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Function оf Ambiguity for a Signal оf Moving Targets in Synthetic Aperture Radar for Forward View Operational Mode


J.D. Kargashin, E.S. Kolesnikov

Observation of moving targets in a front field view by means of RADAR with the synthetic aperture (SAR) is the actual task. Known algorithms of obtaining detailed a radar picture by means of a SAR in a front field view demand elimination of ambiguous relation of a signal frequency and a fixed target corner. In case the ground target moves concerning the carrier of a SAR with radial velocity in a side field of view, additional there is an ambiguity «azimut-radial rate of the targe». The task of detection of a moving target in a forward view SAR is especially actual at the small size of a receive antenna. Then the spectrum of a signal reflected from an earth surface takes the big frequency band and a signal of Doppler frequency of a moving target is in this band. The activity purpose - to estimate influence of target motion on its signal in a SAR of a forward view by analysis analysis of an ambiguity function of a trajectory signal at purpose motion in a front field of view. Influence of motion of the object on its radar picture in a forward view SAR is considered on the basis of the ambiguity function (AF) analysis a trajectory signal. The analysis of the unit normalised AF shows, that at motion of the target maximum AF will displace on value proportional to a target running speed. Unlike a side-forward view SAR when target offset is proportional to rate, in a forward view SAR this relation more complex and exists only for negative meaning of rate. The analysis of the received schedules shows, that at passing motion of the carrier of a SAR and the target (VЦ negative) on the radar picture two marks drifted symmetrical concerning velocity vector of aircraft on value ± Δθ will be watched, and at counter motion (VЦ positive) on the radar picture the moving target mark will not be watched, as offset Δθ will be imaginary as the reflected signal from a moving target quits a spectrum of reflexions from an earth surface Thus, analysis AF of a trajectory signal of the SAR reflected from a moving target in a front field of view, has shown, that there is an ambiguous relation of Doppler frequency of the target and its azimuthal rule therefore the moving target map will consist of two marks drifted symmetrical concerning the true azimuthal co-ordinate on value proportional to a purpose running speed.
June 24, 2020
May 29, 2020

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