GNSS long-code acquisition, ambiguity resolution, and signal validation
The present invention relates to a system and method using hybrid spectral compression and cross correlation signal processing of signals of opportunity, which may include Global Navigation Satellite System (GNSS) as well as other wideband energy emissions in GNSS obstructed environments. Combining spectral compression with spread spectrum cross correlation provides unique advantages for positioning and navigation applications including carrier phase observable ambiguity resolution and direct, long-code spread spectrum signal acquisition. Alternatively, the present invention also provides unique advantages for establishing the validity of navigation signals in order to counter the possibilities of electronic attack using spoofing and/or denial methods.
1. A system for verifying spread spectrum RF navigation emissions, comprising:
at least one emitter that emits a spread spectrum RF emission having at least two signals in a transmission medium;
at least one interceptor that receives the emission propagated through the transmission medium from the at least one emitter, the interceptor comprising:
a spectral compressor configured to process the intercepted spread spectrum RF emission using spectral compression utilizing a non-linear operation to produce at least one chipping clock or carrier-related observable associated with at least one signal within the transmission medium;
a cross correlator configured to produce spreading code phase observables, carrier phase observables and telemetry messaging for at least one signal of the intercepted emission; and
a validator configured to verify the spread spectrum RF navigation emission based on the pseudorange observables, carrier phase observables and telemetry messaging.
2. The system of claim 1 , wherein the validator is configured to compare at least one of the spreading code observables, chipping clock observables, carrier phase observables and telemetry messaging for at least one signal of the intercepted emission with those of another signal of the intercepted emission or predetermined configuration information for the at least one emitter.
3. The system of claim 1 , wherein the validator is configured to compare at least one of the spreading code observables, chipping clock observables, carrier phase observables and telemetry messaging for at least one signal of the intercepted emission with those of another signal of a second intercepted emission or predetermined configuration information for at least one of the emitters.
4. The system of claim 1 , wherein the validator is configured to compare telemetry messaging for a plurality of intercepted emission with predetermined configuration information for the at least one emitter.
5. A method for verifying spread spectrum RF navigation emissions, comprising:
intercepting, by an interceptor, at least one spread spectrum RF navigation emission having at least two signals within a transmission medium;
processing, by a spectral compressor, the emission using spectral compression utilizing a non-linear operation to produce at least one chipping clock or carrier-related observable associated with at least one signal within the transmission medium;
cross correlating, by a cross correlator, the spreading code with at least one spread spectrum RF emission having at least two distinct emission signals to produce pseudorange observables, carrier phase observables and telemetry messaging for at least one of the emission signals;
verifying, by a validator, the spread spectrum RF navigation emission based on the pseudorange observables, carrier phase observables and telemetry messaging.
6. The method of claim 5 , wherein verifying the spread spectrum RF navigation emission comprises comparing at least one of the pseudorange observables, carrier phase observables and telemetry messaging for at least one signal of the intercepted emission with those of another signal of the intercepted emission or predetermined configuration information for the at least one emitter.
7. The method of claim 5 , wherein verifying the spread spectrum RF navigation emission comprises comparing at least one of the pseudorange observables, carrier phase observables and telemetry messaging for at least one signal of the intercepted emission with those of another signal of a second intercepted emission or predetermined configuration information for at least one of the emitters.
8. The method of claim 5 , wherein verifying the spread spectrum RF navigation emission comprises comparing telemetry messaging for a plurality of intercepted emission with predetermined configuration information for the at least one emitter.