RU2256939C1 - Radar for helicopter - Google Patents

Abstract

FIELD: radiolocation, applicable on a helicopter.

SUBSTANCE: the radar for a helicopter has an elevation antenna array located in the helicopter blade, gearing, circulator, receiving device, master oscillator, digital signal processor, synchronizer, attitude sensor, digital data processor, indicator, rotating adapter, it includes also the second scanning antenna array located in the second blade of the helicopter, as well as the first and second separation filters.

EFFECT: enhanced accuracy of determination of the angular coordinated of air targets in the elevation plane.

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Description

The invention relates to the field of radar and can be used by helicopter.

Known airborne radar stations for surveying the earth, water surface and airspace, performing circular viewing in the azimuthal plane, for example, Marconi radar company "SEASPAY-2000", which is used to detect sea and air objects, as well as the radar station "Octopus-E ”, Used in the export version of the helicopter Ka-28, which also has the task of detecting air targets.

These stations are single-beam, in which the determination of the angular coordinate in the elevation plane is made with an error corresponding to the beam width.

As a prototype of the proposed radar, a radar station for a helicopter is described in RF patent No. 2206903, class. G 01 S 13/00. In this radar, the helicopter blade is used as a scanning antenna structure with a linear “L” antenna array of the wave range placed in it.

A block diagram of the radar of the prototype is presented in figure 1. The radar includes

1 - antenna array;

2 - transmitting device;

3 - circulator;

4 - receiving device;

5 - master oscillator;

6 - digital signal processor;

7 - synchronizer;

8 - angle sensor;

9 - digital data processor;

10 - indicator.

Figure 2 presents a detailed structural diagram of a prototype, where

11 - power amplifier;

12 - modulator;

13 - microwave receiver;

14 - intermediate frequency amplifier;

15 - phase detector;

16 - phase detector;

17 - analog-to-digital Converter (ADC);

18 - analog-to-digital Converter (ADC);

19 is an analog-to-digital processor.

The radar operates in both coherent and incoherent mode.

The radar in coherent mode provides a highly stable master oscillator 5, the frequency of which f _g is the base and is used in the synchronizer 7 to generate the radiation signal of the carrier frequency of the L-band, as well as heterodyne and other signals that synchronize the operation of the blocks of the analog-to-digital Converter.

All high-frequency signals necessary for the operation of the radar are generated in the synchronizer 7 by multiplying the frequency of the master oscillator 5, and low-frequency synchronizing signals are formed by dividing the frequency of the signal of the master oscillator 5. Processing the received reflected signals in the radar is carried out in a digital signal processor 6, which provides compression, accumulation , filtering, threshold signal processing, assignment and transformation of coordinates, as well as the formation of an array of radar information to display it on the indicator p 10.

In radar, a digital data processor 9 provides the calculation of radar parameters in coherent and incoherent modes, as well as the generation of signals and commands for controlling radar units. One of the functions of the data processor is to calculate the current coordinates of the radar information based on the values of the angle of rotation of the helicopter blade, taken from the angle sensor.

The radar operates as follows.

When the helicopter engine is in operation, the blade rotates with the antenna array 1 in the circular sector. During the rotation of the antenna array 1, the power amplifier 11 amplifies the high-frequency pulses f coming from the synchronizer 7, and passes them through the circulator 3 and the feeder path to the antenna array 1. By the antenna array 1, these pulses are emitted into space and propagate in the direction determined by the antenna pattern .

The coherence of the signal is determined by the highly stable master oscillator 5. The trigger pulses F _p are received from the synchronizer 7 to the input of the modulator _. The pulse repetition frequency F _p is generated in the synchronizer 7 by dividing the signal frequency f _{g of the} master oscillator 5. The pulse duration is also formed from the master oscillator signal by using a signal period. The modulator 12 modulates the high-frequency signal f and generates pulses entering the power amplifier 11 having a predetermined duration τ and a repetition period T _p defined by a unique range. A high-frequency carrier frequency signal is generated by the synchronizer 7. From the master oscillator 5, a signal with a frequency f _{g is} supplied to the synchronizer 7, multiplied to a higher frequency f and used as the carrier frequency of the radar signal emitted by the antenna array.

Also, during the rotation of the antenna array, reflected signals from objects and the earth's surface are received by the antenna array 1 and through the feeder path and circulator 3 enter the receiving device 4. In the microwave receiver 13, these signals in the receiver mixer are mixed with the synchronizer signal f _c , as a result of which signals of intermediate frequency f _ave The intermediate frequency signals are fed to an analog-to-digital processor 19, where the amplifiers of the intermediate frequency amplifier UPCH 14 are amplified and fed to phase detectors 15 and 16, which receive a signal from the synchronizer 7 with a frequency equal to the intermediate frequency f _pr . Moreover, the signal f _p arrives at one of the phase detectors with a shift π / 2.

At the outputs of the phase detectors, in-phase I and quadrature Q signals are generated. Next, both signals I and Q using the ADC 17 and 18, controlled by the clock signal f _ca , are converted to digital form. From the outputs of the ADCs 17 and 18, the signals of two quadratures are fed to a digital signal processor 6, synchronized by the signal f _cn from the sixth output of the synchronizer 7. In the digital signal processor 6, depending on the station operating mode, the received signals are coherent or incoherent. After threshold processing of the radar signals, the digital signal processor 6 converts the coordinates of the incoming radar information from the polar coordinate system to a specified coordinate system. For this, a digital data processor 9, synchronized by a clock signal f _pd based on the angle of rotation of the antenna array 1 (angle of rotation of the blade of the helicopter) received from the angle sensor 8 (connection “a”) (Fig. 1), calculates the current coordinates of the radar information in a given system, transmits them to a digital signal processor 6 to convert the current coordinates of the radar information.

From the digital signal processor, the radar information arrives at indicator 10.

The disadvantage of this radar is the poor accuracy of determining the elevation coordinate of an air target due to the large angle θ _{l of the} single-beam radiation pattern of the scanning antenna array in the elevation plane (Δβ≥60 °).

The objective of the invention is to increase the accuracy of determining the angular coordinates of air targets in the elevation plane.

This problem is solved by the fact that a second scanning antenna is introduced in the helicopter radar located in the second blade of the helicopter with an antenna array located in it, as a result of which a two-beam antenna system with a difference radiation pattern in the elevation plane is formed in the radar.

The use of a difference radiation pattern allows one to determine the elevation coordinate with an error of σ≤ (0.1 ÷ 0.15) θ _l , where θ _l is the angle of the beam of the antenna array in the elevation plane. To create a difference radiation pattern, the rays of both antenna arrays, when placed, are rotated in the blades in the elevation plane in opposite directions relative to the plane of symmetry by the value “k · θ _l ”, where k = (0.3 ÷ 0.5).

To avoid ambiguous determination of the angular coordinate of an air target in azimuth when using two antenna arrays, the frequency and time separation of the radiation channels and the reception of these antenna arrays is used. Radiation and reception at one of the carrier frequencies f _{1 of the} first antenna array is performed during one revolution of the blade. The second antenna array emits and receives a signal at a carrier frequency f ₂ during the next revolution.

Thus, the radiation and reception of signals of two antenna arrays are separated in time, corresponding to one revolution of the blade.

From the transmitting device, the emitted signal is transmitted through the circulator through a common feeder to a rotating transition. The separation of the transmission signals of two antennas in frequency is carried out after a rotating transition using separation filters installed at the inputs of the antenna arrays.

The formation of the total-difference antenna radiation pattern is carried out in a digital signal processor by processing the received signals from two antenna arrays. When the radar is operating during the scanning of the antenna arrays, the received signals from each of the antenna arrays during the revolution after their initial processing are accumulated in the memory of the signal processor in the range-azimuth coordinates.

. Результаты вычисления, соответствуют углу рассогласования воздушной цели относительно нулевого положения разностной диаграммы направленности по углу места и передаются в процессор данных для формирования параметров паспорта цели.During the secondary processing of the signals stored in the memory, the sum and difference signals are formed from the signals of the same name in range and azimuth. To do this, the same-named signals in range and azimuth are summed in amplitude and thereby the total signal U∑ _{c is formed} . The same signals are algebraically subtracted and form a difference in elevation signal ± UΔ _mind . To obtain a difference signal independent of the amplitude, the difference signal is normalized with respect to the total signal

. The calculation results correspond to the mismatch angle of the air target relative to the zero position of the differential radiation pattern in elevation and are transmitted to the data processor to form the parameters of the target passport.

Figure 1 shows a block diagram of an on-board radar station of the prototype.

Figure 2 shows a detailed structural diagram of the prototype.

Figure 3 presents a block diagram of the proposed radar station.

Figure 4 shows a detailed structural diagram of the proposed station.

Figure 5 shows the electrical diagram of the connection of antenna arrays with transceiver units of the radar using a feeder.

The proposed radar station (figure 3 and 4) includes:

1 - antenna system consisting of the first antenna array - 20

and the second antenna array - 21;

2 - transmitting device;

3 - circulator;

4 - receiving device;

5 - master oscillator;

6 - digital signal processor;

7 - synchronizer;

8 - angle sensor;

9 - digital data processor;

10 - indicator;

11 - power amplifier;

12 - modulator;

13 - microwave receiver;

14 - intermediate frequency amplifier;

15 - phase detector;

16 - phase detector;

17 - ADC;

18 - ADC;

elements 14 ÷ 18 form an analog-to-digital processor 19;

analog-digital processor 19 and the microwave receiver 13 form a receiving device 4.

The electrical circuit for connecting antenna arrays with transceiver units of the radar (figure 5) includes

2 - transmitting device;

3 - circulator

4 - receiving device;

20 - the first antenna array;

21 - the second antenna array;

22 - the first balancing device;

23 is a second balancing device;

24 - the first separation filter;

25 - the second separation filter;

26 - rotating transition;

27 - emitters.

A helicopter radar station consists of a first scanning antenna array 20 and a second antenna array 21 located in the first and second blades of the helicopter, as well as a transmitting device 2, a circulator 3, a receiving device 4, a driving generator 5, a digital signal processor 6, a synchronizer 7, an angle sensor 8, a digital data processor 9, a rotating transition 26, a first separation filter 24, a second separation filter 25 and an indicator 10. In this case, for transmitting a radiating pulse to the antenna arrays, the first input the rotator 3 is connected to the output of the transmitting device 2. To transmit the signal from the antenna arrays, the first output of the circulator 3 is connected to the input of the receiving device 4, and the second output of the circulator 3 is connected to the input-output of the rotating transition 26. To start the transmitting device, the first output of the synchronizer 7 is connected to the first input of the transmitting device 2, and to form a radiating microwave signal f ₁ , f _{2, the} second output of the synchronizer 7 is connected to the second input of the transmitting device 2.

To form an intermediate frequency of the received signal f _{pp, the} third output of the synchronizer 7 is connected to the second input of the receiving device 4 by the local oscillator frequency f _c1 or f _c2 . To shift the frequency of the signal to the Doppler frequency domain f _{d the} fourth output of the synchronizer 7 is connected to the intermediate frequency f _fp the third input of the receiving device 4. For generating the frequency diskreditizatsii analog-digital converter (ADC) 7, fifth synchronizer output signal at the reference frequency f _ca is connected to a fourth input PRIE Nogo device 4, and for synchronizing the operation of the digital signal processor of the sixth output signal of clock frequency f _ch is connected to a second input of the digital signal processor 6. For data synchronization processor seventh synchronizer output 7 to the second clock signal f _pD connected to the first input of the digital processor 9, the second input of which is connected to the output of the angle sensor 8. To control the operating modes and output the initial parameters, the first output of the digital data processor 9 is connected to the third digital input 6 signal processor.

To receive and process radar information, the first input of the signal processor 6 is connected to the output of the receiving device 4, and the first output of the digital signal processor 6 is connected to the input of the indicator 10.

For the operation of the antenna arrays at different carrier frequencies f ₁ or f ₂ , the first and second separation filters 24 and 25 are introduced, while the input-output of the first antenna array 20 through the first separation filter 24 is connected to the input-output of the rotating transition 26, and the input-output the second antenna array 21 is connected through a second separation filter 25 to the input-output of the rotating transition 26.

To switch the carrier frequencies through the review period when two antenna arrays 20 and 21 are in operation, the second input of the synchronizer 7 is connected to the second output of the data processor 9 by control commands.

To generate a passport of the target for radar information, the second output of the signal processor 6 is connected to the third input of the data processor 9.

The radar operates in both coherent and incoherent mode.

The radar in coherent mode provides a highly stable master oscillator 5, the frequency of which f _g is the base and is used in the synchronizer 7 to generate the radiation signal of the carrier frequency of the L-band, as well as heterodyne and other signals that synchronize the operation of the blocks of the analog-to-digital Converter.

All the high-frequency signals necessary for the operation of the radar are generated in the synchronizer 7 by multiplying the frequency of the master oscillator 5, and the low-frequency synchronizing signals are formed by dividing the frequency of the signal of the master oscillator 5. Processing of the received reflected signals in the radar is carried out in a digital reprogrammable signal processor 6, which provides compression , accumulation, filtering, threshold signal processing, assignment and transformation of coordinates, as well as the formation of an array of radar information to remove it on the indicator 10.

In radar, a digital data processor 9 provides the calculation of radar parameters in coherent and incoherent modes, as well as the generation of signals and commands for controlling radar units.

The data processor calculates the current coordinates of the radar information using the values of the angle of rotation of the helicopter blade, taken from the angle sensor.

In the detection mode of ground objects, the radar operates as follows.

During operation of the helicopter engine, the blades rotate with antenna arrays 20 and 21 in the circular sector.

During the rotation of the antenna arrays 20 and 21, the power amplifier 11 amplifies the high-frequency pulses of the carrier frequency f ₁ or f ₂ coming from the synchronizer 7, and through the circulator 3, the feeder path transfers them to one or another antenna array 20 or 21. Depending on the radiated f ₁ or frequency f ₂ signal radiation enters the first array antenna 20 or the second partition 21. This is determined by the filters 24 and 25. the antenna array 20, 21, these pulses are radiated into the space and distributed in a direction determined diagram directed awn antenna. Switching the carrier frequency of the radiation to f ₁ or f _{2 is} carried out in the synchronizer 7 according to the commands issued from the data processor 9 and generated according to the data of the angle sensor of the blade 8. The frequency radiation f ₁ or f ₂ alternates in time corresponding to one revolution of the blade. The coherence of the signal is determined by the highly stable master oscillator 5. The trigger pulses F _p are received from the synchronizer 7 to the input of the modulator _. The pulse repetition frequency F _p is generated in the synchronizer 7 by dividing the signal frequency f _{g of the} master oscillator 5. The pulse duration is also formed from the master oscillator signal by use the period of this signal. The modulator 12 modulates the high-frequency signal f ₁ , f ₂ and generates pulses arriving at the power amplifier 11 having a given duration τ and a repetition period T _p defined by a unique range.

A high-frequency signal of a carrier frequency f ₁ or f ₂ is generated by the synchronizer 7. From the master oscillator 5, a signal with a frequency f _{g is} supplied to the synchronizer 7, multiplied to a higher frequency and used as the carrier frequency f ₁ or f ₂ (where f ₂ = f ₁ + Δf, a Δf is the frequency spacing of the emitted signals by the antenna arrays) of the radar signal emitted by the antenna arrays.

Also, during the rotation of the antenna arrays, the reflected signals from objects and the earth's surface are received by the antenna array 20 or 21 and through the separation filters 24 or 25, the rotating transition 26, the feeder path and the circulator 3 enter the receiving device 4. The reflected signals in the mixer of the microwave receiver 13 are mixed with synchronizer signals “f _c1 ” or “f _c2 ” that differ by the intermediate frequency (where f _c1 = f ₁ + f _pp ; f _c2 = f ₁ + f _pp ), resulting in the formation of intermediate frequency signals f _pp . The intermediate frequency signals are fed to an analog-to-digital processor 19, where they are amplified in the intermediate frequency amplifier UPCH 14 and fed to phase detectors 15 and 16, which receive a signal from synchronizer 7 with a frequency equal to the intermediate frequency f _pp , and to one of the phase detectors the signal f _p arrives with a shift π / 2.

At the outputs of the phase detectors, in-phase I and quadrature Q signals are generated. Then, both signals I and Q in the ADC 17 and 18, triggered by the clock signal f _ca , are converted to digital form. From the outputs of the ADCs 17 and 18, the signals of two quadratures are fed to the digital signal processor 6, synchronized by the signal f _cn from the sixth output of the synchronizer 7 (a special 2 × 16 bit line is used to transmit signals from the ADC to the digital signal processor, to transmit signals from the digital data processor the digital signal processor and vice versa use the standard trunk parallel interface (MPI) GOST 26765.51-86).

In the digital signal processor 6, depending on the operating mode of the station, coherent or incoherent processing of the received signals is performed. After threshold processing of the radar signals, the digital signal processor 6 converts the coordinates of the incoming radar information from the polar coordinate system to a specified coordinate system.

For this, the digital data processor 9, synchronized by the signal f _pd , on the basis of the values of the angle of rotation of the antenna arrays 20, 21 (angle of rotation of the blade of the helicopter) received from the angle sensor 8, calculates the current coordinates of the radar information in the given coordinate system, transfers them to the digital signal processor 6 to convert the current coordinates of the radar information.

From the digital signal processor, the radar information arrives at indicator 10.

In the air target detection mode, the radar station operates in a coherent mode using two antenna arrays 20 and 21 to increase the accuracy of the angular coordinate in the elevation plane. To do this, the antenna arrays 20 and 21 operate sequentially through a rotation turn of the blade. In this case, also through a revolution, the radiation frequency switches from f ₁ to f ₂ . Through the separation filter 24, the radiation frequency f ₁ passes into the first antenna array and through the separation filter 25 the frequency f ₂ into the second antenna array. The signals reflected from the target, received by the first and second antenna arrays, having undergone primary processing in the analog-to-digital processor 19, enter the digital signal processor 6, where the fast Fourier transform, finding the module in two quadratures, and threshold processing are performed. The signals that passed through the threshold during the turnaround time of each of the antenna arrays are accumulated in the memory of the digital signal processor 6 for a time corresponding to at least two revolutions. After accumulating in memory the signals received by the second antenna array 20 in a subsequent revolution after the first antenna array 21 is rotated, the signals in the cells of the same name in range and azimuth are summed in the digital signal processor 6, and thus the signal of the sum U∑ is determined, these signals are algebraically subtracted , and thus the difference ± UΔ _brain corresponding to the angular mismatch in the elevation plane is found.

, не зависящий от амплитуды сигнала.The total signal UΣ of the output of the digital signal processor 6 is supplied to the indicator 10. The difference signal “± UΔ _mind ” in the digital signal processor 6 is normalized to the signal U∑, i.e. angular error signal is determined

independent of signal amplitude.

The signal of the angular mismatch ± Δ _mind from the digital signal processor 6 enters the digital data processor 9, where the parameters for the target passport are formed.

The technical result of the proposal is to increase the accuracy of determining the angular coordinate in the elevation plane of air targets by creating a two-beam antenna system, which implements a difference radiation pattern in the elevation plane, which provides increased accuracy.

This result is achieved by the fact that the helicopter’s radar equipment, in which the helicopter’s blade is used with the antenna array located in it, introduces the second scanning antenna using the second helicopter blade with the second antenna array located in it. Moreover, to create a difference diagram in the elevation plane, the rays of both antennas rotate in the elevation plane in opposite directions by k · θ _l , where k≈ (0.3 ÷ 0.5).

Claims (1)

A helicopter radar station, consisting of a scanning antenna array located in the helicopter blades, a transmitting device, a circulator, a receiving device, a master oscillator, a digital signal processor, a synchronizer, an angle sensor, a digital data processor and an indicator, while the input of the circulator is connected to the output of the transmitting devices, the first output of the circulator is connected to the first input of the receiving device, the second output of the circulator is connected to the input-output of a rotating transition, the first synchronous output the mash is connected to the first input of the transmitting device, the second synchronizer output is connected to the second input of the transmitting device, the third synchronizer output is connected to the second input of the receiving device, the fourth synchronizer output is connected to the third input of the receiving device, the fifth output is to the fourth input of the receiving device, the sixth output is with the second input of the digital signal processor, and the seventh output with the first input of the digital data processor, the second input of which is connected to the output of the angle sensor, the first output of the digital processor data is connected to the third input of the digital signal processor, the first input of which is connected to the output of the receiving device, and the first output of the digital signal processor is connected to the indicator input, characterized in that a second scanning antenna array located in the second helicopter blade is introduced into it, as well as the first and a second separation filter, wherein the input-output of the first antenna array through the first separation filter is connected to the input-output of a rotating transition, the input-output of the second antenna array is connected via second separating filter with an input-output of the rotary junction, a second input connected to a second synchronizer output of the data processor and the second processor signal output is connected to the third input of the data processor.

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