Intelligent passive navigation system for back-up and verification of GPS
First Claim
1. A method for implementing a passive navigation system for an air vehicle which comprises the steps of:
- providing a database for a plurality of emitters, wherein the database includes information regarding the geolocation of each emitter in the database, and information regarding at least one characteristic operating factor contained in signals transmitted by a respective emitter;
receiving a signal from at least one emitter, said signal originating at a distance from the air vehicle;
isolating the signal received from the emitter;
processing the received signal using operating factor information in the database to establish an identity of the emitter;
evaluating the geolocation information for the identified emitter in the database to estimate a direction of arrival for the air vehicle to the identified emitter; and
using the emitter identity and direction of arrival to determine a course location of the air vehicle for use in navigation.
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Accused Products
Abstract
A passive navigation system for an airborne platform includes an on-board computer having a database that contains preprogrammed information regarding pre-existing ground-based signal emitters (e.g. cell-phone, television and radio broadcast transmitters). For each emitter, the database includes the geolocation of the emitter and identifying signal characteristic(s) of each emitter'"'"'s signal such as frequency, bandwidth and strength. An antenna array and digital receiver cooperate with the computer on the platform to passively receive signals from the emitters and determine a direction of arrival (DOA) for selected signals. The computer also extracts identifying signal characteristic(s) from selected received signals and matches them against the database information to ascertain the geolocation of the emitter that corresponds to the received signal. The platform location is then calculated from the DOA(s) and emitter geolocations using a triangulation-type algorithm. Also, preprogrammed site-specific terrain scattering information can be compared to observed scattered signals to enhance system accuracy.
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Citations
22 Claims
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1. A method for implementing a passive navigation system for an air vehicle which comprises the steps of:
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providing a database for a plurality of emitters, wherein the database includes information regarding the geolocation of each emitter in the database, and information regarding at least one characteristic operating factor contained in signals transmitted by a respective emitter;
receiving a signal from at least one emitter, said signal originating at a distance from the air vehicle;
isolating the signal received from the emitter;
processing the received signal using operating factor information in the database to establish an identity of the emitter;
evaluating the geolocation information for the identified emitter in the database to estimate a direction of arrival for the air vehicle to the identified emitter; and
using the emitter identity and direction of arrival to determine a course location of the air vehicle for use in navigation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for determining position information for an airborne platform, said method comprising the steps of:
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pre-programming a computer database with signal information for a plurality of signals from a respective plurality of stationary ground based emitters;
receiving a signal from said plurality of stationary ground based emitters, said signal originating at a distance from the airborne platform, wherein said signal is selected from the group of signals consisting of a communication signal and a radar signal; and
comparing said received signal to said pre-programmed signal information in said database to determine position information for the airborne platform. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A passive navigation system for an airborne platform, said system comprising:
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means for receiving a plurality of signals from a respective plurality of stationary ground based emitters located at a plurality of respective geolocations with at least one said received signal selected from the group of signals consisting of a communication signal and a radar signal, said signal originating at a distance from the airborne platform;
a computer positioned on said platform, said computer having a database pre-programmed with each said emitter'"'"'s geolocation and at least one signal identification characteristic for each said signal;
a means for selecting at least one signal from said received signals and determining a direction of arrival (DOA) for each said selected signal;
a means for comparing each said selected signal to said preprogrammed signal identification characteristics in said database to determine a signal emitter geolocation for each said selected signal; and
a means for using each said signal emitter geolocation and each said DOA to estimate a geolocation for the airborne platform. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22)
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Specification