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US-20260126544-A1 - Operation method of a target detection radar and associated detection radar

US20260126544A1US 20260126544 A1US20260126544 A1US 20260126544A1US-20260126544-A1

Abstract

A method of operation for a target detection radar, including determining a plurality of active tracks in a visibility cone, each active track showing a target to pursue, for each active track, determining a waveform allowing its detection and tracking, determining compatibility of active tracks by comparing the determined waveforms for these tracks to form at least one set of compatible active tracks, and for the or each set of compatible active tracks, emitting/receiving a communal wave including consecutive pulses, each pulse being associated with one of the active tracks of the set.

Inventors

  • Philippe Goy
  • Rodolphe Cottron
  • Yoan VEYRAC

Assignees

  • THALES

Dates

Publication Date
20260507
Application Date
20251105
Priority Date
20241107

Claims (15)

  1. 1 . A method of operating a target detection radar, the detection radar implementing a scanning forming a visibility cone, the method comprising: determining a plurality of active tracks in the visibility cone, each active track showing a target to pursue; for each active track, determining a waveform allowing its detection and tracking; determining compatibility of active tracks comprising comparing the determined waveforms for these tracks to form at least one set of compatible active tracks; and for each set of compatible active tracks, emitting/receiving a communal wave comprising consecutive pulses, each pulse being associated with one of the active tracks of the set, wherein each n th recurrence of the emitting/receiving comprises: generating at least two consecutive pulses associated with different active tracks of the same set of compatible active tracks; emitting the pulses in different frequency bands; and receiving echoes of the pulses in a common time window.
  2. 2 . The method according to claim 1 , wherein active tracks are compatible when there is a same waveform usable for tracking each of the active tracks.
  3. 3 . The method according to claim 2 , further comprising emitting/receiving a simple wave comprising a single pulse for each active track not belonging to any set of compatible active tracks.
  4. 4 . The method according to claim 2 , wherein each waveform is defined by a wavelength, a respective emission frequency and a repetition frequency of a wave having this form.
  5. 5 . The method according to claim 4 , wherein said determining compatibility comprises testing different values of wavelength and/or repetition frequency.
  6. 6 . The method according to claim 2 , wherein said determining compatibility is determined for each pair of active tracks.
  7. 7 . The method according to claim 2 , wherein the pulses of the same communal wave are associated with different emission directions.
  8. 8 . The method according to claim 2 , wherein each pulse is emitted with a random phase associated with the corresponding frequency band, and wherein said receiving echoes comprises compensating dephasing of the echoes received in each frequency band, by the random phase associated with this frequency band.
  9. 9 . The method according to claim 2 , wherein said emitting pulses comprises emitting the corresponding pulses using different slopes of chirps to emit them, and wherein said receiving echoes comprises distinguishing echoes associated with different active tracking pointing by determining the slopes of the corresponding chirps.
  10. 10 . The method according to claim 2 , wherein said emitting pulses comprises emitting the corresponding pulses using different polarizations, and wherein said receiving echoes comprises distinguishing echoes associated with different active tracking pointing by determining their polarizations.
  11. 11 . The method according to claim 10 , further comprising emitting a polarization for each pulse, or emitting a set of polarizations forming a signature for each pulse.
  12. 12 . The method according to claim 1 , wherein each waveform defines a field of visibility of a wave having this form.
  13. 13 . The method according to claim 12 , wherein each field of visibility comprises a field in distance and a field in speed of an active track.
  14. 14 . The method according to claim 12 , wherein two active tracks are compatible when they are in the same field of visibility with a probability greater than a predetermined threshold.
  15. 15 . A target detection radar comprising technical units configured to implement the method according to claim 1 .

Description

REFERENCE TO RELATED APPLICATIONS This application is a U.S. non-provisional application claiming the benefit of French Patent Application No. 24 12182 filed on Nov. 7, 2024, the contents of which are incorporated herein by reference in their entirety. TECHNICAL FIELD OF THE INVENTION The present invention relates to a method of operation for a target detection radar. The invention also relates to a detection radar implementing such a method. The technical field of the invention is that of radar systems embedded on aircraft, ships, submarines or satellites, for example, implementing target detection/identification. The general problem solved by the invention is the time budget management in view of the growing demand for new detection and identification functionalities required by radar systems. BACKGROUND OF THE INVENTION Traditionally, a radar system can be used in a “single-task” manner, meaning a single “mode” of operation throughout the mission, such as 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 the mission or mode. The time budget is then associated only with this task. For many years, radar operators have sought to expand the employment spectrum of radar detection systems, seeking for them to become “multi-tasking.” For example, simultaneously having a maritime/aerial tactical situation and possibly having feedback on weather conditions. The system must then define the time budget to allocate to each task to be performed. Obviously, the more time allocated to a task, the more effective it will be (better detection or discrimination capability, for example). Therefore, the management and optimization of the time budget appear crucial for new radar systems. Traditionally, the radar employs “short time” (at the processing block scale) or “long time” (at the scanning scale) interleaving strategies to carry out its different tasks. A time budget is allocated to each of these tasks based on a compromise of the performance of each function taken individually (refresh time, detection range, etc.) The interleaving of radar blocks is then a technique that temporally schedules tasks that are not simultaneous. To obtain simultaneous tasks, the way of proceeding known by those skilled in the art is to break down the radar antenna system into several sub-networks and allocate a task to each sub-network, to perform what is called colored emission. This operation is mainly found in MIMO-type radar systems (from the English “Multiple Input Multiple Output”). The simultaneous emission of several orthogonal waveforms is thus made to color the space, that is, to associate a pair {sub-network, waveform} with a direction {azimuth-elevation}. The colored emission enables either obtaining a complete vision of the environment by drastically increasing the refresh time of a task or performing several tasks simultaneously. However, this break down of the antenna space into sub-networks and the colored emission are not necessarily available or desirable in terms of the balance of a given radar architecture. Active tracking is a radar function that ensures optimal visibility and detectability of a tracked target by using dedicated illuminations in the direction of the target, with one or more waveforms calculated to optimize visibility in the area (distance, speed) where the track is located. In active tracking, an evaluation of an estimated equivalent radar surface (also called SER, from the English, “Surface Equivalent Radar”) and the distance of the target is available. In general, active tracking Doppler waveforms are designed by choosing the repetition frequencies Fr, the associated wavelengths λ, and the number of recurrences per Fr to minimize the associated time budget while maintaining a very comfortable Signal-to-Noise Ratio (SNR) to detect the target. Such an algorithm named {λ, Fr} is known to those skilled in the art. A radar scheduler then integrates the active tracking tasks concerning the relative priorities vis-à-vis surveillance pointing and maintenance tasks. A fixed or dynamic time budget is allocated to the active tracking tasks, in practice limiting either the number of active tracks or the surveillance capacity to be maintained, depending on the compromise sought: imperative maintenance of surveillance at the expense of active tracking or imperative maintenance of active tracking at the expense of surveillance. The optimization of the time budget allocated to active tracking thus presents a significant problem in radar budget management. SUMMARY OF THE INVENTION The present invention aims to address this problem and therefore to propose the means to optimize the time budget allocated to active tracking. To this end, the invention aims at a method of operation of a target detection radar, the detection radar implement