RU2589886C1 - Apparatus for probing building structures - Google Patents

Abstract

FIELD: radar ranging and radio navigation.

SUBSTANCE: device relates to subsurface radar ranging, namely to devices for determining location and shape of inhomogeneities and inclusions in building structures and facilities, and can be used in different fields of vital activity. Said result is achieved by the fact that device comprises a portable computer (PC), surface of building structure, electronic unit, antenna unit, high-frequency generator, controller over processing and computer data input, high-frequency signal receiver, transmitting antenna, receiving antenna, object, trigger, correlator, amplifier, delay line, subtractor, integrator, two dividers, reference voltage generating unit, comparator unit, analogue-to-digital converter, interface, switch, liquid-crystal display, audio indicator, automatic controlled delay unit, commutator, low-pass filter, extreme controller, depth indicator of subsurface object and adder, connected to each other in certain manner.

EFFECT: high accuracy of measuring depth of subsurface object location by increasing curvature of correlation function in area of its maximum.

1 cl, 1 dwg

Description

The proposed device relates to the field of subsurface radar, and in particular to devices for determining the location and shape of heterogeneities and inclusions in building structures and structures, and can find application in the following areas:

- counterintelligence activities to identify listening devices;

- operational-search activities of law enforcement agencies;

- sounding of building structures in order to determine the position of reinforcement, voids and other heterogeneities;

- sounding of especially important building structures (runways of airfields, bridges, passages, subway tunnels, stations, stadiums, rocket launching launching sites, etc.) in order to identify hidden defects in them.

Known devices and sensing systems for building structures (ed. Certificate of the USSR No. 321.783, 344.391, 385.251, 397.877, 455.307, 708.277, 746.370, 817.640, 1.078.385, 1.092.453, 1.100.603, 1.151.900, 1.300.396 , 1.594.477, 1.721.566; RF patents No. 2.044.331, 2.105.330, 2.121.671, 2.158.015; 2.234.694, 2.228.875, 2.375.729, 2.460.090; German patent No. 2.360. 778; Japan patent No. 57-17.273; Petrovsky AD Radio wave methods in underground geodesy. - M., 1971; Dikarev V.I., Zarenkov V.A., Zarenkov D.V. Methods and means of detecting objects in covering Wednesdays. - SPb .: Science and technology, 2004. - 280 p. and others).

Of the known systems and devices, the closest to the proposed one is the “Device for sensing building structures” (RF patent No. 2,460.090, G01S 13/88, 2011), which is chosen as the base object.

The known device allows to increase the resolution, reliability of detection and identification of heterogeneities and inclusions in building structures. This is achieved by eliminating reflections from the air - building structure interface, the quasi-stationary component, periodic variations in the Earth's electromagnetic field, and using a sequence of radio pulses with a small number of periods of high-frequency oscillations in each of them (up to one).

The known device provides an increase in the reliability of detection and identification of subsurface objects. This is achieved by automatically determining the depth of the subsurface objects using the correlation function R (τ) of the probing and reflected signals.

However, the known technical solution, realizing the measurement of time delay

,

,

where h is the depth of the subsurface object;

c is the propagation velocity of radio waves,

to the maximum of the correlation function R (τ), has low accuracy, since a typical dependence of the coefficient of the correlation function is described by the expression

where f is the signal frequency,

has insufficient steepness in the region of maximum.

An object of the invention is to increase the accuracy of measuring the depth of the subsurface object by increasing the steepness of the correlation function in the region of its maximum.

The problem is solved in that the device for sensing building structures, containing, in accordance with the closest analogue, a series-connected high-frequency generator made in the form of a shock excitation generator, and a transmitting antenna, a series-connected receiving antenna, a high-frequency signal receiver, a key, the second input of which the trigger is connected to the second output of the high-frequency generator, an amplifier, a delay line, a subtraction unit, the second input of which is connected to the output of the amplifier, and an integrator, a first division unit, the second input of which is connected to the output of the subtraction unit, a comparison unit, the second input of which is connected to the output of the unit for generating the reference voltage, and an analog-to-digital converter, the output of which is connected via an interface to a portable computer, while the corresponding outputs of the interface are connected to a high-frequency generator, a receiver of a high-frequency signal, a unit for generating a reference voltage, sound and liquid crystal indicators, the transmitting and receiving antennas are combined into an antenna unit, an automatic adjustable delay unit, a multiplier, the second input of which is connected to the output of the high-frequency signal receiver, and a low-pass filter, the output of the extreme controller is connected to the second input of the automatic adjustable delay unit, the second output of which is connected to the second the trigger input and to the depth indicator of the subsurface object, differs from the closest analogue in that it is equipped with a second unit and an adder, moreover, a second division unit is connected to the output of the low-pass filter, the logical unit is fed to the second input of it, and an adder, to the second input of which is a logical negative unit, and the output is connected to the input of the extreme controller.

The structural diagram of the device for sensing building structures is shown in the drawing. The device includes: 1 - portable computer; 2 - surface of a building structure; 3 - an electronic unit comprising a high-frequency generator 5 and a receiver 7 of a high-frequency signal; 4 - antenna unit, including spatially combined transmitting antenna 8 and receiving antenna 9, 6 - controller for processing and entering data into a computer; 10 - an object, which can be building reinforcement, voids and other heterogeneities, various defects, listening devices, etc .; 12 - correlator, 14 - delay line; 13 - amplifier; 15 - subtraction unit, 16 - integrator, 17 - first division unit, 18 - reference voltage generating unit, 19 - comparison unit, 20 - analog-to-digital converter, 21 - interface, 22 - key, 24 - sound indicator, 23 - liquid crystal indicator, automatic adjustable delay unit 25, multiplier 26, low-pass filter 27, extreme regulator 28, subsurface object depth indicator 29, second division unit 30, and adder 31.

Moreover, a transmitting antenna is connected to a high-frequency generator 5. A receiver 7 of a high-frequency signal, a key 22, the second input of which is connected to the output of the trigger 11, an amplifier 13, a delay line 14, a subtraction unit 15, the second input of which is connected to the output of the receiving antenna 9, is connected in series. the output of the amplifier 13, the integrator 16, the division unit 17, the second input of which is connected to the output of the subtraction unit 15, the comparison unit 18, the second input of which is connected to the output of the reference voltage generating unit 19, an analog-to-digital converter l 20, and interface 21 of computer 1. The respective outputs of the interface 21 are connected to a high frequency generator 5, RF signal receiver 9, the block 19 forming the reference voltage, the liquid crystal 24 and audio 23 indicators.

To the output of the high-frequency signal receiver 7, a multiplier 26 is connected in series, the second input of which is connected via the automatic adjustable delay unit 25 to the second output of the high-frequency generator 5, a low-pass filter 27, a second divider 30, an adder 31, and an extreme controller 28, the output of which is connected to the second input block 25 automatic adjustable delay, the second output of which is connected to the second input of the trigger 11 and the indicator 29 depth of occurrence of the subsurface object.

The automatic adjustable delay unit 25, the multiplier 26, the low-pass filter 27, the second division unit 30, the adder 31 and the extreme controller 28 form a correlator 12.

The principle of operation of the device is based on the method of ultra-wideband radar sounding of building structures, in which the change in the unsteady electromagnetic field formed by reflected from various inhomogeneities and inclusions by electromagnetic waves after their irradiation with a probing radio signal is estimated, which is used as a sequence of radio pulses with a small number of periods of high-frequency oscillations in each of them (up to one). The probing ultra-wideband radio signal is generated by the shock excitation generator 5 and the transmitting antenna 8. At the interface, the building structure is a heterogeneity characterized by a jump in the relative permittivity and specific attenuation, a reflected radio signal is formed, which returns to the receiving antenna 9. The received ultra-wideband radio signal using a stroboscopic receiver time-scale conversion and digitization, convenient for presentation and processing. The digital signal contains information about the location of the heterogeneity and inclusions, as well as their shape, material, etc. The selection of useful information is carried out by processing in computer 1 and displayed on the screen of the visual indicator 23 in real time.

A device for sensing building structures works as follows.

The main mode of operation of the device is the "Search" mode. This mode is set automatically when the device is turned on and is used when searching and recognizing various heterogeneities and inclusions in building structures.

When the voltage is turned on, the initial modes of all units of the device are established. At the command of the computer 1, the shock excitation generator 5 generates a probe ultra-wideband signal in the form of a single sine wave amplitude of 20 B and a duration of 1 ns, emitted by the transmitting antenna 8 in the direction of the surface 2 of the building structure.

Detection of heterogeneities and inclusions in the "Search" mode is carried out by the operator by moving from left to right, back and forth of the antenna unit 4, mounted on a rod and including spatially combined transmitting 8 and receiving 9 antennas. In this case, it is necessary to ensure that the antenna unit 4 moves parallel to the examined surface 2 of the building structure at a fixed distance (5 ... 10 cm from it). The speed of movement of the antenna unit 4 is selected depending on the search conditions and the configuration of the building structure. In this case, it is necessary to ensure that the entire inspected area of the surface 2 of the structure is examined.

An electromagnetic wave reflected from the inhomogeneity 10 acts on the receiving antenna 9. This antenna is also affected by the direct radiation interfering with the generator 5 and the reflected signal from the air-building interface. Part of the energy of the probe signal from the second output of the high-frequency generator 5 is supplied to the first input of the trigger 11, which is translated into the first (zero) state. The output of the trigger 11 is formed negatively voltage.

The reflected signal containing information on the interface between media and heterogeneity 10, from the output of the receiving antenna 9 is fed to the first input of the receiver 7, the second input of which is supplied via the interface 21 with a short strobe pulse from computer 1.

Part of the energy of the probe signal from the second (reference) output of the high-frequency generator 5 is simultaneously supplied through the automatic adjustable delay unit 25, which provides a variable time delay τ, to the first input of the multiplier 26, to the second input of which the reflected signal from the output of the receiver 7, the delay time of which is determined expression:

,

,

where h is the depth of the subsurface object;

C is the propagation velocity of radio waves.

The voltage obtained at the output of the multiplier 26 is passed through a low-pass filter 27, at the output of which a correlation function R (τ) is formed.

Calculation of the ratio of the coefficient ρ (τ) of the correlation function to a unit value gives the following expression:

In turn, comparing expression (2) with a single value leads to the expression

The steepness of the process (3) is equal to

and the famous device has a steepness

An estimate of the steepness increase in expression (3) in comparison with (1) gives

An analysis of this expression shows that increasing the steepness, and hence the accuracy of measuring the depth and location of a subsurface object, as an argument to function (3).

The extreme controller 28, designed to maintain the maximum value of the correlation function R (τ) and connected to the output of the low-pass filter 27, acts on the control input of the automatic adjustable delay unit 25 and maintains the delay τ introduced by it equal to τ ₃ (τ = τ ₃ ), which corresponds to the maximum value of the correlation function R (τ).

The scale of the indicator 29, connected to the second output of the block 25 automatic adjustable delay, allows you to directly read the measured value of the depth of the subsurface object in the building structure.

.

.

The pulse generated at the second output of block 25 of the automatic adjustable delay corresponding to the time delay τ> τ ₃ is supplied to the second input of trigger 11.

The latter is transferred to the second (single) state, in which a positive voltage is formed at its output. This voltage is supplied to the control input of the key 22 and opens it. In the initial state, key 22 is always closed. The correlator 12 automatically determines the depth of the subsurface object and eliminates the influence of direct radiation of the transmitting antenna 8 and signals reflected from the air-building structure and from layers of different depths, i.e. “vertical gating” is carried out, which provides sequential viewing of the subsurface space of the building structure from the air - building structure interface to layers of various depths.

“Horizontal gating” allows against the background of electromagnetic field variations, not related to the electromagnetic wave reflected from the inhomogeneity or inclusion, to reliably isolate heterogeneity, inclusion, etc. in the subsurface layers of the building structure. To exclude the influence of periodic and quasi-stationary variations of the Earth’s electromagnetic field, a periodic measurement of the field strength and the normalization of the difference signal of two successive measurements are carried out, i.e. the difference signal is integrated, the difference signal is divided into the integrated difference signal. The operation of comparing a normalized signal with a given threshold value allows you to make a decision about the presence or absence of heterogeneity or inclusion.

For this, the pulse generated in the receiver 7, which is the instantaneous value of the received periodic signal reflected from the inhomogeneity 10, through the public key 22 after amplification in the amplifier 13 is fed to the subtraction unit 15 directly and through the delay line 14. Moreover, at each observation point, at least two consecutive measurements of these pulses are made. Then, the operation of subtracting two consecutive measurements is performed. For this, the pulse corresponding to the previous measurement is delayed by the delay line 14 until it is compared with the subsequent pulse in the subtraction unit 15. The operations of integrating the difference signal and dividing the difference signal by the integrated difference signal are performed in blocks 16 and 17. In block 18, the normalized signal is compared with the threshold value of the signal generated by block 19. When the threshold level is exceeded, the signal is input to the analog-to-digital converter 20, where it is converted to digital form and enters through the interface 21 on the computer 1.

After analog-to-digital conversion, the data through the interface board 21 enters the computer 1, and then on the screen of the liquid crystal display 23, the vertical (horizontal) and horizontal (frame) frequencies of which can vary within certain limits. On the screen of the indicator 23 in real time there is a flat brightness picture of the heterogeneity and inclusions of the investigated building structure.

The maximum amplitude of the received signal is compared with the set threshold value, above which the audible indicator 24 is turned on.

The appearance of an audio signal and a visual signal on the screen requires the operator to stop and indicates that there is heterogeneity and inclusion in the detection area of the antenna unit 4, the nature of the origin of which should be established and, if necessary, clarified its location and shape.

To analyze the detected heterogeneity, it should be scanned (moving the antenna unit 4 from the detection boundary to the loss boundary) at a speed determined by the light bar on the indicator screen 23. The Scan mode and the formation of a vertical slice of the building structure with the detected heterogeneity are carried out by switching from the Search mode ”By pressing the“ Scan ”button located on the front panel of the device. 20 s after signal processing, the radar image of the heterogeneity or inclusion appears on the screen of the indicator 23, giving an idea of the shape and size of the heterogeneity (inclusion).

At the request of the operator, the contrast of the image can be changed with the corresponding buttons in the direction of increase or decrease.

To identify the detected heterogeneity with the existing standards, the operator needs to turn to the trained algorithm, while on the screen of the indicator 23, when identifying the detected heterogeneity with the reference available in the computer memory 1, the corresponding name is displayed, for example, "heterogeneity No. 2". In case of discrepancy, the message “heterogeneity is not recognized” is displayed.

To determine the material of the detected heterogeneity (inclusion), the operator, by pressing the appropriate button, proceeds to the basic algorithm. A message about the type of material is displayed on the screen: “Metal”, “Composite”, “Plastic”, etc.

By pressing the “Scan” button and moving the antenna unit 4 over the heterogeneity (inclusion), it is possible to conduct a repeated examination of the heterogeneity (inclusion) if necessary according to the criterion of the basic and trained algorithms.

The identification of the detected heterogeneity (inclusion) by the trained algorithm, the recognition of the type of material by the basic algorithm, the analysis by the operator of the image and the “slice” of the heterogeneity (inclusion) allows the operator to decide on further actions regarding the detected heterogeneity (inclusion) and to continue exploration.

The interaction of the computer 1 with the other nodes of the device, as well as the organization of the management of work is carried out through the interface circuit 21.

Controls, switching and indication are placed on a common control panel. Various options for using the display in search mode, as well as the operation of the device in auxiliary modes, do not change the essence of the described physical processes, but are determined only by the computer program 1.

The proposed device allows to increase the accuracy, resolution, reliability of detection and identification of heterogeneities and inclusions in building structures. This is achieved by eliminating reflections from the air - building structure interface, the quasi-stationary component, periodic variations in the Earth's electromagnetic field, and using a sequence of radio pulses with a small number of periods of high-frequency oscillations in each of them (up to one).

The use of short duration signals as probing signals determines a number of specific features of their registration. However, the periodicity of the reflected signals allows the use of a stroboscopic method of signal processing. The essence of this method lies in the fact that the registration is carried out not of the investigated signal itself, but of its individual samples, each of which is formed at different repetition periods of the given signal.

Thus, the proposed device in comparison with the base object and other technical solutions for a similar purpose provides an increase in the accuracy of measuring the depth of the subsurface object in K times. This is achieved by increasing the steepness of the correlation function in the region of its maximum in K times in comparison with the prototype.

Claims (1)

A device for sensing building structures, comprising a serially connected high-frequency generator made in the form of a shock excitation generator, and a transmitting antenna, serially connected a receiving antenna, a high-frequency signal receiver, a key, the second input of which is connected via a trigger to the second output of the high-frequency generator, an amplifier, a delay line, a subtraction unit, the second input of which is connected to the output of the amplifier, an integrator, the first division unit, the second input of which is connected to the output of the amplifier and a subtraction, a comparison unit, the second input of which is connected to the output of the reference voltage generating unit, and an analog-to-digital converter, the output of which is connected via an interface to a portable computer, while the corresponding outputs of the interface are connected to a high-frequency generator, a high-frequency signal receiver, and a reference voltage-generating unit , sound and liquid crystal indicators, the transmitting and receiving antennas are combined in the antenna unit, to the second output of the high-frequency generator, sequentially an automatic adjustable delay unit, a multiplier, the second input of which is connected to the output of the high-frequency signal receiver, and a low-pass filter, the output of the extreme controller is connected to the second input of the automatic adjustable delay unit, the second output of which is connected to the second input of the trigger and to the depth indicator of the subsurface object characterized in that it is equipped with a second division unit and an adder, and the second block de is connected in series to the output of the low-pass filter a line, to the second input of which a logical unit is supplied, and an adder, to the second input of which a logical negative unit is supplied, and the output is connected to the input of the extreme controller.

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