CN102608617B - Chaotic laser-based ultra wide band throughwall radar detection device - Google Patents

Abstract

The invention discloses a chaotic laser-based ultra wide band throughwall radar detection device, wherein the chaotic laser is sent out by an ultra wide band chaotic laser source and is modulated by a time signal into a periodically-emitted chaotic laser impulse sequence after passing through an electrooptical modulator, the chaotic laser impulse sequence is separated into a detected signal and a reference signal by an optical fiber coupler, the detected signal is injected into a photoelectric detector to be converted into an ultra wide band microwave signal, the ultra wide band microwave signal is amplified by a preamplifier and sent out by an ultra wide band microwave transmitting antenna; and at a receiving end, the return signal which is scattered by a target object passes through an obstacle and then received by two paths of receiving antennas, the received return signal is amplified by a low noise amplifier, synchronously acquired by a synchronous acquisition system, and then input into a digital correlator for being correlated with the reference signal which is converted into an electrical signal after passing through a quick light variable delay line and the photoelectric detector, so the characteristic information of the target object is obtained, two paths of characteristic information are input into a signal processing system to be processed for obtaining the azimuth angle and distance of the target object, so the locating and the two-dimensional imaging of the target object are realized.

Description

A chaotic laser-based ultra-wideband through-wall radar detection device

technical field

The invention relates to a radar detection device, in particular to a chaotic laser-based ultra-wideband through-wall radar detection device composed of a transmitting end and a receiving end, which is used for post-disaster personnel rescue, military affairs, anti-terrorism, non-destructive detection of cultural relics and life detection.

Background technique

Since World War II, radar has played an increasingly important role in aviation, aerospace, transportation, weather forecasting, geodesy and military affairs. As an important means of obtaining spatial information, radar plays a pivotal role in modern battlefields and ruins in disaster areas.

Today, major powers in the world are facing severe challenges in the fight against terrorism. If you can find the enemy hidden behind the wall, you will undoubtedly increase your chances of winning and reduce casualties; in the ruins of fire and earthquake, if you can know the survivors The exact location will undoubtedly bring more hope of life; when monitoring patients with extensive burns or severe infections, if various physiological data can be remotely measured, more lives will undoubtedly be saved. The wall-penetrating detection technology came into being under these demands. This technology can detect targets blocked by obstacles, especially life targets and its various characteristics. It can be widely used in military reconnaissance, port warfare, firefighting and disaster rescue, and medical treatment. , developed rapidly in recent years, especially after the Wenchuan earthquake in 2008, the important value and role of through-wall detection radar have been highlighted.

In the decades of development of radar, narrowband signals have always been the main signal form it emits. Research on radar signals has also been mainly focused on narrowband signals. In a certain sense, the conventional narrow-band radar technology is a mature and perfect technology, and the resolution, ranging, speed measurement, anti-interference, and operating distance of the radar have also been greatly improved. However, at the same time, the radar application environment is also deteriorating. Correspondingly, electronic countermeasures are mainly used to interfere with narrowband radars. Under the conditions of informationized warfare, the electromagnetic environment in which radars are located will be even harsher. Traditional narrowband radars often become helpless in the face of the four major threats to radars-electronic interference, anti-radiation missiles, low-altitude penetration and stealth technology.

Over the years, people have been looking for ways to improve the anti-jamming ability of the original radar system, or to design a new system radar with good anti-jamming ability and good speed and distance resolution ability.

In the 1970s, an ultra-wideband (UltraWide-Band, UWB) signal was proposed (James D.Taylor. Introduction to ultrawideband radar system． USA: CRC Press Boca Raton. 1995.) concept. It is defined as the relative bandwidth of the system and the signal exceeds 25%, and the relative bandwidth refers to the ratio of the bandwidth to the center frequency, that is

B _f = (f _H -f _L )/f ₀ =2(f _H -f _L )/(f _H +f _L )

In the formula, f _H and f _L correspond to the upper limit frequency and lower limit frequency of the signal at -10dB respectively.

Ultra-wideband radar refers to the radar whose detection is an ultra-wideband signal. It is a promising radar of a new system. Compared with narrowband radar, wideband radar has more advantages (Alfonso Farina (Xu Xiaojian) , translated by Huang Peikang). High-resolution radar detection-pre-research topics and potential applications. Systems Engineering and Electronic Technology, 1992(1): 1~9.): high range resolution, good target recognition ability, imaging ability, The ability to find hidden targets, small multipath fading and simple system structure. Moreover, with the end of the Iraq War, more and more military researchers have realized that large-scale urban street fighting will become the future area. Therefore, ultra-wideband radar has attracted more and more attention, and more and more researchers have focused on the research and design of ultra-wideband radar.

In radar design, the waveform design of radar is one of the important contents of the overall design of radar. The waveform of radar determines the radar system, signal generation design and optimal receiving signal processing method. If the radar uses a deterministic radar waveform with a low complexity, it is very easy to be intercepted by the enemy, and a very low Probability of being intercepted and strong anti-jamming performance. The chaotic signal waveform of the research experiment in the inventor's laboratory has high complexity, which is very suitable for the transmitting signal of the radar.

Chaos is a random-like phenomenon generated in a deterministic nonlinear dynamical system. It has special properties such as long-term unpredictability, sensitivity to initial values, and the existence of strange attractors. Its shape is similar to noise. It reflects The inherent randomness of the nonlinear system presents a strong anti-interference performance and has the characteristics of ergodic (Shen Ying, Liu Guosui. Fuzzy function of chaotic phase modulation radar signal. Journal of Electronic Science, 2000, 22(1 ):55-60.).

The chaotic signal itself has strong anti-interference, noise-like, non-replicable, easy-to-control spectrum characteristics and other characteristics that conventional systems cannot have at the same time, so that it has very good low intercept probability and anti-interference characteristics; , can realize the attribute of "multi-user"; at the same time, its fuzzy function is an ideal "pushpin type", which makes it have non-fuzzy distance measurement, speed measurement performance and good distance and speed resolution. The ultra-wideband chaotic signal with sharp correlation characteristics and "pushpin" ambiguity function just meets the needs of modern radar systems. Modern radars are increasingly inclined to use signal forms with wider frequency bands, higher frequencies, and more and more random signals. The UWB chaotic signal obviously meets these requirements.

Moreover, the chaotic signal is a noise-like signal. Compared with the random noise radar, the deterministic nature of the chaotic signal makes the generation system of the chaotic radar waveform simple, and the statistical characteristics and trajectory are easy to control. In actual use, it is better than directly using random signals such as Noisy signals have a greater advantage. Therefore, the research on chaotic wireless communication system and chaotic source random signal radar device is also highly concerned by various scientific research institutions in the world.

In 2007, Ran Lixin's group proposed an ultra-wideband radar system using chaotic signals and chaotic synchronization (S. Qiao, Z. G. Shi, K. S. Chen, W. Z. Cui W. Ma, T. Jiang and L. X. Ran, “A new architecture of UWB radar utilizing microwave chaotic signals and chaos synchronization”, Progress In Electromagnetics Research, PIER 75, 225–237, 2007. and Z. G. Shi, S. Qiao, K. S. Chen, W. Z. Cui, W. Ma, T. Jiang and L. X. Ran, “Ambiguity functions of direct chaotic radar employing microwave chaotic colpitts oscillator”, Progress In Electromagnetics Research, PIER 77, 1–14, 2007.). They used the chaotic signal generated by the microwave chaotic oscillator directly as the radar signal, and realized the recovery of the target reflected signal through chaotic synchronization. They simulated the system, and the simulation results showed that the fundamental frequency of the signal generated by the microwave oscillator reached 1.6GHz. There is also good anti-interference performance of chaotic radar: the system can still work normally when the signal-to-noise ratio is lower than -20dB.

However, if the UWB microwave signal is directly generated and modulated in the electrical domain, no matter the traditional technology or the method of using a microwave chaotic oscillator to generate a chaotic signal, all face the same problem: that is, limited by the electronic bottleneck problem, it is impossible to directly Generate and modulate a higher frequency band (millimeter wave or near millimeter wave band), higher bandwidth ultra-wideband microwave signals in the electrical domain. The UWB wall-penetrating radar resolution depends on the bandwidth of the UWB signal, so the UWB signal generated in the electrical domain will greatly limit the resolution of the UWB wall-penetrating radar.

The present invention combines the idea of microwave photonics to realize the optically-generated ultra-broadband microwave technology, cleverly circumvents the unavoidable electronic bottleneck problem of the traditional technology, and utilizes the ultra-broadband characteristics of the chaotic laser generated by the optical injection/optical feedback semiconductor laser to realize the center frequency and Flexible and controllable millimeter-wave band high-frequency band, high-bandwidth ultra-wideband random signal generation, and through the combination of ultra-wideband microwave signal transceiver technology and chaotic autocorrelation ranging technology, it is finally realized for underground resource detection, non-destructive detection of cultural relics, Millimeter-level high-resolution ultra-wideband chaotic random signal wall-penetrating radar system in the fields of military anti-terrorism and post-disaster search and rescue.

Contents of the invention

The object of the present invention is to provide a chaotic laser-based ultra-wideband through-wall radar detection device, which solves the problem of low resolution of the existing ultra-wideband through-wall radar.

Based on the above-mentioned problems and purposes, the measures taken by the present invention are a kind of ultra-wideband wall-penetrating radar detection device based on chaotic laser, including a radar detection device composed of a transmitting end and a receiving end, characterized in that the transmitting antenna of the transmitting end emits ultra-wideband The microwave signal passes through the obstacle to reach the target, and then is reflected by the target, and the reflected signal is received and processed by the antenna at the receiving end; where:

The transmitting end is a chaotic laser pulse sequence emitted by an ultra-broadband chaotic laser source and modulated by a clock-controlled electro-optic modulator into a periodically emitted chaotic laser pulse sequence, which is divided into a detection light І and a reference light Ⅱ by a fiber coupler, and the detection light І After the first photodetector, the optical signal is converted into an electrical signal, and then sent out by the transmitting antenna after passing through the preamplifier;

The receiving end is to receive the echo signal in two ways, the first route receives the echo signal by the first receiving antenna, after being amplified by the first low noise amplifier, the signal is collected by the first synchronous acquisition system, and input to the first digital correlator and The characteristic information of the target object is obtained by correlating the optical fast variable delay line with the reference signal of the photodetector; the second route receives the echo signal by the second receiving antenna, and after being amplified by the second low-noise amplifier, it is amplified by the second synchronous acquisition system The signal is collected and input to the second digital correlator to correlate with the reference signal passing through the optical fast variable delay line and photodetector to obtain the characteristic information of the target object, and then extract two channels of characteristic information and input them to the signal processing system for signal processing and input to the display. The ultra-broadband chaotic laser source is produced by double-injection combined with double-feedback semiconductor lasers.

One of the characteristics of the ultra-broadband wall-penetrating radar detection device based on chaotic laser in the present invention is that the ultra-broadband chaotic laser is used as the detection signal, and the spectrum characteristics of the ultra-broadband microwave signal are flexible and adjustable by adjusting the internal parameters of the laser. control, which greatly improves the direction and angular resolution of UWB radar, thus realizing the precise positioning and micro-feature detection of target objects; the second characteristic is that the ultra-wideband chaotic laser source is based on the nonlinear effect of semiconductor lasers. Double injection combined with double feedback to realize the laser of optical chaotic ultra-broadband signal; the third characteristic is that the intensity of injected light is controlled by the optical adjustable attenuator between semiconductor lasers, and the intensity of feedback light is controlled by the combination of coupler and adjustable attenuator Control, finally realized the ultra-wideband chaotic signal with continuously variable center frequency, high bandwidth and controllable signal spectrum.

The device of the present invention combines UWB microwave signal transceiving technology and chaotic self-correlation ranging technology, and finally realizes millimeter-level high-resolution ultra-wideband (UWB) chaos for the fields of resource detection, non-destructive detection of cultural relics, military anti-terrorism, and post-disaster search and rescue. Random signal detection radar system.

Compared with other ultra-wideband radar devices, a chaotic laser-based ultra-wideband through-wall radar detection device proposed by the present invention has the following advantages:

(1) The ultra-wideband signal generated based on chaotic laser has the advantages of flat power spectrum, wide frequency range, low power consumption, and no ambiguity, and can achieve extremely high distance resolution and strong anti-interference ability;

(2) Combining UWB microwave signal transceiver technology and chaotic random signal autocorrelation processing technology, realize a simple, stable, high-resolution, high-precision UWB chaotic random signal detection radar system;

(3) The present invention utilizes a double-injection combined with double-feedback chaotic laser to realize flexible and controllable spectral characteristics of UWB microwave signals in the optical domain by adjusting the laser, injected light, and feedback light, thereby generating tunable center frequency and signal spectral bandwidth The adjustable ultra-wideband chaotic microwave signal enables the device to face different detection fields.

Description of drawings

Fig. 1 is a structural schematic diagram of the present invention. In the figure, 1: ultra-broadband chaotic laser source, 2: electro-optic modulator, 3: fiber coupler, 4a: first photodetector, 4b: second photodetector, 5: preamplifier, 6: transmitting antenna, 7a: first receiving antenna, 7b: second receiving antenna, 8a: first low noise amplifier, 8b: second low noise amplifier, 9a: first synchronous acquisition system, 9b: second synchronous acquisition system, 10a: first Digital correlator, 10b: second digital correlator, 11: data processing system, 12: display, 13: clock, 14: optical fast variable delay line.

Fig. 2 is a schematic structural diagram of a double-injection combined double-feedback chaotic laser of the present invention. In the figure, 1a: FP laser, 1b: DFB laser I, 1c: DFB laser II, 2a: polarizer I, 2b: polarizer II, 2c: polarizer III, 2d: polarizer IV, 3a: variable attenuator Ⅰ, 3b: Variable Attenuator II, 3c: Variable Attenuator III, 3d: Variable Attenuator IV, 4a: Coupler I, 4b: Coupler II, 4c: Coupler III, 4d: Coupler IV, 4e: coupler V, 5: fiber optic circulator.

Detailed ways

Specific embodiments of the present invention are described below:

Implementation of the ultra-wideband wall-penetrating radar detection device based on chaotic laser according to the present invention is composed of a transmitting end and a receiving end. Photodetector 4a, preamplifier 5, transmitting antenna 6, light fast variable delay line 14 and the second photodetector 4b; At the receiving end, receive with identical two-way, the first way comprises the first receiving antenna 7a, The first low noise amplifier 8a, the first synchronous acquisition system 9a and the first digital correlator 10a; the second path includes the second receiving antenna 7b, the second low noise amplifier 8b, the second synchronous acquisition system 9b and the second digital correlator 10b, the feature information of the two signals is extracted and input to the signal processing system 11, the data is processed to obtain the specific information of the object, and the object image is displayed on the display 12, so as to realize the positioning and two-dimensional imaging of the object. Wherein, both the electro-optic modulator 2 and the synchronous acquisition system 9 are connected with the clock signal 13 .

First, when the chaotic laser emitted by the ultra-broadband chaotic laser source 1 passes through the electro-optical modulator 2, it is modulated by a clock signal 13 into a periodically emitted chaotic laser pulse sequence, and the chaotic laser pulse sequence is divided into a detection signal and a reference signal by a fiber coupler 3. The signal, the chaotic laser detection signal, is injected into the first photodetector 4a and transformed into an ultra-broadband microwave signal, which is amplified by the preamplifier 5 and sent out by the broadband microwave transmitting antenna 6 . At the receiving end, the echo signal scattered by the target object is received by two receiving antennas after passing through the obstacle: the echo signal received by the first receiving antenna 7a of the first route is amplified by the first low-noise amplifier 8a, and is then amplified by the first synchronous The acquisition system 9a performs synchronous acquisition, and then inputs to the first digital correlator 10a to correlate with the reference signal to obtain the characteristic information of the target object, and the echo signal received by the second receiving antenna 7b of the second route is amplified by the second low-noise amplifier 8b , is synchronously collected by the second synchronous acquisition system 9b, and then input to the second digital correlator 10b to correlate with the reference signal to obtain the characteristic information of the target object, and the extracted two-way characteristic information is input to the signal processing system 11 for processing to obtain the target object The azimuth and distance are input to the display 12 to realize the detection and positioning and two-dimensional imaging of the target object.

The chaotic laser source 1 of the above-mentioned device of the present invention can produce an ultra-broadband transmission signal with a bandwidth up to 32 GHz and a flat power spectrum. The device of the present invention can penetrate a concrete wall with a thickness of 10-20 cm and can reach a resolution of 5 mm, which is better than that of the existing wall-penetrating radar. The rate is increased by an order of magnitude, so as to realize the micro-feature detection of the target; moreover, the invention can generate ultra-wideband chaotic microwave signals with tunable center frequency and adjustable signal spectrum bandwidth, so that the device can be oriented to different detection fields. It can be used in post-disaster personnel rescue, military, anti-terrorism, non-destructive testing of cultural relics and life detection and other fields.

In order to better illustrate the specific implementation of a chaotic laser-based ultra-broadband wall-penetrating radar detection device provided by the present invention, a further description will be made below in conjunction with FIG. 1 .

As shown in Figure 1, when the chaotic laser emitted by the ultra-broadband chaotic laser source 1 passes through the electro-optic modulator, it is modulated by a clock signal 13 into a periodically emitted chaotic laser pulse sequence, and the chaotic laser pulse sequence is divided into a detection signal by a fiber coupler 3 The chaotic laser detection signal is injected into a photodetector 4a and converted into an ultra-wideband microwave signal, which is amplified by the preamplifier 5 and sent out by the ultra-wideband microwave transmitting antenna. The ultra-wideband microwave signal has strong penetrating performance. Objects can be detected through obstacles. The echo signal scattered by the target object is received by two channels after passing through the obstacle. The echo signal received by the first receiving antenna 7a of the first channel is amplified by the low noise amplifier 8a, and then is synchronously collected by the synchronous acquisition system 9a, and then input to The digital correlator 10a correlates with the reference signal that becomes an electrical signal after passing through the optical fast variable delay line 14 and the photodetector 4b to obtain the characteristic information of the target object; the echo signal received by the second receiving antenna 7b of the second road passes through the second After being amplified by the second low-noise amplifier 8b, the second synchronous acquisition system 9b performs synchronous acquisition, and then inputs to the second digital correlator 10b to correlate with the reference signal that becomes an electrical signal through the optical fast variable delay line 14 and the photodetector 4b To obtain the feature information of the target object, the extracted two-way feature information is input to the signal processing system 11 for processing, and the azimuth and distance of the target object are obtained to realize the detection and positioning of the target object and two-dimensional imaging. Finally, the input display 12 displays the object image. .

Claims (2)

1. ultra-broadband wall-through radar detection apparatus based on chaotic laser light, constituted by transmitting terminal and receiving end, the transmission antennas transmit ultra-wideband microwave signal that it is characterized in that transmitting terminal passes barrier arrival object, and the back is by the object reflection, and reflected signal is received and handled by the receiving end antenna;

Described transmitting terminal is the chaotic laser light pulse train that is modulated to the cycle emission by ultra wide band chaotic lasing light emitter (1) emission chaotic laser light through the electrooptic modulator (2) of a clock (13) control, and be divided into through fiber coupler (3) and survey light and reference light II, survey light and change electric signal through first photodetector (4a) into by light signal, after prime amplifier (5) amplifies, sent by emitting antenna (6);

Described receiving end is received by two-way, the first via receives echoed signal by first receiving antenna (7a), after first low noise amplifier (8a) amplifies, gather signal by the first synchronous acquisition system (9a), import first digital correlator (10a) with through the relevant and characteristic information of acquisition target object of the reference signal that changes electric signal behind the quick vairable delay line of light (14) and second photodetector (4b) into; Secondary route second receiving antenna (7b) receives echoed signal, after second low noise amplifier (8b) amplifies, gather signal by the second synchronous acquisition system (9b), import second digital correlator (10b) with relevant and obtain the characteristic information of target object through the reference signal that changes electric signal behind the quick vairable delay line of light (14) and second photodetector (4b) into, extract then the two-way characteristic information be input to signal processing system (11) data handle after input displays (12) demonstration.

2. the ultra-broadband wall-through radar detection apparatus based on chaotic laser light as claimed in claim 1 is characterized in that ultra wide band chaotic lasing light emitter (1) is that two two feedback semiconductor lasers of associating that inject produce.

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