RU2273033C2 - Method for determining traveling speed of airborne target at ground-based radiolocation station - Google Patents

Abstract

FIELD: radiolocation technologies, possible use for engineering of ground-based radiolocation stations with inverse synthesizing of antenna aperture.

SUBSTANCE: method for determining travel speed of airborne target at ground-based radiolocation station includes measuring Doppler frequency of signals reflected from moving target at ground-based radiolocation station, measuring Doppler frequency of reflected signals in additional receiving position, distanced in space relatively to ground-based radiolocation station for base distance, angle between directions "additional receiving position - target" and "additional receiving position - ground-based radiolocation station", angle between directions "ground-based radiolocation station - target" and "ground-based radiolocation station - additional receiving position", bi-static angle is calculated and on basis of all measurements flight travel speed of airborne target is determined.

EFFECT: measured flight travel speed of airborne target.

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Description

The invention relates to the field of radar and can be used in ground-based radar stations with inverse synthesis of the antenna aperture when forming the reference function for processing the trajectory signal.

A known method for determining the ground speed of an air target in a ground-based radar (Grachev V.V., Kane V.M. Radio-technical means of air traffic control. - M.: Transport, 1975. - S. 281-285).

The essence of the method is as follows. The ground-based radar with known coordinates, operating in a pulsed mode, performs circular scanning with a narrow beam of the antenna radiation pattern in the horizontal plane. The measured coordinates of the air target in the polar coordinate system "azimuth-range" are translated into the coordinates (X, Y) of the rectangular coordinate system. To measure the ground speed of an air target, the coordinates (x ₁ , y ₁ ) and (x ₂ , y ₂ ) of the air target are calculated at the times t ₁ and t ₂ , respectively, and the module of the ground speed is determined from the expression:

The disadvantage of this method of determining the ground speed of an air target is its low accuracy.

As a prototype, the method of measuring the radial speed of an air target in a ground-based radar set forth in (Lezin, Yu.S. Introduction to the Theory and Technique of Radio Engineering Systems / Textbook for Higher Educational Institutions. - M .: Radio and Communication, 1986. - p. 32-36).

The essence of the method of measuring the radial speed of an air target in a ground-based radar is that the Doppler frequency is measured in the radar as the difference between the frequency of the radiated signal and the frequency of the reflected signal from a moving target with ground speed V. The radial speed of the target is determined from the expression:

where λ is the working wavelength used in the ground radar; In _radar - radial velocity of the target.

The disadvantage of this method is the inability to measure the ground speed of the air target.

The technical result of the proposed method is the expansion of its scope for measuring the ground speed of an air target.

The essence of the proposed method for determining the ground speed of an air target in a ground-based radar consists in measuring the Doppler frequency of signals reflected from a moving target in a ground-based radar f _DRLS , as well as the Doppler frequency f _{dR of} reflected signals in an additional receiving position R spaced in space relative to the ground-based radar to the base distance R _B , measure the angle θ between the directions "additional receiving position R - target C" and "additional receiving position R - radar", the angle γ between the directions "radar - target C" and "radar - supplement lnnaya receiving position R ", calculate the bistatic angle β = 180 ° - (θ + γ), and the ground speed of the air target is determined by the formula:

where λ is the working wavelength used in the ground radar; f _radar - Doppler frequency, measured in ground-based radar; f _дR - Doppler frequency measured in the additional receiving position R; β is the bistatic angle between the directions "radar - target C" and "additional receiving position R - target C".

The essence of the method is illustrated by the following. Let target C fly at an arbitrary unknown angle μ to the line of sight of the target from the side of the ground-based radar (Fig. 1) with ground speed V. Then the measured Doppler frequency of the signal reflected from the center in the radar is determined by the expression:

and the target flight speed is

where V · cosμ = V _radar - radial flight speed of the target relative to the ground radar.

From (3) it follows that to determine the ground speed it is necessary to obtain the angle μ. To do this, we introduce an additional receiving position R (figure 2), spaced in space relative to the ground radar at the base distance R _In . In this case, the Doppler frequency, measured at the additional receiving position R, is determined by the expression:

where α is the angle between the path velocity vector V and the target line of sight from the receiving position R.

Taking into account expressions (3) and (4), the ratio of f _radar and f _dR is equal to:

When combining the vector diagrams shown in FIGS. 1 and 2 into a single diagram (FIG. 3), it was obtained that α + β + μ = 180 °. Given that α = 180 ° -β-μ, expression (5) takes the form:

After elementary transformations

After substituting (7) in (3), we obtain formula (1).

Figure 4 presents a diagram of a device for implementing the proposed method. It consists of ground-based radar 1; antennas of additional 2 and additional receiving position R 3, combined in space; 4 angle meter θ; meter 5 angle γ; frequency counter 6; frequency counter 7; calculator of a bistatic angle β 8; speed calculator 9.

The narrow in the azimuthal plane rays of the ground-based radar antenna 1 and the additional 2 antenna are aimed at target C. The target is irradiated by the ground-based radar antenna with high-frequency pulses generated in the radar transmitter. Echo signals are received at the input of the receiver of the ground radar and the input of the additional receiving position R 3, and the antenna additional and additional receiving position R spaced in space relative to the ground radar at an arbitrary base distance R _B. In the meter 5, the angle θ between the directions "radar - target C" and "radar - additional receiving position R" is calculated. In the meter 4, the angle θ is determined between the directions "additional receiving position R - target C" and "additional receiving position R - radar". The measured angles γ and θ are supplied to the calculator 8 of the bistatic angle β, which is calculated as the difference 180 ° - (θ + γ) (see figure 2). In the frequency meter 7, the Doppler frequency f _{dRLS is measured} , and the frequency meter 6 is the Doppler frequency f _dRL .

The measured values of f _drls and f _dR , as well as the calculated value of the angle β, are supplied to the speed computer 9. In this computer, the ground speed of the target V is determined by the formula (1).

Thus, this method provides the opportunity to obtain the ground speed V of an air target in a ground-based radar.

Claims (1)

A method for determining the ground speed of an air target in a ground-based radar, which consists in measuring the Doppler frequency of signals reflected from a moving target in a ground-based radar f _dls , characterized in that they measure the Doppler frequency f _{dR of the} reflected signals in an additional receiving position spaced in space relative to the ground radar on base distance R _B, θ the angle between the "additional desk position R - C goal" and "additional desk position R - radar", γ the angle between the "radar - target C" and "radar - extra pr emnaya position R ", calculated bistatic angle β = 180 ° - (θ + γ), wherein the aerial target ground speed of flight is determined by the formula

where λ is the working wavelength used in the ground radar; f _drls - Doppler frequency, measured in ground-based radar; f _дR - Doppler frequency measured in the additional receiving position R; β is the bistatic angle between the directions "target C - additional receiving position R" and "target C-radar".

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