Disclosed is a high-resolution accurate two-dimensional direction-of-arrival estimation method based on coarray tensor spatial spectrum searching with coprime planar array, which solves the problem of multi-dimensional signal loss and limited spatial spectrum resolution and accuracy in existing methods. The implementation steps are: constructing a coprime planar array; tensor signal modeling for the coprime planar array; deriving coarray statistics based on coprime planar array cross-correlation tensor; constructing the equivalent signals of a virtual uniform array; deriving a spatially smoothed fourth-order auto-correlation coarray tensor; realizing signal and noise subspace classification through coarray tensor feature extraction; performing high-resolution accurate two-dimensional direction-of-arrival estimation based on coarray tensor spatial spectrum searching. In the present method, multi-dimensional feature extraction based on coarray tensor statistics for coprime planar array is used to implement high-resolution, accurate two-dimensional direction-of-arrival estimation based on tensor spatial spectrum searching, and the method can be used for passive detection and target positioning.

A system and method for determining an Angle of Arrival (AOA) for frequency modulated communications. The system may include first and second antennas spaced apart from each other by a distance, and configured to receive wireless communications in the form of a frequency modulated signal. The system may determine a phase difference between the received signals irrespective of the modulations in the signal, thereby facilitating determining an AOA.

A system and method are disclosed and include receiving a wireless signal. The method includes generating a first and second set of digital data that are representative of the wireless signal. The method includes obtaining a first and second sample that is representative of a cosine and sine component, respectively, of a pre-known portion of the first set. The method includes obtaining a third and fourth sample that is representative of a cosine and sine component, respectively, of a pre-known portion of the second set. The method includes determining a first phase angle value based on an amplitude of the first and second samples and a second phase angle based on an amplitude of the third and fourth samples. The method includes determining an angle of arrival based on a difference between the first and second phase angle values.

Disclosed are techniques for wireless communication. In an aspect, a network entity determines a location of a target base station and a location of at least one reference device, determines an angle-of-arrival (AoA) measurement of one or more reference signals received by at least one antenna array of the target base station from the at least one reference device, determines an expected AoA between the at least one antenna array and the at least one reference device based on the location of the target base station and the location of the at least one reference device, and determines an orientation offset of the at least one antenna array based on a difference between the expected AoA and the AoA measurement.

Systems and methods are provided for determining a polarization state of an input RF signal. Two distinct RF antennas receive the input RF signal and output a first antenna signal and a second antenna signal. Polarizsations of the first and second antenna signals are orthogonal to one another. The first antenna signal is converted to a first optical signal, and the first optical signal is passed through a first optical signal to introduce a first delay. The delayed first optical signal is converted to a first RF signal. An amplitude ratio and a phase difference are determined between the first RF signal and a second RF signal that is associated with the second antenna and optionally includes a second delay. A polarization angle or polarization type of the input RF signal is determined based on the amplitude ratio and phase difference of the first and second RF signals.

A traffic collision avoidance system (TCAS), configured to transmit a wide transmit beam of approximately 180 degrees. The wide transmit beam may be, for example at the interrogation frequency or a transponder response frequency. The TCAS of this disclosure includes a directional antenna system with two signal input ports and two or more antenna elements. In some examples, the direction of the 180 degree beam may be controlled by the phase relationship between the signals input to the two port antenna. In other examples, the direction of the transmit beam from the antenna system is predefined to be in two complementary directions (e.g., forward and aft).

Example techniques relate to playback based on acoustic signals in a system including a first playback device and a second playback device. A first playback device may detect a user-spoken signal. The first playback device sends, to a network device, data corresponding to the detected user-spoken signal. The network device causes playback of the media item to be transferred to the first playback device such that the second playback device stops playing back a media item and the first playback device begins playing back the media item.

A traffic collision avoidance system (TCAS), configured to transmit a wide transmit beam of approximately 180 degrees. The wide transmit beam may be, for example at the interrogation frequency or a transponder response frequency. The TCAS of this disclosure includes a directional antenna system with two signal input ports and two or more antenna elements. In some examples, the direction of the 180 degree beam may be controlled by the phase relationship between the signals input to the two port antenna. In other examples, the direction of the transmit beam from the antenna system is predefined to be in two complementary directions (e.g., forward and aft).

Example techniques relate to playback based on acoustic signals in a system including a first playback device and a second playback device. A first playback device may detect a user-spoken signal. The first playback device sends, to a network device, data corresponding to the detected user-spoken signal. The network device causes playback of the media item to be transferred to the first playback device such that the second playback device stops playing back a media item and the first playback device begins playing back the media item.

A tracking receiver includes: a complex sum signal generator to generate a complex sum signal; a complex difference signal generator to generate a complex difference signal; a first correction coefficient storage to store a first correction coefficient represented by a complex number; complex difference signal correcting circuitry to calculate a corrected complex difference signal by correcting the complex difference signal based on the complex sum signal and the first correction coefficient; and an orientation direction error calculator to calculate an orientation direction error based on the corrected complex difference signal and the complex sum signal, the orientation direction error being a difference between an arrival direction and an orientation direction, the arrival direction being a direction from which the radio wave comes and arrives, the orientation direction being a direction in which the antenna is orientated.