A locating and communication method for a radio terminal by means of a satellite locating and communication system, which implements a first step, in the course of which the radio terminal transmits to a non-geostationary satellite a repeating sequence a predetermined number of times N for the same data packet, which is time-shifted by the same predetermined time shift Δτ each time is provided. Subsequently, a satellite access and processing ground station determines the location of the radio terminal from the data packets with access, which are extracted from a listening signal digitized and dated by the satellite and from the same detected sequence associated with said radio terminal, and from the ephemerides of the satellite by using a technique for measuring angle or angles of arrival by means of sequenced interferometry associated with a technique for measuring Doppler drift or drifts.

A method includes obtaining multiple geolocation measurements, where each geolocation measurement is generated using cross-ambiguity function (CAF) detection. The geolocation measurements are associated with at least one signal from at least one signal source and received by multiple receivers. The method also includes associating related geolocation measurements to form at least one collection of related geolocation measurements, where each collection of related geolocation measurements is associated with a common one of the at least one signal received by at least some of the receivers. The method further includes performing geolocation using the at least one collection of related geolocation measurements to identify one or more geolocations of the at least one signal source.

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.

Systems, methods, and devices are disclosed herein for Doppler based position estimation. Systems may include an antenna configured to receive a radio frequency (RF) signal from an emitter, and configured to generate an output signal based on the received RF signal. Systems may also include a receiver configured to receive the output signal from the antenna. The receiver may include one or more processors configured to identify a plurality of initial conditions for a plurality of state variables associated with the emitter, obtain a measurement of the RF signal from the emitter and an estimate of an uncertainty associated with the measurement, and generate an output based, at least in part, on an updated estimate of the plurality of state variables, the output identifying a position, velocity, and carrier frequency of the emitter. Systems may also include a communications interface configured to communicatively couple the antenna with the receiver.

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.

A transmission source position estimation system includes a sensor and a position estimation apparatus. The sensor is provided with a characteristic vector classification part and an attribute data extraction part. The characteristic vector classification part classifies a set of characteristic vectors obtained from received signal data of a transmitted wave, into subsets in a feature space. The attribute data extraction part extracts attribute data for each of the subsets and outputs the extracted data as an attribute data sequence. The position estimation apparatus is provided with a data combination part and a position estimation part. The data combination part combines attribute data that match or are similar to at least one attribute for a plurality of attribute data sequences. The position estimation part estimates the position of the transmission source from the combined attribute data and the position of the sensor that receives the transmitted wave.

Multivariate position estimation can be performed to provide a position estimate of a moving object. The multivariate position estimation approach can employ multiple types of information including time of arrival (or time difference of arrival), angle of arrival, Doppler, and/or prior location information in an iterative process to calculate a location estimate that is highly accurate. In particular, the multivariate position estimation approach can employ the statistical quality of each of these types of information to quickly arrive at a highly accurate position estimate within a 3D coordinate system. The multivariate position estimation approach can be implemented in environments where a single receiver is available as well as in environments where multiple receivers exist.

An apparatus, method and computer program is described comprising: generating a first loss function component comprising comparing first location data with first location estimates, wherein the first location estimates are based on channel state data, wherein the first location estimates are generated using a model, and wherein the model comprises a plurality of trainable parameters; generating a second loss function component comprising comparing the first location data with second location estimates, wherein the second location estimates are based on channel state data that have been subjected to a first augmentation and wherein the second location estimates are generated using the model; generating a third loss function component comprising comparing third location estimates based on channel state data and fourth location estimates based on channel state data that have been subjected to a second augmentation, wherein the third and fourth location estimates are generated using the model; and training the trainable parameters of the model by minimising a loss function based on a combination of the first, second and third loss function components.

Systems, methods, and apparatus for location determination of an emitter using frequency-of-arrival (FOA) measured from a single moving platform are disclosed. In one or more embodiments, a disclosed system allows for location determination of stationary, pulsed radio frequency (RF) emitters from a moving platform by using coherent frequency of arrival (CFOA) Doppler history measurements. The term coherent is used to indicate that the process requires a RF-coherent pulse train, such as that generated by modern radar. In one or more embodiments, the disclosed system employs one of two disclosed CFOA measurement methods (Method 1: CFOA linear regression of phase (LRP), and Method 2: CFOA cross-correlated frequency spectra (CCFS)). The disclosed system also enables geo-discrimination (GeoD) of emitters at known locations, or alternatively geo-location of emitters at unknown locations.

First information is obtained from a sensing device at a first time. The first information corresponds to a radio signal received at the device from a candidate location. The device is at a first location at the first time. Second information is obtained from the device at a second time. The second information corresponds to a radio signal received at the device from the candidate location. The device is at a second location at the second time. A system determines that a pattern is in each of the first and second information and determines relationships between the candidate location and the device at each first and second location. The system obtains inverses of the relationships and determines estimates of the received radio signals based on the information and inverses. The system measures or estimates energy emitted from the candidate location based on the estimates.