Techniques are provided for geolocation of an airborne radar emitting source. A methodology implementing the techniques according to an embodiment includes initializing a search grid with hypothesized emitter geolocations boxes of the grid. The method further includes refining geolocations based on calculated pulse repetition intervals of de-Dopplerized times of arrival (TOAs) of emitter pulses received at multiple collection platforms within a dwell period. A residue metric is employed to qualify candidate target geolocations based on differences between the measured TOAs and hypothesized TOAs associated with the refined geolocations. A candidate history tracks the geolocations of the candidates with the smallest residue over subsequent dwells, identifying such candidates that match locations in the history and updating counts of times the candidate has been matched. Candidates with lagging match counts are dropped from the history. The search grid size is reduced to encompass regions surrounding the viable candidates by a selected margin.

Techniques are provided for geolocation of an airborne radar emitting source. A methodology implementing the techniques according to an embodiment includes initializing a search grid with hypothesized emitter geolocations boxes of the grid. The method further includes refining geolocations based on calculated pulse repetition intervals of de-Dopplerized times of arrival (TOAs) of emitter pulses received at multiple collection platforms within a dwell period. A residue metric is employed to qualify candidate target geolocations based on differences between the measured TOAs and hypothesized TOAs associated with the refined geolocations. A candidate history tracks the geolocations of the candidates with the smallest residue over subsequent dwells, identifying such candidates that match locations in the history and updating counts of times the candidate has been matched. Candidates with lagging match counts are dropped from the history. The search grid size is reduced to encompass regions surrounding the viable candidates by a selected margin.

An illustrative embodiment disclosed herein is a method including determining, by a location server, a satellite constellation, a location of a target endpoint, and a next available time of the target endpoint. The method further includes determining, by the location server, a plurality of candidate satellites based on the satellite constellation, the location of the target endpoint, and the next available time of the target endpoint. The method further includes instructing, by the location server, a ground station to broadcast a downlink signal to the plurality of candidate satellites.

First information corresponding to a radio signal received at a first sensing device from a candidate location is obtained. Second information corresponding to a radio signal received at a second sensing device from the candidate location is obtained. A first relationship between the first sensing device and the candidate location and a second relationship between the second sensing device and the candidate location are determined. A first inverse and a second inverse of respectively the first and second relationships are obtained. A first estimate of the radio signal at the first sensing device is determined from the first information and the first inverse. A second estimate of the radio signal at the second sensing device is determined from the second information and the second inverse. Energy emitted from the candidate location is measured based on the first estimate and the second estimate.

A method of wireless ranging between an initiator node and a responder node, involves performing a measurement procedure resulting in a two-way phase measurement between an initiator node and a responder node, the measurement procedure involving the initiator node transmitting an initiator carrier signal; the responder node performing a phase measurement of the initiator carrier signal relative to a responder node clock reference; the responder node transmitting a responder carrier signal; and the initiator node performing a phase measurement of the responder carrier signal relative to the initiator node clock reference, the method further involving calculating a distance between the initiator node and the responder node using as input the two-way phase measurements for the plurality of nominal frequencies; and a clock reference offset correction of the initiator node and of the responder node.

Systems, methods, and apparatus are provided for automated identification of open space in a wireless communications spectrum, by identifying sources of signal emission in the spectrum by automatically detecting signals, analyzing signals, comparing signal data to historical and reference data, creating corresponding signal profiles, and determining information about the open space based upon the measured and analyzed data in near real-time.

Radio frequency (RF) sensing by a sensing entity with an oscillator that introduces frequency errors is supported using dual direction bistatic sensing. The sensing entity transmits a sensing signal that is reflected by an object and received by a second sensing entity, which measures a first frequency offset that includes an oscillator error from the transmission of the sensing signal and a Doppler shift from the object. The sensing entity also receives and measures a second frequency offset of a sensing signal transmitted by the second sensing entity and reflected by the object, which includes a second frequency offset that includes an oscillator error from the reception of the sensing signal and a Doppler shift from the target object. The velocity of the object may be estimated based on a combination of the first and second frequency offsets, which cancels the oscillator error caused by the sensing entity.

An illustrative embodiment disclosed herein is a satellite including a transceiver, a first antenna, a second antenna, and a switch to enable only the first antenna by electrically coupling the first antenna to the transceiver responsive to a satellite constellation having less than a threshold number of satellites and enable only the second antenna by electrically coupling the second antenna to the transceiver responsive to the satellite constellation having greater than the threshold number of satellites.

A method includes obtaining signal information corresponding to a plurality of radio signals received at two or more sensing devices from a candidate location, determining a plurality of reconstructed signals based on the signal information, determining time-estimates and frequency-estimates based on a correlation between the plurality of radio signals and the plurality of reconstructed signals, determining metadata corresponding to the plurality of radio signals based on the signal information, the time-estimates, or the frequency-estimates, transmitting at least a portion of the metadata to an information combining node, obtaining the portion of the metadata from the information combining node, determining a relationship between the metadata, and determining the candidate location based on the metadata and the relationship between the metadata. Transmission of the plurality of radio signals to the information combining node is restricted based on a bandwidth of the two or more sensing devices or the information combining node.

A system is disclosed for exploiting a transmitted signal from an aircraft to determine characteristics of any of the aircraft's motion or meteorological conditions in which the aircraft is moving. The system includes a plurality of platforms for detecting Doppler shift information of the transmitted signal at each of the plurality of platforms, and a processing system for determining characteristics of any of the aircraft's motion or meteorological conditions in which the aircraft is moving.