RU2488810C1 - Method for remote detection of substance - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: suspected hiding place of a narcotic drug is subjected to electromagnetic probing with a plane-polarised signal and right- and left-hand circularly polarised signals reflected from the narcotic drug in the concealment environment are received, wherein the reflected right-hand circularly polarised signal is time-gated in proportion to the depth of burial of the narcotic drug, and the reflected left-hand circularly polarised signal is frequency-converted using the frequency w_r1 of a first heterodyne; first voltage at intermediate frequency is selected, and harmonic voltage at stable frequency w_r1 of the first heterodyne is then selected; the phase shift between the reflected right- and left-hand circularly polarised signals at the stable frequency w_r1 of the first heterodyne is then measured; the measured; the measured value of phase shift is compared with a reference value and a decision on presence of a narcotic drug in the concealment environment is made based on the comparison results, wherein the reflected left-hand circularly polarised signal is simultaneously frequency-converted using frequency w_r2 of a second heterodyne.

EFFECT: high noise immunity of the receiving signals and reliability of detecting a substance by suppressing spurious signals received over image and combinational channels.

2 dwg

Description

The proposed method relates to physical measurements, namely to radio engineering tools using magnetic resonance to search and detect drugs and explosives in the composition of substances presented for research, as well as polarization selection and phase analysis to search and detect 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, suitcases, diplomats, bags, etc., and we can t find use in airports, customs terminals, checkpoints, parking, railway stations, etc.

Known methods for remote detection of a substance (RF patents Nos. 2.128.832, 2.148.817, 2.150.105, 2.161.300, 2.165.104, 2.179.716, 2.185.614, 2.226.686, 2.244.942, 2.249.202, 2.308.734, 2.340.913; US patents No. 4,756.866, 5.986.455, 6.194.898, 6.392.408; UK patents No. 2,159.626, 2.254.923, 2.289.344, 2.293.885; Grechishkin V.D. . and other Local NQR in solids. Advances in Physical Sciences, 1993, vol. 163, No. 10; Dikarev V.I. Safety, protection and salvation of a person. St. Petersburg, 2007, pp. 466-467, etc.).

Of the known methods closest to the proposed one is the "Method for the remote detection of substances" (RF patent No. 2,308.734, G01R 33/20, 2006), which is selected as a prototype.

In this method, the reflected signal with the left circular polarization is converted in frequency using the local oscillator voltage, the intermediate frequency voltage is extracted, it is multiplied with the reflected signal with the right circular polarization, the harmonic voltage is isolated at the stable frequency of the local oscillator, the phase shift between the reflected signals from the right and left circular polarization at a stable frequency of the local oscillator, compare the measured value of the phase shift with a reference value and the decision A report on the presence of a narcotic substance in a shelter.

In the known method for receiving reflected signals with left circular polarization, a superheterodyne receiver is used, in which the same value of the intermediate frequency w _up can be obtained by receiving signals at two frequencies w _c and w _з1 , i.e.

w _c -w _g1 = w _up and w _g1 -w _z1 = w _up .

Therefore, if the tuning frequency w _{c is} taken as the main receiving channel, then along with it there will be a mirror receiving channel, the frequency w _{s1 of} which differs from the frequency w _c by 2w _up and is located symmetrically (mirror) with respect to the local oscillator frequency w _g1 (Fig. 2). 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 a superheterodyne receiver.

In addition to the mirror, there are other additional (combinational) reception channels. In general terms, any Raman receive channel occurs when the condition

, $$w_{up}=\left|\pm m{w}_{\mathrm{to}i}\pm n{w}_{g\mathrm{one}}\right|$$

,

where w _ki is the frequency of the i-th Raman reception channel;

m, n, i are positive integers.

The most harmful combinational reception channels are those generated by the interaction of the first harmonic of the signal frequency with the harmonics of the frequency of the local oscillator of the small order (second, third, etc.), since the sensitivity of the receiver through these channels is close to the sensitivity of the main channel. So, for two combinational channels with m = 1 and n = 2 there correspond frequencies

w _k1 = 2w _g1 -w _up and w _k2 = 2w _g1 + w _up .

The presence of false signals (interference) received via mirror and Raman channels leads to a decrease in noise immunity of signal reception and the reliability of detection of a substance.

An object of the invention is to increase the noise immunity of signal reception and the reliability of detection of a substance by suppressing false signals (interference) received via mirror and Raman channels.

The problem is solved in that according to the method of remote detection of a substance using remote excitation by an electromagnetic wave of magnetic resonance in a substance and then measuring the response frequency, by the presence of which it is concluded that the substance is present, while the exciting electromagnetic signal is emitted at a frequency much higher magnetic resonance of the substance to be detected, and modulate the emitted exciting electromagnetic signal by polarization at a frequency of m resonance response, and the response is recorded at the modulation frequency, electromagnetic probing of the alleged site of the narcotic substance with a plane-polarized signal is carried out and signals with right and left circular polarization reflected from the narcotic substance in the covering medium are received, while the reflected signal with right circular polarization is gated time, proportional to the depth of the narcotic substance, and the reflected signal with left circular polarization is often converted e using frequency w _r1 of the first local oscillator is isolated first voltage intermediate frequency, and then emit the harmonic voltage at a stable frequency w _r1 of the first local oscillator is measured by the phase shift between the reflected signals from the right and left circular polarization to a stable frequency w _r1 of the first local oscillator, comparing the measured the phase shift value with the reference value and, based on the comparison result, decide on the presence of a narcotic substance in the covering medium, differs from the closest analogue in that the reflected si cash left-circularly polarized simultaneously converted in frequency by using frequency w _r2 of the second local oscillator is isolated second voltage intermediate frequency multiply it with the first voltage of the intermediate frequency, allocate a low-frequency voltage proportional to the correlation function R (τ), compare it with a threshold voltage U _thresh and if it is exceeded, further processing of the received signals is allowed, which begins with the multiplication of the first intermediate frequency voltage with the reflected right signal Rugova polarization, and frequency w w _r1 and _r2 of the first and second local oscillators spread to twice the value of the intermediate frequency

w -w _{r2 r1} = 2w _up

and choose symmetric with respect to the frequency w _{c the} main reception channel

w _c -w _g1 = w _g2 -w _c = w _up .

The structural diagram of a device that implements the proposed method is presented in figure 1. A frequency diagram illustrating signal conversion is shown in FIG.

The device comprises serially connected pulse generator 3, the control input of which is connected to the first output of the synchronizer 4, the transmitter 2, the control input of which is connected to the second output of the synchronizer 4, and the transmitting antenna 1, the first receiving antenna 5, the first receiver 6, the control input of which is connected in series connected to the third output of the synchronizer 4, the drive 7, the control input of which is connected to the third output of the synchronizer 4, and the registration unit 22, sequentially connected to the second receiving Ennu 13, the second receiver 14, the control input of which is connected to the third output of the synchronizer 4, the first mixer 15, the second input of which is connected to the output of the first local oscillator 16, the first intermediate frequency amplifier 17, the second key 28, the multiplier 18, the narrow-band filter 19, the phase detector 20, the second input of which is connected to the output of the first local oscillator 16, and the comparison unit 21, the output of which is connected to the second input of the registration unit 22, connected in series to the fourth output of the synchronizer 4, the time delay unit 11 and the first key 12, the second input of which is connected to the output of the second receiver 6, and the output is connected to the second input of the multiplier 18, serially connected to the output of the second receiver 14, the second mixer 23, the second input of which is connected to the output of the second local oscillator 24, the second intermediate frequency amplifier 25, correlator 26 , the second input of which is connected to the output of the first intermediate frequency amplifier 17, and the threshold unit 27, the output of which is connected to the second input of the second key 28.

The transmitting antenna 1, the receiving antennas 5 and 13 form the antenna unit 10. In addition, the device contains the test substance 8 and the narcotic substance 9, placed in a shelter. The transmitter 2, the receivers 6 and 14 are equipped with polarizers.

The proposed method is implemented as follows.

A device that implements the proposed method 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 electromagnetic radar sensing by a plane-polarized wave of the alleged location of a drug substance packed in a nonmetallic shell and placed in a covering medium, with subsequent measurement of the phase shift between 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 and (w ₁ -w) generated in the pulse generator 3 are transmitted to the transmitter 2 and emitted by the transmitting antenna 1 in the direction of the test substance 8. The latter can be located, for example, on the human 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, which, in turn, from the transmitter 2 is fed two orthogonal (polarized) components, one at a frequency w ₁ and the other at a frequency (w ₁ -w), resulting in an antenna emitted 1 wave will be modulated by polarization with a magnetic resonance frequency w.

The test substance 8, irradiated by an electromagnetic wave containing a component at 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 operation of the device is controlled by the synchronizer 4.

The signal from the receiving antenna 5 is supplied to the receiver 6, which also receives the reference voltage from the 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 signal enters the drive 7, where the signals gradually accumulate, which allows to increase the distance from the receiving antenna 5 to the test substance 8 in 2-3 times. The drive 7 also receives the reference voltage, providing synchronization of the accumulated pulses.

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, when the frequency of the emitted signal is w ₁ > w, the magnetic field vector H of the emitted electromagnetic signal contains a component

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

.

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 реализации передающая антенна 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 $$\overline{H}\text{'}$$

и $$\overline{H}\text{'}\text{'}$$

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

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 chosen sufficiently high w ₁ > w, in this case, the transmitting antenna 1 can be implemented, 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 $$\overline{H}\text{'}\text{'}$$

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

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 signal

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

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

which goes to the input of the transmitter 2, where it acquires a flat polarization. The specified signal through the transmitting antenna 1 is emitted in the direction of the surface of the covering medium, under which the narcotic substance 9 can be.

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

When a plane-polarized electromagnetic wave is reflected from a narcotic substance 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 substance 9 has electrical parameters other than 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 a narcotic substance, is found from the ratio

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

,

φ _p , φ _l - 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 _p (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 substance 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 the synchronizer 4. The time delay of the pulses is determined by the depth h of the occurrence of the narcotic substance 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 inputs of the first 15 and second 23 mixers, the second inputs of which are supplied with the voltage of the first 16 and second 24 local oscillators, respectively

u _g1 (t) = U _g1 · Cos (w _g1 t + φ _g1 ),

u _g2 (t) = U _g2 Cos (w _g2 t + φ _g2 ).

Moreover, the frequencies w _g1 and w _{g2 of the} first 16 and second 24 local oscillators are spaced by twice the intermediate frequency

w -w _{r2 r1} = 2w _up

and are selected symmetrical with respect to the frequency w _{c of the} main receiving channel (FIG. 2)

w _c -w _g1 = w _g2 -w _c = w _up .

This circumstance leads to a doubling of the number of additional receiving channels, but creates favorable conditions for their suppression due to the correlation processing of the received signals; at the output of the mixers 15 and 23, the frequencies of the combination frequencies are formed.

Amplifiers 17 and 25 are allocated voltage intermediate (differential) frequency

, $$u_{up\mathrm{one}}\left(t\right)=U_{Pp\mathrm{one}}\cdot Cos\left[\left(w_{up}\pm \Delta w\right)t+{\varphi }_{up\mathrm{one}}\right]$$

,

, 0≤t≤T₁, $$u_{up2}\left(t\right)=U_{PR2}\cdot Cos\left[\left(w_{up}\pm \Delta w\right)t+{\varphi }_{up\mathrm{one}}\right]$$

, 0≤t≤T ₁ ,

; $$U_{пр2}=\frac{1}{2}{U}_{л}\cdot U_{г2}$$

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

; $$U_{PR2}=\frac{\mathrm{one}}{2}{U}_l\cdot U_{g2}$$

;

w _up = w _c -w _g1 = w _g2 -w _c - intermediate (difference) frequency;

φ _up1 = φ _l -φ _g1 ; φ _up2 = φ _g2- φ _l ,

which enter the two inputs of the correlator 26. The latter is a series-connected multiplier and a low-pass filter. The output of the correlator 26 produces a low-frequency voltage proportional to the correlation function R (τ), which is compared with the threshold voltage _Uop in threshold block 27. The threshold level _{Uop is} exceeded only at the maximum value of the correlation function R (τ). Since the channel voltages u _up1 (t) and u _up2 (t) are formed by the same reflected signal received on two channels at the same frequency w _{c of the} main channel (Fig. 2), there is a strong between the specified channel voltages correlation relationship. The correlation function reaches a maximum value and exceeds the threshold level _Uop in the threshold block 27. When the threshold level _Uop is exceeded, a constant voltage is generated in the threshold block 27, which is supplied to the control input of the key 28, opening it. In the initial state, the key 28 is always closed. In this case, the voltage u _up1 (t) from the output of the first amplifier 17 of the intermediate frequency through the public key 28 is supplied to the second input of the multiplier 18. At the output of the latter, a harmonic voltage is generated

, 0≤t≤T₁, $$u_2\left(t\right)=U_2\cdot Cos\left(w_{g\mathrm{one}}t+{\varphi }_P+\Delta \varphi \right)$$

, 0≤t≤T ₁ ,

Where $$U_2=\frac{\mathrm{one}}{2}{K}_2\cdot U_P\cdot U_{PR\mathrm{one}};$$

K ₂ - transfer coefficient of the multiplier;

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 is supplied with the voltage of the first local oscillator u _g1 (t). The output of the latter forms a low-frequency voltage

u _n (Δφ) = U _n CosΔφ,

;Where $$U_n=\frac{\mathrm{one}}{2}{K}_3\cdot U_2\cdot U_{g\mathrm{one}}$$

;

K ₃ - the transfer coefficient of the phase detector, proportional to the measured phase shift Δφ.

This voltage is compared in block 21 of the comparison 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 narcotic substance 9.

The phase shift Δφ 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 _n (Δφ) ≈u _e (Δφ _e ), then in the block 21 of the comparison does not form a constant voltage.

When u _n (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 substance in this covering environment.

The operation of the device described above corresponds to the case of receiving useful signals on the main channel at a frequency w _c (FIG. 2).

If a false signal (interference) enters the first mirror channel at a frequency w _s1

, 0≤t≤T_з1, $$u_{s\mathrm{one}}\left(t\right)=U_{s\mathrm{one}}\cdot Cos\left(w_{s\mathrm{one}}t+{\varphi }_{s\mathrm{one}}\right)$$

, 0≤t≤T _P1,

then at the output of the mixers 15 and 23 the following voltages are formed:

, $$u_{up3}\left(t\right)=U_{Pp3}\cdot Cos\left(w_{up}t+{\varphi }_{up3}\right)$$

,

, 0≤t≤T_з1, $$u_{up\mathrm{four}}\left(t\right)=U_{PR\mathrm{four}}\cdot Cos\left(3w_{up}t+{\varphi }_{up\mathrm{four}}\right)$$

, 0≤t≤T _P1,

;Where $$U_{PR3}=\frac{\mathrm{one}}{2}{U}_{s\mathrm{one}}\cdot U_{g\mathrm{one}}$$

;

; $$U_{PR\mathrm{four}}=\frac{\mathrm{one}}{2}{U}_{s\mathrm{one}}\cdot U_{g2}$$

;

w _up = w _g1 -w _z1 - intermediate frequency;

3w _up = w _g2 -w _z1 - triple the value of the intermediate frequency;

φ _up3 = φ _g1 -φ _z1 ; φ _up4 = φ -φ _{r2 P1.}

However, only the voltage u _up3 (t) is allocated by the first intermediate frequency amplifier 17. At the output of the correlator 26, in this case, the voltage is absent, the key 28 does not open, and the spurious signal (interference) received through the first mirror channel at a frequency w _s1 is suppressed.

If a false signal (interference) enters the second mirror channel at a frequency w _s2

, 0≤t≤T_з2, $$u_{s2}\left(t\right)=U_{s2}\cdot Cos\left(w_{s2}t+{\varphi }_{s2}\right)$$

, 0≤t≤T _s2,

then at the output of the mixers 15 and 23 the following voltages are formed:

, $$u_{up5}\left(t\right)=U_{Pp5}\cdot Cos\left(3w_{up}t+{\varphi }_{up5}\right)$$

,

, 0≤t≤T_з2, $$u_{up6}\left(t\right)=U_{Pp6}\cdot Cos\left(w_{up}t+{\varphi }_{up6}\right)$$

, 0≤t≤T _s2,

; $$U_{пр6}=\frac{1}{2}{U}_{з2}\cdot U_{г2}$$

;Where $$U_{PR5}=\frac{\mathrm{one}}{2}{U}_{s2}\cdot U_{g\mathrm{one}}$$

; $$U_{PR6}=\frac{\mathrm{one}}{2}{U}_{s2}\cdot U_{g2}$$

;

3w _up = w _z2- w _g1 - triple the value of the intermediate frequency;

w = w _{up z2-} w _r2 - intermediate frequency;

φ _up5 = φ _{s2 -} φ _g1 ; φ _up6 = φ _z2- cp _r2.

However, only the voltage u _up6 (t) is allocated by the second intermediate frequency amplifier 25. At the output of the correlator 26, in this case, the voltage is also absent, the key 28 does not open, and a false signal (interference) received via the second mirror channel at a frequency w _s2 is suppressed.

For a similar reason, false signals (interference) received on the first Raman channel at a frequency w _k1 , along the second Raman channel at a frequency w _k2, and any other additional channel are also suppressed.

If spurious signals (interference) are received simultaneously by the first w _P1 and second w _s2 mirror channels, the amplifiers 17 and 25 intermediate frequency allocated voltage u _up3 (t) and u _up6 (t), respectively, at the output of the correlator 26, a low-frequency voltage appears proportional correlation function. But the key 28 in this case does not open. This is because different false signals (interference) u _z1 (t) and u _z2 (t) are received at different frequencies w _z1 and w _z2 . Therefore, there is a weak correlation between the channel voltages u _up3 (t) and u _up6 (t). The output voltage of the correlator 26 in this case does not reach the maximum value and does not exceed the threshold level _Uop in the threshold unit 27, the key 28 does not open, and false signals (interference) received simultaneously through the first _wz1 and second _wz2 mirror channels are suppressed.

For a similar reason, false signals (interference) received simultaneously on two other additional channels are suppressed.

The proposed method provides the search and detection of narcotic substances packed 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 method allows to increase the reliability of the search and detection and resolution in depth when determining the location of narcotic substances in covering 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 the right and left circular polarization is measured at a stable frequency w _{g1 of the} first local oscillator. 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 narcotic substance and other destabilizing factors, which improves the accuracy of measuring the phase shift Δφ and, therefore, the accuracy of determining the location of narcotic substances.

Thus, the proposed method in comparison with the prototype and other technical solutions for a similar purpose provides increased noise immunity of signal reception and reliability of detection of substances. This is achieved by suppressing false signals (interference) received on the mirror channels and Raman channels due to the correlation processing of the received signals.

Claims (1)

A method for remotely detecting a substance using remote excitation by an electromagnetic wave of magnetic resonance in a substance and then measuring a response frequency, by the presence of which it is concluded that the substance is present, while the exciting electromagnetic signal is emitted at a frequency much higher than the magnetic resonance frequency of the substance to be detected, and modulate the emitted exciting electromagnetic signal by polarization at the frequency of the magnetic resonance, and the response is recorded at the modulation frequency, electromagnetic sounding of the alleged place of the narcotic substance by a plane-polarized signal and reception of signals with the right and left circular polarization reflected from the narcotic substance in the covering medium are carried out, while the reflected signal with the right circular polarization is gated in time proportional to the depth of the narcotic substance and signal reflected left circularly polarized light is converted in frequency by using frequency w _z1 first geterodi and is isolated first voltage intermediate frequency, and then emit the harmonic voltage at a stable frequency w _r1 of the first local oscillator is measured by the phase shift between the reflected signals from the right and left circular polarization to a stable frequency w _r1 of the first local oscillator, comparing the measured phase shift to a reference value and according to the result of the comparison, they decide on the presence of a narcotic substance in the covering medium, characterized in that the reflected signal with left circular polarization is simultaneously converted in frequency those using frequency w _r2 of the second local oscillator is isolated second voltage intermediate frequency multiply it with the first voltage of the intermediate frequency, allocate a low-frequency voltage proportional to the correlation function R (τ), compare it with a threshold voltage U _pores and in case of exceeding permit further processing received signals, which begins with the multiplication of the first intermediate frequency voltage with the reflected signal of the right circular polarization, and the frequencies w _g1 and w _{g2 of the} first and second get Nuclei spaced at twice the intermediate frequency
w -w _{r2 r1} = 2w _up
and choose symmetric with respect to the frequency w _{c of the} main receiving channel
w _c -w _g1 = w _g2 -w _c = w _up .

Images