RU2346290C1 - Method for finding vessels in distress - Google Patents

Abstract

FIELD: physics; radio.

SUBSTANCE: method relates to radiolocation and may be used in rescue operations for remote detection of accident victims, those lost in the forest, fishermen in distress, especially under low visibility conditions, as well as for remote detection of persons mutilated in contingency or under other circumstances. The said method is implemented by means of a device, which comprises scanner transmitter, scanner receiver and transponder. Scanner receiver comprises single metering and four direction finding channels. Transponder is a SAW interdigital transducer, which comprises two interdigitated-finger electrode systems and interconnecting buses.

EFFECT: enhanced range of unequivocal measurement of angles for rough measurement bases of small length.

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Description

The proposed method relates to radar technology and can be used in mountain rescue operations for remote detection of accident victims, search for fishermen lost and lost in the forest, distressed in marine conditions, especially in low visibility conditions, for searching for tourists, geologists, as well as for remote detection injured in emergency and other circumstances (accidents, military operations, disasters, natural disasters, natural disasters, etc.).

Known methods for detecting those in distress (ed. Certificate of the USSR No. 385.819, 431.063, 637.298, 765.113, 988.655, 1.348.256, 1.505.840, 1.588.636, 1.615.054, 1.664.653, 1.832.237; RF patents No. No. 2.000.995, 2.009.956, 2.038.259, 2.043.259, 2.051.956, 2.206.902; US patents No. 3.621.501, 4.646.090, 4.889.511; UK patent No. 1.145.051; German patent No. 2.555.505 and others).

Of the known methods, the closest to the proposed is the "Method for the detection of those in distress" (RF patent No. 2.206.902, G01S 7/292, 2001), which is selected as a prototype.

The known method is implemented by a transponder and a scanning device. The principle of transponder operation is based on the acoustic processing of complex signals with phase shift keying using an interdigital transducer of surface acoustic waves (SAW).

The receiver of the scanning device contains five receiving antennas, which are located in the form of a geometrical right angle, at the top of which a receiving antenna of the measuring channel is placed, common for four direction finding channels located in the azimuth and elevation planes, two on each plane, thereby forming in each plane two measuring bases d ₁ and d ₂ , between which establish the inequality:

d ₁ / λ <1/2 <d ₂ / λ,

where λ is the wavelength.

In this case, the smaller base d ₁ form a rough, but unambiguous scale of reference angles, and the large base of d ₂ form an accurate, but ambiguous scale of reference angles.

However, in some cases on board an aircraft with large ranges of unambiguous measurement of the angles α and β, the rough base d ₁ can be so small that it is physically impossible to place two antennas on it (for example, d ₁ = 1 m, antenna diameter D = 2 m) .

In such cases, the formation of a rough base is possible by an indirect method.

In the known method, the phase shifts are measured:

where d ₁ , d ₂ , d ₃ , d ₄ - measuring base;

α, β - angular coordinates of the victim (azimuth and elevation).

Phase Difference Measurement

Δφ _p1 = Δφ ₂ -Δφ ₁ ,

Δφ _p2 = Δφ ₄ -Δφ ₃ ,

equivalent to measuring phase shifts on measuring bases, the length of which is d ₅ = d ₂ -d ₁ , d ₆ = d ₄ -d ₃ .

Thus, choosing the difference of the measuring bases d ₅ , d ₆ sufficiently small, it is possible to ensure the formation of the corresponding rough measuring scales.

It should be noted that the total phase shifts

can be used to form measurements equivalent to measuring the phase difference on measuring bases d ₇ and d ₈ , the length of which is equal to the sum of the two source bases

d ₇ = d ₁ + d ₂ , d ₈ = d ₃ + d ₄ .

An object of the invention is to increase the range of unambiguous measurement of angles with a small length of rough measuring bases.

The problem is solved in that according to the method of detecting a distressed person, consisting in accordance with the closest analogue in the emission of a signal, receiving a re-emitted transceiver located on a distressed channel, a signal in a given reception band Δf _pr with its subsequent detection, while as a probe signal, radiated by the transmitter of the scanning device, use a broadband signal with phase shift keying, and as a transponder use a delay line on surface acoustic waves (SAW) and the transceiver antenna integrated with it, received by the scanning device receiver, containing the measuring and four direction finding channels, the phase-shift broadband signal is frequency-converted in the measuring channel, multiplied by phase by two, the spectrum width of the frequency-converted broadband is measured signal with phase shift keying and its second harmonic, compare them with each other and according to the results of comparison allow further processing of the frequency-converted wide of the main signal with phase shift keying, divide the second harmonic phase into two, extract the harmonic voltage obtained by a narrow-band filter and use it to synchronously detect a frequency-converted broadband signal with phase shift keying, simultaneously multiply the phase-shift signal with phase shift keying and multiply with those received in four direction finding channels phase-shift broadband signals, produce harmonic signals at the local oscillator frequency, measure between MI and local oscillator voltage phase shifts:

where d ₁ , d ₂ , d ₃ , d ₄ - measuring base;

λ is the wavelength;

α, β - azimuth and elevation angle,

receiving antennas of the measuring and direction finding channels are placed in the form of a geomeric right angle, at the top of which the antenna of the measuring channel is placed, which differs from the closest analogue in that two unequal measuring bases d ₁ and d ₂ , d ₃ and d ₄ are formed in each plane, the differences are determined phase differences:

Δφ _p1 = Δφ ₂ -Δφ ₁ ,

Δφ _p2 = Δφ ₄ -Δφ ₃ ,

equivalent to measuring phase shifts on measuring bases, lengthy

d ₅ = d ₂ -d ₁ ,

d ₆ = d ₄ -d ₃ ,

form, using the difference of the phase differences, coarse, but unique reference frames for the angles α and β, corresponding to small measuring bases d ₅ and d ₆ , determine the sum of the phase differences

equivalent to measuring phase shifts on measuring bases whose length

d ₇ = d ₁ + d ₂ ,

d ₈ = d ₃ + d ₄ ,

form using the sum of the phase differences accurate, but ambiguous reference frames of the angles α and β, corresponding to large measuring bases d ₇ and d ₈ .

The structural diagram of the transmitter of the scanning device is presented in figure 1. The structural diagram of the transponder is shown in Fig.2. The block diagram of the receiver of the scanning device is presented in figure 3. The relative position of the receiving antennas on board the aircraft is shown in Fig.4.

The transmitter of the scanning device contains a serially connected master oscillator 1, a phase manipulator 3, the second input of which is connected to the output of the modulating code generator 2, a power amplifier 4 and a transmitting antenna 5.

The transponder is an interdigital transducer of surface acoustic waves (SAW), which contains two comb systems of electrodes 8, buses 9 and 10, which connect the electrodes of each of the combs to each other. The tires, in turn, are connected to the microstrip antenna 7. The electrodes 8, tires 9, 10, reflectors 11 and the microstrip antenna 7 are deposited on the surface of the piezocrystal 6.

The receiver of the scanning device contains a measuring and four direction finding channels.

The measuring channel contains a receiving antenna 12 connected in series, a high-frequency amplifier 17, a mixer 23, the second input of which is connected to the local oscillator 22 output, an intermediate-frequency amplifier 24, a phase doubler 26, a second spectrum analyzer 27, a comparison unit 28, the second input of which is through the first analyzer 25 of the spectrum is connected to the output of the intermediate frequency amplifier 24, a key 29, the second input of which is connected to the output of the intermediate frequency amplifier 24, a phase detector 32, the second input of which is connected through series a two-phase phase unit 30 and a narrow-band filter 31 are connected to the output of the phase doubler 26, and a recording unit 49.

Each direction finding channel consists of a series-connected receiving antenna 13 (14, 15, 16), a high-frequency amplifier 18 (19, 20, 21), a multiplier 33 (34, 35, 36), the second input of which is connected to the output of a narrow-band key 29 filter 37 (38, 39, 40) and phase meter 41 (42, 43, 44). The outputs of the phase meters 41 and 42 (43 and 44) through the subtractor 45 (46) and the adder 47 (48) are connected to the corresponding inputs of the registration unit 49.

The proposed method is implemented as follows.

All people at risk are equipped with passive transponders, which can be made in the form of key chains, rings or medallions.

The transmitter of the scanning device generates a request signal. To this end, the master oscillator 1 generates high-frequency oscillations

u _s (t) = U _s cos (ω _s t + φ _s ), 0≤t≤T _s ,

which is fed to the first input of the phase manipulator 3, to the second input of which a modulating code M (t) is supplied from the output of the modulating code generator 2. At the output of the phase manipulator 3, a phase-shift (PSK) signal is formed

u ₁ (t) = U _c cos [ω _with t + φ _k1 (t) + φ _c ], 0≤t≤T _c ,

where φ _k1 (t) = {0, π},

which, after amplification in the power amplifier 4, is emitted by the transmitting antenna 5 into the ether, the antenna 7 of the transceiver is captured. Then the QPSK signal u ₁ (t) is converted into an acoustic wave, which propagates along the surface of the piezocrystal 6, is reflected from the reflectors 11, and is again converted into an electromagnetic signal with phase shift keying

u ₂ (t) = U ₂ cos [ω _with t + φ _k2 (t) + φ _c ], 0≤t≤T _c ,

where φk ₂ (t) = {0, π}.

In this case, the internal structure of the generated PSK signal is determined by the topology of the interdigital transducer, has an individual character and contains all the necessary unique information about the owner, for example, last name, first name, middle name, year of birth, etc.

The generated PSK signal u ₂ (t) is radiated by the microstrip antenna 7 and captured by receiving antennas 12 ... 16:

u ₃ (t) = U ₃ cos [(ω _c ± Δω) t + φ _k2 (t) + φ ₁ ],

u ₄ (t) = U ₄ cos [(ω _c ± Δω) t + φ _k2 (t) + φ ₂ ],

u ₅ (t) = U ₅ cos [(ω _c ± Δω) t + φ _k2 (t) + φ ₃ ],

u ₆ (t) = U ₆ cos [(ω _c ± Δω) t + φ _k2 (t) + φ ₄ ],

u ₇ (t) = U ₇ cos [(ω _c ± Δω) t + φ _k2 (t) + φ ₅ ],

where ± Δω is the instability of the carrier frequency caused by various destabilizing factors, including the Doppler effect.

Moreover, the receiving antennas 12 ... 16 are located in the form of a geometric right angle, at the apex of which the receiving antenna 12 of the measuring channel is placed, common for four direction finding channels located in the azimuth and elevation planes, two on each plane.

The scanning device may be mounted on a vehicle, a helicopter, an airplane or a spacecraft.

The voltage u ₃ (t) from the output of the receiving antenna 12 through the high-frequency amplifier 17 is supplied to the first input of the mixer 23, the second input of which is the voltage of the local oscillator 22

u _Г (t) = U _Г cos (ω _Г t + φ _Г ).

At the output of the mixer 23, voltages of combination frequencies are generated. The amplifier 24 is allocated voltage intermediate (differential) frequency

u _ave (t) = U _pr cos [(ω _{ave ± Δω) t + φ k2 (} t) + φ _etc.], 0≤t≤T _c,

;Where

;

K ₁ - gear ratio of the mixer;

ω _CR = ω _with -ω _G is the intermediate frequency;

φ _CR = φ _s -φ _G ,

which is fed to the input of the phase doubler 26, at the output of which a harmonic voltage is generated

u ₈ (t) = U _pr cos [2 (ω _pr ± Δω) t + 2φ _pr ], 0≤t≤T _c ,

in which phase manipulation is already absent [2φ _k2 (t) = {0.2π}].

Тогда как ширина спектра его второй гармоники определяется длительностью сигнала

Следовательно, при умножении фазы на два широкополосного ФМн-сигнала его спектр сворачивается в N разThe width of the spectrum of a complex QPSK signal, determined by the duration τ _e his chip

Whereas the width of the spectrum of its second harmonic is determined by the duration of the signal

Therefore, when the phase is multiplied by two broadband QPSK signals, its spectrum collapses N times

This circumstance makes it possible to detect and select a broadband QPSK signal among other signals and interference.

The spectrum width of the broadband QPSK signal is measured using a spectrum analyzer 25, and the spectrum width Δf _{2 of} its second harmonic is measured using a spectrum analyzer 27.

Voltages U ₀ and U ₂ proportional to Δf _c and Δf _2, respectively, from the inputs of the spectrum analyzers 25 and 27 are supplied to the two inputs of the comparison unit 28.

If two inputs of the comparison unit 28 receive approximately the same voltage intensity, then there is no voltage at its output. If two inputs of the comparison unit 28 receive voltage different in intensity, then a constant voltage appears at its output.

Since U ₀ >> U ₂ , then at the output of the comparison unit 28, a constant voltage is generated, which is supplied to the control input of the key 29, opening it. In the initial state, the key 29 is always closed.

In this case, the PSK signal u _pr (t) at an intermediate frequency through the public key 29 is supplied to the first (information) input of the phase detector 32. The voltage u ₈ (t) from the output of the phase doubler 26 is fed to the input of the phase divider 30 into two, at the output which produces harmonic voltage

₉ u (t) = U _pr cos [(ω _ave ± Δω) t + φ _etc.], 0≤t≤T _c,

which is allocated by the narrow-band filter 31, is used as a reference voltage and is supplied to the second (reference) input of the phase detector 32.

The output of the phase detector 32 produces a low-frequency voltage

u _n (t) = U _n cos φ _k2 (t),

Where

K ₂ is the transfer coefficient of the phase detector;

which is fixed by the registration unit 49. In the low-frequency voltage u _n (t) contains passport data on the injured.

The voltage u _pr (t) from the output of the intermediate frequency amplifier 24 through the public key 29 is simultaneously supplied to the second inputs of the multipliers 33 ... 36, the first inputs of which receive the received PSK signals u ₄ (t) -u ₇ (t) from the outputs of the amplifiers 18 -21 high frequency. At the outputs of multipliers 33-36, the following harmonic oscillations are formed:

u ₁₀ (t) = U ₁₀ cos (ω _g t + φ _g + Δφ ₁ ];

u ₁₁ (t) = U ₁₁ cos (ω _g t + φ _g + Δφ ₂ ];

u ₁₂ (t) = U ₁₂ cos (ω _g t + φ _g + Δφ ₃ ];

u ₁₃ (t) = U ₁₃ cos (ω _g t + φ _g + Δφ ₄ ],

Where

K ₃ - transmission coefficient of the multipliers;

where d ₁ , d ₂ , d ₃ , d ₄ - measuring base;

α, β are the angular coordinates of the victim (azimuth and elevation angle), which are distinguished by narrow-band filters 37-40 and fed to the first inputs of the phase meters 41-44, the second inputs of which are supplied with the voltage u _g (t) of the local oscillator 22.

The measured phase shifts Δφ ₁ and Δφ ₂ from the outputs of the phase meters 41 and 42 are fed to two inputs of the subtractor 45 and the adder 47.

At the output of the subtractor 45, a phase difference difference is formed

Δφ _p1 = Δφ ₂ -Δφ ₁ ,

equivalent to measuring the phase shift on a measuring base, the length of which

d ₅ = d ₂ -d ₁ .

Thus, choosing a difference of bases d ₅ small enough, it is possible to ensure the formation of a rough, but unambiguous azimuth reference scale α.

The output of the adder 47 is formed by the sum of the phase differences

equivalent to measuring the phase shift on a measuring base, the length of which

d ₇ = d ₁ + d ₂ .

Thus, an accurate but ambiguous azimuth reference scale α is formed.

The measured phase shifts Δφ ₃ and Δφ ₄ from the outputs of the phase meters 43 and 44 are fed to two inputs of the subtractor 46 and the adder 48.

At the output of the subtractor 46, a phase difference difference is formed.

Δφ _p2 = Δφ ₄ -Δφ ₃ ,

equivalent to measuring the phase shift on a measuring base, the length of which

d ₆ = d ₄ -d ₃ .

Thus, choosing a difference of bases d ₆ small enough, it is possible to ensure the formation of a rough, but unambiguous scale of reference angle β.

The output of the adder 48 is formed by the sum of the phase differences

Δφ _Σ2 = Δφ ₃ + Δφ ₄ ,

equivalent to measuring the phase shift on a measuring base, the length of which

d ₈ = d ₃ + d ₄ .

In this way, an accurate, but ambiguous, reference angle scale β is formed.

Inequalities are established between the formed measuring bases

The method provides not only the detection of those in distress, but also their direction finding, as well as remote identification of those in distress. Moreover, direction finding is carried out at a stable local oscillator frequency, the method is invariant to the type of modulation and instability of the carrier frequency of the used broadband signals.

From the point of view of detection, these signals have high energy and structural secrecy.

The energy secrecy of broadband QPSK signals is due to their high compressibility in time or spectrum with optimal processing, which reduces the instantaneous radiated power. As a result, the broadband QPSK signal at the receiving point may be masked by noise and interference. Moreover, the energy of a broadband signal is by no means small; it is simply distributed over the time-frequency domain so that at each point in this region the signal power is less than the power of noise and interference.

The structural secrecy of broadband QPSK signals is caused by a wide variety of their forms and significant ranges of parameter values, which makes it difficult to optimize or at least quasi-optimal processing of broadband signals of an a priori unknown structure in order to increase the sensitivity of the receiving device.

Broadband FMN signals allow the use of a new type of selection - structural selection. This means that there is a new opportunity to distinguish these signals from other signals and interference operating in the same frequency band and at the same time intervals.

A positive feature of a surfactant transponder is the lack of power sources and small dimensions.

The advantage of the method is also the high efficiency of using the frequency range, since a radio channel of one frequency, for example, f _c = 26.945 kHz, allocated for remote security alarm can be used to detect many distressed people.

Thus, the proposed method in comparison with the base object and other technical solutions for a similar purpose provides an increase in the range of unambiguous measurements of azimuth and elevation with a small length of rough measuring bases. This is achieved by forming coarse scales by an indirect method.

Claims (1)

A method for detecting a distressed person, which consists in emitting a signal, receiving a signal re-emitted by a transponder placed in distress, in a predetermined reception band Δf _pr and then detecting it, while a broadband signal with phase shift keying is used as a probe signal emitted by the transmitter of the scanning device, and as a transponder use a delay line on surface acoustic waves and an integrated transceiver antenna received by the receiver a measuring device containing a measuring and four direction finding channels, the phase-shift broadband signal is converted in frequency in the measurement channel, multiplied by phase by two, the spectrum width of the frequency-converted phase-shifted signal with phase shift and its second harmonic is measured, they are compared with each other and according to the results of the comparison, further processing of the frequency-converted broadband signal with phase shift keying is allowed, the second harmonic phase is divided into two, the resulting harmonic voltage with a narrow-band filter and use it for synchronous detection of a frequency-converted broadband signal with phase shift keying, simultaneously frequency-converted broadband signal with phase shift keying is multiplied with broadband phase shift signals received in four direction-finding channels, harmonic signals are extracted at the local oscillator frequency, between them and the local oscillator voltage phase shifts
Δφ ₁ = φ ₁ -φ _G = 2πd ₁ / λ cos α,
Δφ ₂ = φ ₂ -φ _G = 2πd ₂ / λ cos α,
Δφ ₃ = φ ₃ -φ _G = 2πd ₃ / λ cos α,
Δφ ₄ = φ ₄ -φ _G = 2πd ₄ / λ cos α,
where d ₁ , d ₂ , d ₃ , d ₄ - measuring base;
λ is the wavelength;
α, β - azimuth and elevation angle,
receiving antennas of the measuring and direction finding channels are placed in the form of a geometric right angle, at the top of which the antenna of the measuring channel is placed, characterized in that two measuring bases d ₁ and d ₂ , d ₃ and d ₄ are formed in each plane, the differences of phase differences are determined:
Δφ _p1 = Δφ ₂ -Δφ ₁ ,
Δφ _p2 = Δφ ₄ -Δφ ₃ ,
equivalent to measuring phase shifts on measuring bases whose length
d ₅ = d ₂ -d ₁ ,
d ₆ = d ₄ -d ₃ ,
form, using the difference of the phase differences, coarse, but unique reference frames for the angles α and β, corresponding to small measuring bases d ₅ and d ₆ , determine the sum of the phase differences:

equivalent to measuring phase shifts on measuring bases whose length
d ₇ = d ₁ + d ₂ ,
d ₈ = d ₃ + d ₄ ,
form using the sum of the phase differences accurate, but ambiguous reference frames of the angles α and β, corresponding to large measuring bases d ₇ and d ₈ .

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