System and method for aiding data processing for signals of opportunity-based assured position, navigation and timing (PNT)
A system and method to opportunistically receive and use measurements on a priori unknown radio signals, not intended for radio navigation or geolocation, in conjunction with aiding data to improve navigation/geolocation position and time estimation yield and accuracy.
1. A method of using aiding data for determining the location of a user, comprising:
a. surveying an RF environment by monitoring a range of RF frequencies or sources;
b. receiving a plurality of non-GNSS RF signals at a user from a plurality of first sources, wherein the first source is not a Global Positioning System or Global Navigation Satellite System;
c. receiving aiding data associated with at least one of received non-GNSS RF signals, sent from a second source which is different than the first source, wherein the aiding data provides information about a received non-GNSS RF signal or a source of the received non-GNSS RF signal;
d. in a processor, accessing the received aiding data associated with the plurality of received non-GNSS RF signals;
e. in the processor, selecting aiding data as a function of a characteristic of the accessed aiding data source;
f. in the processor, selecting at least one of the plurality of non-GNSS signals as a function of the selected aiding data;
g. performing RF related measurements on the selected received non-GNSS signals; and
h. in the processor, determining a location of the user as a function of the performed RF related measurements and the selected aiding data.
2. The method of claim 1 comprising the further steps of using the determined location of the user to select additional aiding data to further refine the location of the user.
3. The method of claim 1 comprising the further steps of (i) weighing each selected non-GNSS RF signal as a function of the aiding data and (ii) determining location of the user as a function of the selected weighted non-GNSS RF signals.
4. The method of claim 1 wherein at least one of the received non-GNSS RF signals is a signal of opportunity (SoOP).
5. The method of claim 1 wherein the aiding data is from an RF source.
6. The method of claim 5 wherein the aiding data includes a time tag.
7. The method of claim 1 wherein the aiding data includes RF spectrum sensing data which indicates what RF frequencies may be received without interference at the user.
8. The method of claim 1 wherein the step of selecting the non-GNSS RF signals includes a measurement of a non-GNSS RF signal and determining an associated quality metric.
9. The method of claim 8 comprising the further steps of (i) weighing each selected non-GNSS RF signal as a function of the associated quality metric and (ii) determining location of the user as a function of the selected weighted non-GNSS RF signal.
10. The method of claim 1 wherein the step of selecting the aiding data further comprises selecting the aiding data as a function of the characteristics of the local spectrum environment at the user platform.
11. The method of claim 1 wherein the step of selecting a non-GNSS RF signals includes selecting a non-GNSS RF signal as a function of a) received signal strength and b) contribution to dilution of precision (DOP).
12. The method of claim 1 wherein the step of selecting the non-GNSS RF signals includes selecting a non-GNSS RF signal as a function of a desired level of performance.
13. The method of claim 1 wherein the step of selecting the non-GNSS RF signals includes selecting the non-GNSS RF signal as a function of a characteristic of an RF signal source that transmitted the non-GNSS RF signal.
14. The method of claim 1 further comprising the steps of (i) receiving a GNSS signal at the user, (ii) performing RF measurements on the selected received non-GNSS signals and the received GNSS signal, and (iii) determining a location of the user as a function of the performed measurements and the selected aiding data.
15. The method of claim 1 wherein the plurality of non-GNSS signals includes a signal from a communications satellite, and the aiding data includes ephemeris data for the communications satellite.
16. The method of claim 1 further comprising the steps of (i) performing ranging measurements using the non-GNSS signal RF related measurements, and (iii) determining a location of the user as a function of the performed ranging measurements and the selected aiding data.
17. The method of claim 1 wherein the user is a pedestrian, a vehicle, an aircraft or a ship.
18. The method of claim 1 comprising the further steps of:
h. sensing the RF environment at the user;
i. changing an operating characteristic of an RF source that transmitted the non-GNSS RF signal as a function of the sensed RF environment;
and j. retuning a receiver at the user as a function of the changed operating characteristics.
19. The method of claim 18 wherein the operating characteristic characteristics include one of frequency and waveform.
20. The method of claim 1 wherein the non-GNSS signal is transmitted from a low earth orbiting satellite and the RF related measurement includes relative Doppler shift.
21. The method of claim 1 wherein at least one of the plurality of non-GNSS signals is transmitted from a first transmitter of a prior unknown location and further comprising the step of determining a location of the first transmitter as a function of the selected accessed aiding data.
22. The method of claim 1 wherein the step of performing RF related ranging measurements includes determining a time difference of arrival of at least two signals.
23. The method of claim 1 wherein the at least one of a plurality of non-GNSS signal includes a communication signal.
24. The method of claim 23 wherein the communication signal includes at least one of a WIFI signal, a WIMAX signal, radar, a cellular signal, a digital television signal, or a signal from an orbiting satellite.
25. The method of claim 1 wherein the step of performing RF related measurements includes ranging measurements.
26. A method of using aiding data for determining the location of a user, comprising:
a. surveying an RF environment by monitoring a range of RF frequencies or sources;
b. receiving a plurality of signals of opportunity (SoOPs) at a user from a plurality of first sources, wherein the first source is an RF source not mainly intended for positional, navigational and timing purposes;
c. receiving aiding data associated with at least one of the received SoOPs sent from a second source which is different than the first source, wherein the aiding data provides information about a received SoOP or the source of the SoOP;
d. in a processor, accessing aiding data associated with the plurality of received SoOPs;
e. in the processor, selecting aiding data as a function of a characteristic of the accessed aiding data source;
f. in the processor, selecting at least one of the plurality of SoOPs as a function of the selected aiding data;
g. performing RF related measurements on the selected received SoOPs;
and h. in the processor, determining a location of the user as a function of the performed RF related measurements and the selected aiding data.
27. A method of using aiding data for determining time at a user, comprising:
a. surveying an RF environment by monitoring a range of RF frequencies or sources;
b. receiving a plurality of non-GNSS RF signals at a user from a plurality of first sources, wherein the first source is not a Global Positioning System or Global Navigation Satellite System;
c. receiving aiding data associated with at least one of received non-GNSS RF signals, sent from a second source which is different than the first source wherein the aiding data provides information about a received non-GNSS RF signal or the source of the received non-GNSS RF signal;
d. in a processor, accessing the received aiding data associated with the plurality of received non-GNSS RF signals;
e. in the processor, selecting aiding data as a function of a characteristic of the accessed aiding data source;
f. in the processor, selecting at least one of the plurality of non-GNSS signals as a function of the selected aiding data;
g. performing RF measurements on the selected received non-GNSS signals;
and h. in the processor, determining a time at the user as a function of the performed RF measurements and the selected aiding data.