RU2426145C2 - Method of detecting objects in distress - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: detection is carried out by means of scanner transmitter and receiver and transponder. Scanner transmitter comprises master oscillator, modulation code generator, phase manipulator, power amplifier and transmitting antenna. Scanner receiver comprises measuring and four identical direction-finding channels. Besides, scanner incorporates correlator, multiplier, controlled delay unit, low-pass filter, extreme controller, range indicator and recorder unit. Transponder incorporates micro strip antenna, piezo crystal, electrodes, buses and reflectors. All said devices are interconnected.

EFFECT: expanded performances, higher validity.

3 dwg

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 conditions of poor visibility, to search for tourists, geologists, and also 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. 988655, 1348256, 1505840, 1588840, 1615054, 1664653, 1832237; RF patents No. 2000995, 2009956, 2038259, 2043259, 2051956, 2206902, 2346290; US patents No. 36621501; , 4646090, 4889511; UK patent No. 1145051; Germany patent No. 2555505 and others).

Of the known methods, the closest to the proposed one is the "Method for the detection of those in distress" (RF patent No. 2346290, G01S 7/292, 2007), which is selected as a prototype.

The known method is implemented by a transponder and a scanning device consisting of a transmitter and a receiver. 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 geometric right angle, at the top of which is placed the receiving antenna of the measuring channel, common to four direction finding channels located in the azimuthal and elevation planes, two on each plane.

However, the known method provides the determination of only the angular coordinates α and β of the transponder and does not allow to determine its location.

In addition, in the known method for identifying the identification number of the direction-finding transponder, synchronous detection of the received FMN signal at an intermediate frequency ω _{pr is used} . In this case, the reference voltage necessary for synchronous detection of the PSK signal is isolated directly from the received PSK signal. For this, the phase of the received QPSK signal at the intermediate frequency is multiplied and divided by two, thereby eliminating phase manipulation. The initial phase of the reference voltage obtained in this way can have two values: φ _pr φ φ _pr + 180 °, which leads to the occurrence of the phenomenon of “reverse operation” and a decrease in the reliability of identifying the identification number of the direction-finding transponder. This can easily be shown analytically.

If in the harmonic voltage u ₈ (t) add the phase angle 2π, which does not change the initial harmonic voltage

₈ u (t) = U _pr · cos [2 (ω _ave ± Δω) t + 2φ _pr + 2π],

then at the output of the phase divider into two the following harmonic voltage is formed

u ₉ (t) = U _CR · cos [(ω _CR ± Δω) t + φ _CR + π],

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

An object of the invention is to expand the functionality of the method by determining the location of the transponder and increasing the reliability of the allocation of the identification number of the transponder by eliminating the phenomenon of “reverse operation”.

The problem is solved in that a method for detecting a person in distress, consisting, in accordance with the closest analogue, in emitting a signal, receiving a signal re-emitted by a transponder located in a distress, in a given reception band Δf _pr and then detecting it, while as a request 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 and the transceiving antenna tegrated with it, received by the scanning device receiver, containing the measuring and four direction-finding channels, the phase-shift broadband signal is converted in frequency in the measuring channel, multiplied by phase by two, the spectrum width of the frequency-converted phase-shifted signal with phase shift and its phase is measured the second harmonic, compare them with each other and according to the results of the comparison allow further processing of the frequency-converted broadband signal with f basic manipulation, multiply it with broadband phase-shifted signals received in four direction-finding channels, produce harmonic signals at the local oscillator frequency, measure the phase shifts between them and the local oscillator voltage

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, 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 coarse, but unambiguous scales of reference angles α and β, corresponding to small measuring bases 6.5 and de, using the difference of phase differences, determine the sum of the phase differences:

Δφ _Σ1 = Δφ ₁ -Δφ ₂ , Δφ _Σ2 = Δφ ₃ -Δφ ₄ ,

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 scales of the angles α and β, corresponding to the large measuring bases d ₇ and d ₈ , differs from the closest analogue in that the re-emitted broadband signal with phase shift keying, delayed by time t _s and received by the fourth direction finding channel, multiplied with the interrogation broadband signal with phase shift keying, passed through the adjustable delay unit, a low-frequency voltage is proportional to the correlation function R (τ), support e at the maximum value, changing the time delay τ adjustable delay unit so as to satisfy the equation τ = τ _s, which corresponds to the maximum value of the correlation function R (τ), determines the range to the transponder disposed on distress

,

,

where C is the propagation velocity of radio waves,

register it, using the measured values of azimuth α, elevation angle β and range R determine the location of the transponder, the interrogated broadband signal with phase shift keying, passed through the adjustable delay unit, is used as a reference voltage for the synchronous detection of the reradiated broadband signal with phase shift keying, delayed for a while τ _{s / 2} and received DF fourth channel, allocate a low-frequency voltage proportional to the transponder identification number, and D istriruyut it.

The block diagram of the transmitter and receiver of the scanning device is presented in figure 1. A block diagram of a transponder located in distress is depicted in FIG. The relative position of the receiving antennas is shown in Fig.3.

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 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, and a key 29, the second input of which is connected to the output of the intermediate frequency amplifier 24.

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 second input of which is connected to the output of the local oscillator 22. The outputs of the phase meters 41 and 42 (43 and 44) through the subtractor 45 (46) and the adder 47 (48 ) connected to the corresponding inputs of block 49 registration.

The scanning device further comprises a variable delay unit 50 connected in series to the output of the phase manipulator 3, a multiplier 31, the second input of which is connected to the output of the high-frequency amplifier 21 of the fourth direction finding channel, a low-pass filter 51, an extreme regulator 52, an adjustable delay unit 50, and range indicator 53, the output of which is connected to the fifth input of the registration unit 49. The outputs of the high-frequency amplifier 21 and the adjustable delay unit 50 through a phase detector 32 are connected to the sixth input of the registration unit 49.

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 proposed method is implemented as follows.

All people associated with a certain 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 a high-frequency oscillation

u _c (t) = U _c cos (ω _with t + φ _c ), 0≤t> T _c ,

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} is the manipulated component of the phase, which displays the law of phase manipulation in accordance with the modulating code M (t); which, after amplification in the power amplifier 4, is emitted by the transmitting antenna 5 on the air, it is captured by the microstrip antenna 7 of the transponder. 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 _k1 (t) + φ _k2 (t) + φ _c ], 0≤t> T _c ,

where φ _k2 (t) = {0, π} is the manipulated component of the phase, which displays the law of phase manipulation in accordance with the topology of the interdigital transducer, has an individual character and contains all the necessary unique information about the owner of the transponder, 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 into the air and is captured by receiving antennas 12 ÷ 16:

u ₃ (t) = U ₃ · cos [(ω _s ± Δω) (t-τ _s ) + φ _k1 (t-τ _s ) + φ _k2 (t-τ _{s / 2} ) + φ ₁ ],

u ₄ (t) = U ₄ · cos [(ω _s ± Δω) (t-τ _s ) + φ _k1 (t-τ _s ) + φ _k2 (t-τ _{s / 2} ) + φ ₂ ],

u ₅ (t) = U ₅ · cos [(ω _s ± Δω) (t-τ _s ) + φ _k1 (t-τ _s ) + φ _k2 (t-τ _{s / 2} ) + φ ₃ ],

u ₆ (t) = U ₆ · cos [(ω _s ± Δω) (t-τ _s ) + φ _k1 (t-τ _s ) + φ _k2 (t-τ _{s / 2} ) + φ ₄ ],

u ₇ (t) = U ₇ · cos [(ω _s ± Δω) (t-τ _s ) + φ _k1 (t-τ _s ) + φ _k2 (t-τ _{s / 2} ) + φ ₅ ],

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

τ _s - the propagation time of the signal from the scanning device to the transponder and vice versa.

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

The scanning device can be installed on a vehicle, helicopter, plane or spacecraft, and can also be carried by the rescuer of the Ministry of Emergencies.

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

u _g (t) = U _g cosω _g t + ω _g .

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

U _pp (t) = U _pr · cos [(ω _pr ± Δω) (t-τ _z ) + φ _k1 (t-τ _z ) + φ _k2 (t-τ _{z / 2} ) + φ _pr ],

;Where

;

ω _CR = ω _c -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

₈ u (t) = U _pr · cos [2 (ω _ave ± Δω) (t-τ _s) + 2φ _etc.], 0≤t> T _c,

in which phase manipulation is already absent, since 2φ _k1 (t-τ _s ) = {0.2π} and 2φ _k2 (t-τ _{s / 2} ) = {0.2π}.

Width Δf _c broadband spectrum PSK signal determined by the duration τ _of its chip

.

.

Whereas the width of the spectrum of its second harmonic Δf ₂ is determined by the signal duration T _c

,

,

where T _c = N · τ _e is the signal duration;

τ _e and N - the duration and number of chips that make up the signal of duration T _c .

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

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

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

Voltages U ₀ and U ₂ proportional to Δf _c and Δf _2, respectively, from the outputs 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.

The voltage u _pr (t) from the output of the intermediate frequency amplifier 24 through the public key 29 is 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 frequencies. The output of the 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

d ₁ , d ₂ , d ₃ , d ₄ - measuring base (figure 3),

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 phase meters 41-44, the second inputs of which are supplied with voltage u _g (t) of local oscillator 22. Phase meters 41-44 measure the phase shifts Δφ ₁ ÷ Δφ _4, respectively.

However, in some cases, especially on board an aircraft, with large ranges of unambiguous measurement of the angles α and β, the rough bases d ₁ and d ₃ can be so small that it is physically impossible to place two antennas on them. In such cases, the formation of rough bases is possible by an indirect method.

The measured phase shifts Δφ ₁ and Δφ ₂ , Δφ ₃ and Δφ ₄ from the outputs of the phase meters 41 and 42, 43 and 44 are fed to the two inputs of the subtractor 45 (46) and the adder 47 (48).

At the outputs of the subtractors 45 and 46, phase differences are formed:

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 .

Thus, choosing the phase difference d ₅ and d ₆ small enough, it is possible to ensure the formation of coarse, but unequivocal scales of readings of the azimuth α and elevation angle β.

At the outputs of the adders 47 and 48, the sums of the phase differences are formed

Δφ _Σ1 = Δφ ₁ -Δφ ₂ , Δφ _Σ2 = Δφ ₃ -Δφ ₄ ,

equivalent to measuring phase shifts on measuring bases whose length

d ₇ = d ₁ + d ₂ , d ₈ = d ₃ + d ₄ ,

This is how accurate but ambiguous scales of azimuth α and elevation angle β are formed.

The following inequalities are established between the formed measuring bases:

,

.

,

.

The voltage u ₇ (t) from the output of the high-frequency amplifier 21 is simultaneously supplied to the first input of the multiplier 31, to the second input of which a broadband PSK signal u ₁ (t) is output from the output of the phase manipulator 3 through the adjustable delay unit 50. The voltage obtained at the output of the multiplier 31 is passed through a low-pass filter 51, at the output of which a correlation function R (τ) is formed. The extreme controller 52, designed to maintain the maximum value of the correlation function R (τ) and connected to the output of the low-pass filter 51, acts on the adjustable delay unit 50 and maintains the delay τ introduced by it equal to τ ₃ (τ = τ ₃ ), which corresponds to the maximum value R (τ). The range indicator 53 associated with the adjustable delay unit 50 allows you to directly read the measured range value to the transponder

,

,

where C is the propagation velocity of radio waves.

Therefore, the task of measuring the range R is reduced to measuring the time delay τ _{s of the} relayed PSK signal relative to the interrogation (probing) one. This is done using a correlator 30, consisting of a multiplier 31, an adjustable delay unit 50, a low-pass filter 51, and an extreme controller 52.

Simultaneously voltage

u ₇ (t) = U ₇ · cos [(ω _c ± Δω) (t-τ _s ) + φ _k1 (t-τ _s ) + φ _k2 (t-τ _{s / 2} ) + φ ₅ ]

from the output of the high-frequency amplifier 21, it is supplied to the first (information) input of the phase detector 32, the second (reference) input of which is supplied with voltage

u ₉ (t) = U _c · cos [ω _c (t-τ _з ) + φ _k1 (t-τ ₃ ) + φ _c ]

from the first output of the adjustable delay unit 50. As a result of the synchronous detection of a broadband QPSK signal u ₇ (t), a low-frequency voltage is released at the output of the phase detector 32

u _n (t) = U _n · cosφ _k2 (t-τ _{s / 2} ), 0≤t≤T _c ,

,Where

,

proportional to the identification number of the transponder located in distress. This voltage is detected by the registration unit 49.

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

The energy secrecy of these 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 the broadband QPSK signal is by no means small; it is simply distributed over the time-frequency domain so that at each point of 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 QPSK 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.

Thus, the proposed method in comparison with the prototype provides not only the detection of those in distress and their direction finding, but also allows you to determine their location. In addition, the proposed method allows to increase the reliability of the allocation of low-frequency voltage, proportional to the identification number of the transponder, by eliminating the phenomenon of "reverse work".

Thus, the functionality of the method is expanded.

Claims (1)

A method for detecting a distressed person, which consists in emitting a signal, receiving a re-emitted transponder located in a distressed signal in a predetermined reception band Δf _pr and then detecting it, while using a broadband signal with phase shift keying as a request 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 scan receiver A 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 comparison, they allow further processing of the frequency-converted broadband signal with phase shift keying, multiply it with those received in four direction finding channels with phase shift keying signals, produce harmonic signals at the local oscillator frequency, measure the phase shifts between them and the local oscillator voltage

,

,

,

,
where d ₁ , d ₂ , d ₃ , d ₄ - measuring base;
λ is the wavelength;
α, β - azimuth and elevation, the 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, two measuring bases d ₁ and d ₂ , d ₃ and d ₄ are formed in each plane, determine phase difference differences:
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 coarse phase difference coarse, but single-valued reference frames of angles α and β, corresponding to small measuring bases d ₅ and d ₆ , determine the sum of the phase differences:
Δφ _Σ1 = Δφ ₁ -Δφ ₂ , Δφ _Σ2 = Δφ ₃ -Δφ ₄ ,
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 for the angles α and β, corresponding to large measuring bases d ₇ and d ₈ , characterized in that the re-emitted signal with phase shift keying, delayed by time t _s and received by the fourth direction-finding channel, is multiplied with by requesting a broadband signal with phase shift keying, passed through an adjustable delay unit, a low-frequency voltage is proportional to the correlation function R (τ), it is maintained at the maximum value, it is changed the delay time τ of the adjustable delay unit τ so that the equality τ = τ _s is satisfied, which corresponds to the maximum value of the correlation function R (τ), determine the distance to the transponder located in distress

,
where C is the propagation velocity of radio waves,
register it, using the measured values of azimuth α, elevation angle β and range determine the location of the transponder, the interrogated broadband signal with phase shift keying, passed through the adjustable delay unit, is used as a reference voltage for the synchronous detection of the reradiated broadband signal with phase shift keying, delayed by time τ _{c / 2} and received DF fourth channel, allocate a low-frequency voltage proportional to the identification number of the transponder, and reg striruyut it.

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