EP-4741877-A1 - METHOD FOR OPERATING A RADAR FOR DETECTING TARGETS AND ASSOCIATED DETECTION RADAR

EP4741877A1EP 4741877 A1EP4741877 A1EP 4741877A1EP-4741877-A1

Abstract

The present invention relates to a method for operating a target detection radar, comprising the following steps: - determination (140) within a cone of visibility of a plurality of active tracks, each active track presenting a target to be pursued; - for each active track, determination (150) of a waveform allowing its detection and tracking; - determination (160) of compatibility of active tracks by comparing the waveforms determined for these tracks to form at least one set of compatible active tracks; - for the or each set of compatible active tracks, transmission/reception (110) of a communalized wave comprising consecutive pulses, each pulse being associated with one of the active tracks of said set.

Inventors

GOY, PHILIPPE
COTTRON, RODOLPHE
VEYRAC, Yoan

Assignees

THALES

Dates

Publication Date: 20260513
Application Date: 20251106

Claims (14)

Method of operation of a target detection radar (10), the detection radar (10) implementing a scan forming a cone of visibility; The process includes the following steps: - determination (140) within the cone of visibility of a plurality of active tracks, each active track presenting a target to be pursued; - for each active track, determination (150) of a waveform allowing its detection and tracking; - determination (160) of compatibility of active tracks by comparing the waveforms determined for these tracks to form at least one set of compatible active tracks, active tracks being compatible when there is the same waveform usable for the tracking of each of these active tracks; - for the or each set of compatible active tracks, transmission/reception (110) of a communalized wave comprising consecutive pulses, each pulse being associated with one of the active tracks of said set; in which each nth recurrence of the step (110) of communalized wave transmission/reception comprises the following sub-steps: + generation (111) of at least two consecutive pulses associated with different active tracks of the same set of compatible active tracks; + emission (112) of pulses in different frequency bands; + reception (113) in a common time window of pulse echoes.
Method according to claim 1, further comprising for each active track not belonging to any set of compatible active tracks, transmission/reception (110) of a simple wave comprising a single pulse.
A method according to any one of the preceding claims, wherein each waveform defines a visibility domain of a wave having that form.
A method according to claim 3, wherein each visibility domain comprises a distance domain and a speed domain of an active track.
A method according to claim 3 or 4, wherein two active tracks are compatible when they are within the same field of view with a probability greater than a predetermined threshold
A method according to any one of the preceding claims, wherein each waveform is defined by a wavelength, respectively an emission frequency, and a repetition frequency of a wave having this shape.
A method according to claim 6, wherein the compatibility of the active tracks is verified by testing different values of wavelength and/or repetition frequency.
A method according to any one of the preceding claims, wherein the compatibility of the active tracks is determined for each pair of active tracks.
A method according to any one of the preceding claims, wherein the pulses of the same communalized wave are associated with different emission directions.
A method according to any one of the preceding claims, wherein: - each pulse is emitted with a random phase associated with the corresponding frequency band; - the reception substep (113) includes the compensation of the phase shift of the echoes received in each frequency band, by the random phase associated with that frequency band.
A method according to any one of the preceding claims, wherein: - during the emission substep (112), the corresponding pulses are emitted using different slopes of the chirps used to emit them; - during the reception substage (113), echoes associated with different active tracking points are distinguished by determining the slopes of the corresponding chirps.
A method according to any one of the preceding claims, wherein: - during the emission substep (112), the corresponding pulses are emitted using different polarizations; - during the reception substage (113), echoes associated with different active tracking points are distinguished by determining their polarizations.
A method according to claim 12, wherein a polarization is emitted for each pulse or a set of polarizations forming a signature is emitted for each pulse.
Target detection radar (10) comprising technical means (21, 22, 23) configured to implement the method according to any one of the preceding claims.

Description

The present invention relates to a method of operating a target detection radar. The present invention also relates to a detection radar implementing such a method. The technical field of the invention is that of radar systems embedded for example on board aircraft, boats, submarines or satellites, implementing target detection/identification. The general problem solved by the invention is the management of the time budget in view of the increasing demand for new detection and identification functionalities required of radar systems. Traditionally, a radar system can be used in a "single-task" manner, that is, a single "mode" of operation throughout the mission, for example when using a maritime surveillance mode adapted to a given altitude and type of target. In particular, in a "single-task" mode, the radar uses a space scanning logic that does not vary over time, as long as the operator does not change missions or modes. The time budget is then associated solely with this task. For many years, radar operators have sought to expand the operational range of radar detection systems and have requested that they become "multi-tasking." For example, they want to be able to simultaneously provide a maritime tactical situation, an air situation, and potentially weather conditions. The system must then define the time budget to be allocated to each of these tasks. Obviously, the more time a task is allocated, the more effective it will be (better detection or discrimination capabilities, for example). Managing and optimizing the time budget therefore appears crucial for new radar systems. Traditionally, radar uses either short-time (at the processing block level) or long-time (at the scan level) interlacing strategies to perform its various tasks. A time budget is allocated to each of these tasks based on a performance trade-off for each individual function (refresh rate, detection range, etc.). Radar block interleaving is therefore a technique that temporally orders tasks that are not simultaneous. To achieve simultaneous tasks, the method known to those skilled in the art involves decomposing the radar antenna system into several sub-arrays and allocating a task to each sub-array to perform what is called color emission. This operation is found primarily in MIMO (Multiple Input Multiple Output) radar systems. The simultaneous emission of several orthogonal waveforms is thus achieved to color the space, that is, to associate a {sub-array, waveform} pair with a {azimuth-elevation} direction. Color emission allows either obtaining a complete view of the environment by drastically increasing the refresh time of a task, or performing several tasks simultaneously. However, this decomposition of the antenna space into sub-arrays and colored emission are not necessarily available or desirable in terms of budget for a given radar architecture. Active tracking is a radar function that ensures optimal visibility and detectability of a tracked target by applying dedicated illumination in the target's direction, using one or more waveforms calculated to optimize visibility in the area (distance, speed) where the track is located. In active tracking, an estimated equivalent radar area (ERA) and the target's distance are available. As a general rule, active tracking Doppler waveforms are designed by choosing the repetition frequency(ies) Fr, the associated wavelength(s) λ , and the number of repetitions per Fr to minimize the associated time budget while maintaining a very comfortable signal-to-noise ratio (SNR) for target detection. Such an algorithm, named { λ , Fr}, is known to those skilled in the art. A radar scheduler then integrates active tracking tasks with regard to relative priorities with respect to watchkeeping and maintenance tasks. A fixed or dynamic time budget is allocated to active tracking tasks, limiting either the number of active tracks or the monitoring capacity that can be maintained, depending on the desired trade-off: maintaining monitoring at the expense of active tracking, or maintaining active tracking at the expense of monitoring. Optimizing the time budget allocated to active tracking therefore presents a significant challenge in radar budget management. The present invention aims to address this problem and therefore to propose means of optimizing the time budget allocated to active pursuit. To this end, the invention aims at a method of operation of a target detection radar, the detection radar implementing a scan forming a cone of visibility; The process includes the following steps: determination within the cone of visibility of a plurality of active tracks, each active track presenting a target to be pursued; for each active track, determination of a waveform allowing its detection and tracking; determination of the compatibility of active tracks by comparing the waveforms determined for these tracks to form at least one set of compatible active tracks; for the or each set of compatible act