RU2276038C1 - System for detection and determination of the position of a man in distress on water - Google Patents

Abstract

FIELD: the invention refers to rescuing technique.

SUBSTANCE: the system for detection and determination of the position of a man in distress on water has dressed on the man a life-saving jacket with a source of light and transmitters with transmitting antennas and a receiver-direction finder installed aboard a helicopter. The receiver-direction finder has receiving antennas 23-25, frequency changers 26, 27, 29, 40 and 61, amplifiers 30, 31, 34 and 62 of the first intermediate frequency, commutators 32, 33, 37 and 65, narrow band filters 35, 36, 44, 51, 54 and 39, an amplifier 41 of the second intermediate frequency, amplitude detectors 42, 67, 74 and 75, phase detectors 45 and 79, phase meters 46 and 47, an integrator 49 of standard voltage, a frequency meter 50, phase inverters 52, 55 and 58, summing units 53, 56, 59 and 64, phase rotators 60 and 63 on 90⁰, a calibrator 69, regulated phase rotators 70 and 71, inverse amplifiers 78 and 81, a subtracting unit 76, filters 77 and 80 of the lower frequencies.

EFFECT: increases antijamming capability and selectivity of an airborne receiver-direction finder.

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Description

The proposed system relates to rescue equipment and can be used to detect a person in distress on the water, and determine his location.

Rescue systems and devices are known (Autosvid. USSR No. 385.819, 431.063, 637.298, 765.113, 988.655, 1.348.819, 1.505.840, 1.505.841, 1.588.636, 1.615.054, 1.643.325, 1.664.653 ; RF patents Nos. 2,000.995, 2.009.956, 2.038.259, 2.043.259, 2.051.838, 2.177.437, 2.226.479; US patents Nos. 3,621.501, 4.889.511; UK patent No. 1.145. 051; Danish patent No. 1,031.118 and others).

Of the known systems and devices closest to the proposed one is the "System for detecting and determining the location of a person in distress on the water" (RF patent No. 2.226.479, B 63 C 9/20, 2002), which is selected as a prototype.

The specified system uses a radio transmitter, which is equipped with a person in distress on the water, and a helicopter, on board which is installed equipment for direction finding of the radio transmitter and determine its location. In this case, the on-board receiving and _{direction-finding} equipment suppresses false signals (interference) received through the mirror channel at a frequency of ω ₃ , through a direct channel at the first intermediate frequency ω _pr1 , through combinational channels at frequencies ω _k1 and ω _k2 , through intermodulation channels in frequency bands Δω _p1 and Δω _p2 located "left" and "right" of the passband Δω _{p of the} receiver.

It should be noted that the conversion on the mirror channel of the reception occurs with the same conversion coefficient K _ol as on the main channel. Therefore, it most significantly affects the selectivity and noise immunity of the onboard direction finder.

The suppression of false signals (interference) received via the mirror channel at a frequency of ω ₃ in the on-board _{direction finder is} based on the use of two reception channels in which the signals are converted to the lower first intermediate frequency ω _pr1 , which is the same for both channels, amplified, and then summed. Moreover, in one of the channels, the received signal is phase shifted by 90 ° both at the high frequency and at the first intermediate frequency. This leads to the fact that false signals (interference) received on the mirror channel at a frequency of ω ₃ at the output of the adder 64 are in antiphase and compensated.

However, the complete suppression of these false signals (interference) is possible only with the identity of the receiving channels. Real amplifiers of the first intermediate frequency and other elements that are part of the channels have different characteristics.

An object of the invention is to increase the noise immunity of the airborne direction finder by completely suppressing false signals (interference) received on the mirror channel at a frequency of ω ₃ by eliminating the non-identity of the receiving channels.

The problem is solved in that a system for detecting and determining the location of a person in distress on the water, including a life jacket worn by a person and containing two light sources, one of which is located in the chest area of the life jacket, and the other in its back area, two miniature transmitters with transmitting antennas, one of which is located in the chest area of the life jacket and the other in its back area, a current source, two circuit breakers, two elec tertiary circuit, two communicating sealed containers, each of which is separated from the environment by a membrane, with one of the sealed containers located in the chest area of the life jacket and the other in its back region, the membrane of each container is connected to the circuit breaker of the corresponding light source by means of a lever, and both light sources and transmitters through switches are connected in parallel with the current source, and the equipment installed on board the helicopter and consisting of one measuring two direction finding channels, while the measuring channel consists of a series-connected receiving antenna, a fourth narrow-band filter, a first phase inverter, a first adder, the second input of which is connected to the output of a receiving antenna, a first band-pass filter, a second phase inverter, a second adder, the second input of which is connected to the output the first adder, the second bandpass filter, the third phase inverter, the third adder, the second input of which is connected to the output of the second adder, and the first mixer, the second in One of which is connected to the first output of the first local oscillator, connected in series to the second output of the first local oscillator of the first phase shifter 90 ° and the second mixer, the second input of which is connected to the output of the third adder, the fourth amplifier of the first intermediate frequency, the second phase shifter 90 °, the fourth adder the second input of which is connected to the output of the first amplifier of the first intermediate frequency, the fourth multiplier, the second input of which is connected to the output of the third adder, p a low-pass filter, a second amplitude detector, a key, the second input of which is connected to the output of the fourth adder, the fourth mixer, the second input of which is connected to the output of the second local oscillator, the amplifier of the second intermediate frequency, the first amplitude detector and the recording unit, each direction-finding channel consists of series-connected a receiving antenna, a mixer, the second input of which is connected to the first output of the first local oscillator, an amplifier of the first intermediate frequency, a multiplier, the second input of which It is connected to the output of the amplifier of the second intermediate frequency, and a narrow-band filter, while the third multiplier is connected in series to the output of the first narrow-band filter, the second input of which is connected to the output of the second narrow-band filter, the third narrow-band filter and the first phase meter, the line is connected in series to the output of the second narrow-band filter delays, the first phase detector, the second input of which is connected to the output of the second narrow-band filter, and the second phase meter, the second inputs of the phase meters are connected to during the course of the reference generator, the receiving antenna of the measuring channel is located above the rotor hub of the helicopter, the receiving antennas of direction finding channels are located at the ends of the rotor blades of the helicopter, the engine is kinetically connected to the helicopter rotor and the reference generator, equipped with a calibrator, two adjustable phase shifters, two inverse amplifiers, two lower filters frequencies, the sixth and seventh narrow-band filters, the third and fourth amplitude detectors, a subtractor and a second phase detector, and to the output the sixth narrow-band filter, the third amplitude detector, the subtracter, the first low-pass filter and the first inverse amplifier, the two outputs of which are connected to the second inputs of the first and fourth amplifiers of the first intermediate frequency, respectively, are connected in series to the output of the fourth amplifier of the first intermediate frequency in series the seventh narrow-band filter and the fourth amplitude detector, the output of which is connected to the second input of the subtractor, are connected to the output at the sixth narrow-band filter, a second phase detector is connected in series, the second input of which is connected to the output of the seventh narrow-band filter, the second low-pass filter and the second inverse amplifier, the two outputs of which are connected to the third inputs of the adjustable phase shifters, respectively, the second inputs of which are connected to the output of the calibrator, the first input the first adjustable phase shifter is connected to the output of the first mixer, and the output is connected to the input of the first amplifier of the first intermediate frequency, the first input is A third adjustable phase shifter is connected to the output of the fifth mixer, and the output is connected to the input of the fourth amplifier of the first intermediate frequency.

Figure 1 schematically shows a life jacket with light sources 1, 2 and transmitters 19, 20 with transmitting antennas 21, 22, dressed in person; figure 2 is the same section. The structural diagram of the equipment installed on board the helicopter is presented in figure 3. The geometric arrangement of the receiving antennas on the helicopter is shown in Fig.4. A frequency diagram explaining the process of forming additional (mirror and Raman) reception channels is shown in FIG. 5. Examples of intermodulation interference are shown in FIGS. 6 and 7.

The life jacket also contains an energy source 3, cables 4 and 5 for supplying energy to light sources 1, 2 and transmitters 19, 20, cartridges 6, 7, membranes 8.9 and associated levers 10, 11 with contacts 12, 13, as well as an airtight pneumatic valve 14 connecting the airtight cavities 15, 16. The entry points for cables 4 and 5 from the energy source 3 in the cavities 15 and 16 are sealed with o-rings 17 and 18. Light source 1 and transmitter 19, light source 2 and transmitter 20 are connected in parallel to the power source 3.

The equipment placed on board the helicopter contains one measuring and two direction finding channels.

The measuring channel consists of a series-connected receiving antenna 23, a fourth narrow-band filter 51, a first phase inverter 52, a first adder 53, the second input of which is connected to the output of a receiving antenna 23, a first band-pass filter 54, a second phase inverter 55, a second adder 56, the second input of which is connected with the output of the adder 53, the second bandpass filter 57, the third phase inverter 58, the third adder 59, the second input of which is connected to the output of the adder 56, the first mixer 29, the second input of which is connected to the first output the house of the first local oscillator 28, the first adjustable phase shifter 70, the second input of which is connected to the output of the calibrator 69, the first amplifier 34 of the first intermediate frequency, the fourth adder 64, the fourth multiplier 65, the second input of which is connected to the output of the adder 59, the fifth narrow-band filter 66, the second amplitude detector 67, key 68, the second input of which is connected to the output of the adder 64, the fourth mixer 40, the second input of which is connected to the output of the second local oscillator 39, amplifier 41 of the second intermediate frequency, first amp itudnogo detector 42 and register unit 43. The first phase shifter 60 is 90 ° connected to the second output of the first local oscillator 28, the fifth mixer 61, the second input of which is connected to the output of the adder 59, the second adjustable phase shifter 71, the second input of which is connected to the output of the calibrator 69, the fourth amplifier 62 of the first intermediate frequency and second a phase shifter 63 through 90 °, the output of which is connected to the second input of the adder 64. The sixth narrow-band filter 72, the third amplitude detector 74, are subtracted in series to the output of the amplifier 34 of the first intermediate frequency 76, the first low-pass filter 77 and the first inverse amplifier 78, the two outputs of which are connected to the second inputs of the amplifiers 34 and 62 of the first intermediate frequency, respectively. To the output of the amplifier 62 of the first intermediate frequency, a seventh narrow-band filter 73 and a fourth amplitude detector 75 are connected in series, the output of which is connected to the second input of the subtractor 76. A second phase detector 79, the second input of which is connected to the output of the narrow-band filter 73, is connected in series to the output of the narrow-band filter 72. a second lowpass filter 80 and a second inverse amplifier 81, the two outputs of which are connected to the third inputs of the adjustable phase shifters 70 and 71, respectively.

Each direction finding channel consists of a series-connected receiving antenna 24 (25), a mixer 26 (27), the second input of which is connected to the first output of the first local oscillator 28, an amplifier 30 (31) of the first intermediate frequency, a multiplier 32 (33), the second input of which is connected with the output of the amplifier 41 of the second intermediate frequency, and a narrow-band filter 35 (36). To the output of the first narrow-band filter 35, a third multiplier 37 is connected in series, the second input of which is connected to the output of the second narrow-band filter 36, the third narrow-band filter 44 and the first phase meter 46, the second input of which is connected to the output of the reference generator 49. To the output of the second narrow-band filter 36 are connected in series delay line 38, the first phase detector 45, the second input of which is connected to the output of the narrow-band filter 36. And the second phase meter 47, the second input of which is connected to the output of the reference generator 49. K Exit narrowband filter 44 connected in series frequency meter 50 and the arithmetic unit 82, whose output is connected to the second input 43 of the recording unit.

A receiving antenna 23 of the measuring channel is located above the rotor hub of the helicopter, receiving antennas 24 and 25 of direction finding channels are located at the ends of the rotor blades of the helicopter. The engine 48 is kinematically connected with the helicopter propeller and the reference generator 49.

The system operates as follows.

In the position shown in FIG. 2, the ambient pressure P ₂ on the membrane 9 is greater than the atmospheric pressure P ₁ on the membrane 8. The membrane 9 is in the preloaded position and the membrane 8 in the depressed state. Accordingly, the lever 11 presses the contact 13 from the light source 2 and the transmitter 22, and the lever 10 presses the contact 12 to the light source 1 and the transmitter 19. The light source 1 lights up, the transmitter 19 emits a distress signal, the light source 2 does not light, the transmitter 20 does not work.

If a person makes a 180 ° rotation about the horizontal axis, then the light source 2 and the transmitter 20 with the transmitting antenna 22 appear at the top. The pressure of the medium on the membrane 8 becomes greater than on the membrane 9, the membrane 8 pushes the lever 10, opens contact 12 and the source 1 of the light and the transmitter 19. The circuit is opened, the light source 1 goes out, the transmitter 19 is turned off. At the same time, air from the cavity 15 flows through the line 14 into the cavity 16, the membrane 9 is squeezed out, the lever 11 closes the contact 13 with the light source 2 and the transmitter 20. The light source 2 lights up, and the transmitter 20 emits a distress signal.

At night and in good weather, the light source can be detected visually at a considerable distance. However, in daylight and in bad weather, it is difficult to detect a light source.

Radio emission is weatherproof and provides distress signal transmission over long distances. In this case, the distress signal (SOS) is emitted periodically with a certain period T _p and duration T _s at a certain frequency ω _s , which is allocated specifically for transmitting a distress signal and is not involved in transmitting other information.

Receiving equipment is placed on board the helicopter. The presence of a rotary rotor of the helicopter can be used to determine the direction of the distress signal to the radiation source (RD sensor) using a device whose antennas are located at the ends of the rotor blades.

Received distress signals, for example, with phase shift keying (PSK):

where U _s , ω _s , φ _s , T _s - amplitude, carrier frequency, initial phase and duration of the distress signal;

± Δω - instability of the carrier frequency of the signal due to various destabilizing factors;

R is the radius of the circle on which the receiving antennas 24 and 25 are located;

 Ω = 2πR — rotation speed of receiving antennas 24 and 25 around receiving antenna 23 (rotational speed of a helicopter rotor);

α - bearing (azimuth) to the source of the distress signal;

φ _r (t) = {0, π} is the manipulated phase component that displays the law of phase manipulation in accordance with the modulating code M (t), and φ _r (t) = const for kτ _e <t <(k + 1) τ _e and can change abruptly at t = kτ _e , i.e. at the boundaries between elementary premises (k = 1,2, ..., N-1);

τ _e , N - the duration and number of chips that make up a signal of duration T _c (T _c = N · τ _e );

from the outputs of the receiving antennas 23, 24 and 25 are fed to the first inputs of the mixers 29, 61, 26 and 27, the second inputs of which are supplied with the voltage of the first local oscillator 28:

In this case, only one arm of the adders 53, 56, and 59 works. At the output of the mixers, voltage of combination frequencies is generated. Amplifiers 34, 62, 30 and 31 are allocated the voltage of the first intermediate frequency:

Where

ω _pr1 = ω _c -ω _g1 is the first intermediate frequency;

φ _pr1 = φ _c1 -φ _g1 ; φ _pr2 = φ _c2 -φ _g1 ;

To ₁ , K ₂ - transmission coefficients of the first and second receiving channels;

φ _c1 , φ _c2 - the initial phases of the signals that have passed the first and second receiving channels.

The voltage U _CR2 (t) from the output of the amplifier 62 of the first intermediate frequency is supplied to the input of the phase shifter 63 by 90 °, at the output of which a voltage is generated:

Voltages u _pr1 and u _pr5 are fed to two inputs of the adder 64, the output of which is formed by the total voltage

.Where

.

This voltage is applied to the first input of the multiplier 65, the second input of which receives the received signal u ₁ (t) from the output of the adder 59. A harmonic voltage is generated at the output of the multiplier 65

Where

K ₃ - transfer coefficient of the multiplier.

The tuning frequency ω _{n1 of the} narrow-band filter 51 is chosen equal to the first intermediate frequency ω _pr1

The tuning frequency ω _{n2 of the} narrow-band filter 66 is chosen equal to the frequency ω _{g1 of the} first local oscillator 28 (figure 5):

The tuning frequency ω _n3 and the passband Δ _{ωп1 of the} band-pass filter 54 are chosen equal (Fig.6):

where ω ₁ , ω ₂ are the boundary frequencies of two possible powerful signals, the appearance of which in the frequency band Δω _p1 , located "to the left" of the passband Δω _{p of the} receiver, will lead to the formation of intermodulation interference.

_H4 tuning frequency ω and Δω _n2 bandwidth bandpass filter 57 is selected equal to (7):

where ω ₃ , ω ₄ are the boundary frequencies of two possible powerful signals, the appearance of which in the frequency band Δω _p2 , located "to the right" of the passband Δω _{p of the} receiver, will lead to the formation of intermodulation interference.

Since the tuning frequency ω _{n2 of the} narrow-band filter 66 is chosen equal to the frequency ω _{g1 of the} first local oscillator 28 (ω _n2 = ω _g1 ), the voltage u ₄ (t) is extracted by the narrow-band filter 66, is detected by the amplitude detector 67 and is supplied to the control input of the key 68, opening him. The key 68 in the initial state is always closed. In this case, the total voltage u _∑1 (t) through the public key 68 from the output of the adder 64 is supplied to the first input of the mixer 40, the second input of which supplies the voltage of the second local oscillator 39:

At the output of the mixer 40, a voltage of combination frequencies is generated. The amplifier 41 is allocated the voltage of the second intermediate frequency

Where

K ₄ - gear ratio of the mixer 40;

_np2 ω = ω _z2 -ω _pr1 - second intermediate frequency;

cp = φ _{pr6 WP2} -φ _r2,

which, after detection in the amplitude detector 42, enters the first input of the registration unit 43 and thereby detects the detection of a source of radio emissions (a person in distress on water).

The voltage u _pr6 (t) from the output of the amplifier 41 of the second intermediate frequency is simultaneously supplied to the second inputs of the multipliers 32 and 33, the first inputs of which receive the voltage u _pr3 (t) and u _pr4 (t) from the outputs of the amplifiers 30 and 31 of the first intermediate frequency, respectively . At the outputs of the multipliers 32 and 33, phase-modulated (FM) voltages are formed:

Where

are allocated narrowband filters 35 and 36 with the tuning frequency ω = ω _{z2 H5.}

соответствуют диаметрально противоположным расположениям антенн 24 и 25 на концах лопастей несущего винта вертолета относительно приемной антенны 23, размещенной над втулкой винта вертолета.Signs "+" and "-" before the value

correspond to diametrically opposite locations of the antennas 24 and 25 at the ends of the rotor blades of the helicopter relative to the receiving antenna 23 located above the hub of the helicopter rotor.

Therefore, useful information about the bearing α is transferred to the stable frequency ω _{g2 of the} second local oscillator 39. Therefore, the instability ± Δω of the carrier frequency caused by various destabilizing factors and the type of modulation of the received distress signals do not affect the direction finding result, thereby increasing the accuracy of determining the location of the radio emission source.

Moreover, the value

which is part of narrow-band oscillations and called the phase modulation index, characterizes the maximum value of the phase deviation of the signals received by the rotating antennas 24 and 25 relative to the phase of the signal received by the fixed antenna 23. The direction finder is more sensitive to the change in angle α, the larger the relative size of the measuring base R / λ . However, with increasing R / λ, the value of the angular coordinate α decreases at which the phase difference Δφ exceeds 2π, i.e. ambiguity of reading the angle α occurs.

Therefore, for R / λ> 1/2, the ambiguity of the reference angle α 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 values of R / λ due to design considerations.

To increase the accuracy of direction finding of the RD radio source in the horizontal (azimuthal) plane, receiving antennas 24 and 25 are located at the ends of the rotor blades of the helicopter. The mixing of signals from two diametrically opposite receiving antennas located at the same distance R from the rotor axis of the rotor causes phase modulation, which is identical to the phase modulation obtained with one receiving antenna rotating in a circle whose radius R ₁ is twice as large (R ₁ = 2R).

Indeed, the output of the multiplier 37 produces a harmonic voltage

Where

with phase modulation index

which is allocated by a narrow-band filter 44 and is supplied to the first input of the phasemeter 46, the second input of which is supplied with the voltage of the reference oscillator 49:

The phasometer 46 provides an accurate but ambiguous measurement of the angular coordinate α.

To eliminate the ambiguity in reading the angle α, it is necessary to reduce the phase modulation index without decreasing the R / λ ratio. This is achieved by using an autocorrelator consisting of a delay line 38 and a phase detector 45, which is equivalent to reducing the phase modulation index to a value

where d ₁ <R.

A voltage is generated at the output of the autocorrelator

with the phase modulation index Δφ _m2 , which is supplied to the first input of the phasemeter 47, the second input of which is supplied with the voltage u ₀ (t) of the reference generator 49. The phase meter 47 provides a rough but unambiguous measurement of the angle α.

The value of the Doppler frequency shift allows you to determine the radial speed and location of the RD radio sensor.

The minimum distance R _o from the radio sensor RD to the helicopter propeller can be determined from the expression:

where F _d (t) is the Doppler frequency shift;

V = ΩR,

λ is the wavelength.

The Doppler frequency shift is measured using a frequency meter 50, and the desired range R ₀ is determined in the arithmetic unit 69 and fixed in block 43 registration.

The location of the RD radio sensor (a person in distress on water) is determined by the measured values of α and β.

The above-described operation of the airborne direction finder corresponds to the case of receiving a useful distress signal on the main channel at a frequency ω _s (Fig. 5).

If a false signal (interference) is received on the mirror channel at a frequency of ω ₃ :

the amplifiers 34 and 62 of the first intermediate frequency are allocated the following voltages:

Where

ω _pr1 = ω _g1 -ω _s - intermediate frequency;

φ _pr7 = φ _g -φ _z1 ; φ _pr8 = φ _g -φ _z2 ,

K ₁ , K ₂ - transmission coefficient of the first and second receiving channels, respectively;

φ _z1 , φ _z2 are the initial phases of a false signal (interference) passing through the first and second receiving channels, respectively.

The inputs of the amplifiers 34 and 62 of the first intermediate frequency through adjustable phase shifters 70 and 71, respectively, from the output of the calibrator 69 receives a calibration harmonic signal

From the outputs of the amplifiers 34 and 62 of the first intermediate frequency, calibration signals are extracted by narrow-band filters 72 and 73 and, after detection in the amplitude detectors 74 and 75, are sent to the calculator 76 of the amplitude identification system. In the case of an inequality in the modules of the transmission coefficient of the receiving channels (K ₁ ≠ K ₂ ) at a frequency ω _k , a voltage (positive or negative) appears at the output of the calculator 76, which acts through the low-pass filter 77 and the inverse amplifier 78 on the second (control) inputs of the amplifiers 34 and 62 of the first intermediate frequency, changing their transmission coefficients so that the voltage at the output of the calculator 76 tends to zero. Moreover, the transmission coefficients of the amplifiers 34 and 62 of the first intermediate frequency turn out to be almost the same at the frequency ω _{k of the} calibration signal (K ₁ = K ₂ = K).

From the outputs of the narrow-band filters 74 and 75, the calibration signals are supplied to the phase identification system, which consists of a phase detector 79, a low-pass filter 80, an inverse amplifier 81, and two adjustable phase shifters 70 and 71. In the presence of phase non-identity of the receiving channels, a voltage is generated at the output of the phase detector 79 (positive or negative), which through the low-pass filter 80 and the inverse amplifier 81 act on the third (control) inputs of the adjustable phase shifters 70 and 71, changing the phase shifts of the calibration signals in such a way that the output voltage of the phase detector 79 tends to zero. Thus, the phase identification of the receiving channels is achieved.

With a small value of Δω, the calibration signal carries information about the non-identity of the receiving channels at the first intermediate frequency ω _pr1 due to the correlation of close values of the frequency characteristics.

Therefore, at the outputs of amplifiers 34 and 62 of the first intermediate frequency, the following voltages are generated:

where U _ave = U = U _{pr pr7;}

φ _pr7 = φ _pr8 = φ _pr

The voltage u ' _pr8 (t) from the output of the amplifier 62 of the first intermediate frequency is supplied to the input of the phase shifter 63 by 90 °, at the output of which a voltage is generated

Voltage u ' _pr7 (t) and u _pr9 (t) supplied to the two inputs of the adder 64, at its output are fully compensated.

Consequently, a false signal (interference) received through the mirror channel at a frequency of ω _s is completely suppressed with the help of an “outer ring” consisting of mixers 29 and 61, amplifiers 34 and 62 of the first intermediate frequency, phase shifters 60 and 63 by 90 °, the local oscillator 28, an adder 64 and implements a phase compensation method.

For a similar reason, a false signal (interference) received on the first combinational channel at a frequency ω _{k1 is also} suppressed.

If a false signal (interference) is received on the second combinational channel at a frequency ω _k2 (figure 5)

the amplifiers 34 and 62 of the first intermediate frequency are allocated voltage:

Where

ω _pr1 = ω _k2 -2ω _g1 - the first intermediate frequency;

φ _pr10 = φ _k2 -φ _g1 .

The voltage u _pr11 (t) from the output of the amplifier 62 of the first intermediate frequency is supplied to the input of the phase shifter 63 by 90 °, at the output of which a voltage is generated:

Voltage u _pr10 (t) and U _pr12 (t) are supplied to two inputs of the adder 64, the output of which is formed by the total voltage:

This voltage is supplied to the first input of the multiplier 65, the second input of which receives the received signal u _k2 (t). The output of the multiplier 65 produces a voltage:

Where

which does not fall into the passband of the narrow-band filter 66. The key 68 does not open and a false signal (interference) received on the second combination channel at a frequency ω _k2 is suppressed. In this case, an "inner ring" is used, consisting of a multiplier 65, a narrow-band filter 66, an amplitude detector 67, a ring 68 and implementing the narrow-band filtering method.

If a false signal (interference) is received on the direct channel at the first intermediate frequency

then from the output of the receiving antenna it goes to the first care of the adder 53, is allocated by a narrow-band filter 51 tuned to the first intermediate frequency ω _pr1 , and is inverted in phase by 180 ° in the phase inverter 52

The voltage u _pr (t) and u ' _pr (t), supplied to the two inputs of the adder 53, are compensated at its output.

Consequently, a false signal (interference) received through the direct channel at a frequency ω _pr1 is suppressed by a filter plug consisting of a narrow-band filter 51, a phase inverter 52, an adder 53, and implements a phase compensation method.

If two powerful false signals (interference) at frequencies ω ₁ and ω ₂ or several powerful signals (interference) appear simultaneously in the frequency band Δω _p1 "to the left" of the passband Δω _{p of the} receiver, capable of generating intermodulation interference, then they are fed to the first input the adder 56, allocated by the band-pass filter 54, phase inverted 180 ° phase inverter 55 and offset in the adder 56 (Fig.6).

Consequently, false signals (interference) received in the frequency band Δω _p1 and generating intermodulation interference are suppressed by a filter plug consisting of a bandpass filter 54, a phase inverter 55, an adder 56 and implementing a phase compensation method.

If two powerful false signals (interference) at frequencies ω ₃ and ω ₄ or several powerful signals (interference) appear simultaneously in the frequency band Δω _p2 "to the right" of the passband Δω _{p of the} receiver, capable of generating intermodulation interference, then they are fed to the first input the adder 59, are allocated by the band-pass filter 57, are inverted by 180 ° phase in phase inverter 58 and compensated in the adder 59 (Fig.7).

Consequently, false signals (interference) received in the frequency band Δω _p2 and generating intermodulation interference are suppressed by a filter plug consisting of a bandpass filter 57, a phase inverter 58, an adder 59 and implementing a phase compensation method.

On-board equipment installed on board the helicopter is invariant to the instability of the carrier frequency and the type of modulation of the received radio signals, since the direction finding of the distress signal source is carried out at a stable frequency of the second local oscillator 39.

Thus, the proposed system in comparison with the prototype provides a complete suppression of false signals (interference) received on the mirror channel at a frequency of ω _s. This is achieved by eliminating the non-identity of the receiving channels using integrated (amplitude and phase) identification systems. This increases the noise immunity and selectivity of the on-board direction finder.

Claims (1)

A system for detecting and determining the location of a person in distress on water, including a life jacket worn by a person and containing two light sources, one of which is located in the chest area of the life jacket, and the other in the back area of it, two miniature transmitters with transmitting antennas , one of which is located in the chest area of the life jacket, and the other in its back area, a current source, two circuit breakers, two interconnected sealed containers, each of which is divided from the environment by a membrane, while one of the sealed containers is located in the chest area of the life jacket, and the other in its back area, the membrane of each container is connected to the circuit breaker of the corresponding light source by a lever, and both light sources and transmitters through the breakers connected to a current source in parallel, and equipment installed on board the helicopter and consisting of one measuring and two direction finding channels, while the measuring channel consists of consistently included in the receiving antenna, the fourth narrow-band filter, the first phase inverter, the first adder, the second input of which is connected to the output of the receiving antenna, the first band-pass filter, the second phase inverter, the second adder, the second input of which is connected to the output of the first adder, the second band-pass filter, the third phase inverter, the third adder, the second input of which is connected to the output of the second adder, and the first mixer, the second input of which is connected to the first output of the first local oscillator, sequentially connected to the second output of the first local oscillator of the first phase shifter by 90 ° and the second mixer, the second input of which is connected to the output of the third adder, the fourth amplifier of the first intermediate frequency connected in series, the second phase shifter by 90 °, the fourth adder, the second input of which is connected to the output of the first amplifier of the first intermediate frequency, the fourth multiplier, the second input of which is connected to the output of the third adder, the fifth narrow-band filter, the second amplitude detector, key, second the input of which is connected to the output of the fourth adder, the fourth mixer, the second input of which is connected to the output of the second local oscillator, the amplifier of the second intermediate frequency, the first amplitude detector and the recording unit, each direction finding channel consists of a series-connected receiving antenna, a mixer, the second input of which is connected to the first the output of the first local oscillator, the amplifier of the first intermediate frequency, the multiplier, the second input of which is connected to the output of the amplifier of the second intermediate frequency, and narrow a third filter, the second input of which is connected to the output of the second narrow-band filter, the third narrow-band filter and the first phase meter, a delay line is connected in series to the output of the second narrow-band filter, the first phase detector, the second input of which is connected with the output of the second narrow-band filter, and the second phase meter, the second inputs of the phase meters are connected to the output of the reference generator, to the output of the third narrow-band filter after A frequency meter and an arithmetic unit are connected, the output of which is connected to the second input of the recording unit, the receiving antenna of the measuring channel is located above the rotor hub of the helicopter, the receiving antennas of direction finding channels are located at the ends of the rotor blade of the helicopter, the motor is kinematically connected to the helicopter rotor and the reference generator, which differs the fact that it is equipped with a calibrator, two adjustable phase shifters, two inverse amplifiers, two low-pass filters, the sixth and seventh narrow bandpass filters, third and fourth amplitude detectors, a subtractor and a second phase detector, and the sixth narrow-band filter, the third amplitude detector, subtractor, the first low-pass filter and the first inverse amplifier, the two outputs of which are connected to the second, are connected in series to the output of the first amplifier of the first intermediate frequency the inputs of the first and fourth amplifiers of the first intermediate frequency, respectively, connected to the output of the fourth amplifier of the first intermediate frequency the seventh narrow-band filter and the fourth amplitude detector, the output of which is connected to the second input of the subtractor, the second phase detector is connected in series to the output of the sixth narrow-band filter, the second input of which is connected to the output of the seventh narrow-band filter, the second low-pass filter, and the second inverse amplifier, two outputs which are connected to the third inputs of the adjustable phase shifters, respectively, the second inputs of which are connected to the output of the calibrator, the first input of the first adjustable phase shifter is is dined with the output of the first mixer, and the output is connected to the input of the first amplifier of the first intermediate frequency, the first input of the second adjustable phase shifter is connected to the output of the fifth mixer, and the output is connected to the input of the fourth amplifier of the first intermediate frequency.

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