RU2649310C1 - Method of pressing the notes from the objects located beyond the zone of single-value estimation of the distance surveillance radar, and realizing its device - Google Patents

Abstract

FIELD: radar ranging and radio navigation.

SUBSTANCE: invention relates to the field of active radar and is intended for use in surveillance radar (SR). This result is achieved by changing the repetition period of the pulse probe signal by a certain amount ±ΔT and a comparative analysis of two neighboring realizations of the amplitude of the reflected signal, with the sign of the quantity ΔT varies from pulse to pulse.

EFFECT: suppression of marks from targets located outside the zone of unambiguous evaluation of the range of the survey radar, as well as marks caused by an asynchronous impulse noise.

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Description

Application area

The invention relates to the field of active radar and is intended for use in surveillance radars for processing the output signal of an amplitude detector.

State of the art

There is a method of suppressing marks from targets located outside the zone of an unambiguous assessment of the range of the surveillance radar, based on the coherent accumulation of the reflected signal over the time interval during which the azimuthal segment of space is probed [1, p. 80]. The disadvantage of this method is the low efficiency of suppression at the actually applied azimuthal viewing speeds (hundreds of degrees per second) and narrow (from fractions to units of degrees) radiation patterns of antennas of surveillance radars, since the time of irradiation of objects is short and, accordingly, the gain in signal accumulation is also small.

A known method for the selection of non-synchronous impulse noise, based on the delay of the received signal by the repetition period, calculating the difference between the direct and delayed signal and blanking the non-synchronous impulse noise [2, p. 286-287]. The signal from the target during the delay for the repetition period does not change its temporal position and therefore is subtracted from the current signal without generating a blanking pulse. The signal from non-synchronous interference changes the temporal position from period to period, so the difference will give a blanking pulse, which will not let the non-synchronous interference pass. The disadvantage of this method is that if the signal from the target is additively superimposed on the non-synchronous interference, the target will be completely blanked (lost).

There is a method of suppressing marks from targets located outside the zone of unambiguous assessment of the range of the surveillance radar, as well as marks due to non-synchronous impulse noise (for example, a signal from another radar), which we selected for the prototype [3]. The method is based on smooth modulation of the period T of the repetition of the probe signal and inter-azimuth filtering of the output signal of the amplitude detector in each radar range gate, which is realized by selecting the minimum value from the two current realizations of the reflected signal generated for each radiation pulse in the coordinates "amplitude - delay relative to the radiation pulse ". The disadvantage of this method is the low efficiency of suppression due to (as in the method [1]) a small accumulation time of the signal. An increase in the accumulation time requires a decrease in the speed of the azimuthal radar survey, which is often unacceptable in real-life applications of survey radars.

SUMMARY OF THE INVENTION

The main technical problem solved by the claimed invention is to increase the efficiency of suppressing marks from targets located outside the zone of an unambiguous assessment of the range of the surveillance radar, as well as marks due to non-synchronous impulse noise, without reducing the speed of the azimuthal survey.

The problem is solved in that in the method of suppressing marks from targets located outside the zone of an unambiguous range assessment in the surveillance radar, as well as marks due to non-synchronous impulse noise, including pulsed radar sounding of the surrounding space with a variable pulse repetition period T, the formation of the reflected signal in the coordinates "amplitude-delay relative to the radiation signal" for each probe pulse, the repetition period of the probe pulses varies ± ΔТ, the sign of ΔT varies from pulse to pulse, realizations of R _{1 are formed} as a result of moving averaging over the ensemble of N realizations of the reflected signal, the duration of which is T-ΔT, and realizations of R _{2 are formed} as the result of moving averaging over the ensemble from N realizations of the reflected signal, the duration of which is T + ΔT, realizations R ₃ = R ₁ -R ₂ are formed, realizations R _{4 are formed} , like realizations R ₃ , in which negative values are equal to zero, realizations R _{5 are formed} , like realizations R ₃ , in which the positive values are equal to zero, the realizations R ₆ = R ₂ -R ₄ are formed, the realizations R ₇ = R ₁ + R ₅ are formed, the radar output signal is formed, like the current realizations R ₈ = R ₆ + R ₇ , when the difference (sum) of two implementations A and B is defined as an implementation whose duration is equal to the duration of the shorter of implementations A and B, and its current values are defined as the difference (sum) of the values of implementations A and B corresponding to the same delays.

The implementation of the method

In FIG. 1 and FIG. 2 clearly shows the physical nature of the proposed method.

The probe pulse ZI (see Fig. 1) is emitted with a variable repetition period T ± ΔT, while the sign of ΔT varies from pulse to pulse. In FIG. 1 shows the current set of R realizations of the reflected signal in the presence of two targets in the field of view.

Mark 1 from the target located within the zone of an unambiguous assessment of the radar range does not change its position (delay τ ₁ ) relative to the ZI in all implementations of the reflected signal generated for each ZI. Note that this situation occurs only at relatively low radial speeds of the targets, when the distance covered by the target during the formation of N realizations of the reflected signal does not exceed the radar resolution element in range. For navigational surveillance radars, this condition is usually fulfilled.

Mark 2 from a target located outside the zone of an unambiguous range assessment (delay τ ₂ ) changes its position inside the realizations of the reflected signal (delay τ ₃ ), since the repetition period of the ZI changes from pulse to pulse by ΔТ. It is this physical fact that makes it possible to suppress marks from "ambiguous" goals of the claimed method.

Note that for the first implementation of the reflected signal (the start of the radar), mark 2 (see Fig. 1) from the target located outside the zone of unambiguous range estimation is absent, since the signal appears only in the second implementation of the reflected signal.)

The essence of the operations of the method is illustrated by the timing diagrams of FIG. 2.

Stage 1. The entire current set of R (see Fig. 1) implementations of the reflected signal is divided into two streams, R _i and C _i (see Fig. 2). Durations of realizations R _i , for example, are equal to T-ΔТ, and durations of realizations C _i are equal to T + ΔТ or vice versa. Realizations of R ₁ and R _{2 are formed} as a result of moving averaging over an ensemble of N realizations of the flows R _i and C _i , respectively.

Stage 2. Formed implementations of R ₃ = R ₁ -R ₂ as the current difference between the implementations of R ₁ and R ₂ .

Stage 3. Implementations of R _{4 are formed} , as implementations of R ₃ , in which negative values are equal to zero. Implementations of R _{5 are formed} , as implementations of R ₃ , in which positive values are equal to zero.

Stage 4. Realizations R ₆ = R ₁ -R _{4 are formed} as the current difference of the realizations R ₁ and R ₄ , realizations R ₇ = R ₂ + R _{5 are formed} as the current sum of the realizations R ₂ and R ₅ .

Stage 5. Implementations of R ₈ = R ₆ + R ₇ (output radar signal) are formed as the current sum of the implementations of R ₆ and R ₇ . At the same time, there is no component (mark) in the output signal due to reflection of 2 from a target located outside the zone of an unambiguous assessment of the radar range.

The described steps are displayed in the form of a flowchart in FIG. 3.

Note that the proposed method will suppress non-synchronous interference, the marks from which are uncorrelated in neighboring implementations of the output signal of the amplitude detector, with the same efficiency as the analogue and the prototype, since the proposed method performs moving averaging over an ensemble of 2N implementations of the output signal of the amplitude detector .

Device description

The device (Fig. 4) can be implemented on the basis of three functionally complete electronic components of modern radio engineering: ADC, FPGA (programmable logic integrated circuit, for example Cyclone V Altera), Ethernet controller (for example, KSZ9021RN).

The input analog signal from the radar receiver is fed to the input of the ADC 1, which is converted to digital form. Further, the digitized signal is transmitted to the FPGA via the data bus, which performs the algorithm for suppressing marks from targets located outside the zone of unambiguous range estimation, in accordance with the operations described in the method (see the description of the method above).

To isolate sequences with a different period, the FPGA additionally receives a synchronizing signal from the device for generating the probing signal. From the FPGA output, the data is fed to the interface 10 for communication with external devices, for example, to the Ethernet controller.

In FPGA (Fig. 4) at the software level, the following blocks are implemented: demultiplexer 2, two averaging buffers 3, 4, adder 5, signal selector by polarity 6, adders 7, 8, 9, and the range scan in the form of a digital code of input amplitudes the signal from the output of the ADC 1 is fed to the input bus of the demultiplexer 2, which divides the input stream into two streams R _i and C _i , according to alternating sensing periods T-ΔT and T + ΔT, respectively (Fig. 3).

In identical averaging buffers 3 and 4, realizations of R ₂ and R ₁ are calculated as a moving average over N realizations of C _i and R _i , respectively (Fig. 3). In adder 5, the values of the realizations R ₃ = R ₁ -R ₂ are calculated as the difference between the values of the realizations R ₁ and R ₂ corresponding to the same delay (having the same indices).

In the signal selector by polarity, two flows are formed from the input (current) implementations of R ₃ , the implementations of R ₄ and R ₅ , while the number of samples of these implementations coincides with the number of samples of the implementation of R ₃ , and the implementation of R ₄ is the implementation of R ₃ in which negative the values are equal to zero, and the implementations of R ₅ are implementations of R ₃ in which positive values are equal to zero.

Implementations of R ₄ from the corresponding (positive) output of the signal selector in polarity 6 go to the inverting input of the adder 8, the second input of which receives the implementation of R ₁ . Implementations of R ₅ go to the input of the adder 7, the second input of which receives the implementation of R ₂ .

The output implementations R ₆ , R _{7 of the} adders 8 and 7 are respectively summed in the adder 9, at the output of which the implementations of R ₈ (Fig. 3) are formed, which are input to the interface 10, the output of which is the output of the device and is used to transfer data to external devices.

In the output signal in accordance with the claimed method, which determines the algorithm of the claimed device, suppressed marks from targets that are outside the zone of an unambiguous assessment of the radar range, as well as marks due to non-synchronous interference. At the same time, the mark from the “unambiguous” target is not suppressed (not lost) in the output signal if a mark from non-synchronous interference and a mark from the “ambiguous” target are superimposed on it (together or separately).

Literature

1. Kuzmin, S.Z. Digital processing of radar information. - M.: Soviet Radio, 1967. - 400 p.

2. Botov, M.I. Fundamentals of the theory of radar systems and complexes: textbook. / M.I. Botov, V.A. Vyakhirev; under the general. ed. M.I. Botova. - Krasnoyarsk: Sib. Feder. Univ., 2013 .-- 530 s.

3. Radar "Bussol-S". Manual.

Claims (2)

1. A method of suppressing marks from targets located outside the range of an unambiguous range assessment in a surveillance radar, as well as marks caused by non-synchronous impulse noise, including pulsed radar sounding of the surrounding space with a variable pulse repetition period T, the formation of the implementation of the reflected signal in the coordinates "amplitude- delay relative to the radiation signal ”for each probe pulse, the calculation of the minimum over the ensemble of two realizations of the reflected signal, differing in those m, that the repetition period of the probe pulses changes by ± ΔT, while the sign of ΔT changes from pulse to pulse, realizations of R _{1 are formed} as a result of moving averaging over an ensemble of N realizations of the reflected signal, the duration of which is T-ΔT, realizations of R _{2 are formed} as a result of moving averaging over an ensemble of N realizations of the reflected signal, the duration of which is T + ΔT, realizations R ₃ = R ₁ -R ₂ are formed, realizations R _{4 are formed} , like realizations R ₃ in which negative values are equal to zero, realizations of R _{5 are formed} , like realizations of R ₃ , in which positive values are equal to zero, realizations of R ₆ = R ₁ -R ₄ are formed, realizations of R ₇ = R ₂ + R ₅ are formed, an output radar signal is formed, like realizations of R ₈ = R ₆ + R ₇ , and the difference (sum) of two implementations A and B is defined as an implementation whose duration is equal to the duration of the shorter of implementations A and B, and its current values are defined as the difference (sum) of the values of implementations A and B corresponding same delays. 2. A device for suppressing marks from targets located outside the range of an unambiguous range assessment in the surveillance radar, as well as marks due to non-synchronous impulse noise, including: ADC 1, demultiplexer 2, characterized in that two averaging buffers 3, 4, adder 5, a signal selector by polarity 6, adders 7, 8, 9, output interface 10, where the analog input of the ADC 1 is the input of the device, the output bus of the ADC 1 is connected to the input bus of the demultiplexer 2, to the synchronization input of the demultiplexer 2 clock pulses, output 1 of demultiplexer 2 is connected to the input of averaging buffer 3, output 2 of demultiplexer 2 is connected to the input of averaging buffer 4, the output of averaging buffer 3 is connected to the inverting input of adder 5 and the first input of adder 7, the output of averaging buffer 4 is connected to a non-inverting summing input 5 and the non-inverting input of the adder 8, the output of the adder 5 is connected to the input of the signal selector in polarity 6, the negative output of which is connected to the second input of the adder 7, and the positive output which connects to the inverting input of the adder 8, the output of the adder 7 is connected to the first input of the adder 9, the output of the adder 8 is connected to the second input of the adder 9, the output of the adder 9 is connected to the input of the interface 10, and the output of the interface 10 is the output of the device.

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