The phase difference method for determining the convergence acceleration of fighter with an air target

Аuthors

Ryazantsev L. B.^*, Likhachev V. P.^**, Shatovkin R. R.^***

Air force academy named after professor N.E. Zhukovskii and Y.A. Gagarin, Voronezh, Russia

*e-mail: кernel386@mail.ru
**e-mail: lvp_home@mail.ru
***e-mail: shatovkin@yandex.ru

Abstract

Purpose

The behavior of air targets during an air combat is characterized by performing of complex maneuvers accompanied by large overloads. Maneuvering targets has a strong impact on the quality of support. Late detection of the start of the targets’ maneuver quite often leads to the disruption of auto-tracking due to the emergence of large tracking errors caused by the mismatch of the models to the real behavior of air targets. Recapturing of the target takes an additional time, and this may be the cause of the first attack failure, which is utterly important in conditions of highly maneuverable combat.

To prevent the failure of the automatic tracking, the onboard systems should be supplemented with supporting devices that detect the beginning of the targets’ maneuver providing correction parameters or the structure of servo gauges. The traditional method of determining the start of the maneuver is computing the statistical characteristics of deviations of the actual and estimated parameters of target motion. This requires obtaining measurements over several periods of the on-board radar station observation space. Another way to determine the beginning of the maneuver if a target is to use the information about the acceleration of of air targets and the fighter closing-in. However, the known methods for this purpose are additional sensors, e.g., optical-location system support.

Significant reduction the time spent to determine the start of the maneuver to one contact of the on-board radar antenna with an air target, and elimination of additional sensors is possible by analyzing the changing characteristics of the reflected echo caused by maneuvering.

Design/methodology/approach

The content of this method consists in the following. After each radar contact of the on-board radar station beam pattern with an airborne target, the slope of linear-frequency modulation of a received pack echoed signals, which is proportional to close-in acceleration, is measured. Evaluation of the linear-frequency modulation slope is based on the phase difference method. This method consists in dividing the received echo signal into two parts equal in time, which are multiplied in a complex conjugated way. The position of the obtained correlation function maximum in frequency domain herewith is proportional to close-in acceleration.

Originality/value

The originality of the result is that the adoption of the decision about maneuvering air target coincides with the period of a contacting antenna.

Practical implications

Implementation of the proposed method allows increasing the stability of the tracking gauges on-board radars while tracking maneuvering air targets.

Keywords:

airborne radar, linear frequency modulation, phase-difference auto focus method, echo signal, convergence acceleration

References

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