Systems and methods for detecting, localizing, and filtering signals such as radiofrequency signals using an array of antennas are disclosed. Input signals each containing a signal of interested are received, along with a reference signal sharing one or more characteristics of the signal-of-interest. Predetermined time delays and frequency shifts are applied to the input signals such that the signal-of-interest components of the signals are synchronized and to cancel any Doppler-shifting between the signal-of-interest components. A filtering process is employed to filter the shifted input signals and sum them such that a metric indicating the degree of difference between the reference signal and the summed filtered signals (such as the mean squared error, for example) is minimized.

The described technology is generally directed towards adaptively changing which transmission scheme a user equipment is to use based on a Doppler metric (e.g. Doppler frequency) as evaluated against a threshold Doppler value. A network instructs a user equipment to use a Rank-1 precoder cycling transmission scheme if the Doppler metric of user equipment is above a threshold value, or to use a closed loop MIMO transmission scheme if the user equipment has a Doppler metric below the threshold value. The network can instruct the user equipment via a suitable message, or by switching off TPMI and notifying the user equipment thereof.

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.

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.

A method for determining the start of movement of a motor vehicle equipped with a system for monitoring tire pressure of a motor vehicle. Communication between the receiver and each pressure monitoring system emitter being subjected to a Doppler effect so that a periodic component is inserted by the emitter into the signal emitted to the receiver. The method includes: acquiring the intermediate-frequency signal before demodulation by a processor to extract data carried by the radiofrequency signal, determining the FFT of the IF signal, determining the average value of the FFT of the IF signal over a preset duration, and determining whether there is a frequency deviation by comparing the instantaneous value of the fast Fourier transform to the average value of the fast Fourier transform, if so, determining whether the emitter for monitoring the pressure of a tire is moving and that the vehicle is moving.

A method for determining the start of movement of a motor vehicle equipped with a system for monitoring tire pressure of a motor vehicle. Communication between the receiver and each pressure monitoring system emitter being subjected to a Doppler effect so that a periodic component is inserted by the emitter into the signal emitted to the receiver. The method includes: acquiring the intermediate-frequency signal before demodulation by a processor to extract data carried by the radiofrequency signal, determining the FFT of the IF signal, determining the average value of the FFT of the IF signal over a preset duration, and determining whether there is a frequency deviation by comparing the instantaneous value of the fast Fourier transform to the average value of the fast Fourier transform, if so, determining whether the emitter for monitoring the pressure of a tire is moving and that the vehicle is moving.

Example methods and systems described herein relate to determining average arrival time of a radio wave emitted by a lightning discharge and/or determining the lobe and/or polarity of the radio wave. The determination of the average arrival time may take a weighted average of arrival times of peaks of the radio wave. The determination of the lobe and/or polarity may depend on an estimated propagation distance, a propagation path profile, and one or more waveform features.

Example methods and systems described herein relate to determining average arrival time of a radio wave emitted by a lightning discharge and/or determining the lobe and/or polarity of the radio wave. The determination of the average arrival time may take a weighted average of arrival times of peaks of the radio wave. The determination of the lobe and/or polarity may depend on an estimated propagation distance, a propagation path profile, and one or more waveform features.

The described technology is generally directed towards adaptively changing which transmission scheme a user equipment is to use based on a Doppler metric (e.g. Doppler frequency) as evaluated against a threshold Doppler value. A network instructs a user equipment to use a Rank-1 precoder cycling transmission scheme if the Doppler metric of user equipment is above a threshold value, or to use a closed loop MIMO transmission scheme if the user equipment has a Doppler metric below the threshold value. The network can instruct the user equipment via a suitable message, or by switching off TPMI and notifying the user equipment thereof.