RU2510015C1 - Method for remote detection of substance - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: disclosed system relates to radio means which employ magnetic resonance to search for and detect primarily narcotic and explosive substances in items to be inspected, as well as polarisation selection and phase analysis to search for and detect narcotics packed in a non-metal casing and located in concealment environments, for example in the abdominal cavity of a person, used to transport narcotics, luggage, suitcases, briefcases, bags etc. The system comprises a transmitting antenna 1, a transmitter 2, a pulse generator 3, a synchroniser 4, first 5 and second 13 receiving antennae, first 6 and second 14 receivers, a storage device 7, the inspected substance 8, a narcotic substance 9 placed in a concealment environment, an antenna unit 10, a time delay unit 11, a switch 12, a mixer 15, a heterodyne 16, an intermediate frequency amplifier 17, multipliers 18, 23, 24, 26 and 27, a narrow-band filter 19, a phase detector 20, a comparator unit 21, a recording unit 22, a 90° phase changer 25, a scaling multiplier 28, a subtractor unit 29 and an adder 30.

EFFECT: high sensitivity when measuring small phase shifts which correspond to low-contrast narcotics via fourfold amplification thereof.

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Description

The invention relates to radio equipment using magnetic resonance for searching and detecting mainly drugs and explosives in the composition of objects presented for research, as well as polarization selection and phase analysis for searching and detecting drugs packed in a non-metallic shell and located in covering environments, for example in the abdominal cavity of a person used to transport narcotic drugs, luggage, suitcases, diplomats, bags, etc., and may find application operation at airports, customs terminals, roadblocks, car parks, railway stations, etc.

Known methods and systems for the remote detection of substances (RF patents No. 2128832, 2148817, 2150105, 2161300, 2165104, 2179716, 2185614, 2226686, 2244942, 2249202, 2340913, 2377549; US patents No. 47756866, 5986455, 6194898, 6392; No. 2159626, 2254923, 2289344, 2293.885; Grechishkin V.D. et al. Local NQR in solids, Uspekhi Fizicheskikh Nauk, 1993, v.163, No. 10; Dikarev V.I., Zarenkov V.A., Zarenkov D.V. Detection of explosive objects, weapons, drugs, hazardous gases and radioactive contamination (St. Petersburg, 2004, etc.).

Of the known systems closest to the proposed is the "System for remote detection of substances" (RF patent No. 2377549, G01N 24/00, 2008), which is selected as a prototype.

The specified system is based on remote detection of a substance using remote excitation by an electromagnetic wave of magnetic resonance in a substance, followed by measurement of the response, the presence of which makes a conclusion about the presence of this substance, while the exciting electromagnetic signal is emitted at a frequency much higher than the frequency of the magnetic resonance of the substance to be detected, and modulate the emitted exciting electromagnetic signal by polarization at the magnetic resonance frequency, and the response p it is recorded on the modulation frequency, as well as on polarization selection and phase analysis for the search and detection of drugs packed in a non-metallic shell and located in covering environments, for example, in the abdominal cavity of a person used to transport drugs, baggage, bags, suitcases, diplomats, etc. .P.

A disadvantage of the known system is the low sensitivity when measuring small phase shifts corresponding to low-contrast narcotic substances.

An object of the invention is to increase the sensitivity when measuring small phase shifts corresponding to low-contrast narcotic substances, by four times their "amplification".

The problem is solved in that a system for remote detection of a substance containing, in accordance with the closest analogue, a test substance, a narcotic drug placed in a covering medium, a synchronizer, a pulse generator, a transmitter, the second input of which is connected to the second output of the synchronizer, and a transmitting antenna, the first receiving antenna in series, the first receiver, the second input of which is connected to the third output of the synchronizer, a drive, the second input of which is inen with the third output of the synchronizer, and the registration unit, the second input of which is connected to the output of the comparison unit, the second receiving antenna is connected in series, the second receiver, the second input of which is connected to the third output of the synchronizer, the mixer, the second input of which is connected to the local oscillator output, an intermediate frequency amplifier , the first multiplier, a narrow-band filter and a phase detector, the second input of which is connected to the local oscillator output, the time block is connected in series to the fourth output of the synchronizer delays and a key, the second input of which is connected to the output of the first receiver, and the output is connected to the second input of the first multiplier, while the transmitting antenna, the first and second receiving antennas are equipped with polarizers and combined into an antenna unit, differs from the closest analogue in that it is equipped with a second , the third, fourth and fifth multipliers, a 90 ° phase shifter, a scaling multiplier, a subtraction unit and an adder, and a second multiplier, the second input of which is connected in series to the output of the phase detector connected to the output of the phase detector, the third multiplier, the second input of which is connected to the output of the second multiplier, the subtraction unit and the adder, the output of which is connected to the input of the comparison unit, the phase shifter 90 °, the fourth multiplier, the second input of which is connected to the output of the phase detector with the output of the phase shifter by 90 °, and the fifth multiplier, the second input of which is connected to the output of the fourth multiplier, and the output is connected to the second input of the adder, the second input of the subtraction unit through scale an aberrant multiplier connected to the outputs of the second and fourth multipliers.

The structural diagram of the proposed system is presented in the drawing. The system contains the test substance 8, narcotic drug 9, placed in a shelter, sequentially connected synchronizer 4, pulse generator 3, transmitter 2, the second input of which is connected to the second output of synchronizer 4, and transmitting antenna 1, sequentially connected to the first receiving antenna 5, the first a receiver 6, the second input of which is connected to the third output of the synchronizer 4, a drive 7, the second input of which is connected to the third output of the synchronizer 4, and a recording unit 22, the second input of which is connected to the output loka 21 comparison, sequentially connected to the second receiving antenna 13, the second receiver 14, the second input of which is connected to the third output of the synchronizer 4, the mixer 15, the second input of which is connected to the output of the local oscillator 16, an amplifier 17 of an intermediate frequency, the first multiplier 18, a narrow-band filter 19, a phase detector 20, the second input of which is connected to the output of the local oscillator 16, the second multiplier 23, the second input of which is connected to the output of the phase detector 20, the third multiplier 24, the second input of which is connected to the output of the second the life of the device 23, the subtraction unit 29 and the adder 30, the output of which is connected to the input of the comparison unit 21. To the output of the phase detector 20, a phase shifter 25 is 90 ° connected, a fourth multiplier 26, the second input of which is connected to the output of the phase shifter 25 by 90 °, and a fifth multiplier 27, the second input of which is connected to the output of the fourth multiplier 26, and the output is connected to the second input the adder 30. The second input of the subtraction unit 29 through the scaling multiplier 28 is connected to the outputs of the second 23 and fourth 26 multipliers. To the fourth output of the synchronizer 4, a time delay unit 11 and a key 12 are connected in series, the second input of which is connected to the output of the first receiver 6, and the output is connected to the second input of the first multiplier 18.

The transmitting antenna 1, the first 5 and the second 13 receiving antennas are equipped with polarizers and are combined in the antenna unit 10.

The proposed system can operate in two modes.

The first mode is based on remote excitation by an electromagnetic wave of magnetic resonance in the test substance with subsequent measurement of the response frequency.

The second mode is based on radiomagnetic radar sensing by a plane-polarized wave of the alleged location of the drug, packed in a nonmetallic shell and placed in a covering medium, with subsequent measurement of the phase shift between the two reflected components, which generally have elliptical polarization with opposite directions of rotation of the electromagnetic field vector.

In the first mode, pulses with a filling frequency w ₁ (w ₁ -w), generated in the pulse generator 3, enter the transmitter 2 and are emitted by the transmitting antenna 1 in the direction of the test substance 8. The latter can be located, for example, on a person’s body under his clothes. Transmitting 1 and receiving 5, 13 antennas are made, for example, in the form of horn antennas, which are equipped with polarizers. The signal to the transmitting antenna 1 comes from a circular waveguide, to which, in turn, from the transmitter 2 are supplied two orthogonal (polarized) components, one at a frequency w ₁ and the other at a frequency (w ₁ -w), resulting in the wave 1 radiated by the antenna will be modulated by polarization with a magnetic resonance frequency w.

The test substance 8, irradiated by an electromagnetic wave containing a component of the magnetic resonance frequency w, is excited and, at the end of the irradiation pulse, emits a response signal at the same frequency. The response signal is received by the receiving antenna 5, containing four ferrite rods with a diameter of 8 mm and a length of 138 mm, while the rods are wound inductors containing 20 turns and connected in parallel. The system is controlled by synchronizer 4.

The signal with the receiving antenna 5 is supplied to the first input of the receiver 6, the second input of which receives the reference voltage from the third output of the synchronizer 4, which locks the receiver 6 for the duration of the emission of pulses. From the output of the receiver 6, the signals are fed to the input of the drive 7, where they gradually accumulate, which allows to increase the distance from the receiving antenna 5 to the test substance 8 by 2-3 times. The second input of the drive 7 also receives the reference voltage from the third output of the synchronizer 4, which ensures synchronization of the accumulated pulses.

магнитного поля излучаемого электромагнитного сигнала содержит составляющую:In the case of modulation by polarization of the emitted signal with a frequency w equal to the frequency of the magnetic resonance of the test substance 8, at a frequency of the emitted signal w ₁ >> w, the intensity vector $$\widehat{H}$$

the magnetic field of the radiated electromagnetic signal contains a component:

$$\widehat{H}=Cos{w}_{\mathrm{one}}\cdot t\cdot \left(\begin{array}{l}Sinw\cdot t\\ Cosw\cdot t\end{array}\right)$$

на частоте w (Дудкин В.И., Пахомов Л.Н. Основы квантовой электроники. СПб ГТУ, 2001). Поскольку частота w₁ может быть выбрана достаточно высокой w₁>>w, то в этом случае реализация передающей антенны 1 может быть осуществлена, например, с помощью техники антенн сверхвысоких частот (СВЧ), на которую модулированный по поляризации сигнал поступает из круглого волновода, на который, в свою очередь, поступают две линейно-поляризованные ортогональные волны $$\widehat{H}\text{'}$$

и $$\widehat{H}\text{'}\text{'}$$

, частоты которых равны соответственно w₁ и (w₁-w).Test substance 8 will actively interact with the magnetic field $$\widehat{H}$$

at a frequency w (Dudkin V.I., Pakhomov L.N. Fundamentals of quantum electronics. St. Petersburg State Technical University, 2001). Since the frequency w ₁ can be selected sufficiently high w ₁ >> w, in this case, the implementation of the transmitting antenna 1 can be carried out, for example, using the technique of microwave antennas, to which the polarized modulated signal comes from a circular waveguide, which, in turn, receives two linearly polarized orthogonal waves $$\widehat{H}\text{'}\text{'}$$

and $$\widehat{H}\text{'}\text{'}\text{'}\text{'}$$

whose frequencies are respectively w ₁ and (w ₁ -w).

The transition to the frequency of the exciting radiation in the microwave range allows you to provide a "far zone" for the emitted electromagnetic signal at a range of several tens of centimeters. As a result, at distances of the order of several meters from the emitter, the level of electromagnetic radiation is sufficient to excite resonance in the substance.

In the second mode, the pulse generator 3 generates a probe pulse:

u ₁ (t) = U ₁ · Cos (w ₁ t + φ ₁ ), 0≤t≤T,

where U ₁ , w ₁ , φ ₁ , T ₁ - amplitude, carrier frequency, initial phase and pulse duration;

which goes to the input of the transmitter 2, and then to the input of the transmitting antenna 1, where it acquires a flat polarization and is emitted in the direction of the surface of the covering medium, under which the narcotic drug 9 can be.

Detection of narcotic drugs in covering environments is carried out by the operator by moving the antenna unit 10 above the proposed location of the narcotic drug 9. In this case, an electromagnetic field is created in the covering medium by electromagnetic sounding. When the probing signal reaches the drug 9, it partially reflects towards the surface of the covering medium.

When a plane-polarized electromagnetic wave is reflected from a narcotic drug 9, which is affected by the external magnetic field of the Earth, it is divided into two independent components, which in the general case have elliptical polarization with opposite directions of rotation of the electromagnetic field vector. At frequencies of the decimeter range, both components have circular polarization. Narcotic drug 9 has electrical parameters different from the covering medium (conductivity and permittivity).

Both waves are reflected and propagated at different speeds, as a result of which the phase relations between these waves change. This phenomenon is usually called the Faraday effect, due to which the reflected signal experiences the rotation of the plane of polarization. The angle of rotation of the plane of polarization, which is determined by different speeds of propagation and reflection of signals with right and left circular polarization from narcotic drug 9, is found from the ratio

$$\delta Z=\frac{\mathrm{one}}{2}\left({\varphi }_P-{\varphi }_l\right)$$

where φ _p , φ _l are the phase delays of the reflected signals from the right (rotation of the plane of polarization clockwise) and left (rotation of the plane of polarization counterclockwise) circular polarization, respectively.

The reflected signal is captured by the receiving antennas 5 and 13. In this case, the receiving antenna 5 is susceptible only to the reflected signal with the right circular polarization, and the receiving antenna 13 is only sensitive to the reflected signal with the left circular polarization.

The output of the receivers 6 and 14 produces the following signals:

u _n (t) = U _p · Cos [w ₁ ± Δw) t + φ _p ],

u _l (t) = U _l · Cos [(w ₁ ± Δw) t + φ _l ], 0≤t≤T ₁ ,

where the indices "p" and "l" refer respectively to signals with right and left circular polarization;

± Δw is the instability of the carrier frequency due to incoherent reflection and other destabilizing factors.

The signal u _p (t) from the output of the receiver 6 through the key 12 is fed to the first input of the multiplier 18. In order for the measured phase difference to correspond to the depth h of the narcotic drug 9, the multiplier 18 is time-gated using the key 12, to the control input of which gating pulses are received, formed by the block 11 time delay. The latter is controlled by synchronizer 4. The time delay of the pulses is determined by the depth h of the occurrence of the drug 9 in the covering medium. When the depth changes, the delay time also changes.

The reflected signal u _l (t) from the output of the receiver 14 is fed to the first input of the mixer 15, the second input of which is the voltage of the local oscillator 16:

u _g (t) = U _g Cos (w _g + φ _g ).

At the output of the mixer 15, voltages of combination frequencies are generated. Amplifier 17 is allocated voltage intermediate (differential) frequency:

U _pr (t) = U _pr · Cos [(w _pr ± Δw) t + φ _etc.], 0≤t≤T ₁

Where $$U_{PR}=\frac{\mathrm{one}}{2}{U}_l\cdot U_g$$

w _CR = w ₁ -w _G - intermediate frequency;

φ _ol = φ _l -φ _g ,

which is fed to the second input of the multiplier 18. At the output of the latter, a harmonic voltage is generated:

u ₂ (t) = U ₂ · Cos (w _g t + φ _g + Δφ), 0≤t≤T ₁ ,

Where $$U_2=\frac{\mathrm{one}}{2}{U}_P\cdot U_{PR}$$

Δφ = φ _p -φ _l is the phase difference between the reflected signals with right and left circular polarization,

which is allocated by a narrow-band filter 19 and enters the first input of the phase detector 20, the second input of which the local oscillator voltage u _g (t) is applied. The output of the latter forms a low-frequency voltage:

u _n (Δφ) = U _n CosΔφ,

Where $$U_n=\frac{\mathrm{one}}{2}{U}_2\cdot U_g$$

proportional to the measured phase shift Δφ.

This voltage is supplied to the two inputs of the second multiplier 23, the output of which produces a voltage

, $$u_3\left(\Delta \varphi \right)=U_n^2\cdot Co{s}^2\Delta \varphi$$

,

which is supplied to the two inputs of the third multiplier 24. At the output of the latter, voltage is generated

. $$u_{\mathrm{four}}\left(\Delta \varphi \right)=U_n^{\mathrm{four}}\cdot Co{s}^{\mathrm{four}}\Delta \varphi$$

.

At the same time, the low-frequency voltage u _n (Δφ) from the output of the phase detector 20 is fed to the input of the phase shifter 25 by 90 °, at the output of which a voltage is formed

U ₅ (Δφ) = u _n Cos (Δφ + 90 °) = - U _n SinΔφ,

which is fed to the two inputs of the fourth multiplier 26. At the output of the latter, voltage is generated

, $$u_6\left(\Delta \varphi \right)=U_n^2\cdot Si{n}^2\Delta \varphi$$

,

which is fed to the two inputs of the fifth multiplier 27. At the output of the latter, voltage is generated

. $$u_7\left(\Delta \varphi \right)=U_n^{\mathrm{four}}\cdot Si{n}^{\mathrm{four}}\Delta \varphi$$

.

The voltages from (Δφ) and u ₆ (Δφ) are supplied to the two inputs of the scaling multiplier 28, the scaling coefficient K _{m of} which is chosen equal to 6 (K _m = 6). The output of the scaling multiplier 28 is formed voltage

. $$u_8\left(\Delta \varphi \right)=6u_3\left(\Delta \varphi \right)\cdot u_6\left(\Delta \varphi \right)=6U_n^{\mathrm{four}}\cdot Co{s}^2\Delta \varphi \cdot Si{n}^2\Delta \varphi$$

.

The voltage u ₄ (Δφ) and u ₈ (Δφ) are supplied to the two inputs of the subtraction unit 29, at the output of which a voltage is generated

. $$u_9\left(\Delta \varphi \right)=u_{\mathrm{four}}\left(\Delta \varphi \right)-u_8\left(\Delta \varphi \right)=U_n^{\mathrm{four}}\cdot Co{s}^{\mathrm{four}}\Delta \varphi -6U_n^{\mathrm{four}}\cdot Co{s}^2\Delta \varphi \cdot Si{n}^2\Delta \varphi$$

.

Voltages u ₇ (Δφ) and u ₉ (Δφ) are supplied to two inputs of the adder 30, the output of which is formed voltage

$$\begin{array}{l}{u}_{10}\left(\Delta \varphi \right)=u_9\left(\Delta \varphi \right)+u_7\left(\Delta \varphi \right)=U_n^{\mathrm{four}}\cdot Co{s}^2\Delta \varphi -6U_n^{\mathrm{four}}\cdot Co{s}^2\Delta \varphi \cdot Si{n}^2\Delta \varphi +U_n^{\mathrm{four}}\cdot Si{n}^{\mathrm{four}}\Delta \varphi =\\ =U_n^{\mathrm{four}}\cdot Cos\mathrm{four}\Delta \varphi =U_{\mathrm{one}}\cdot Cos\Delta {\varphi }_{\mathrm{one}}\end{array}$$

.Where $$U_{\mathrm{one}}=U_n^{\mathrm{four}},\Delta {\varphi }_{\mathrm{one}}=\mathrm{four}\Delta \varphi$$

.

Therefore, the phase shift is "amplified" by 4 times.

The voltage u ₁₀ (Δφ) is compared in the comparison unit 21 with the reference voltage

u _e (Δφ _e ) = u _e CosΔφ _e ,

where Δφ _e is the unchanged phase shift obtained by probing the covering medium in the absence of a narcotic drug 9.

The phase shift Δφ _e is determined by the frequency of the probing signal and the electrical parameters of the covering medium. This phase shift remains unchanged when probing the shelter in the absence of drugs.

If u ₁₀ (Δφ) ≈u _e (Δφ _e ), then in the block 21 of the comparison, a constant voltage is not formed.

When u ₁₀ (Δφ)> u _e (Δφ _e ), a constant voltage is generated in the comparison unit 21, which is supplied to the second input of the registration unit 22.

Moreover, the fact of registration of this voltage indicates the presence of a narcotic in this sheltering environment.

The proposed system provides the search and detection of drugs packaged in a non-metallic shell and located in covering environments, for example, in the abdominal cavity of a person used to transport drugs, luggage, suitcases, diplomats, bags, etc.

Moreover, the proposed system allows to increase the reliability of the search and detection and resolution in depth when determining the location of narcotic drugs in hiding environments. This is achieved through the use of polarization selection and the elimination of the ambiguity of phase measurements, which is ensured by the fact that phase measurements are carried out between the reflected signals with right and left circular polarization, and not between the probing and reflected signals. In this case, the phase shift between the reflected signals with right and left circular polarization is measured at a stable local oscillator frequency w _r . Therefore, the process of measuring the phase shift Δφ is invariant to instability of the carrier frequency of the reflected signal arising from incoherent reflection of the signal from the drug and other destabilizing factors, which allows to increase the accuracy of measuring the phase shift Δφ, and therefore the accuracy of determining the location of the drug.

Thus, the proposed system in comparison with the prototype and other technical solutions for a similar purpose provides increased sensitivity when measuring small phase shifts corresponding to low-contrast narcotic substances. This is achieved by "amplification" of small phase shifts in accordance with the expression:

Cos ⁴ Δφ-6 Cos ² Δφ Sin ² Δφ + Sin ⁴ Δφ = Cos4Δφ,

four times.

Claims (1)

A system for remote detection of a substance containing a test substance, a narcotic drug placed in a covering medium, a synchronizer, a pulse generator, a transmitter whose second input is connected to the second output of the synchronizer, and a transmitting antenna, a first receiving antenna, a first receiver, and a second input in series which is connected to the third output of the synchronizer, a drive, the second input of which is connected to the third output of the synchronizer, and the registration unit, the second input of the cat the second receiver, the second input of which is connected to the third output of the synchronizer, a mixer, the second input of which is connected to the output of the local oscillator, an intermediate frequency amplifier, the first multiplier, a narrow-band filter and a phase detector, the second input which is connected to the output of the local oscillator, a time delay unit and a key, the second input of which is connected to the output of the first receiver, are connected in series to the fourth output of the synchronizer and the output is connected to the second input of the first multiplier, while the transmitting antenna, the first and second receiving antennas are equipped with polarizers and combined into an antenna unit, characterized in that it is equipped with a second, third, fourth and fifth multipliers, a 90 ° phase shifter, a scaling multiplier , a subtraction unit and an adder, and a second multiplier is connected to the output of the phase detector, the second input of which is connected to the output of the phase detector, a third multiplier, the second input of which is connected n with the output of the second multiplier, the subtraction unit and the adder, the output of which is connected to the input of the comparison unit, the phase shifter 90 °, the fourth multiplier, the second input of which is connected to the output of the phase shifter 90 °, and the fifth multiplier, the second input are connected to the output of the phase detector which is connected to the output of the fourth multiplier, and the output is connected to the second input of the adder, the second input of the subtraction unit through the scaling multiplier is connected to the outputs of the second and fourth multipliers.