RU2499277C1 - Pulsed nonlinear radar - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: device consists of a probing signal transmitter, receivers tuned to double and triple the frequency of the probing signal, a control unit, a processing unit, a control and display panel, an antenna unit, a broadband receiver, a spectrum analyser and a display for the spectrum analyser, connected to each other in a certain manner.

EFFECT: high information value when scanning an area for radio-controlled explosives by detecting an oscillatory circuit in the inspected facility and determining resonance frequency thereof.

Description

The invention relates to technical means of protection and can be used to search for radio-controlled explosive devices (RVU).

Currently, a large number of devices have been developed for the search for electronic devices [1, 2, 4].

Confidently identify a radio signal using a scanning receiver [1]. It is possible to increase the efficiency of using the receiver by connecting it to a portable frequency counter. In this case, the frequency meter detects radiation in the near zone, automatically tunes the receiver to the found frequency and makes it possible to listen to the found signal.

It is much more convenient to use spectrum analyzers. When using them, the operator can not only listen to the signal, but also visually record it. With a certain experience, the operator can reliably classify him as known or suspicious in terms of signal shape, amplitude and location in the frequency range. Some analyzers allow you to observe the picture of the distribution of signals in a fairly wide frequency band (several hundred megahertz) and allow you to quickly register new dangerous sources of radio emissions.

However, the use of scanning receivers does not make it possible to detect non-emitting devices and devices working for reception, and even more so, the frequency at which the input oscillating circuit of the receiver of the RVU is tuned.

The use of pulsed nonlinear radars [2] allows you to detect hidden devices that do not currently emit a radio signal, electronic devices.

To search for radio-controlled explosive devices, pulsed nonlinear radars (INRL) are used [2, 3].

The principle of operation of pulsed nonlinear radars is based on the effect of excitation of the pn junction of a semiconductor when it enters the zone of powerful radio emission. All electronic products have semiconductors in their composition: microcircuits, transistors, diodes, therefore, sensing these products with a powerful radio signal leads to the excitation of the pn junction of the semiconductor and reemission of the signal, and the non-linear nature of the current-voltage characteristic of the pn junction leads to the appearance of many harmonics at frequencies multiples of the sounding signal frequency. According to the harmonic series, the amplitude of the second harmonic will exceed the amplitude of the third.

By registering signals at frequencies corresponding to the second and third harmonics with the aid of a pulsed nonlinear radar receiver, and observing the picture of a decrease in the signal amplitude towards higher harmonics, it is possible to attribute the object under study to a radio-electronic means. Thus, when irradiating electronic devices in the spectrum of the re-emitted signal, as a rule, even harmonic components of the probe radiation prevail (2nd harmonic).

The contacts of metal objects, especially those subjected to corrosion, also have semiconductor properties. When such objects are irradiated, in the spectrum of the reradiated signal, as a rule, the odd harmonic components of the probe radiation predominate (3rd harmonic).

By the ratio of the levels of the response signals at the frequencies of the second and third harmonics of the sounding frequency, objects containing electronic circuits with semiconductor elements can be distinguished from objects made of metal.

Known for the widely used portable nonlinear transition detector "NR-900EK", which is a pulsed nonlinear radar consisting of a probe signal transmitter, two receivers tuned to double and triple the frequency of the transmitter signal, control unit, processing unit, control and display panel, and antenna unit (receiving and transmitting). [4, 5] The structural diagram of a pulsed nonlinear radar NR-900 EC is shown in figure 1 [4].

The control and display panel contains two lines of 16 LEDs of red and green colors, indicated by the numbers "2" and "3" (indicators of the levels of received signal-response signals of the probing signal, respectively), a button and an indicator of changes in radiated power "max", three buttons for attenuating the levels input signals of receivers ("-10", "-20", "-30") with indicators and a power on / off button for the product with an indicator.

Using the control and display panel, the radiation power level of the transmitter of the probe signal (maximum or minimum) is set through the control unit, and the attenuation level of the input signals of the receivers (10, 20 and 30 dB) is set through the processing unit.

The control unit controls the operation of the transmitter of the probe signal, two receivers of the 2nd and 3rd harmonics, the processing unit and the control and display panel, connecting and disconnecting the units to ensure the operation of the tool [2, 3]. At the time of operation of the device to radiation to prevent the failure of the units, the receivers of the 2nd and 3rd harmonics and the processing unit are turned off. At the time of operation of the device for receiving the re-emitted signal, the transmitter of the probing signal is turned off, and the receivers of the 2nd and 3rd harmonics and the processing unit turn on and begin to work.

The monoharmonic probe signal generated by the transmitter is supplied to a directional transmitting antenna and is radiated in the direction of the object being examined. On non-linear (semiconductor) elements of the object under examination, the probing signal is converted to polyharmonic and re-emitted.

The re-emitted signal is received by the receiving antenna and fed to the inputs of the receivers, which emit signals of the 2nd and 3rd harmonics of the sounding frequency. From the receivers, the selected signals arrive for further processing in the processing unit. After processing the received signals in the processing unit, their levels are displayed on the LED indicators of the control and display panel.

The decision on the type of object is made by the ratio of the levels of the response signals at the frequencies of the 2nd and 3rd harmonics of the sounding frequency.

The disadvantages of INRL NR-900 EC are the inability to determine the type of electronic device and the high sensitivity to artificial interference characteristic of the locations (bookmarks) of radio-controlled explosive devices. Such interference includes semiconductor devices elements left in place by performers, metal parts having special galvanic coatings or traces of corrosion, rust, elements and materials having non-linear characteristics. These obstacles reduce the pace of intelligence by engineering units of the federal forces by about three times, and, consequently, the effectiveness of combat missions [4].

The aim of the invention is to increase the efficiency of the search for DGS.

To achieve this goal, the problem is solved - the creation of a pulsed nonlinear radar of increased information content.

One of the ways to increase the informativeness of an INRL is to determine the presence of an oscillatory circuit, which is part of the RVU transceiver and its resonant frequency.

To determine the resonant frequency of the oscillatory circuit, a parametric location is successfully used. [3] However, the use of parametric location in NRL significantly increases its complexity and cost.

The studies showed that during the irradiation of the transceiver with a monoharmonic probe signal in the oscillatory circuit of the RVU receiver, the oscillation circuit is excited and the signal is re-emitted in the form of a response at the resonant frequency of the oscillatory circuit.

This phenomenon occurs as follows. Under the influence of a probe pulse, energy is stored in the oscillatory circuit, under the influence of which forced damped oscillations are excited at the resonant frequency of the circuit. The decay rate of these oscillations depends on the quality factor of the oscillatory circuit (the higher the quality factor, the longer the self-oscillations last) [6].

Increasing the information content of a nonlinear radar consists in making it possible to determine the presence of an oscillatory circuit, which is part of the RVU transceiver, and its resonant frequency. Thus, the information content of the nonlinear radar during the search is increased.

To increase the information content of a pulsed nonlinear radar, it is proposed to supplement the existing NR-900EK NRL device containing a probe signal transmitter, two receivers tuned to the double and triple frequency of the transmitter signal, a control unit, a processing unit, an antenna unit (receiving and transmitting), and a control and indication panel , broadband receiver, spectrum analyzer and spectrum analyzer indicator.

The invention is illustrated by drawings, where:

- figure 1 presents the structural diagram of INRL NR-900 EC [4, 5];

- figure 2 is a structural diagram of the proposed pulsed nonlinear radar.

The proposed device consists of a transmitter 1 of the probing signal, receivers 2 and 3 (2nd and 3rd harmonics of the probing signal, respectively), tuned to double and triple the frequency of the signal of the transmitter 1, respectively, control unit 4, processing unit 5, control panel 6 and indication, block 7 antennas, broadband receiver 8, spectrum analyzer 9 and spectrum analyzer indicator 10.

Receivers 2 and 3 are designed to amplify the response signal received from the antenna and to extract its even and odd harmonics. Receiver 2 is tuned to isolate from the received signal response equal to twice the frequency of the transmitter signal (2nd harmonic), and receiver 3 is tuned to triple the frequency of the transmitter signal (3rd harmonic). From the outputs of the receivers 2 and 3, the received signals are fed to the processing unit 5.

The control unit 4 controls the operation of the transmitter of the probe signal, receivers 2 and 3, the broadband receiver 8, the processing unit 5, the control and indication panel 6, and connects and disconnects the units to ensure the operation of the means. The control unit 4 is controlled by the controls of the control and indication panel 6, on which the radiation power of the transmitter 1 of the probe signal and the attenuation level of the output signals of receivers 2 and 3 in the processing unit 5 are set.

The control and display panel 6 contains two lines of 16 red and green LEDs, indicated by the numbers “2” and “3” (indicators of the level of received signal-responses of the 2nd and 3rd harmonics of the probing signal, respectively), the “max” button and an indicator of the change in the radiated power of the transmitter 1 of the probe signal, three buttons for attenuating the levels of the input signals of receivers 2 and 3 ("-10", "-20", "-30") with indicators and an on / off button for powering the product with an indicator. To ensure the operation of the spectrum analyzer 8, an additional toggle switch for turning on the power of the spectrum analyzer 8 is installed on the control and indication panel 6. The level indicators of the received signals of responses of the 2nd and 3rd harmonics display the levels of signals coming from receivers 2 and 3. According to the ratio of the signal levels of the 2nd and 3rd harmonics, objects containing electronic circuits with semiconductor elements are distinguished, and objects made of metal.

The transmitter 1 of the probe signal at the command of the control unit 4 generates short probing radio frequency pulses specified from the control panel 6 and the power indication, which are supplied to the directional transmitting antenna of the unit 7 of the antennas and are radiated in the direction of the object being examined.

Block 7 antennas consists of a receiving and transmitting antennas located in one housing coaxially. The transmitting antenna is connected to the transmitter 1 of the probing signal and is intended for directional emission of a monoharmonic signal in the direction of the object being examined. The receiving antenna of the antenna unit 7 is designed to receive response signals from objects irradiated with a sounding signal. The re-emitted response signals received by the receiving antenna are fed to the inputs of receivers 2 and 3 and broadband receiver 8. To prevent the failure of these receivers during the transmission of the probing signal, they are disconnected by the control unit 4 from the antenna unit 7. Thus, the control unit 4 controls the operation of the transmitting and receiving parts of a pulsed nonlinear radar.

Processing unit 5 is intended for processing signals from receivers 2 and 3, and determining their levels with subsequent transmission of these signals to the control and indication panel 6. The processing unit 5, using the attenuation coefficients set by the controls of the control and indication panel 6, processes the signals from the receivers and determines their levels, with the subsequent display of these levels on the indicators of the control and indication panel 6.

According to the signal from the control unit 4, the broadband receiver 8 is simultaneously connected to the receivers 2 and 3 to the receiving antenna of the antenna unit 7. It is tuned to the frequency band in which the transceiver devices used to control the radio-controlled explosive devices operate. From the output of this receiver, the signal goes to the spectrum analyzer 9.

The spectrum analyzer 9 is intended for spectral analysis of a signal that falls into the passband of a broadband receiver 8. A fast Fourier transform is used to analyze the signal spectrum. The response signal coming from the oscillatory circuit of the detection object (if present in the detection object) has a resonant frequency of the oscillating circuit. The signal is not present continuously, but appears simultaneously with the re-emitted response signal from the semiconductor elements. The frequency value of this signal is displayed on the indicator 10 of the spectrum analyzer. To reduce energy consumption, the inclusion of the spectrum analyzer 9 occurs from the control panel 6 of the display.

The indicator 10 of the spectrum analyzer displays the spectrum received by the broadband receiver 8 and processed by the analyzer 9 of the signal spectrum. If there is an oscillatory circuit in the detection object, the value of its resonant frequency appears on the indicator. By the presence of a resonant frequency in the signal, it is concluded that there is an oscillatory circuit in the detection object and, therefore, the nature of the detected object.

The device operates as follows.

After switching on and supplying the supply voltage to the device, the control units of the control and indication panel 6, through the control unit 4, the power level (maximum or minimum) of the radiation of the transmitter 1 of the probe signal is set, and through the processing unit 5, the attenuation value (10, 20 and 30 dB) of the levels input signals of receivers 2 and 3.

In the radiation mode, the transmitter 1 of the probing signal, remote control 6 and display. To prevent the failure of receivers 2 and 3, broadband receiver 8 and processing unit 5 for the duration of the transmission of the probing signal, they are disconnected from the antenna unit 7 by the control unit 4.

At the time of reception of the re-emitted signal, receivers 2 and 3 are operating, tuned to double and triple the frequency of the signal of the transmitter 1 of the probing signal, respectively, a broadband receiver 8, a processing unit 5, and a control and indication panel 6. To reduce power consumption, the inclusion of the spectrum analyzer 9 occurs from the control panel 6 by the operator. Thus, the control unit 4 controls the operation of the transmitting and receiving parts of the nonlinear radar.

The control unit 4 controls the operation of the transmitter 1 of the probe signal, receivers 2, 3 and 8 and the processing unit 5. The probe signal transmitter 1, upon command from the control unit 4 and taking into account the control panel 6 for controlling and indicating the radiation power level, forms short sounding radio frequency pulses that are transmitted to the directional transmitting antenna of the antenna unit 7 and radiated towards the object being examined.

On non-linear (semiconductor) elements and the oscillatory circuit (if any) of the object under examination, the probe signal is converted to a polyharmonic signal and re-emitted.

The re-emitted signal-response received by the receiving antenna is fed to the inputs of receivers 2 and 3, where the signals of the second and third harmonics of the sounding frequency are amplified and extracted. In receiver 2, a signal is extracted equal to twice the frequency of the signal of transmitter 1 of the probe signal (2nd harmonic), corresponding to the response signal from electronic devices, and in receiver 3, a signal equal to three times the frequency of the signal of the transmitter (3rd harmonic) corresponding to a response signal from metal objects, especially those subjected to corrosion. The re-emitted signal-response received by the receiving antenna also arrives at the input of the broadband receiver 8, which receives the signal from the oscillatory circuit of the object, arising from the action of the pulse non-linear locator on the probe circuit. From the outputs of the receivers 2 and 3, the selected signals are fed to the processing unit 5. From the output of the broadband receiver 8, the signal goes to the spectrum analyzer 9.

The processing unit 5, using the attenuation coefficients of the input signal levels of the receivers (10, 20 and 30 dB) established by the control and indication panel 6, processes the signals from the receivers and determines their levels with the subsequent transmission of these signals to the control and indication panel 6. On the corresponding indicators of the control and indication panel 6, these levels are displayed. The control and indication panel 6 has two signal level indicators (16 red and green LEDs, indicated by the numbers "2" and "3", respectively, indicating the level of the received response signals of the 2nd and 3rd harmonics of the probe signal). By the ratio of the signal levels of the 2nd and 3rd harmonics, the operator distinguishes between objects containing electronic circuits with semiconductor elements and objects made of metal.

Upon receipt of a signal about the presence of semiconductor elements in the object of study, the operator includes a spectrum analyzer. The spectrum analyzer 9 processes the response signal amplified by the broadband receiver 8. If there is an oscillating circuit in the test object, the signal at its resonant frequency is present in the response signal. The result of the operation of the spectrum analyzer 9 is displayed on the indicator 10 of the spectrum analyzer.

The combination of all signals allows the operator to determine the nature of the detected object, the presence in the object of the survey of the oscillatory circuit and determine its resonant frequency.

The proposed pulsed non-linear radar can increase the information content when performing the tasks of reconnaissance of the terrain (objects) for the presence of RVD by fixing the presence of the oscillatory circuit in the survey object and determining its resonant frequency. This makes it possible to increase the efficiency of the search for the DOC and to more effectively apply the means of suppressing the radio control channel of the DOC.

LIST OF USED LITERATURE

1. Website http://www.aor.ru/aor/2000.htm.

2. Website http://www.mordvinovoe.narod.ru/poisk.htm.

3. Dikarev V.I. Methods and means of detecting objects in covering environments / V.I. Dikarev, V.A. Zarenkov, D.V. Zarenkov. - St. Petersburg: Science and Technology, 2004. - 280 p.

4. Portable detector of nonlinear transitions "NR-900EK" / Operation manual. UTDN 468165003 RE. - CJSC “Protection Group - UTTA”.

5. Internet site http://www.detektor.ru.

6. Yavorsky B.M. Handbook of Physics / B.M. Yavorsky, A.A. Detlaf // 2nd ed., Rev. - M .: Nauka, 1985 .-- 512 p.

Claims (1)

A pulsed nonlinear radar comprising a probe signal transmitter, 2nd and 3rd harmonic receivers, a control unit, a processing unit, a control and display panel and an antenna unit in which the control unit is connected to the probe signal transmitter to set the desired level of the emitted signal, receivers 2nd and 3rd harmonics and a processing unit for synchronizing operation with a probe signal transmitter, a control and display panel for displaying the state of parameters of the emitted and received signals, the output is transmitted The probe signal is connected to the input of the antenna unit (transmitting antenna) to emit a signal in the direction of the object of study, the output of the antenna unit (receiving antenna) is connected to the inputs of the 2nd and 3rd harmonics receivers for receiving signals reflected from the objects being examined, outputs of the receivers 2 the 3rd and 3rd harmonics are connected to the input of the processing unit to detect the presence of semiconductors and metals in the object under examination, the output of the processing unit is connected to the input of the control and display panel to display information about the presence of semiconductors monitors and metals in the object of study, the output of the control and display panel is connected to a processing unit for setting sensitivity thresholds in it and a control unit for controlling the power of the emitted signal, characterized in that a broadband receiver, a spectrum analyzer and a spectrum analyzer indicator are introduced, where the broadband input the receiver is connected to the output of the antenna unit, the output of the broadband receiver is connected to the input of the spectrum analyzer, the output of the spectrum analyzer is connected to the indicator input a spectrum analyzer, while to ensure the operation of the device, the broadband receiver is connected to the control unit, and the spectrum analyzer is connected to the control and display panel.

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