An adaptive-robust method for simultaneous detection/capture of an object's trajectory in radars with quasi-continuous chirp radiation at an extended speed range

Abstract

The paper considers the problem of providing long-range observation (detection and capture of the trajectory) of an air object with an extended range of its positive and negative relative velocities, including zero and supersonic, and with interfering reflections from the ground in radars with quasi-continuous radiation at a high pulse repetition rate. The urgency of solving this problem is substantiated, taking into account the increasing requirements for the efficiency, accuracy and noise immunity of observation sessions. A number of factors associated with the expansion of the velocity range are shown, which make it difficult to solve this problem only on the basis of known methods of combined observation of low- and high-speed objects - within the framework of the concept of adaptive-robust observation with unified quasi-continuous radiation with a carrier wave chirp. Multidimensional ambiguity of time-frequency measurements at the time of detection, low information content of the detection stage, lack of speed data against the background of increasing signal delay drift at high speeds, and a number of other destabilizing factors lead to a decrease in the efficiency and accuracy of typical procedures for adaptive-robust trajectory capture. The purpose of the work is to propose a method for long-range observation of an object against the background of interfering reflections from the ground and at an extended range of speeds, including negative ones, which allows: expand the functionality of the radar in the mode of high pulse repetition rate with chirp, providing observation of the object and at a wide sub-range of negative velocities; to increase the accuracy/efficiency of observation sessions, providing an increase in the information content of the stage of primary detection of an object, without additional probing packs and with a minimum of measurement information. In fact, at the detection stage using the proposed method, the range/velocity capture functions are simultaneously implemented, and at an accuracy level that allows one to significantly reduce or exclude from the cyclogram typical adaptive-robust capture procedures traditionally performed after detection. At the same time, under the conditions of a minimum of “real” measurements at the detection stage, as quasi-measurements of the ambiguous delay and rangefinder-Doppler frequency of the chirp signal of the object, information is used about its location in the blind zone of the pulse repetition period (when the receiver is closed for the duration of the pulse radiation) and the blind zone according to frequency (due to the spectrum of interfering reflections from the ground). Simulation mathematical modeling of algorithms for simultaneous detection/capture, synthesized on the basis of the proposed method, has been carried out for a wide range of speeds and ranges of initial detection of an approaching/retreating object. Statistical processing of the simulation results and a comparative analysis with the statistical characteristics obtained by modeling typical sequential procedures for adaptive-robust detection and capture in range and speed are performed. The operability and efficiency of the proposed method were confirmed, and, first of all, in situations with a single ambiguous time-frequency measurement during the initial detection of an object, i.e., with a minimum of measurement information at the detection stage. The results obtained in the work can be used to improve the algorithmic and software of the developed/modernized radars with quasi-continuous chirp radiation, and no additional requirements are put forward for the radar hardware.