means for transmitting a beacon signal from at least one satellite orbiting a celestial object;
means for receiving the beacon signal at a location of the asset and transmitting a first signal to the at least one satellite on an uplink channel;
means for receiving the first signal and transmitting a second signal on a downlink channel;
means for receiving the second signal and determining a range measurement and a range rate measurement therefrom, and for calculating a location of the transceiver using the range measurement, the range rate measurement, and a known orbital location of the satellite.
20. The system according to claim 19 , wherein the system uses means selected from the group consisting of analog means and digital means.