Abstract: A communication device is capable of estimating an incoming wave number with high accuracy. A communication device includes an antenna and circuitry configured to calculate an arrival direction of a reception signal received from the antenna in a case of a predetermined incoming wave number based on the reception signal and the predetermined incoming wave number, calculate an incoming signal for each of one or more arrival directions in a case of a certain incoming wave number based on the incoming wave number and the one or more arrival directions, and estimate an incoming wave number of the reception signal based on levels of the incoming signals in a plurality of arrival directions.

Abstract: A communication apparatus capable of estimating the number of incoming waves with high accuracy is provided. A communication apparatus includes an antenna, a matrix calculator that calculates, based on reception signals received from the antenna, a first matrix having singular values of a reception signal matrix, a matrix calculator that extracts reception signals whose frequency is within a specific frequency range from the reception signals and calculates, based on the extracted reception signals, a second matrix having singular values of a second reception signal matrix, and a number-of-incoming-waves estimator that estimates, based on the first matrix and the second matrix, the number of incoming waves of the reception signals.

Abstract: A radar device includes an oscillator that generates a transmission signal including a plurality of chirp signals, the chirp signal having a frequency that increases or decreases from an initial frequency in each predetermined sweep cycle. The oscillator changes the initial frequency of each chirp signal. A transmitter emits the transmission signal, and a receiver receives a reflected wave of the transmission signal reflected at an object and an unwanted wave as a reception signal. Circuitry is configured to estimate a phase of the reception signal from the transmission signal and the reception signal, calculate a correlation between a change pattern of the initial frequency of each chirp signal and a change pattern of the phase of the reception signal, estimate the reflected wave from the reception signal based on the correlation, and calculate a number of incoming waves based on a result of the estimation of the reflected wave.

Abstract: A receiver accurately performs, using an annihilation filter, angle estimation in two-dimensional directions of an incoming wave. The receiver operates with at least two linear array antenna. The receiver may be implemented in a radar apparatus includes the receiver, as well as a vehicle and a communication system, which also include the receiver.

Abstract: A time of arrival t and a carrier wave phase ? of a positioning pulse that is transmitted from a mobile station in each posteriori period and that is received by each of at least three fixed stations are input. Then, by using an error reduction algorithm, a time of arrival tk+1 of the positioning pulse in the following posteriori period is predicted by using a carrier wave phase difference ?? of the positioning pulse. Then, by using the predicted time of arrival t of the positioning pulse, the location of the mobile station is calculated. A time interval dt of a posteriori period is set to a time interval with which a difference ??nm between the carrier wave phase differences, which is changed by the movement of the mobile station at an assumable maximum movement speed, is no greater than 180°.

Abstract: A time of arrival t and a carrier wave phase ? of a positioning pulse that is transmitted from a mobile station in each posteriori period and that is received by each of at least three fixed stations are input. Then, by using an error reduction algorithm, a time of arrival tk+1 of the positioning pulse in the following posteriori period is predicted by using a carrier wave phase difference ?? of the positioning pulse. Then, by using the predicted time of arrival t of the positioning pulse, the location of the mobile station is calculated. A time interval dt of a posteriori period is set to a time interval with which a difference ??nm between the carrier wave phase differences, which is changed by the movement of the mobile station at an assumable maximum movement speed, is no greater than 180°.