RU2173864C1 - Helicopter radar station - Google Patents

Abstract

FIELD: radio engineering. SUBSTANCE: device has synchronizer unit, transmitters, antenna switches, view sector switch, receivers, stroboscopic pulse oscillator, processing units, indication display, keys and recording unit. EFFECT: wide range of functional applications. 8 dwg

Description

 The invention relates to radar technology, namely to helicopter radars with a synthesized aperture, designed to detect and determine the coordinates of objects located below the earth's surface, snow or ice cover, as well as for direction finding of radiation sources of complex phase-manipulated (PSK) signals (radio sensors).

 Known helicopter radar stations (auth. Certificate NN 1109700, 1810859; G 01 S 13/04; US patents NN 3550130, 3778835, G 01 S 3/52; French patents NN 2060261, 1502412, G 01 S 3/52; Gribanov AS Radio-electronic surveillance equipment placed on helicopters. "Foreign Radio Electronics", 1991, N 12, p. 15 ... 33 and others).

 Of the known stations closest in technical essence to the proposed one is the "Helicopter radar station" (ed. Certificate. N 1810859, G 01 S 13/04, 1991), which is selected as a prototype.

 The device specified synthesized aperture helicopter radar station allows you to detect and determine the coordinates of objects located under the underlying surface of the earth, snow or ice cover with high angular resolution. At the same time, the depth of the location of objects below the surface can be judged by the color of the image.

 However, the base station does not provide the opportunity for accurate and unambiguous determination of the coordinates of the radiation sources of complex QPSK signals (radio sensors).

 The solution to this problem requires high-precision coordinate measurement, which in relation to a helicopter has its own characteristics. The presence of a rotary screw can be used as a positive factor to determine the direction of the complex PSK signals (radio sensors) to the radiation source using a direction finding device, the antennas of which are located at the ends of two opposite rotor blades. Having determined the direction to the radiation source of the PSK signals in two planes, and knowing the altitude of the helicopter, you can accurately and unambiguously determine its location.

 As sources of radiation of FMN signals, there can be radio sensors of stolen vehicles, emergencies of technogenic, natural and environmental origin.

Technological emergencies include:
- transport accidents (catastrophes);
- fires, explosions;
- accidents with the release of radioactive substances;
- accidents with the release of potent toxic substances;
- accidents with the release of biohazardous substances;
- accidents on electric power systems;
- Accidents on communal life support systems;
- accidents at wastewater treatment plants;
- hydrodynamic accidents (breakthroughs of dams, dams, locks).

Natural emergencies include:
- geophysically dangerous phenomena (earthquakes, volcanic eruptions);
- geologically dangerous phenomena (landslides, mudflows, avalanches, landslides, dust storms);
- meteorological hazards (hurricanes, tornadoes, showers, tsunamis);
- infectious diseases of humans and animals;
- damage to agricultural plants by diseases and pests.

Environmental emergencies include:
- situations associated with changes in land composition (soils, subsoil, landscapes);
- situations associated with changes in the composition and properties of the atmosphere (air);
- situations related to changes in the composition and properties of the hydrosphere (aquatic environment);
- situations associated with a change in the composition of the biosphere.

 The aim of the invention is to expand the functionality of the station by detecting the received PSK signals, accurate and unambiguous direction finding of their radiation sources in two planes.

 This goal is achieved by the fact that a helicopter radar station, containing serially synchronized and a strobe generator, a sector of view switch, an indicator and four channels, each of which consists of a transmitter connected to the synchronizer output, an antenna switch, the input-output of which is connected to receiving-transmitting antenna, and the control input is connected to the output of the switch of the field of view, the receiver, the control input of which is connected to the output of the strobe generator pulses, the processing unit, the synchronizing input of which is connected to the output of the synchronizer, and the indicator, the synchronizing input of which is connected to the output of the synchronizer, the fifth and sixth receiving antennas, two keys, the fifth receiver and the registration unit are introduced, and to the output of the fifth (sixth) receiving antenna in series the first (second) key is connected, the control input of which is connected to the output of the field of view switch, the fifth receiver, the third and fourth inputs of which are connected to the output of the first and third antenna switches oil, respectively, and the registration unit, the fifth receiving antenna is located above the helicopter rotor hub on its upper part of the fuselage, and the sixth receiving antenna is located on the lower part (helicopter fuselage.

 The structural diagram of a helicopter radar station is shown in FIG. 1. The relative position of the antennas on the helicopter and the radio sensor (RD) is shown in FIG. 2. The values of the angular resolution of a helicopter radar station at different wavelengths at different depths are shown in FIG. 3. The block diagram of the fifth receiver is shown in FIG. 4. The principle of direction finding of the radiation source of complex QPSK signals in two planes is shown in FIG. 5. A frequency diagram illustrating the formation of additional (mirror and Raman) receive channels is shown in FIG. 6. The principle of detecting QPSK signals by the method of relative phase shift keying is shown in FIG. 7. The structural diagram of the flood radio sensor (mudflow) is shown in FIG. 8.

 The helicopter radar station contains sequentially connected synchronizer 1 and strobe pulse generator 7, a viewing sector switch 5, indicator 9 and four channels, each of which consists of transmitter 2.1 (2.2-2.4), antenna switch 3.1 (3.2) connected in series to synchronizer 1 output. -3.4), the input-output of which is connected to the transmit-receive antenna 4.1 (4.2-4.4), the control input is connected to the output of the switch 5 of the field of view, the receiver 6.1 (6.2-6.4), the control input of which is connected to the output of the generator 7 strobe-pulses xy, and processing unit 8.1 (8.2-8.4), the control input of which is connected to the output of the synchronizer 1, and the output is connected to the indicator 9, the control input of which is connected to the output of the synchronizer 1. To the output of the fifth 4.5 receiving antenna, the first key 10.1, which controls the input of which is connected to the output of the switch 5 of the review sector, the fifth receiver 6.5 and the registration unit 11. The output of the sixth receiver antenna 4.6 through the second key 10.2, the control input of which is connected to the output of the switch 5 of the field of view, is connected to the second input of the fifth receiver 6.5, the third and fourth inputs of which are connected to the outputs of the first 3.1 and third 3.3 antenna switches, respectively, and the second, third and the fourth outputs are connected to the corresponding inputs of the registration unit 11.

 Transmitting antennas 4.1-4.4 are located at the end of the helicopter rotor blades, receiving antenna 4.5 is located above the helicopter rotor hub on its upper part, and receiving antenna 4.6 is located on the lower part of the helicopter fuselage.

 The receiver 6.5 contains four direction finding channels, the first (second) of which consists of the first 12 (second 13) mixer key connected in series to the output of the first 10.1 (second 10.2), the second input of which is connected to the first output of the first 16 (second 17) local oscillator, the second the input of which is connected to the output of the search unit 18 and the first 19 (second 20) amplifier of the first intermediate frequency. The first multiplier 23 is connected in series to the second output of the first local oscillator 16, the second input of which is connected to the second output of the second local oscillator 17. the first narrow-band filter 24, the first phase detector 26, the second input of which is connected to the output of the first reference oscillator 25, and the control unit 27, the output which is connected to the second input of the first local oscillator 16. To the output of the first amplifier 19 of the first intermediate frequency is connected a selector 28, consisting of serially connected to the output of the amplifier 19 of the first intermediate hour from the frequency doubler 29, the first spectral width meter 30, a comparison unit 32, the second input of which is connected through the second spectral width meter 31 to the output of the amplifier 19 of the first intermediate frequency, the first threshold unit 33, the second input of which is connected to its output through the first delay line 34 and a third key 35, the second input of which is connected to the output of the amplifier 19 of the first intermediate frequency, the correlator 36, the second input of which is connected to the output of the second amplifier 20 of the first intermediate frequency, the second threshold unit 37, fifth spanner 44, the second input of which is connected to the output of the narrowband filter 24, and the first phase meter 45, whose output is the second output of the receiver II. To the output of the amplifier 20 of the first intermediate frequency, a second multiplier 38 is connected in series, the second input of which is connected to the output of the key 35, and a second narrow-band filter 39, the output of which is connected to the second input of the phase meter 45. A fourth key 40, the second input of which is connected in series to the output of the key 35 connected to the out. threshold. block 37, the second delay line 42 and the second phase detector 43, the second input of which is connected to the output of the key 40, and the output is the first output of the receiver. The fifth mixer 47, the second input of which is connected to the output of the third local oscillator 46, and the amplifier 48 of the second intermediate frequency are serially connected to the output of the key 40.

 The third (fourth) direction-finding channel consists of a third 14 (fourth 15) mixer connected in series to the first 3.1 (third 3.3) antenna, the second input of which is connected to the first output of the first local oscillator 16, the third 21 (fourth 22) amplifier of the first intermediate frequency, third 49 (fourth 50) multiplier, the second input of which is connected to the output of the amplifier 48 of the second intermediate frequency, and the third 51 (fourth 52) narrow-band filter. The fifth multiplier 53, the second input of which is connected to the output of the narrow-band filter 52, the fifth narrow-band filter 54 and the second phase meter 57, the second input of which is connected to the output of the second reference oscillator 59, and the output is the third III output of the receiver, are connected in series to the third narrow-band filter 51. A third delay line 55, a third phase detector 56, the second input of which is connected to the output of the narrow-band filter 52, and a third phase meter 58, the second input of which is connected to the output of the reference oscillator 59, and the output is the fourth output of the receiver, are serially connected to the output of the narrow-band filter 52. The engine 60 is kinematically connected with the helicopter propeller and the reference generator 59.

 A synthesized aperture helicopter radar provides for the detection and determination of the coordinates of objects located below the surface of the earth, snow or ice. As a result, on a four-color indicator 9, one can observe a layered image of a subsurface structure and objects located in this structure with high angular resolution. Moreover, the color of the image of objects is determined by their depth, which increases with increasing length of the working wave (Fig. 3).

 Using a synthesized aperture helicopter radar with antennas located at the ends of the rotor rotor blades and operating at different frequencies allows you to obtain results that are not achievable in conventional helicopter radars with a synthesized aperture with one antenna located at the end of the rotor blade when operating at the same frequency .

где d - расстояние между приемными антеннами 4.5 и 4.6 (измерительная база);
λ - длина волны;
β - угол прихода радиоволн (угол места).Direction finding of radiation sources of complex QPSK signals (radio sensors) in the vertical (elevation) plane is carried out by the phase method, in which the phase difference ΔΦ _{1 of the} signals received by antennas 4.5 and 4.6 is determined by the expression (Fig. 5)

where d is the distance between the receiving antennas 4.5 and 4.6 (measuring base);
λ is the wavelength;
β is the angle of arrival of radio waves (elevation angle).

где S = Rcos(2πF-ψ) - разность хода радиоволн от антенны 4.1 (4.3) до антенны 4.5;
Ω = 2πF - скорость вращения антенн 4.1 и 4.3 вокруг антенны 4.5 (скорость вращения винта вертолета);
R - радиус окружности, на которой расположены антенны 4.1 и 4.3;
ψ - пеленг на источник излучения ФМн-сигналов.However, the phase direction finding method is characterized by a contradiction between the requirements of measurement accuracy and the uniqueness of reference angle β. Indeed, according to the above expression, the phase system is more sensitive to a change in the angle β, the larger the relative size of the base d / λ. But with an increase in d / λ, the value of the angular coordinate decreases, at which the phase difference ΔΦ ₁ exceeds the value 2π, i.e., the reading is ambiguous. The ambiguity of direction finding of the radiation source of the PSK signals by the phase method in the vertical (elevation) plane is eliminated by the correlation processing of the channel PSK signals at the first intermediate frequency. Moreover, the maximum of the correlation function R (τ ₀ ) corresponds to the zone of uniqueness, that is, the region where the phase difference ΔΦ ₁ changes by less than 2π.
Direction finding of radiation sources of QPSK signals in the horizontal (azimuthal) plane is carried out by the differential-phase method using phase modulation due to the Doppler effect that occurs during the circular rotation of receiving and transmitting antennas 4.1 and 4.3 around the receiving antenna 4.5. The phase of the envelope of the modulation of the signals depends on the direction to the radiation source. Since the antennas 4.1 and 4.3 either approach the source, then move away from it, the Doppler effect arises, causing spatial-phase modulation of the received PSK signals. The phase of the signals of the mobile antennas 4.1 and 4.3 will differ from the phase of the signal of the stationary antenna 4.5 by an amount (Fig. 5)

where S = Rcos (2πF-ψ) is the difference in the path of the radio waves from antenna 4.1 (4.3) to antenna 4.5;
Ω = 2πF - rotation speed of antennas 4.1 and 4.3 around antenna 4.5 (rotational speed of a helicopter rotor);
R is the radius of the circle on which the antennas 4.1 and 4.3 are located;
ψ is the bearing to the radiation source of the QPSK signals.

 The ambiguity of direction finding of radiation sources of PSK signals by the differential-phase method in the horizontal (azimuthal) plane is eliminated by autocorrelation processing of channel PSK signals.

 The elimination of the ambiguity of direction finding of radiation sources of PSK signals in two planes is additionally provided, in addition, by sequential sector-by-sector scanning of the Earth's surface over which the helicopter flies.

 The location of the radiation sources of the PSK signals (radio sensors) is carried out using the measured values of the elevation angle β, azimuth ψ and the flight altitude of the helicopter.

 Determining the type of radiation source of PSK signals (radio or natural disaster, radio or flood, radio sensor of a stolen vehicle, beacon of a ship or aircraft, accident, etc.) is carried out using the modulating code M (t), which is allocated from the received PSK signal by its detection by the method of relative phase manipulation (Fig. 7).

 Helicopter radar operates as follows.

 The pulses generated in synchronizer 1 trigger four transmitters 2.1-2.4 and control four signal processing units 8.1-8.4. The synchronizer pulse 1 also controls the operation of the strobe pulse generator 7 and the color indicator 9. The generator 7 generates a pulse whose position in time and duration determine the position and extent of the observed element of the earth's surface in range. This pulse is fed to the processing units.

 Each transmitter operates at its own wavelength, which determines the depth of penetration of electromagnetic radiation under the underlying surface. The probe pulses from the transmitters 2.1-2.4 arrive at their antennas 4.1-4.4, each of which is located at the end of the rotor blade of the helicopter (Fig. 2). Each antenna, located at the end of the rotating blade, is connected to its transmitter and receiver only at the moment of passing a certain predetermined field of view. This is done using the switch 5 of the field of view, which is an electrical contact made in the form of four brushes located under the corresponding blades, moving during rotation along a stationary conductive segment, which, in turn, can be installed in a fixed position around the axis of the screw. Each transmitter and receiver are connected to the antenna only during the passage of the corresponding brush segment. The position of the segment determines the position of the viewing sector in space. From antennas 4.1-4.4, signals are emitted in the direction of the underlying surface. The signals reflected from the targets are received by antennas 4.1-4.4 and through antenna switches 3.1-3.4 are fed to receivers 6.1-6.4, and then to processing units 8.1-8.4, in which the received signals are processed according to the synthesized aperture algorithm. In the same blocks, the effect of changing the distance from the antenna to the target, caused by the antenna moving around the circumference during synthesis, is taken into account. In blocks 8.1-8.4, signals received only from a certain distance section are processed, the position and length of which is determined by the strobe pulse supplied from the strobe generator 7 -pulses. From the processing units 8.1-8.4, the signals are sent to the indicator 9 with a color image, and the signals from each processing unit correspond to the image in a certain color.

где U₁÷ U₄,f_c,Φ₁,Φ₂,T_c - амплитуды, несущая частота, начальные фазы и длительность сигналов;
±ΔΦ - нестабильность несущей частоты, вызванная различными дестабилизирующими факторами;
Φ_k = {0,π} - манипулируемая составляющая фазы, отображающая закон фазовой манипуляции в соответствии с модулирующим кодом M(t) (фиг. 7,а), причем Φ_k = const при kτ_u<t<(k+1)τ_u и может изменяться скачком при t = kτ_и, то есть на границах между элементарными посылками {k = 1, 2, ... N-]);
τ_u,N - длительность и количество элементарных посылок, из которых составлен сигнал длительностью T_c(T_c= Nτ_u)
с выходов приемных антенн 4.5, 4.6, 4.1 и 4.3 поступают через ключи 10.1 и 10.2 и антенные переключатели 3.1 и 3.3 соответственно на первые входы смесителей 12-15, на вторые которых подаются напряжения гетеродинов 16 и 17:
u_г1(t) = U_г1cos(2πf_г1t+πγt²+Φ_г1),
u_г2(t) = U_г2cos(2πf_г2t+πγt²+Φ_г2), 0≅t≅T_П,
где U_г1, U_г2, f_г1, f_г2, Φ_г1, Φ_г2 - амплитуды, частоты, начальные фазы напряжений гетеродинов;
причем частоты f_Г1 f_Г2 гетеродинов 16 и 17 разнесены на удвоенное значение первой промежуточной частоты (фиг. 6)
f_Г2 - f_Г1 = 2f_ПР1
и выбраны симметричными относительно частоты f_с принимаемого сигнала
f_с - f_Г1 = f_Г2 - f_с = f_ПР1.In case of emergency, the corresponding radio sensors are automatically turned on. In the event of an airplane, helicopter or ship accident, the corresponding beacons are automatically switched on. In case of unauthorized use of vehicles, the corresponding radio sensors are also turned on. These radio sensors and beacons emit PSK signals in a certain range at different frequencies other than the frequencies of the transmitters 2.1-2.4. Received QPSK signals:
u ₁ (t) = U ₁ cos [2π (f _c ± Δf) t + ΔΦ _k (t) + Φ ₁ ],
u ₂ (t) = U ₂ cos [2π (f _c ± Δf) t + ΔΦ _k (t) + Φ ₂ ],

where U ₁ ÷ U ₄ , f _c , Φ ₁ , Φ ₂ , T _c - amplitude, carrier frequency, initial phases and signal duration;
± ΔΦ is the instability of the carrier frequency caused by various destabilizing factors;
Φ _k = {0, π} is the manipulated phase component that displays the phase manipulation law in accordance with the modulating code M (t) (Fig. 7a), and Φ _k = const for kτ _u <t <(k + 1) τ _u and can change abruptly at t = kτ _and , that is, at the borders between elementary premises (k = 1, 2, ... N-]);
τ _u , N is the duration and number of chips that make up a signal of duration T _c (T _c = Nτ _u )
from the outputs of the receiving antennas 4.5, 4.6, 4.1 and 4.3 come through the keys 10.1 and 10.2 and antenna switches 3.1 and 3.3, respectively, to the first inputs of the mixers 12-15, to the second of which the voltage of the local oscillators 16 and 17 is applied:
u _g1 (t) = U _g1 cos (2πf _g1 t + πγt ² + Φ _g1 ),
u _z2 (t) = U _r2 cos (2πf _r2 t + πγt ² + Φ _z2), 0≅t≅T _P,
where U _g1 , U _g2 , f _g1 , f _g2 , Φ _g1 , Φ _g2 - amplitudes, frequencies, initial phases of the local oscillator voltages;
moreover, the frequencies f _G1 f _{G2 of the} local oscillators 16 and 17 are spaced by twice the value of the first intermediate frequency (Fig. 6)
f _G2 - f _G1 = 2f _PR1
and are chosen symmetrical with respect to frequency f _{from the} received signal
f _s - f _G1 = f _G2 - f _s = f _PR1 .

 This circumstance leads to a doubling of the number of additional (mirror and Raman) reception channels, but at the same time creates favorable conditions for their suppression by correlation processing of channel voltages.

соответствуют диаметрально противоположным положениям антенн 4.1 и 4.3 на концах двух противоположных лопастей несущего винта вертолета.Signs "+" and "-" before the value

correspond to diametrically opposite positions of antennas 4.1 and 4.3 at the ends of two opposite rotor blades of the helicopter.

На выходах смесителей 12-15 образуются напряжения комбинационных частот. Усилителями 19-22 выделяются напряжения только первой промежуточной частоты:

где

K₁ - коэффициент передачи смесителей;
f_пр1 = f_с - f_г1 = f_г2 - f_с - первая промежуточная частота;

- скорость перестройки гетеродинов 16 и 17 (скорость просмотра заданного частотного диапазона);
Φ_пр1 = Φ₁- Φ_г1; Φ_пр2 = Φ₂- Φ_г2.
Эти напряжения представляют собой сложные сигналы с комбинированной фазовой манипуляцией и линейной частотной модуляцией (ФМн-ЛЧМ).Viewing a given frequency range D _f , in which the frequencies of the radio sensors and beacons are located, is carried out using the search unit 18, which periodically with a period T _p according to the sawtooth law tunes the frequencies f _g1 and f _{g2 of the} local oscillators 16 and 17

At the outputs of the mixers 12-15, the voltage of the combination frequencies. Amplifiers 19-22 are allocated only the first intermediate frequency voltage:

Where

K ₁ - gear ratio of the mixers;
f _pr1 = f _s - f _g1 = f _g2 - f _s - the first intermediate frequency;

- the tuning rate of the local oscillators 16 and 17 (the speed of viewing a given frequency range);
Φ _pr1 = Φ ₁ - Φ _g1 ; Φ _pr2 = Φ ₂ - Φ _r2 .
These voltages are complex signals with combined phase shift keying and linear frequency modulation (FMN-LFM).

The voltage u _pr1 (t) from the output of the amplifier 19 of the first intermediate frequency is supplied to the input of the selector 28, consisting of a frequency doubler 29, measuring instruments for the width of the spectrum 30 and 31, block 32 comparison, threshold block 33, delay line 34 and key 35.

в котором фазовая манипуляция уже отсутствует.A voltage is generated at the output of the frequency doubler 29

in which phase manipulation is already absent.

тогда как ширина спектра гармонического колебания определяется длительностью сигнала

Так как в блоке сравнения 32 сравниваются значения ширины спектра ФМн-сигнала первой промежуточной частоты и его второй гармоники, то принудительная линейная частотная модуляция не вносит существенных изменений в указанные соотношения.The spectrum width of the QPSK signal is determined by the duration τ _{u of} its elementary premises

while the width of the spectrum of harmonic oscillation is determined by the duration of the signal

Since the comparison block 32 compares the values of the spectrum width of the QPSK signal of the first intermediate frequency and its second harmonic, the forced linear frequency modulation does not significantly change these relations.

The width of the spectrum Δf _{1 of the} voltage u _CR1 (t) is measured using a meter 31 of the spectrum width, and the width of the spectrum Δf _{1 of the} voltage u _CR2 (t) is measured using a meter 3 of the spectrum width. When doubling the frequency (phase) of the QPSK signal, the width of its spectrum "coagulates" N times (N = Δf ₁ / Δf ₂ ). This circumstance makes it possible to detect the QPSK signal and select it from other signals and interference.

Voltages U ₁₁ and U ₂₂ , proportional to Δf ₁ and Δf ₂ , from the outputs of the meters 31 and 30 of the spectrum width are supplied to the two inputs of the comparison unit 32. Since U ₁₁ >> U ₂₂ , a voltage is generated at the output of the comparison unit 32 that exceeds the threshold voltage U _por1 in the threshold block 33. When the threshold voltage U _{por1 is exceeded} , and this only occurs when the PSK signal is detected, in the threshold block 33 a constant voltage is formed, which is supplied to the control input of the key 35 and opens it. In the initial state, the keys 35, 40 and 44 are always closed. A constant voltage from the output of the threshold unit 33 simultaneously passes through the delay line 34 to the control input of the threshold unit 33, as well as to the control inputs of the search unit 18 and the reference generator 25. In this case, the search unit 18 is turned off and the reference generator 25 is turned on for the duration of the analysis of the detected FMN signal and direction finding of the source of its radiation, which is determined by the delay time τ _s1 delay line 34.

Со вторых входов гетеродинов 16 и 17 напряжения u_г1(t) и u_г2(t) подаются на два входа перемножителя 23, на выходе которого образуется напряжение
u_г(t) = U_гcos(4πf_пр1t+ΔΦ_г),
где

K₂ - коэффициент передачи перемножителя;
f_г2 - f_г1 = 2f_пр1;
ΔΦ_г = Φ_г2-Φ_г1.
Это напряжение выделяется узкополосным фильтром 24.When the tuning of the local oscillators 16 and 17 ceases, the following voltages are allocated by the amplifiers 19-22 of the first intermediate frequency

From the second inputs of the local oscillators 16 and 17 voltage u _g1 (t) and u _g2 (t) are fed to two inputs of the multiplier 23, the output of which is generated voltage
u _g (t) = U _g cos (4πf _pr1 t + ΔΦ _g ),
Where

K ₂ - transfer coefficient of the multiplier;
f _g2 - f _g1 = 2f _pr1 ;
ΔΦ _g = Φ _g2 -Φ _g1 .
This voltage is allocated by the narrow-band filter 24.

To maintain the symmetry of the frequencies f _g2 and f _{g1 of the} local oscillators 16 and 17 relative to the carrier frequency f _{from the} detected PSK signal, a phase locked loop (PLL) is used, consisting of a reference oscillator 25, a phase detector 26, a narrow-band filter 24, and a control unit 27. When this is the reference voltage
u ₀₁ (t) = U ₀₁ cos (2πf ₀₁ t + Φ ₀₁ ),
where U ₀₁ , f ₀₁ , Φ ₀₁ - the amplitude, frequency and initial phase of the reference voltage;
f ₀₁ = 2f _pr1 ,
from the output of the reference oscillator 25 is fed to the first input of the phase detector 26, to the second input of which a harmonic voltage U _g (t) is supplied from the output of the narrow-band filter. If the indicated voltages differ from each other in frequency and phase, then a control voltage is generated at the output of the phase detector 26. Moreover, the amplitude and polarity of this voltage depend on the degree and direction of deviation of the doubled value of the first intermediate frequency 2f _pr1 from the frequency f _{01 of the} reference oscillator 25. The control voltage through the control unit 27 affects the frequency f _{g1 of the} local oscillator 16, changing (adjusting) it so that the following equality and symmetry
f _g2 - f _g1 = 2f _pr1 = f ₀₁ ,
f _s - f _g1 = f _g2 - f _s = f _pr1 .

Therefore, the indicated equality and symmetry of the frequencies of the local oscillators 16 and 17 is controlled by the PLL at the frequency f _{01 of the} reference oscillator 25, which is chosen to be equal to twice the value of the first intermediate frequency (2f _CR1 = f ₀₁ ). Moreover, the doubled value of the first intermediate frequency 2f _CR1 always remains fixed, and the value of the first intermediate frequency f _CR1 can vary within relatively large limits.

2f_пр1 = f_г2 - f_г1;
ΔΦ_г = Φ_г2- Φ_г1;

- фазовый сдвиг, определяющий направление на радиодатчик в вертикальной (угломестной) плоскости;
которое выделяется узкополосным фильтром 39 и поступает на первый вход фазометра 45.Voltages U _CR5 (t) and U _CR6 (t) from the outputs of amplifiers 19 and 20 of the first intermediate frequency via key 35 and directly go to the two inputs of the multiplier 38, at the output of which a harmonic oscillation is generated
u ₆ (t) = U ₀ cos (4πf _pr1 t + ΔΦ _g + ΔΦ ₁ ),
Where

2f _{pr1 r2} = f - f _d1;
ΔΦ _g = Φ _g2 - Φ _g1 ;

- phase shift, which determines the direction to the radio sensor in a vertical (elevation) plane;
which is allocated by a narrow-band filter 39 and enters the first input of the phase meter 45.

где t₁, t₂ - время прохождения сигналом расстояния от радиодатчика (РД) до приемных антенн 4.5 и 4.6 соответственно;
c - скорость распространения радиоволн.The voltage U _CR5 (t) and U _CR6 (t) are simultaneously supplied to two inputs of the correlator 36. The cross-correlation function R ₁ (τ) obtained at the output of the correlator 36 has a maximum at

where t ₁ , t ₂ - the time the signal travels the distance from the radio sensor (RD) to the receiving antennas 4.5 and 4.6, respectively;
c is the propagation velocity of radio waves.

In this case, the threshold level U _pore2 in the threshold block 37 is exceeded only at the maximum value of the correlation function R ₁ (τ ₀ ) and is not exceeded at the values of τ corresponding to the side lobes of the correlation function R ₁ (τ). The correlation function of complex QPSK signals has a remarkable property: a relatively high level of the main lobe and a relatively low level of side lobes. Moreover, the high level of the main lobe, that is, the maximum of the correlation function R ₁ (τ ₀ ) corresponds to the zone of uniqueness, that is, the region where the phase difference ΔΦ ₁ changes by less than 2π. Moreover, the threshold voltage U _pore2 in the threshold block 37 is exceeded only at the maximum value of the correlation function R ₁ (τ ₀ ) and is not exceeded at values of τ corresponding to the side lobes of the correlation function R ₁ (τ). When the threshold level U _pore2 is exceeded, a constant voltage is generated in the threshold block 37, which is supplied to the control inputs of the keys 40 and 44 and opened. In this case, the harmonic voltage U _g (t) from the output of the narrow-band filter 24 through the public key 44 is supplied to the second input of the phase meter 45, where the phase shift ΔΦ ₁ is measured. The measured phase shift ΔΦ ₁ enters the registration unit 11.

Тогда как ширина спектра Δf₂ гармонического колебания U₆(t) определяется длительностью T_с сигналов

Следовательно, при перемножении ФМн-сигналов на первой промежуточной частоте U_пр5(t) и U_пр6(t) их спектр "сворачивается" в N раз (Δf₁/Δf₂ = N) и переносится на удвоенное значение первой промежуточной частоты, равное разности частот f_г2 и f_г1 гетеродинов 16 и 17 (2f_пр1 = f_г2 - f_г1). Это обстоятельство дает возможность выделить гармоническое колебание U₆(t) с помощью узкополосного фильтра 39, отфильтровав при этом значительную часть шумов и помех, и повысив тем самым реальную чувствительность бортового приемника 6.5 при пеленгации радиодатчиков в вертикальной (угломестной) плоскости.The width of the spectrum Δf ₁ received by antennas 4.5 and 4.6 PSK signals, as already noted, is determined by the duration τ _{u of} their elementary premises

Whereas the width of the spectrum Δf ₂ harmonic oscillations U ₆ (t) is determined by the duration T of _the signals

Therefore, when multiplying the QPSK signals at the first intermediate frequency, U _CR5 (t) and U _CR6 (t), their spectrum “folds” N times (Δf ₁ / Δf ₂ = N) and is transferred to twice the value of the first intermediate frequency equal to the difference frequency f _r2 f _r1 and local oscillators 16 and 17 (2f _{pr1 r2} = f - f _z1). This circumstance makes it possible to isolate the harmonic oscillation U ₆ (t) using a narrow-band filter 39, filtering out a significant part of the noise and interference, and thereby increasing the real sensitivity of the 6.5 airborne receiver when detecting radio sensors in a vertical (elevation) plane.

Furthermore, the phase measurements are carried out on a stable frequency equal to twice the value of the first intermediate frequency 2f _pr1 = f _r2 - f _r1, instability ± Δf the carrier frequency f _c, the frequency f _r2 and f _r1 oscillators 16 and 17 as well as phase shift keying not have influence on the results of phase measurements. To maintain the stability of the frequency 2f _pr1 = f ₀₁ , the PLL system is used.

 Therefore, the on-board receiver 6.5 is invariant to the type of manipulation of the received complex signals and the instability of their carrier frequency. It provides accurate and unambiguous direction finding of the radiation source of the FMN signals (radio sensor) in a vertical (elevation) plane.

The voltage U _pr5 (t) from the output of the amplifier 19 of the first intermediate frequency through the public keys 35 and 40 is supplied to the two inputs of the phase detector 43, and to one of them through the delay line 42, the delay time τ _{s2 of} which is chosen equal to the duration τ _{u of the} elementary package ( τ _z2 = τ _u ) (Fig. 7, c). To extract the modulating code M (t) (Fig. 7, a) from the received _QPSK signal U _CR5 (t) at the first intermediate frequency, the method of relative phase shift keying is used, in which the previous transmission serves as a reference voltage for each subsequent elementary transmission. The phases of the previous and subsequent parcels are compared in the phase detector 43. As a result of detecting the received signal of the QPSK signal at the first intermediate frequency U _CR5 (t) (Fig. 7, c) at the output of the autocorrelator, consisting of a delay line 42 and a phase detector 43, is formed an analog M '(t) (Fig. 7, d) of the modulating code M (t) (Fig. 7, a), which is fixed by the registration unit 11. Moreover, each radio sensor that is triggered in the event of an emergency of one nature or another has its own personal modulating code, which consists of an address and information part. The address part consists of n elementary premises and is used to transmit information, for example, on the nature of the emergency and its geographical coordinates, which are then specified and compared by direction finding from the helicopter, etc. The information part consists of m elementary premises (m = Nn) and is used to transmit, for example, the level of high water (mudflow), the level of radioactivity, etc.

The voltage U _pr5 (t) from the output of the amplifier 19 of the first intermediate frequency through the public keys 35 and 40 is simultaneously supplied to the first input of the mixer 47, the second input of which is supplied with the voltage of the third local oscillator 46.

u _g3 (t) = U _g3 cos (2πf _g3 t + Φ _g3 ),
where U _g3 , f _g3 , Φ _g3 - amplitude, frequency and initial phase of the local oscillator voltage 46.

где

f_пр2 = f_пр1 - f_г3 - вторая промежуточная частота;
Φ_пр9 = Φ_пр1- Φ_г3,
которое подается на вторые входы перемножителей 49 и 50, на первые входы которых поступают напряжения U_пр7(t) и U_пр8(t) с выходов усилителей 21 и 22 первой промежуточной частоты соответственно. На выходах перемножителей 49 и 50 образуются фазомодулированные колебания.At the output of the mixer 47, voltages of combination frequencies are generated. Amplifier 48 distinguishes the voltage of the second intermediate frequency

Where

f _CR2 = f _CR1 - f _g3 - the second intermediate frequency;
Φ _pr9 = Φ _pr1 - Φ _r3 ,
which is fed to the second inputs of the multipliers 49 and 50, the first inputs of which receive voltage U _CR7 (t) and U _CR8 (t) from the outputs of the amplifiers 21 and 22 of the first intermediate frequency, respectively. At the outputs of the multipliers 49 and 50, phase-modulated oscillations are formed.

где

которые выделяются узкополосными фильтрами 51, 52 и поступают на два входа перемножителя 53.

Where

which are allocated by narrow-band filters 51, 52 and fed to two inputs of the multiplier 53.

Therefore, when the voltages U _CR7 (t) and U _CR8 (t) are _multiplied with the voltage U _CR9 (t), the spectrum of the input PSK signals is “convoluted” N times and transferred to the stable frequency f _{g3 of the} third local oscillator 46. This circumstance provides an opportunity for isolating the obtained PSK oscillations U _CR7 (t) and U _CR8 (t) using narrow-band filters 51 and 52, filtering out a significant part of noise and interference, thereby increasing the real sensitivity of the on-board receiver 6.5 when direction finding the radio sensors in the horizontal (azimuthal) plane.

входящая в состав указанных колебаний и называемая индексом фазовой модуляции, характеризует максимальное значение отклонения фазы вращающихся приемных антенн 4.1 и 4.3 относительно антенны 4.5. Пеленгатор тем чувствительнее к изменению угла ψ, чем больше относительный размер измерительной базы R/λ. Однако с ростом R/λ уменьшается значение угловой координаты ψ, при котором разность фаз превосходит значение 2π, то есть наступает неоднозначность отсчета.In addition, due to this operation, the carrier frequencies received by antennas 4.1 and 4.3 of the FMN signals are freed from instability ± Δf of the carrier frequency. Useful information about the bearing ψ to the radio sensor is contained in the PSK oscillations u ₇ (t) and u ₈ (t). Moreover, the value

which is part of these oscillations and is called the phase modulation index, characterizes the maximum value of the phase deviation of the rotating receiving antennas 4.1 and 4.3 relative to the antenna 4.5. The direction finder is the more sensitive to changes in the angle ψ, the larger the relative size of the measuring base R / λ. However, with an increase in R / λ, the value of the angular coordinate ψ decreases, at which the phase difference exceeds 2π, i.e., the reading is ambiguous.

наступает неоднозначность отсчета угла ψ. Устранение указанной неоднозначности путем уменьшения соотношения R/λ обычно себя не оправдывает, так как при этом теряется основное достоинство широкобазовой системы. Кроме того, в диапазоне метровых и особенно дециметровых волн брать малые значения R/λ часто не удается из-за конструктивных соображений.Therefore, for

the ambiguity of the reference angle ψ occurs. The elimination of this ambiguity by reducing the R / λ ratio usually does not justify itself, since the main advantage of a wide-base system is lost. In addition, in the range of meter and especially decimeter waves, it is often not possible to take small R / λ values due to design considerations.

To increase the accuracy of direction finding of radio sensors in the horizontal (azimuthal) plane, receiving antennas 4.1 and 4.3 are located at the ends of two opposite rotor blades of the helicopter. The mixing of signals from two diametrically opposite receiving antennas 4.1 and 4.3 located at the same distance R from the rotor axis of the rotor causes phase modulation, which is identical to the phase modulation obtained using one receiving antenna rotating in a circle whose radius R ₁ is two times more (R ₁ = 2R).

с индексом фазовой модуляции

, которое выделяется узкополосным фильтром 54 и поступает на первый вход фазометра 57, на второй вход которого подается напряжение опорного генератора 59
u₀₂(t) = U₀₂cos(2πFt+Φ₀₂).
Фазометр 57 обеспечивает точное измерение пеленга ψ на радиодатчик. Измеренное значение пеленга ψ фиксируется блоком 11 регистрации.Indeed, a harmonic voltage is generated at the output of the multiplier 53
u ₉ (t) = U ₉ cos (2πFt-ψ), 0≅t≅T _c ,
Where

with phase modulation index

, which is allocated by a narrow-band filter 54 and enters the first input of the phasemeter 57, the second input of which is supplied with the voltage of the reference oscillator 59
u ₀₂ (t) = U ₀₂ cos (2πFt + Φ ₀₂ ).
Phasometer 57 provides accurate measurement of the bearing ψ to the radio sensor. The measured value of the bearing ψ is recorded by the registration unit 11.

снимаемых с двух синхронно вращающихся с угловой скоростью Ω = 2πF антенн 4.3 и 4.3' (4.1 и 4.1'), сдвинутых между собой на угол ε (фиг. 5). Индекс фазовой модуляции в этом случае определяется выражением

где

- расстояние между антеннами 4.1 и 4.1'.To eliminate the ambiguity of reading the angle ψ, it is necessary to reduce the phase modulation index without decreasing the R / λ ratio.
This problem can be solved by using a differential-phase direction finder, in which the phase difference between voltages is measured

taken from two synchronously rotating with an angular speed Ω = 2πF antennas 4.3 and 4.3 '(4.1 and 4.1'), shifted to each other by an angle ε (Fig. 5). The phase modulation index in this case is determined by the expression

Where

- distance between antennas 4.1 and 4.1 '.

Однако, при таком расположении антенн не устраняется паразитная фазовая модуляция, обусловленная непостоянством фазы принимаемого сигнала в течение интервала времени τ_з3.
Уменьшения индекса фазовой модуляции можно достигнуть и с одной вращающейся антенной 4.3 (4.1). При этом вместо напряжения u_8′(t) необходимо использовать напряжение u₈(t), задержанное на время τ_з3, эквивалентное сдвигу второй антенны 4.3' (4.1') на угол ε = Ωτ_з3.
В предлагаемой станции напряжение u₈(t) с выхода узкополосного фильтра 52 поступает на автокоррелятор, состоящий из линии задержки 55 (τ_з3) и фазового детектора 56. Это эквивалентно уменьшению индекса фазовой модуляции до величины

На выходе автокоррелятора образуется напряжение
u₁₀(t) = U₁₀cos(2πFt-ψ), 0≅t≅T_c,
где

с индексом фазовой модуляции

которое поступает на первый вход фазометра 58, на второй вход которого подается напряжение u₀₂(t) с выхода опорного генератора 59. Фазометр 58 обеспечивает однозначное измерение пеленга ψ на источник излучения. По существу. Фазометры 57 и 58 представляют собой две шкалы измерений. Фазометр 57 представляет точную, но неоднозначную шкалу измерений, а фазометр 58 - грубую, но однозначную шкалу измерений.For d ₁ <R, the phase modulation index ΔΦ _m2 is smaller than that of a direction finder with one rotating antenna and the same base

However, with this arrangement of antennas, spurious phase modulation is not eliminated, due to the inconsistency of the phase of the received signal during the time interval τ _s3 .
A decrease in the phase modulation index can also be achieved with a single rotating antenna 4.3 (4.1). In this case, instead of the voltage u _{8 ′} (t), it is necessary to use the voltage u ₈ (t), delayed by the time τ _s3 , equivalent to the shift of the second antenna 4.3 '(4.1') by the angle ε = Ωτ _s3 .
In the proposed station, the voltage u ₈ (t) from the output of the narrow-band filter 52 is supplied to the autocorrelator, consisting of a delay line 55 (τ _s3 ) and a phase detector 56. This is equivalent to a decrease in the phase modulation index to

A voltage is generated at the output of the autocorrelator
u ₁₀ (t) = U ₁₀ cos (2πFt-ψ), 0≅t≅T _c ,
Where

with phase modulation index

which is supplied to the first input of the phasemeter 58, the second input of which is supplied with voltage u ₀₂ (t) from the output of the reference generator 59. The phase meter 58 provides an unambiguous measurement of bearing ψ to the radiation source. In essence. Phasometers 57 and 58 are two measurement scales. The phasometer 57 represents an accurate but ambiguous measurement scale, and the phasometer 58 represents a crude but unambiguous measurement scale.

Consequently, during the analysis (τ _z1 ), the receiver 6.5 provides detection of the detected PSK signal and direction finding of its radiation source in two planes. After this time, the constant voltage from the output of the delay line 34 is supplied to the control input of the threshold unit 33 and returns to its original state. In this case, the key 35 also returns to its original state, that is, it closes, the reference generator 25 is turned off, and the search unit 18 is turned on. From this point in time, the process of searching for QPSK signals in a given frequency range D _f by tuning the local oscillators 16 and 17 continues.

 Upon detection of the next QPSK signal, the operation of the receiver 6.5 and the radar station as a whole is carried out in a similar way.

The operation of the onboard receiver described above corresponds to the case of receiving the PSK signals on the main channel at a frequency f _s (Fig. 6).

If a false signal (interference) is received through the first mirror channel at a frequency f _s1 , then in mixers 12 and 13 it is converted to voltages of the following frequencies
f ₁₁ = f _g1 + γ • tf _s1 = f _pr1 -γ • t,
f ₁₂ = f _g2 + γ • tf _s1 = 3f _pr1 -γ • t,
where the first index means the channel through which the signal is received, and the second is the number of the local oscillator involved in the conversion of the carrier frequency of the received signal.

However, only voltage with frequency f ₁₁ falls into the passband Δf _{p of} amplifier 19 of the first intermediate frequency. If this is a hindrance, it is filtered out by the selector 28. If the indicated voltage is formed by a false PSK signal, then it is selected by the selector and applied to the first input of the correlator 36. There is no voltage at the output of the amplifier 20 of the first intermediate frequency in this case. Therefore, no voltage is supplied to the second input of the correlator 36, the output voltage of the correlator 36 is zero, the keys 40 and 44 do not open, and a false signal (interference) received through the first mirror channel at a frequency f _s1 is suppressed.

If a false signal (interference) is received through the second mirror channel at a frequency f _s2 , then in mixers 12 and 13 it is converted to the voltage of the following frequencies
and ₂₁ = _r1 and _s2 -s -γt = 3f _pr1 -γt,
f ₂₂ = f _s2 -f _r2 -γt = f _pr1 -γt.
However, only a voltage with a frequency f ₂₂ falls into the passband Δf _{p of the} amplifier 20 of the first intermediate frequency, and then enters the second input of the correlator 36. There is no voltage at the output of the amplifier 19 of the first intermediate frequency. The output voltage of the correlator 36 is also equal to zero, the keys 40 and 44 do not open and a false signal (interference) received through the second mirror channel at a frequency f _s2 is suppressed.

For a similar reason, false signals (interference) received on the first combination channel at a frequency f _k1 or on the second combination channel at a frequency f _k2 or any other combination channel are also suppressed.

If false signals (interference) are simultaneously received on the first and second mirror channels at frequencies f _s1 and f _s2 , then the voltages are generated at the outputs of amplifiers 10 and 20 of the first intermediate frequency. These voltages are applied to the two inputs of the correlator 36. However, the keys 40 and 44 do not open. This is due to the fact that channel voltages are generated by different false signals (interference) received at different frequencies f _s1 and f _s2 . Therefore, there is a weak correlation between them. The output voltage of the correlator 36 does not reach the maximum value and does not exceed the threshold level U _{pore 3} in the threshold block 37, the keys 40 and 44 do not open, and false signals (interference) received simultaneously on the first and second mirror channels at frequencies f _s1 and f _s2 are suppressed .

For a similar reason, false signals (interference) are simultaneously suppressed via the first and second combinational channels at frequencies f _k1 and f _k2 or two other additional channels.

If the useful QPSK signal is received on the main channel at a frequency f _s , then in mixers 12 and 13 it is converted to voltages of the following frequencies
f _c1 = f _c -f _g1 -γt = f _pr pr1 -γt,
f _c1 = f _r2 + γt-f _c = f _pr1 + γt.
The channel voltages in the amplifiers 19 and 20 of the first intermediate frequency in this case are generated by the same PSK signal received at a frequency f _s . There is a strong correlation between channel voltages. The output voltage of the correlator 36 reaches a maximum value and exceeds the threshold level U _pores3 in the threshold block 37. When the threshold level U _pores3 is exceeded, a constant voltage is generated in the threshold block 37, which is supplied to the control inputs of the keys 40, 44 and opens them.

 As an example in FIG. 8 is a structural diagram of a radio flood detector (mudflow), where the following designations are introduced: 61 - power source; 62-64 - level sensors, 65-67 - sensitive elements, 68-70 - relays, 71 - multivibrator, 72 - multivibrator relay, 73 - transmitter, 74 - master oscillator, 75 - modulating current generator, 76 - telegraph key, 77 - phase manipulator, 78 - power amplifier, 79 - transmitting antenna.

 The principle of flood warning (village) is based on the use of a complex PSK signal that is emitted by the sensor 73, received, processed, detected and direction-finding by the on-board receiver 6.5, while the radio sensors are installed in flood-hazardous (mud-hazardous) regions, and the receiver 6.5 - on board the helicopter.

 The radio sensor flood (mudflow) works as follows.

 When the sensing element 65 of the water level sensor 62 is filled, the relay 68 circuit closes to ground, the relay 68 activates and closes the contacts 68.1, through which the supply voltage is supplied to the multivibrator 71 and the transmitter 73. In this case, the multivibrator 71 operates in unbalanced mode. The contacts 72.1 of the relay 72 of the multivibrator 71 periodically, for example, after 10 seconds, closes the circuit of the telegraph key 76 of the transmitter 73, which sends radio signals over the air at the same time interval.

After turning on the transmitter 73 high-frequency oscillation
U ₁ (t) = U _c cos (2πf _c t + Φ _c ), 0≅t≅T _c ,
from the output of the master oscillator 74 through the telegraph key 76, it is supplied to the first input of the phase manipulator 77, the second input of which is supplied with a modulating code M (t) from the output of the modulating code generator 75. As a result of phase manipulation, the output of the phase manipulator 77 generates a PSK signal
U ₂ (t) = U _c cos (2πf _c t + Φ _k (t) + Φ _c ), 0≅t≅T _c ,
which, after amplification in the power amplifier 78, is transmitted by the transmitting antenna 79 to the air.

With a further rise in water in the alignment and filling of the sensing element 66 of the level sensor 63, the relay 69 is activated, its contacts 69.1 are closed and the resistor R4 is included in the multivibrator circuit 71. The inclusion of the resistor R4 in the circuit of the multivibrator 71 puts its operation in symmetrical mode, the relay 72 of the multivibrator 71 is activated at regular intervals, for example, after 1 second, and its contacts 72.1 close the circuit of the telegraph key 76 after the same time interval (T _p = T _s )

 Upon reaching the flood level (mudflow) of the third value, the sensing element 67 of the level sensor 64 is flooded, the relay 70 is activated, its contact pair 70.1 closes the telegraph key circuit 76. When the telegraph key circuit 76 is short-circuited, the transmitter 73 sends a continuous FMN signal to the air.

 When the water level (mudflow) drops, the QPSK signals will be transmitted by the transmitter 73 in the reverse order.

 Therefore, by the nature of the transmitted FMN signals, one can judge the level of flood (mudflow), and the modulating code contains information about the type of emergency, its geographical coordinates, etc.

 The use of a complex QPSK signal allows the use of structural selection, which provides higher noise immunity and the reliability of the selection of the specified signal from other signals and interference operating in the same frequency band and at the same time intervals.

 Thus, the proposed helicopter radar station in comparison with the prototype provides an extension of functionality by detecting received PSK signals, accurate and unambiguous direction finding of their radiation sources in two planes. At the same time, direction finding of radiation sources of FMN signals (radio sensors) in the vertical (elevation) plane is carried out by the phase method using receiving antennas 4.5 and 4.6 located on the upper and lower parts of the fuselage of the helicopter, respectively. The ambiguity of direction finding is eliminated by correlation processing of the channel PSK signals of the first intermediate frequency.

 Direction finding of radiation sources of PSK signals in the horizontal (azimuthal) plane is carried out by the differential-phase method using receiving antennas 4.1 and 4.3, located at the ends of two opposite helicopter rotor blades and rotating around the receiving antenna 4.5. The ambiguity of direction finding is eliminated by autocorrelation processing of FMN signals.

 The location of the radiation sources of the PSK signals (radio sensors) is carried out using the measured values of the elevation angle β, azimuth ψ and the height h of the flight of the helicopter.

 Phase direction finders in two planes are invariant to instability of the carrier frequency of the received complex signals and to the type of their manipulation. They provide phase measurements at fixed frequencies and make it possible to increase the sensitivity of the on-board receiver 6.5 at low signal-to-noise ratios due to convolution of the spectrum of received PSK signals.

 Determination of the type of radiation source of FMN signals (radio sensors of natural or environmental disaster, radio sensor of high water or mudflow, radio sensor of a stolen vehicle, radio buoy of a ship or aircraft, an accident, etc.) is carried out using the modulating code M (t), which is allocated from the received PSK signal by its detection by the method of relative phase manipulation.

 The use of complex QPSK signals allows the use of a new type of selection - structural selection.

 Suppression of additional (mirror and combination) reception channels and increased noise immunity of the on-board receiver 6.5 is achieved by correlation processing of the received signals.

Claims (1)

 A helicopter radar station containing a synchronizer and a strobe generator, a viewing sector switch, an indicator and four channels, each of which consists of a transmitter connected in series to the synchronizer output, an antenna switch, the input-output of which is connected to the transmit-receive antenna, and the control input is connected to the output of the switch of the field of view, the receiver, the control input of which is connected to the output of the strobe generator, and the processing unit, controlling the input of which is connected to the output of the synchronizer, the signals from the processing unit are sent to an indicator, the control input of which is connected to the output of the synchronizer, while the transmit-receive antennas are located at the ends of the rotor blades of the helicopter, characterized in that the fifth and sixth receive antennas are introduced into it , two keys and a fifth receiver, and to the output of the fifth receiving antenna, a first key is connected in series, the control input of which is connected to the output of the field of view switch, and a fifth receiver to the sixth output when the second antenna, the control input of which is connected to the output of the field of view switch, and the fifth receiver, the third and fourth inputs of which are connected to the output of the first and third antenna switches, respectively, the fifth receiving antenna is located on the top of the fuselage of the helicopter above the screw hub, and the sixth receiving antenna is located on the bottom of the fuselage of the helicopter, the fifth receiver contains four direction finding channels, the first of which consists of series-connected to the output to the first key of the first mixer, the second input of which is connected to the first output of the first local oscillator, the control input of which is connected to the output of the search unit, and the first amplifier of the first intermediate frequency, and the second from the second key in series connected to the output of the second mixer, the second input of which is connected to the first output of the second local oscillator, the control input of which is connected to the output of the search unit, and the second amplifier of the first intermediate frequency, serially connected to the second output of the first local oscillator a second multiplier, the second input of which is connected to the second output of the second local oscillator, the first narrow-band filter, the first phase detector, the second input of which is connected to the output of the first reference oscillator, and the control unit, the output of which is connected to the second input of the first local oscillator, to the output of the first amplifier of the first intermediate a frequency doubler, a second spectral width meter, a comparison unit, the second input of which is connected through the first spectral width meter to the output of the first amplifier the first intermediate block, the second input of which is connected through the first delay line to its output, the third key, the second input of which is connected to the output of the first amplifier of the first intermediate frequency, the correlator, the second input of which is connected to the output of the second amplifier of the first intermediate frequency, second a threshold unit, a fourth key, the second input of which is connected to the output of the third key, a second delay line and a second phase detector, the second input of which is connected to the output of the fourth key, and the output is I am the first output of the receiver, the second multiplier is connected in series to the output of the second amplifier of the first intermediate frequency, the second input of which is connected to the output of the third key, the second narrow-band filter and the first phase meter, the second input of which is connected through the fifth key to the outputs of the second threshold block and the first narrow-band filter, and the output is the second output of the receiver, the control inputs of the search block and the first reference generator are connected to the output of the first threshold block, the output of the fourth key is followed by a fifth mixer is connected, the second input of which is connected to the output of the third local oscillator, and the amplifier of the second intermediate frequency, the third direction finding channel consists of serially connected to the first antenna switch of the third mixer, the second input of which is connected to the first output of the first local oscillator, the third amplifier of the first intermediate frequency, the third multiplier, the second input of which is connected to the output of the amplifier of the second intermediate frequency, and the third narrow-band filter, the fourth direction finding the channel consists of a fourth mixer connected in series to the third antenna switch, the second input of which is connected to the first output of the first local oscillator, the fourth amplifier of the first intermediate frequency, the fourth multiplier, the second input of which is connected to the output of the second intermediate frequency amplifier, and the fourth narrow-band filter, to the output of which the fifth multiplier is connected in series, the second input of which is connected to the output of the third narrow-band filter, the fifth narrow-band filter and the second the third phase meter, the second input of which is connected to the output of the second reference generator, and the output is the third output of the receiver, the third delay line, the third phase detector, the second input of which is connected to the output of the fourth narrow-band filter, and the third phase meter, the second, are connected to the output of the fourth narrow-band filter the input of which is connected to the output of the second reference generator, and the output is the fourth output of the receiver, the engine is kinematically connected with the helicopter propeller and the second reference generator.

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