Patent EP-3983822-A1 (EP)
Inventor: SAITTO ANTONIO
IPC: G01S13/00
Filed: 2020-06-04
Abstract: Disclosed herein is a multistatic radar system (10) for detecting and tracking targets (50, 71, 72, 73) moving in a surveillance area (16, 60); said multistatic radar system (10) comprising: a radar transmitter (11, 61) and a plurality of radar receivers (12, 62, 63, 64, 65, 66, 67) located in different positions in said surveillance area (16, 60); and processing means (13). The radar transmitter (11, 61) and the radar receivers (12, 62, 63, 64, 65, 66, 67) include, each, a respective GNSS receiver (15) configured to receive GNSS signals from one or GNSSs. Said radar transmitter (11, 61) and said radar receivers (12, 62, 63, 64, 65, 66, 67) are configured to obtain a GNSS-based time reference based on the GNSS signals received by the respective GNSS receiver (15), wherein said GNSS-based time reference is common to said radar transmitter (11, 61) and said radar receivers (12, 62, 63, 64, 65, 66, 67). The radar transmitter (11, 61) is configured to transmit radar signals according to a predefined transmission time and frequency pattern and on the basis of the GNSS-based time reference. The radar receivers (12, 62, 63, 64, 65, 66, 67) are configured to receive radar echoes from one or more targets (50, 71, 72, 73) moving in the surveillance area (16, 60) and illuminated by the radar signals transmitted by the radar transmitter (11, 61). Each radar receiver (12, 62, 63, 64, 65, 66, 67) is configured to: determine, for each radar echo received by said radar receiver (12, 62, 63, 64, 65, 66, 67) from a respective target (50, 71, 72, 73), a corresponding distance-related information item based on the predefined transmission time and frequency pattern, the GNSS-based time reference and a respective reception time of said radar echo, wherein said corresponding distance-related information item is related to an overall distance from the radar transmitter (11, 61) to the respective target (50, 71, 72, 73) and from said respective target (50, 71, 72, 73) to said radar receiver (12, 62, 63, 64, 65, 66, 67), and a corresponding Doppler frequency of said radar echo based on the predefined transmission time and frequency - 63 - pattern and the GNSS-based time reference; and provide the processing means (13) with data indicative of the distance-related information items and the Doppler frequencies determined by said radar receiver (12, 62, 63, 64, 65, 66, 67), and reference times associated with said distance-related information items and said Doppler frequencies, wherein said reference times are referenced to the GNSS-based time reference. The processing means (13) are configured to perform: a data selection step including selecting distance-related information items and Doppler frequencies that have been provided by different radar receivers (12, 62, 63, 64, 65, 66, 67), are temporally corresponding to each other, and relate to one and the same target (50, 71, 72, 73); a target position computation step including computing a three-dimensional position of said one and the same target (50, 71, 72, 73) based on the selected distance-related information items, the position of the radar transmitter (11, 61), and the positions of, and distances from the radar transmitter (11, 61) of, the radar receivers (12, 62, 63, 64, 65, 66, 67) that have provided said selected distance-related information items; and a target velocity computation step including computing a three-dimensional velocity of said one and the same target (50, 71, 72, 73) based on the computed three-dimensional position thereof and the selected Doppler frequencies.