CN106199535B - It is a kind of to switch the method and device for generating high-voltage pulse radar signal based on photoinduction - Google Patents

Abstract

The invention discloses a method and a device for generating a high-voltage pulse radar signal based on an optical induction switch. The method includes: 1) generating an induced laser pulse signal, which is divided into two paths after passing through an optical coupler; 2) making the two paths of induced laser pulse signal generate a forward wave and a reverse wave through an optical inductive switch; 3) passing a time delay The control module adjusts the relative time delay between the forward wave and the reverse wave to generate a radar signal with adjustable pulse width. The device includes: an induction laser control circuit, which outputs the generated induction laser pulses as two induction laser pulse signals; a pulse generation circuit, which generates two pulses in opposite directions, and outputs a radar signal with adjustable pulse width. The invention has higher stability and repeatability, so that the generated radar signal has better quality and smaller waveform tailing. In actual detection, the pulse width of the ground-penetrating radar signal can be adjusted automatically or manually to achieve a high Adaptive and targeted optimal resolution detection.

Description

A method and device for generating high-voltage pulse radar signals based on an optically induced switch

technical field

The invention belongs to the technical field of ground penetrating radar, and in particular relates to a method and a device for generating high-voltage pulse radar signals based on an optical induction switch.

Background technique

The mechanism of ground-penetrating radar equipment and technology for underground target detection is to analyze and infer according to the echo signal amplitude, time, frequency characteristics and other parameters by emitting high-frequency electromagnetic pulse waves, using the difference in electrical parameters between the underground target and the surrounding medium. Information such as the spatial position, depth and size of underground targets. GPR is an efficient shallow geophysical detection technology. Different from airsonde radar, the frequency used by GPR is generally lower than that of the former. Its theoretical research is mainly on the propagation of electromagnetic waves in lossy media. Uniformity, anisotropy, strong attenuation, etc., its complexity is much greater than that of sounding radar. Compared with traditional geophysical methods, ground penetrating radar has the advantages of quickness, simple operation, strong anti-interference and site adaptability, and high detection resolution. Especially since the 1970s, with the rapid development of computer and microelectronic technology, ground penetrating radar has been generally improved in terms of equipment and data processing, and its application range has been continuously expanded. In geology, engineering, resources, environment, military and other aspects.

Ground penetrating radar is generally composed of electromagnetic pulse signal generation circuit, transceiver antenna, signal acquisition circuit and data processing and other parts. The electromagnetic pulse signal generation circuit part is one of the core modules of ground penetrating radar. For generating nanosecond electromagnetic pulse signals, the electrical pulse generation methods mainly include gas discharge, tunnel diode, mercury switch and avalanche triode, etc. . Among them, the principle of electromagnetic pulse signal generation combined with gas discharge and mercury switch is to use the instantaneous discharge breakdown and recovery characteristics of the mercury switch tube to generate a high-voltage narrow pulse with a leading edge and a width of nanoseconds and an amplitude of up to kilovolts; while the mercury switch is It is a high-performance high-voltage switch, and the pulse symmetry generated is better; the tunnel diode pulse generator is not very commonly used because of its wide pulse width and low amplitude; the repetition rate of the avalanche triode can reach several MHz, and the response The amplitude of the pulse generated by the fast time can reach hundreds of volts. Half of the common electromagnetic pulse signal circuit generation circuit uses semiconductor avalanche diodes, step diodes and other multi-stage series connections to realize high-voltage radar wave pulse signals. There are parameter differences, delay out-of-sync, and parasitic parameters among individual devices, which will cause the pulse width of the radar pulse waveform to widen, and at the same time cause the tail of the high-voltage pulse signal.

At present, the vast majority of ground penetrating radar equipment used in actual engineering in China relies on foreign imports, but judging from the current application situation, there are still big problems and technical bottlenecks in the application of ground penetrating radar in engineering detection, first of all The high price of equipment limits the promotion and popularization of ground penetrating radar equipment and detection technology. Another very important reason is that the application and selection of equipment are very dependent on the characteristics of the target to be detected. For example, different target detection depths and different target sizes should choose different series. Or radars of different frequency bands; technically speaking, the high-voltage short pulse generation technology with a certain repetition frequency is an important key to the ground-penetrating radar detection technology based on pulse signals, and the characteristics of ground-penetrating radars of different models and different frequency bands correspond to specific emission The pulse width of radar waves, such as the 500MHz band impacting the radar, corresponds to a pulse width close to 1 nanosecond; moreover, there is an inherent contradiction between the radar detection resolution and the detection range. Although the high-frequency radar has a higher resolution, its The penetration depth is very limited, generally 400MHz penetration depth is 4 meters, while the typical 1.6GHz radar penetration depth is only 0.5 meters.

As far as the current situation is concerned, for the radar electromagnetic pulse signal generation module, how to generate faster rise time, higher stability and repeatability, and how to make the generated radar pulse signal have better quality and smaller waveform drag Tail is one of the problems faced by high-resolution radar electromagnetic pulse generation technology; The optimal resolution detection of specific target objects is also one of the key issues faced by current ground penetrating radar technology.

Contents of the invention

Aiming at the problems existing in the above-mentioned technologies, the present invention provides a method for generating high-voltage pulse radar signals based on optically induced switches, and realizes that the output high-voltage pulse radar signals have the function of adjustable pulse width.

A method for generating a high-voltage pulse radar signal based on an optically induced switch, comprising the steps of:

1) Generate an induced laser pulse signal, which is divided into two paths after passing through an optical coupler;

2) Through the optical induction switch, the two induction laser pulse signals generate forward wave and reverse wave;

3) The relative time delay between the forward wave and the reverse wave is adjusted by the delay control module to generate a radar signal with adjustable pulse width.

The present invention also provides a device for generating a high-voltage pulse radar signal based on an optically induced switch, which can generate a high-voltage electromagnetic pulse signal with a faster rise time, higher stability and repeatability, and can well solve the problem of no single radar device. Generate multi-band adjustable ground penetrating radar function, which is applied to the pulse width adjustable ground penetrating radar system for detection objects to achieve high-resolution detection at different depths.

A device for generating high-voltage pulse radar signals based on an optically induced switch, comprising:

1) The induced laser control circuit outputs the generated induced laser pulses as two induced laser pulse signals;

2) The pulse generating circuit generates two pulses in opposite directions, and outputs a radar signal with adjustable pulse width.

The induced laser control circuit includes an induced signal laser source, an optical coupler and two delay control modules; the induced signal laser source generates an induced laser pulse, which is divided into two paths through the optical coupler, and is controlled by two delays. The module separately controls the time delay of the two induced laser pulses, and finally outputs two induced laser pulse signals.

The pulse generation circuit includes a high-voltage bias input module, two photo-induced switches, a load matching module, and an output coupling module; the high-voltage bias input module generates a high-level pulse signal to provide energy for the two photo-induced switches The two optical induction switches receive the induction laser pulse signal output by the induction laser control circuit to generate a transient response, the load matching module is used to match the load, and the pulse output coupling module outputs a high-voltage pulse radar signal with adjustable pulse width.

The high-voltage bias input module is connected to the common end of the two photo-induced switches through a microstrip line to provide the high-voltage energy required by the circuit, generate a high-level pulse signal, and provide the photoelectric effect generated by the photosensitive part of the photo-induced switch. required strong electric field conditions.

The two light-induced switches are connected to each other in a push-pull structure to generate pulse signals with opposite directions.

The two photo-induced switches receive the induced laser pulse signal output by the induced laser control circuit, and the induced laser pulse signal irradiates the photosensitive part of the photo-induced switch in a very short time, and the on-off state of the photo-induced switch will occur in a very short time Change, so that the circuit produces a transient response in a very short time. Under the irradiation of induced laser pulses, the two optically induced switches can successively output two pulse waves in opposite directions (that is, forward wave and reverse wave), and the delay control module can control the output of forward wave and reverse wave. Relative time delay, and then adjust the pulse width of the high-voltage pulse radar signal.

The photo-induced switch is a semiconductor photo-induced switch. Its constituent materials are III-V compound semiconductor materials. The semiconductor material has the characteristics of high dark state resistance, short carrier lifetime and high carrier mobility. Compared with the traditional avalanche diode or step diode, the radar signal generated by the radar pulse generation circuit using the light-induced switch has a faster rise time, higher stability and repeatability, and has better quality and smaller Waveforms smear.

Preferably, the light-induced switch is a light-induced switch based on GaAs material. When photons with a certain energy are injected into the semiconductor of GaAs material, the photons absorbed inside the semiconductor will generate electron-hole pairs, and its internal resistance will change rapidly with the laser injection.

Further preferably, a 1064nm laser with a photon energy of 1.16eV is selected as the control optical signal of the light-induced switch based on GaAs material. In the present invention, the input end is a bias high voltage, which provides a high voltage electric field condition, so that the effective energy gap of the GaAs material with a band gap of 1.42eV is reduced, so a 1064nm laser with a photon energy of 1.16eV is used as a light-induced switch based on the GaAs material light-induced control signals.

When the device for generating high-voltage pulse radar signals based on an optical inductive switch is in operation, the inductive signal laser light source generates an inductive laser pulse signal, which is divided into two paths after being passed through an optical coupler, and the two inductive laser pulse signals are controlled by two delay control modules respectively. The time delay is controlled and adjusted, and the two induced laser pulse signals formed respectively control the opening and closing states of the two optically induced switches. The photosensitive area of the photoinducible switch has a photoelectric effect under the irradiation of the inductive laser pulse signal, which makes the circuit produce a transient response. Under the control of the delay control module, the relative time delay between the two induced laser pulse signals reaches the sub-nanosecond level, so that the relative time delay between the reverse wave and the forward wave reaches the sub-nanosecond level precision. By adjusting the relative time delay between the reverse wave and the forward wave, the rising transition time of the signal waveform from the reverse minimum value to the forward maximum value will change, the synthesized transient wave waveform and the synthesized radar The center frequency band of the pulse signal will change. After adjustment, the adjustment accuracy of the formed radar pulse waveform can be controlled at sub-nanosecond accuracy.

Through scheme design and simulation, the relationship between the time delay between two opposite pulse waves and the corresponding pulse width of the synthesized radar signal is determined. In the actual measurement scene, the delay of the induced laser is adjusted by the induced laser control circuit to control the trigger delay of the light-induced switch, and then adjust the pulse width of the radar signal, so that the formed radar signal can ensure the best measurement in the current application scenario resolution.

Compared with the traditional ground penetrating radar system, the pulse width adjustable radar signal that the present invention can generate can generate high-voltage electromagnetic pulse signals with faster rise time, higher stability and repeatability, and can solve the problem of single radar equipment well. Without the function of generating multi-band adjustable ground penetrating radar, the pulse width adjustable ground penetrating radar system for detection objects is applied to realize high-resolution detection at different depths.

Description of drawings:

Fig. 1 is a schematic diagram of a device for generating high-voltage pulse radar signals based on an optical inductive switch according to the present invention.

Fig. 2 is a schematic diagram of two positive and negative pulse waves output by the device of the present invention.

Fig. 3 is a schematic diagram of the radar signal formed by changing the time delay of the device of the present invention.

Fig. 4 is a schematic diagram of the frequency spectrum of the radar signal formed by changing the time delay of the device of the present invention.

Detailed ways:

In order to describe the present invention more specifically, the technical solution of the present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

A method for generating a high-voltage pulse radar signal based on an optically induced switch, comprising the steps of:

1) Generate an induced laser pulse signal, which is divided into two paths through an optical coupler;

2) Through the optical induction switch, the two induction pulse signals generate forward wave and reverse wave;

3) The relative time delay between the forward wave and the reverse wave is adjusted by the delay control module to generate a radar signal with adjustable pulse width.

As shown in Figure 1, the device for generating high-voltage pulse radar signals based on an optical inductive switch includes an inductive laser control circuit and a pulse generation circuit; the inductive laser control circuit includes an inductive signal laser source 1, an optical coupler 2, a delay control module 3a and a delay Timing control module 3b; pulse generating circuit includes light induction switch 5a, light induction switch 5b, load matching module 6, high voltage bias input module 8, output coupling module 9, microstrip line 10 connecting each module, signal ground 7a and signal Land 7b.

During specific work, the induced signal laser source 1 generates an induced laser pulse signal, which is divided into two paths through the optical coupler 2, and the two induced laser pulses respectively pass through the delay control modules 3a and 3b and then output two signals with relative time delays. The induced laser pulse signal 4a, 4b, the induced laser pulse signal 4a is used to control the optically induced switch 5a, and the induced laser pulse signal 4b is used to control the optically induced switch 5b; the high voltage bias input module 8 is connected to two optical The common end of the inductive switch 5a, 5b; the optical inductive switch 5a, 5b is connected to each other in a push-pull structure; the other end of the optical inductive switch 5a is connected to the signal ground 7a through the microstrip line 10, and the other end of the optical inductive switch 5b is connected to the load matching module 6 , and output the radar signal through the output coupling module 9 at the same time.

The two photoinduced switches are based on GaAs material. When photons with a certain energy are injected into the semiconductor of GaAs material, the photons absorbed inside the semiconductor will generate electron-hole pairs, and the internal resistance will change with the laser injection. change quickly. In this scheme, the input end is a bias high voltage, which provides high voltage electric field conditions to reduce the effective energy gap of the GaAs material with a bandgap width of 1.42eV. The 1064nm laser with photon energy of 1.16eV can be used as the light-induced switch of the GaAs material. Light-induced control signals.

The photosensitive areas of the photoinduced switches 5a and 5b are respectively irradiated by the induced laser pulse signals 4a and 4b, and the circuit will produce a transient response. The specific process is as follows: When the induced laser pulse 4a is effective for the photoinduced switch 5a, the induced laser pulse 4b It is invalid for the photo-induced switch 5b. At this time, the photo-induced switch 5a is turned on, and the photo-induced switch 5b is closed. When 4a is invalid for the photo-induced switch 5a, the induced laser pulse 4b is effective for the photo-induced switch 5b. At this time, the photo-induced switch 5a is closed, the photo-induced switch 5b is opened, and the photo-induced switch 5b is connected to the load matching module 6, and the output coupling module 9 Output positive wave. As shown in FIG. 2 , 11 and 12 are the generated reverse wave and forward wave respectively, and 13 is the time delay of the forward wave 12 relative to the reverse wave 11 .

The adjustment of the induction laser control circuit makes the time delay between the generated two induction laser pulse signals 4a and 4b reach the sub-nanosecond level. When the optical induction switch based on GaAs material is used, the optical induction switch has a very high speed and dynamic range. Large, high withstand voltage and stable response, the generated pulse width can reach picosecond precision, which can fully meet the design requirements of this scheme.

By changing the relative time delay of the two induced laser pulse signals 4a, 4b, the relative time delay between the reverse wave and the forward wave generated by the induced laser pulse signal is also changed, and the two reverse waves with relative time delay output Partially overlap the wave, and control the time width of the overlapping part of the two reverse waves by controlling the time delay of the induced laser pulse signal, that is, control the transition time of the synthesized radar signal waveform from the reverse minimum value to the positive maximum value , so as to control the pulse width of the output radar signal, that is, to realize the adjustable pulse width of the output high-voltage pulse radar signal.

In order to further verify that the technical scheme proposed by the present invention can realize the adjustable pulse width of the synthesized radar signal, the simulation verification of the scheme has been carried out:

As shown in Figure 2, by adjusting the time delay 13 between the two pulses, under different time delays, the reverse wave and the forward wave are synthesized with a certain delay, and the radar signal waveform as shown in Figure 3 can be formed. The transition time between the obtained radar signal waveform from the reverse minimum value to the positive maximum value also changes accordingly, and the corresponding frequency spectrum is shown in Figure 4. In Fig. 3, select the Gaussian pulse of pulse width τ=0.2ns as the Gaussian pulse signal that this embodiment of simulation produces, control the relative time delay between two positive and negative Gaussian pulses respectively as t _shift =0.1ns, t _shift = 0.6 ns, t _shift = 0.7 ns. Wherein, the numbers in FIG. 3 correspond to the numbers in FIG. 4 one by one, that is, each spectrum waveform in FIG. 4 is the spectrum of each radar signal in FIG. 3 . By adjusting the relative time delay between the forward wave and the reverse wave, the center frequency of the output radar signal waveform can be adjusted.

The simulation verification results prove that the center frequency of the synthesized radar signal waveform can be adjusted within a certain frequency range by changing the time delay, so that a single ground-penetrating radar device can adapt to more detection scenarios.

Claims (4)

1. A kind of device that produces high-voltage pulse radar signal based on light-induced switch, is characterized in that, comprises: 1) The induced laser control circuit outputs the generated induced laser pulses as two induced laser pulse signals; 2) The pulse generating circuit generates two pulses in opposite directions and outputs a radar signal with adjustable pulse width; The pulse generation circuit includes a high-voltage bias input module, two optically induced switches, a load matching module, an output coupling module, and a microstrip line connecting each module; the high-voltage bias input module generates a high-level pulse signal, Provide energy for two photo-induced switches, the two photo-induced switches receive the induced laser pulse signal output by the induced laser control circuit, and generate a transient response, the load matching module is used to match the load, and the output coupling module outputs a high-voltage pulse with adjustable pulse width radar signal; The high-voltage bias input module is connected to the common end of two photo-induced switches through a microstrip line; the two photo-induced switches are connected to each other in a push-pull structure; the other end of one of the photo-induced switches is connected via a microstrip line Signal ground, the other end of the other optical induction switch is connected to the load matching module, and at the same time outputs the radar signal through the output coupling module. 2. the device that generates high-voltage pulse radar signal based on optical induction switch according to claim 1, is characterized in that, described induction laser control circuit comprises induction signal laser source, optical coupler and two delay control modules; The signal laser source generates induced laser pulses, which are divided into two channels after being passed through an optical coupler. The time delays of the two channels of induced laser pulses are respectively controlled by two delay control modules, and finally two channels of induced laser pulse signals are output. 3. The device for generating high-voltage pulse radar signals based on an optical inductive switch according to claim 1, wherein the optical inductive switch is a semiconductor optical inductive switch. 4. A method for producing a high-voltage pulse radar signal according to any one of claims 1 to 3, characterized in that it comprises the steps of: 1) Generate an induced laser pulse signal, which is divided into two paths after passing through an optical coupler; 2) Through the optical induction switch, the two induction laser pulse signals generate forward wave and reverse wave; 3) The relative time delay between the forward wave and the reverse wave is adjusted by the delay control module to generate a radar signal with adjustable pulse width.