RU2095825C1 - Target recognition radar - Google Patents

Abstract

FIELD: pulse radars. SUBSTANCE: additional antenna control system, distance measuring system, amplitude clipper, dispersion ultrasound delay line, amplitude detector, differentiating circuit, K analog-to-digital converters, K-1 delay lines, memory unit which has control inputs for start and end of operations, commutator with control input and K communication channels, code inverter, K-channel AND gate are introduced to accomplish goal of invention. EFFECT: increased quality of automatic recognition of radar targets due to increased quality of information processing of signal that is reflected from target taking into account relative position of reflecting surfaces of object and aspect of target sighting which determine structure of distance image. 1 dwg

Description

 Target recognition radar refers to radar technology and can be used to recognize airborne targets of various classes (types) at various ranges and angles of location.

 Known radar "Micronetics" [1] which can be used to recognize radar targets from the radar range portraits obtained by irradiating targets with pulses of very short duration (1 ns). The use of these pulses makes it possible to achieve a range resolution of δD 15 cm and, thereby, observe the results of the reflection of pulses from various elements of the target structure. Micronetics radar includes an antenna equivalent, a high-frequency tee, an output amplifier and a first antenna connected in series, a magnetron generator, a probe pulse generation circuit, a communication element, a start detector and a pulse oscilloscope, a second antenna connected in series, a precision attenuator, a low-noise traveling wave lamp , a power amplifier and a short pulse detector, the output of which is connected to the second input of a pulsed oscilloscope. In this case, the second output of the communication element is connected to the input of the high-frequency tee, the second output of which is connected to the input of the antenna equivalent.

 The disadvantage of this (and similar to it) radar is that it allows you to determine the radar characteristics of targets at ranges up to units of kilometers, and this currently narrows the scope of use of such radars, especially for solving recognition problems. The described radar in view of this drawback is used only in experimental studies [1] Another disadvantage of the Micronetics radar is the need for two antennas, which complicates the design. And, finally, in the absence of accurate a priori information about the signatures of targets of certain classes at various angles, as well as because of the difficulty of visual identification by the operator of reference and real signatures, the reliability of target recognition of this radar is insufficient.

 Also known is a radar with an automatic recognition filter [2] in which target recognition and identification can be carried out by the operator by comparing the received echo signals with reference radio pulse portraits of known targets, that is, by comparing radar portraits of real and reference targets. At the same time, it is known that when using the indicated radar, it is possible to achieve more efficient recognition of radar targets if, instead of radar portraits, signals representing the sum of radio pulses reflected by separate scattering centers (RC) of the target surface are evaluated.

 A radar with an automatic recognition filter includes a transmitter, a local oscillator, a digital control device (CCU), a series-connected antenna, an antenna switch, a high-frequency amplifier (UHF), a mixer, an intermediate-frequency amplifier (UPCH), an automatic recognition filter (AFR), a detector, and an indicator moreover, the second input of the antenna switch is connected to the output of the transmitter, the second input of the mixer with the output of the local oscillator, and the second input of the AFR with the output of the central control unit.

 This radar uses powerful linear-frequency-modulated pulses for sounding, which makes it possible to recognize targets at long ranges. However, the probability of target recognition in such a radar needs to be increased, since the visual-identification capabilities of the radar operator are limited. The operator cannot keep in memory a large number of standards of long-range portraits, critical to the view of the location of the target. In the case of recognition by the sum of the signals reflected by different target RCs, the probability of confusing targets of equal classes (types) can be even greater, since a different number of RCs on the surface of equal targets, having different reflection intensities and a radial geometric arrangement, does not exclude the same resulting total signal defining the class (type) of the target. Unfortunately, information on the difference in reflection intensities between different RCs is not used, since in typical radars with LFM signals, an optimal signal filter is placed before the optimal compression filter (the location of which is not specified in [2]), which ensures normal filter operation and excluding its overload. It is also known [2, p. 126] that "the parameters of the recognition system, or rather the automatic recognition filter, are determined by the expected target length.", That is, the recognition process in this case requires a priori information about the goals, which is absent in most real situations.

 The aim of the invention is to increase the reliability of automatic recognition of radar targets in the quasi-optical region of the reflection of radio waves due to adaptive accounting of the relative position of the RC on the surface of the target in the radial direction.

 Achieving this goal is ensured by the fact that the composition of the known recognition radar [2] (including a transmitter, local oscillator, digital control device, a series-connected antenna, antenna switch, UHF, mixer, IF, AFR, detector and indicator, and the second input of the antenna switch is connected with the transmitter output, the second input of the mixer with the output of the local oscillator, and the second input of the AFR with the output of the central control unit) additionally introduce an antenna control system (SUA), a range measuring system (LED), an amplitude limiter (AO), dis Persian ultrasonic delay line (DUZLZ), amplitude detector, differentiating circuit (DC), K analog-to-digital converters (ADC), K-1 delay lines (LZ), memory device (memory) with control inputs for beginning and end of work, a switch with control input and K switching channels, a code inverter and a K-channel circuit I. In this case, the output of the amplifier is connected to the input of the control system, the input of the LED and the input of AO, the output of which is connected to the input of the amplitude detector and the input of the remote sensing amplifier, the output of which is connected to the input of the 1st ADC and input of the 1st LZ, output of each k the 1st from the 1st to (K-2) -th LZ is connected with the input of the corresponding (k + 1) -th LZ and the input of the corresponding (k + 1) -th ADC, the output of the (K-1) -th LZ is connected with input of the K-th ADC, the output of each k-th of K ADCs is connected to the corresponding k-th input of the memory, each k-th of K outputs of which is connected to the corresponding k-th input of the switch, each k-th output of which is connected to the corresponding k -th input of the circuit And and the k-th output of the code inverter, the input of which is connected to the control input of the switch and the second output of the control unit, the first output of which is connected to the 1st control input of the device , The 3rd output to the second control input of the memory, the output of the And circuit and the first input of the indicator, and the 4th output to the 2nd input of the indicator, the output of the amplitude detector is connected to the input of the data center, the output of which is connected to the 2nd input of the central control unit, 1 whose input is connected to the LED output, and the third input to the 2nd output of the control system, the first output of which is mechanically connected to the antenna.

 The proposed construction of the target recognition radar scheme can significantly increase the likelihood of recognizing air targets due to a better use of radar information contained in the signal reflected from the target, by taking into account the relative position of the RC on the target surface, and also by taking into account the viewing angle of the target, on which the structure depends radial range portrait. A detailed analysis of the relative position of the target surface RC provides the ability to recognize targets up to types within the same class.

 The drawing shows a structural diagram of a radar target recognition.

 Target recognition radar includes SUA 1, antenna 2, antenna switch 3, UHF 4, mixer 5, UPCH 6, AO 7, transmitter 8, local oscillator 9, LED 10, amplitude detector 11, DUZLZ 12, DC 13, TsUU 15, K ADC 16, K-1 LZ 14, memory 17, switch 18, code inverter 19, circuit I 20, indicator 21. In this case, antenna 2, antenna switch 3, UHF 4, mixer 5, amplifier 6, LED 10 and central control unit 15 are connected in series . The transmitter 8 is connected to the 2nd input of the antenna switch 3, and the local oscillator 9 is connected to the 2nd input of the mixer 5, the output of the IF 6 is also connected to the input of the SUA 1 and the input of AO 7, the output of which is connected to the input of the amplitude detector 11 and the input of the remote sensing amplifier 12 , the output of which is connected to the input of the 1st ADC 16 and the input of the 1st LZ 14, the output of each k-th from the 1st to (K-2) -th LZ 14 is connected to the input of the corresponding (k + 1) -th LZ 14 and the input of the corresponding (k + 1) -th ADC 16, the output of the (K-1) -th LZ 14 is connected to the input of the K-th ADC 16, the output of each k-th of K ADCs 16 is connected to the corresponding k-th input of the memory 17, each k-th of K outputs of koto It is connected to the corresponding k-th input of the switch 18, each k-th output of which is connected to the corresponding k-th input of the And 20 circuit and the k-th output of the code inverter 19, the input of which is connected to the control input of the switch 18 and the 2nd output of the central control unit 15, the 1st output of which is connected to the 1st control input of the memory 17, the 3rd output to the 2nd control input of the memory 17, the output of circuit I 20 and the 1st input of indicator 21, and the 4th output to 2- the input of the indicator 21. The output of the amplitude detector 11 is connected to the input of the DC 13, the output of which is connected to the 2nd input of the central control unit 15, the 3rd input of which is connected to the 2nd output ode SUA-1, the first output of which is mechanically connected to antenna 2.

 Target recognition radar operates as follows.

The transmitter 8 generates pulsed LFM signals that pass through the antenna switch 3 to the antenna 2 and are emitted by it in the direction of the air target selected for recognition. Reflected from the target, the radio pulses are received by the antenna 2, through the antenna switch 3 are fed to the input of the UHF 4, where they are amplified. Then the amplified radio pulses are fed to the first input of the mixer 5, to the second input of which a local oscillator 9 signal is supplied. As a result, the filling frequency of the radio pulses is reduced to an intermediate f _pr and the signal from the output of the mixer 5 is fed to the amplification amplifier 6, from the output of which the amplified pulses at an intermediate frequency follow the inputs of SUA 1, LED 10 and AO 7.

Amplitude limiter 7 restricts the amplitude of the useful signal of intermediate frequency f _pr to a level that ensures the normal operation of DLPS 12. From the output of AO 7, the signal limited in amplitude is fed to the input of DLPS 12, where optimal compression is performed, as well as to the input of the amplitude detector 11 that selects the envelope input signal. At the output of DUZLZ 12, a set of short pulses is obtained, the temporary arrangement between which corresponds to the distances between individual RCs in the radial direction. The set of such pulses, characterizing the structure and size of the target, is usually called the radial range portrait of the target.

For the simultaneous analysis of the presence or absence of RC signals in all the ranges of the signal reflected from the target, a cascade of K-1 delay lines 14 and K of the ADC 16 is used. The number of channels K is selected based on the need to view the structure of the largest size target with a radial length L _max and element size range resolution δD. The value of δD in a radar with optimal signal compression in DLPS is determined by the duration of the compressed pulse δD = cτ _and / 2 = c / 2Δf, where Δf is the frequency deviation of the chirp signal and c is the speed of propagation of radio waves. Therefore, the number of channels, that is, the number of analyzed range (time) intervals K, will be determined by the dependence K = L _max / δD = 2L _max / cτ _and . For example, for L _max 50 m and Δf 30 MHz we get K 10, and for Δf 150 MHz, respectively, K 50.

Having passed a cascade of delay lines, each of which has a delay time t _h equal to τ _{and the} range portrait is “split” into K components, so that at the moment when the signal of the last element (resolved section) of the portrait is present at the input of the 1st ADC , at the output of the (K-1) -th LZ there will be a signal of the 1st resolution element of the range portrait. The presence of a signal in the k-th channel (at the output of the k-th LZ) indicates the presence of a local RC in a certain k-th element of range.

 The signal from the output of the kth from K-1 LZ 14 is fed to the input of the corresponding (k + 1) -th ADC 16. The input of the 1st ADC 16 receives the signal directly from the output of DUZLZ 12, the ADC 16 converts the analog signals into digital form and feed them from their outputs to the corresponding inputs of the memory 17. The storage device 17 has two control inputs and is a collection of registers of the type K 555 IR 32 [3, p. 69, Fig. 98] The first control input is used to record the moment of storing digital information at K inputs associated with the outputs of the corresponding K ADCs 16. A signal that permits storing information is generated in the CPU 15 by the signal received at the 2nd input of the CPU 15. the signal at the intermediate frequency from the output of AO 7 is fed to the input of the amplitude detector 11, where its envelope is extracted, coming from the output of the amplitude detector 11 to the input of the DC 13. The differentiating circuit 13 generates a positive pulse corresponding to the moment the front edge of the video signal arrives at its input from the output of the amplitude detector. A positive impulse of the position of the leading edge of the target video signal is supplied to the 2nd input of the control unit 15, which generates and delivers at the calculated time point to the 1st control input of the control unit 17 a signal allowing information storage.

 Storing the signals from the outputs of the K ADC 16 is necessary in order to compare the reference range portraits of targets of various classes (types) with the portrait structure of the real recognizable target represented by the signals at the K outputs of the memory 17 for a certain period of time. the 3rd and 3rd inputs of the central control unit 15 are supplied with signals from the outputs of the LED 10 (this signal is proportional to the distance to the target) and ASM 1 (this signal is proportional to the angular coordinates of the target), respectively. Based on the coordinate information about the target and the nature of its change over time, under the assumption that the linear velocity vector of the target coincides with the longitudinal axis of the aircraft, TsUU 15 selects from the data bank reference range portraits of targets of various classes corresponding to the calculated location angle, which are in the form of code constellations are alternately fed to the control input of switch 18 (the switch is a set of elementary managed keys of type I circuit [3, p. 24, Fig. 2]) from the 2nd output of the central control unit 15. First, to control The input of the switch 18 receives the code arrangement of the reference portraits of targets of the largest sizes and more complex configurations, and as they are identified with the real portrait, a transition to long-range standards of less complex targets is performed.

 The switch 18 has K inputs and K outputs. Upon receipt of the next reference code arrangement at the control input of the switch 18, the switch 18 passes the signal of the kth input to its kth output only if there is a single code value in the code arrangement at the kth place. On the contrary, if the reference arrangement of K characters at the kth place has a zero code value, this switching channel remains in the open state and there will be no signal at the kth output of the switch 18. At the same time, the code arrangement is input to the inverter of code 19, which can be built on the Kth number of elementary circuits NOT [3, p. 24, fig. 1] where the code is inverted to the opposite (for example, the arrangement 01000101 will be converted to 10111010). And since each k-th output of the switch 18 is connected to the k-th output of the code inverter 19, a single code value will be present on all closed (open) outputs of the switch 18 with a certain code arrangement. At the remaining open outputs of the switch 18 connected to the corresponding outputs of the storage device 17, the presence or absence of a single signal value in the kth channel will be determined by the presence or absence of a signal at the output of the kth ADC 16, i.e., the presence or absence of a RC in the kth range element.

 The signals K of the outputs of the switch 18 are supplied to the corresponding from the K inputs of the AND 2O circuit, which produces an output signal only if there is a single code on all K inputs at the same time. Thus, the signal appears at the output of the And 20 circuit only if the generated long-range portrait at the outputs of the ZU 17 matches the reference portrait that came from the TsUU 15, since the individual portrait signals of the real target, passing through the switch 18, will fill in the missing input cells circuit And 20 if no signals from the corresponding outputs of the memory device 17 appear in any switched channels of the switch 18, circuit And 20 will not work and a signal will not be generated at its output.

 Simultaneously with applying to the 1st control input of the memory unit 17 another code arrangement defining the structure of the reference portrait of the 1st class target, the central control unit 15 sends a signal from its 4th output to the 2nd input of the indicator 21, which prepares an information board to turn on (lamp , LED, etc.) the presence of the target of this 1st class. When the portrait of the target coincides with the reference portrait, the I-2O circuit sends a signal to the 1st input of the indicator 21, upon receipt of which a panel is turned on, informing the radar operator about the recognition results. The output signal of the And 20 circuit is also used to transfer the memory device 17 to its initial (standby) state, since it automatically arrives at the 2nd control input of the memory device 17. If the portrait of the target does not correspond to any of the standards in the selected angle, the memory transfer signal 17 in the initial state it comes to its 2nd control input from the 3rd output of the central control unit 15. In this case, the target is considered unrecognized and the recognition cycle resumes.

 As can be seen from the description of the proposed radar target recognition, it is devoid of the disadvantages inherent in the prototype [2] Targets, having in their composition the same number of RCs, but different configurations, that is, the relative position of the RCs in the radial direction, will be unambiguously recognized among themselves, especially since unlike the prototype, in this radar, when choosing reference portraits, the target location angle was taken into account, on which the structure of the standard substantially depends. The result of target recognition of the proposed radar does not depend on the training and personal qualities of the operator, as the recognition process is fully automated.

 Thus, the feasibility of using proposed in this invention a new technical solution is obvious.

Literature
1. Nebabin V.G. Sergeev V.V. Methods and techniques of radar recognition. -M. Radio and Communications, 1984, p. 112 114, fig. 4.6 (analog).

 2. Nebabin V.G. Sergeev V.V. Methods and techniques of radar recognition. -M. Radio and Communications, 1984, p. 120 126, Fig. 4.11 (prototype).

 3. Digital analog integrated circuits. Reference book / S.V. Yakubovsky, L.I. Nisselson, V.I. Kuleshov et al. Ed. S.V. Yakubovsky.-M. Radio and Communications, 1989, 446 pp.

Claims (1)

 A target recognition radar station comprising a transmitter, a local oscillator, a digital control device, an indicator, a series-connected antenna, an antenna switch, a high-frequency amplifier, a mixer, an intermediate frequency amplifier, the second input of the antenna switch connected to the output of the transmitter, and the second input of the mixer to the output of the local oscillator characterized in that the composition of the radar station additionally includes an antenna control system, a range measuring system, dispersive ultrasound new delay line, K analog-to-digital converters, K-1 delay lines, memory, switch, code inverter, circuit AND, series-connected amplitude limiter, amplitude detector and differentiating circuit, the output of which is connected to the second input of the digital control device, the first input which is connected to the output of the ranging system, and the third to the second output of the antenna control system, the first output of which is mechanically connected to the antenna, and the input is connected to the output of the intermediate frequency amplifier , the input of the range measuring system and the input of the amplitude limiter, the output of which is also connected to the input of the dispersion ultrasonic delay line, the output of which is connected to the input of the first of K analog-to-digital converters and the input of the first of K-1 delay lines, the output of each of the first the (K 2) th delay line is connected to the input of the corresponding (k + 1) th delay line and the input of the corresponding (k + 1) th analog-to-digital converter, the output of the (k 1) th delay line is connected to the K input analog to digital converter, output each about one of K analog-to-digital converters is connected to the corresponding k-th input of the storage device, each k-th of K outputs of which is connected with the corresponding k-th input of the switch, each of the k of K outputs of which is connected simultaneously with the corresponding the input of the circuit AND and the output of the code inverter, the input of which is connected to the control input of the switch and the second output of the digital control device, the first output of which is connected to the first control input of the storage device, and the third with the second control input apominayuschego device output of the AND circuit and the first input of the indicator, the second input of which is connected to the fourth output of the digital control device.