CN115877076A - Signal detection system - Google Patents
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- CN115877076A CN115877076A CN202211461596.6A CN202211461596A CN115877076A CN 115877076 A CN115877076 A CN 115877076A CN 202211461596 A CN202211461596 A CN 202211461596A CN 115877076 A CN115877076 A CN 115877076A
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Abstract
The application discloses signal detection system, the system includes: frequency pre-estimating device and signal detecting device; the output end of the frequency pre-estimating device is connected with the input end of the signal detecting device. The system can be realized by utilizing the frequency of an incident signal and an optical carrier signal estimated by the environment to generate a chaotic photoelectric oscillator radio frequency signal, and then utilizing the chaotic photoelectric oscillator radio frequency signal to realize target signal (namely microwave photon weak signal) detection.
Description
Technical Field
The application relates to the technical field of detection, in particular to a signal detection system.
Background
At present, most of the radar wave receiving is still based on the coherent detection principle, and the strength of radar signals is generally small and even submerged in noise; the traditional electronic signal amplification method is difficult to break through the bottleneck limitation on devices, the working bandwidth is narrow, the noise deterioration degree is high, the requirements of modern battlefield are difficult to meet, and the action range and the effectiveness of a radar jammer are difficult to be improved in a breakthrough manner.
The main methods of the existing weak signal detection are a time domain detection method, a frequency domain detection method and a time-frequency analysis method, the main means of the methods is to amplify signals by using an electronic method and then filter the signals by adopting different filtering means on a time domain and a frequency domain, the core of the traditional electronic detection method is to amplify the signals firstly and then filter the signals, and finally carry out coherent detection in a beat frequency mode, so that the high-sensitivity detection in a large dynamic range is difficult to realize, and the method is not beneficial to the detection of weak radar signals in various modern signal forms. For example, in current signal amplification methods: the signal is amplified by a multistage electronic amplifier, resulting in a significant increase in white noise. Secondly, the coherent detection method needs to generate a plurality of radio frequency signals in advance for blind detection, and detection in a large dynamic range cannot be achieved.
Disclosure of Invention
The application provides a signal detection system, which can enlarge the bandwidth of a target signal (namely a weak signal), reduce noise interference during signal processing, receive the weak signal in a larger dynamic bandwidth range, and improve the defects of narrow working bandwidth and low detection sensitivity of the traditional signal detection method.
In a first aspect, the present application provides a signal detection system, the system comprising: frequency pre-estimating device and signal detecting device; the output end of the frequency pre-estimating device is connected with the input end of the signal detecting device;
the frequency pre-estimating device is used for generating a plurality of optical carrier signals; obtaining the frequency of an estimated incident signal according to the radio frequency signals; outputting the frequency of the estimated incident signal through the output terminal;
the signal detection device is used for acquiring the frequency of the estimated incident signal through the input end and generating an optical carrier signal; generating a chaotic photoelectric oscillator radio frequency signal according to the estimated frequency of the incident signal and the optical carrier signal; and detecting a target signal by using the chaotic photoelectric oscillator radio frequency signal.
Optionally, the frequency pre-estimating apparatus includes a laser, a radio frequency signal generating unit, and a digital-to-analog converter; the signal output end of the laser is connected with the input end of the radio frequency signal generating unit, the output end of the radio frequency signal generating unit is connected with the input end of the digital-to-analog converter, and the output end of the digital-to-analog converter is connected with the input end of the signal detection device;
the laser is used for generating a plurality of optical carrier signals;
the radio frequency signal generating unit is used for determining a plurality of radio frequency signals according to the plurality of beams of optical carrier signals;
the digital-to-analog converter is used for obtaining the frequency of the estimated incident signal according to the radio frequency signals.
Optionally, the laser comprises two lasers, each laser generating an optical carrier signal.
Optionally, the radio frequency signal generating unit includes: the device comprises a wavelength division multiplexer, a polarization controller, a Mach-Zehnder modulator, a filter, a wavelength division demultiplexer and a photoelectric detector; the input end of the wavelength division multiplexer is connected with the signal output end of the laser, the output end of the wavelength division multiplexer is connected with the input end of the polarization controller, the output end of the polarization controller is connected with the input end of the Mach-Zehnder modulator, the output end of the Mach-Zehnder modulator is connected with the input end of the filter, the output end of the filter is connected with the input end of the wavelength division demultiplexer, the output end of the wavelength division demultiplexer is connected with the input end of the photoelectric detector, and the output end of the photoelectric detector is connected with the input end of the signal detection device;
the wavelength division multiplexer is used for mixing the two beams of optical carrier signals to obtain a beam of optical carrier signal;
the polarization controller is used for adjusting the polarization state of the optical carrier signal to obtain an optical carrier signal with the adjusted polarization state;
the Mach-Zehnder modulator is used for modulating the optical carrier signal after the polarization state adjustment to obtain a modulated optical signal;
the filter is used for filtering the modulated optical signal to obtain a carrier-suppressed optical signal;
the wavelength division multiplexer is used for performing wavelength division multiplexing processing on the optical signals subjected to carrier suppression to obtain two optical signals;
and the photoelectric detector is used for carrying out beat frequency processing on the two beams of optical signals to obtain two radio frequency signals.
Optionally, the photodetector includes two photodetectors, and each photodetector is configured to receive a light signal and perform beat frequency processing on the light signal to obtain a radio frequency signal corresponding to the light signal.
Optionally, the signal detection apparatus includes: the device comprises a laser, a signal generating unit and a signal detecting unit; the output end of the laser is connected with the input end of the signal generation unit, and the input end of the signal generation unit is connected with the output end of the frequency estimation device; the output end of the signal generating unit is connected with the input end of the signal detecting unit; the output end of the signal detection unit is connected with the input end of the signal generation unit;
the laser is used for generating an optical carrier signal;
the signal generating unit is used for generating a chaotic photoelectric oscillator radio-frequency signal according to the estimated frequency of the incident signal and the optical carrier signal;
and the signal detection unit is used for detecting a target signal by utilizing the radio frequency signal of the chaotic photoelectric oscillator.
Optionally, the signal generating unit includes: a polarization controller, a Mach-Zehnder modulator, a single-mode optical fiber and a tunable optical fiber Bragg grating; the input end of the polarization controller is connected with the signal output end of the laser, the output end of the polarization controller is connected with the input end of the Mach-Zehnder modulator, the output end of the Mach-Zehnder modulator is connected with the input end of the single-mode optical fiber, and the output end of the single-mode optical fiber is connected with the input end of the tunable optical fiber Bragg grating;
the polarization controller is used for adjusting the polarization state of the optical carrier signal to obtain an optical carrier signal with the adjusted polarization state;
the Mach-Zehnder modulator is used for modulating the optical carrier signal after the polarization state adjustment to obtain a modulated optical signal;
the single-mode optical fiber is used for carrying out time delay processing on the modulated optical signal to obtain a time-delay optical signal;
and the tunable fiber Bragg grating is used for generating a radio frequency signal of the chaotic photoelectric oscillator according to the estimated frequency of the incident signal and the delayed optical signal.
Optionally, the signal detecting unit includes: the device comprises a coupler, a spectrum analyzer, a photoelectric detector, a frequency-adjustable radio frequency amplifier, a radio frequency beam splitter, a radio frequency analyzer and a low noise amplifier;
the input end of the coupler is connected with the output end of the tunable fiber Bragg grating, the output end of the coupler is connected with the input end of the spectrum analyzer, the output end of the coupler is connected with the input end of the photoelectric detector, the output end of the photoelectric detector is connected with the input end of the frequency-adjustable radio frequency amplifier, the output end of the frequency-adjustable radio frequency amplifier is connected with the input end of the radio frequency beam splitter, the output end of the radio frequency beam splitter is connected with the input end of the radio frequency analyzer, the output end of the radio frequency beam splitter is connected with the input end of the low noise amplifier, and the output end of the low noise amplifier is connected with the input end of the Mach-Zehnder modulator;
the coupler is used for dividing the chaotic photoelectric oscillator radio-frequency signal into two chaotic photoelectric oscillator radio-frequency signals;
the spectrum analyzer is used for analyzing the signal state of the radio frequency signal of the chaotic photoelectric oscillator;
the photoelectric detector is used for carrying out beat frequency processing on the radio frequency signal of the chaotic photoelectric oscillator to obtain a radio frequency signal;
the frequency-adjustable radio frequency amplifier is used for amplifying the radio frequency signal to obtain an amplified radio frequency signal;
the radio frequency beam splitter is used for splitting the amplified radio frequency signals to obtain two beams of amplified radio frequency signals;
the radio frequency analyzer is used for observing the amplified radio frequency signal to obtain a target signal;
the low noise amplifier is used for amplifying a target signal in the amplified radio frequency signal.
Optionally, the tunable fiber bragg grating further includes a reflection end, the input end of the tunable fiber bragg grating inputs the delay optical signal, the delay optical signal enters from the reflection end, and after the delay optical signal is reflected by the fiber bragg grating according to the estimated frequency of the incident signal, a radio frequency signal of the chaotic optoelectronic oscillator is obtained, and the radio frequency signal of the chaotic optoelectronic oscillator enters from the reflection end to the output end.
Optionally, a knob is disposed on the tunable fiber bragg grating, and when the knob is adjusted, the length of the grating changes, and the wavelength of the reflected light changes accordingly.
It can be seen from the above technical solutions that the present application provides a signal detection system, the system including: frequency estimation means and signal detection means; the output end of the frequency pre-estimating device is connected with the input end of the signal detecting device; the frequency estimation device is used for generating a plurality of optical carrier signals; determining a plurality of radio frequency signals according to the plurality of light carrier signals; obtaining the frequency of an estimated incident signal according to the radio frequency signals; outputting the frequency of the estimated incident signal through the output terminal; the signal detection device is used for acquiring the frequency of the estimated incident signal through the input end and generating an optical carrier signal; generating a chaotic photoelectric oscillator radio frequency signal according to the estimated frequency of the incident signal and the optical carrier signal; and detecting a target signal by using the chaotic photoelectric oscillator radio frequency signal. The embodiment can realize that the frequency of the incident signal and the optical carrier signal are estimated by using the environment to generate the chaotic photoelectric oscillator radio-frequency signal, and then the chaotic photoelectric oscillator radio-frequency signal is used to realize the target signal (namely the microwave photon weak signal) detection.
Further effects of the above-mentioned unconventional preferred modes will be described below in conjunction with specific embodiments.
Drawings
In order to more clearly illustrate the embodiments or prior art solutions of the present application, the drawings used in the description of the embodiments or prior art will be briefly described below, it is obvious that the drawings in the description below are only some embodiments described in the present application, and that other drawings can be obtained by those skilled in the art without inventive labor.
Fig. 1 is a schematic diagram of a system architecture of a frequency estimation device in a signal detection system according to the present application;
fig. 2 is a schematic diagram of a system architecture of a signal detection apparatus in a signal detection system according to the present application.
Detailed Description
To make the objects, technical solutions and advantages of the present application more clear, the technical solutions of the present application will be clearly and completely described below with reference to specific embodiments and corresponding drawings. It should be apparent that the described embodiments are only a few embodiments of the present application, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
Various non-limiting embodiments of the present application are described in detail below with reference to the accompanying drawings.
Referring to fig. 1 and 2, a signal detection system in an embodiment of the present application is shown.
The signal detection system comprises: frequency estimation means and signal detection means. The output end of the frequency pre-estimating device is connected with the input end of the signal detection device.
The frequency pre-estimating device is used for generating a plurality of optical carrier signals; determining a plurality of radio frequency signals according to the plurality of light carrier signals; obtaining the frequency of an estimated incident signal according to the radio frequency signals; and outputting the frequency of the estimated incident signal through the output end. It is understood that the frequency estimation device can estimate the frequency value of the radio frequency signal in the environment, and control the error of the frequency estimation value thereof within the range of 300 MHz.
As shown in fig. 1, the frequency estimation apparatus includes a laser, a radio frequency signal generation unit, and a digital-to-analog converter. The signal output end of the laser is connected with the input end of the radio frequency signal generating unit, the output end of the radio frequency signal generating unit is connected with the input end of the digital-to-analog converter, and the output end of the digital-to-analog converter is connected with the input end of the signal detecting device.
The laser is used to generate a number of optical carrier signals. As shown in fig. 1, the laser may include two lasers, each of which produces an optical carrier signal.
The radio frequency signal generating unit is used for determining a plurality of radio frequency signals according to the plurality of light carrier signals. As shown in fig. 2, the radio frequency signal generating unit includes: the device comprises a wavelength division multiplexer, a polarization controller, a Mach-Zehnder modulator, a filter, a wavelength division demultiplexer and a photoelectric detector; the input end of the wavelength division multiplexer is connected with the signal output end of the laser, the output end of the wavelength division multiplexer is connected with the input end of the polarization controller, the output end of the polarization controller is connected with the input end of the Mach-Zehnder modulator, the output end of the Mach-Zehnder modulator is connected with the input end of the filter, the output end of the filter is connected with the input end of the wavelength division demultiplexer, the output end of the wavelength division demultiplexer is connected with the input end of the photoelectric detector, and the output end of the photoelectric detector is connected with the input end of the signal detection device.
And the wavelength division multiplexer is used for mixing the two beams of optical carrier signals to obtain one beam of optical carrier signal. And the polarization controller is used for adjusting the polarization state of the optical carrier signal to obtain the optical carrier signal after the polarization state is adjusted.
And the Mach-Zehnder modulator is used for modulating the optical carrier signal after the polarization state adjustment to obtain a modulated optical signal.
And the filter is used for filtering the modulated optical signal to obtain a carrier-suppressed optical signal.
And the wavelength division multiplexer is used for performing wavelength division multiplexing processing on the optical signals subjected to carrier suppression to obtain two optical signals.
And the photoelectric detector is used for carrying out beat frequency processing on the two beams of optical signals to obtain two radio frequency signals. As shown in fig. 1, the photodetector includes two photodetectors, each of which is configured to receive a light signal and perform beat frequency processing on the light signal to obtain a radio frequency signal corresponding to the light signal.
The digital-to-analog converter is used for obtaining the frequency of the estimated incident signal according to the radio frequency signals.
It can be understood that the frequency estimation device adopts a scheme of instantaneous measurement of frequency-optical power radio frequency signals composed of double light sources, so as to realize the effect of instantaneous measurement of microwave signals, as shown in fig. 1, two beams of optical carrier signals emitted by two semiconductor lasers are subjected to optical multiplexing and mixing through a wavelength division multiplexer to obtain a beam of optical carrier signal, and the beam of optical carrier signal is input into a mach-zehnder modulator after the polarization state is adjusted through a Polarization Controller (PC). The Mach-Zehnder modulator can work at the minimum working point by adjusting the bias voltage of the Mach-Zehnder modulator, so that the optical carrier in the modulated optical signal output by the Mach-Zehnder modulator is restrained to the maximum extent. The modulated optical signal is input into a filter with a sinusoidal spectral response to obtain a carrier-suppressed optical signal, wherein the wavelength of the modulated optical signal may include two optical channels, and the wavelengths of the two optical channels may be respectively aligned with the peak and trough positions of the filter. The carrier-suppressed optical signal is obtained by separating two optical channels in the modulated optical signal by a demultiplexer, obtaining two radio frequency signals by beating the frequency of the modulated optical signal by two photodetectors (such as low-frequency photodetectors), and finally obtaining the frequency of the estimated incident signal by comparing the ratio of the two radio frequency signals through analog-to-digital conversion and comparison of a digital-to-analog converter and by combining the response curve of a filter, i.e. obtaining the frequency of the estimated incident signal by using a plurality of radio frequency signals and the response curve of the filter.
The signal detection device is used for acquiring the frequency of the estimated incident signal through the input end and generating an optical carrier signal; generating a chaotic photoelectric oscillator radio frequency signal according to the estimated frequency of the incident signal and the optical carrier signal; and detecting a target signal by using the chaotic photoelectric oscillator radio frequency signal.
As shown in fig. 2, the signal detection apparatus includes: the device comprises a laser, a signal generating unit and a signal detecting unit. The output end of the laser is connected with the input end of the signal generation unit, and the input end of the signal generation unit is connected with the output end of the frequency estimation device; the output end of the signal generating unit is connected with the input end of the signal detecting unit; and the output end of the signal detection unit is connected with the input end of the signal generation unit.
The laser is used for generating an optical carrier signal.
And the signal generating unit is used for generating a chaotic photoelectric oscillator radio-frequency signal according to the estimated frequency of the incident signal and the optical carrier signal. As shown in fig. 2, the signal generating unit includes: the device comprises a polarization controller, a Mach-Zehnder modulator, a single-mode optical fiber and a tunable optical fiber Bragg grating; the input end of the polarization controller is connected with the signal output end of the laser, the output end of the polarization controller is connected with the input end of the Mach-Zehnder modulator, the output end of the Mach-Zehnder modulator is connected with the input end of the single-mode optical fiber, and the output end of the single-mode optical fiber is connected with the input end of the tunable optical fiber Bragg grating.
And the polarization controller is used for adjusting the polarization state of the optical carrier signal to obtain the optical carrier signal with the adjusted polarization state.
And the Mach-Zehnder modulator is used for modulating the optical carrier signal after the polarization state adjustment to obtain a modulated optical signal.
And the single-mode optical fiber is used for carrying out time delay processing on the modulated optical signal to obtain a time-delayed optical signal.
And the tunable fiber Bragg grating is used for generating a radio frequency signal of the chaotic photoelectric oscillator according to the estimated frequency of the incident signal and the delayed optical signal. The tunable fiber bragg grating further comprises a reflection end, the input end (i.e. port 1 in fig. 2) of the tunable fiber bragg grating inputs the delay optical signal, the delay optical signal enters from the reflection end (i.e. port 2 in fig. 2), the delay optical signal is reflected by the fiber bragg grating according to the estimated frequency of the incident signal to obtain a radio frequency signal of the chaotic photoelectric oscillator, and the radio frequency signal of the chaotic photoelectric oscillator enters from the reflection end to the output end (i.e. port 3 in fig. 2). In one implementation, a knob is disposed on the tunable fiber bragg grating, and when the knob is adjusted, the length of the grating changes, and the wavelength of the reflected light changes accordingly.
The signal detection unit is used for detecting a target signal (namely a weak signal) by utilizing the radio frequency signal of the chaotic photoelectric oscillator.
As shown in fig. 2, the signal detection unit includes: the device comprises a coupler, a spectrum analyzer, a photoelectric detector, a frequency-adjustable radio frequency amplifier, a radio frequency beam splitter, a radio frequency analyzer and a low noise amplifier.
The input end of the coupler is connected with the output end of the tunable optical fiber Bragg grating, the output end of the coupler is connected with the input end of the spectrum analyzer, the output end of the coupler is connected with the input end of the photoelectric detector, the output end of the photoelectric detector is connected with the input end of the frequency-adjustable radio-frequency amplifier, the output end of the frequency-adjustable radio-frequency amplifier is connected with the input end of the radio-frequency beam splitter, the output end of the radio-frequency beam splitter is connected with the input end of the radio-frequency analyzer, the output end of the radio-frequency beam splitter is connected with the input end of the low-noise amplifier, and the output end of the low-noise amplifier is connected with the input end of the Mach-Zehnder modulator.
The coupler is used for dividing the chaotic photoelectric oscillator radio frequency signal into two chaotic photoelectric oscillator radio frequency signals.
And the spectrum analyzer is used for analyzing the signal state of the radio frequency signal of the chaotic photoelectric oscillator.
And the photoelectric detector is used for carrying out beat frequency processing on the radio frequency signal of the chaotic photoelectric oscillator to obtain a radio frequency signal.
The frequency-adjustable radio frequency amplifier is used for amplifying the radio frequency signal to obtain an amplified radio frequency signal.
And the radio frequency beam splitter is used for splitting the amplified radio frequency signal to obtain two beams of amplified radio frequency signals.
And the radio frequency analyzer is used for observing the amplified radio frequency signal to obtain a target signal.
The low noise amplifier is used for amplifying a target signal in the amplified radio frequency signal.
The signal detection device adopts a method for building a photoelectric oscillation ring cavity to generate a chaotic photoelectric oscillator radio-frequency signal, the chaotic state of the photoelectric oscillator of the chaotic photoelectric oscillator radio-frequency signal is a critical state between oscillation starting and non-oscillation starting, namely the open-loop gain of an OEO (namely a photoelectric oscillator) is close to 1, the oscillation mode is about to appear, and the chaotic state OEO is a nonlinear delay feedback loop. When a radio-frequency signal is injected into the OEO, the in-loop gain of the photoelectric oscillation ring cavity is increased, the oscillation starting frequency is locked by the injected signal, and energy is concentrated towards the central frequency of oscillation starting, so that the weak signal amplification function is realized.
As shown in fig. 2, in the signal detection device, after a polarization direction of an optical carrier emitted by a laser is adjusted by a polarization controller (i.e., the optical carrier signal is adjusted in polarization state to obtain an optical carrier signal after the polarization state is adjusted), the optical carrier signal after the polarization state is adjusted is input to a mach-zehnder modulator, and the mach-zehnder modulator outputs a modulated optical signal, and a delay is generated by a long single-mode optical fiber to obtain a delayed optical signal. The chaotic photoelectric oscillator radio frequency signal is divided into two chaotic photoelectric oscillator radio frequency signals (namely two chaotic photoelectric oscillator radio frequency signals) through a coupler (namely an optical beam splitter), one chaotic photoelectric oscillator radio frequency signal is input into a spectrum analyzer so that the spectrum analyzer can analyze the chaotic optical signal state of the chaotic photoelectric oscillator radio frequency signal, the other chaotic photoelectric oscillator radio frequency signal is connected with a photoelectric detector, and the photoelectric detector can beat the chaotic photoelectric oscillator radio frequency signal to generate a radio frequency signal. The method comprises the steps that a generated radio frequency signal is amplified through a gain-adjustable radio frequency amplifier (namely, a frequency-adjustable radio frequency amplifier) to obtain an amplified radio frequency signal, the amplified radio frequency signal is divided into two paths of amplified radio frequency signals through a radio frequency beam splitter, one path of the amplified radio frequency signal is input into a radio frequency analyzer and used for observing the state of an electric chaotic signal of the amplified radio frequency signal, so that the bias voltage of a Mach-Zehnder modulator and the gain of the frequency-adjustable radio frequency amplifier can be adjusted in an auxiliary mode, and the other path of the amplified radio frequency signal is fed back and injected into the Mach-Zehnder modulator after passing through a low-noise amplifier, so that link closed loop is completed. Because the chaotic state of the photoelectric oscillator of the radio-frequency signal of the chaotic photoelectric oscillator is a nonlinear modulation state of the MZM, the requirements on the flatness and the frequency response bandwidth of a device are high, and the flatness of the frequency-adjustable radio-frequency amplifier in a link is required to be relatively flat.
The signal detection device realizes the receiving and amplification of weak radar signals through an injection locking effect, and increases the bandwidth range of detectable signals by using a small signal receiver frequency tuning technology. Because the frequency response of the tunable fiber Bragg grating in the chaotic state is greatly influenced by the bandwidth and the unevenness of each device in the system, the working bandwidth of the tunable fiber Bragg grating is difficult to be widened, and the generated radio frequency signal of the chaotic photoelectric oscillator is generally 300-800MHz. If the system is used in an electromagnetic environment with a larger frequency range span, a tunable fiber Bragg grating with adjustable bandwidth can be designed. In combination with a frequency instantaneous measurement scheme, the frequency of an estimated incident signal in an environment is determined, and then a tunable fiber Bragg grating with the bandwidth exceeding 500MHz is formed in a ring cavity (namely, the frequency estimation device and the signal detection device), so that the receiving and amplifying functions of a target signal (namely a weak signal) in a larger frequency range are achieved. A scheme of a frequency-tunable photoelectric oscillator is combined, a tuning scheme of an OEO working frequency band in a chaotic state is provided, the characteristic that the central frequency of reflected light of a tunable fiber Bragg grating changes along with the length of the reflected light is utilized, a frequency-tunable chaotic photoelectric oscillator radio-frequency signal is generated in a loop, and the scheme principle is shown in figure 2.
After an optical carrier signal sent by the laser passes through the polarization controller, the Mach-Zehnder modulator, the single-mode optical fiber and the tunable fiber Bragg grating, a radio-frequency chaotic signal fed back in a loop is modulated onto the optical carrier to obtain a chaotic photoelectric oscillator radio-frequency signal, at the moment, the Mach-Zehnder modulator works on a minimum bias point, and a central carrier is suppressed. Modulated optical signals output by the Mach-Zehnder modulator pass through a single-mode optical fiber to obtain delayed optical signals, the delayed optical signals can be transmitted to a circulator in the tunable optical fiber Bragg grating, the delayed optical signals enter a reflecting end (port 2 in the figure 2) from an input end (port 1 in the figure 2) of the tunable optical fiber Bragg grating and then exit, radio-frequency signals of the chaotic photoelectric oscillator reflected by the tunable optical fiber Bragg grating enter an output end (port 3 in the figure 2) from the reflecting end (port 2 in the figure 2), and the radio-frequency signals of the chaotic photoelectric oscillator enter an OEO (namely, a ring cavity formed by a frequency estimation device and a signal detection device). When a difference exists between a first-order sideband in a reflected chaotic photoelectric oscillator radio-frequency signal and a first-order sideband directly modulated to output light (namely an optical carrier signal) of the laser, the photoelectric detector generates a radio-frequency signal with the frequency equal to the frequency difference of the first-order sideband and the second-order sideband through a beat frequency effect. The radio frequency signal is amplified by the frequency-adjustable radio frequency amplifier and then fed back to the radio frequency beam splitter, the radio frequency analyzer and the low noise amplifier to complete the whole loop. When the knob on the tunable fiber Bragg grating is adjusted, the length of the grating is changed, and the wavelength of the reflected light is changed. The single-mode fiber can increase the delay of the whole loop, thereby improving the quality factor of the output radio frequency signal. Therefore, unknown weak radar signals can be detected in a large frequency range with high sensitivity, the detection bandwidth is larger than that of a traditional electronic method, the detection sensitivity is high, and weak signals of-70 dBm can be detected.
It can be seen from the above technical solutions that the present application provides a signal detection system, the system including: frequency estimation means and signal detection means; the output end of the frequency pre-estimating device is connected with the input end of the signal detecting device; the frequency pre-estimating device is used for generating a plurality of optical carrier signals; determining a plurality of radio frequency signals according to the plurality of light carrier signals; obtaining the frequency of an estimated incident signal according to the radio frequency signals; outputting the frequency of the estimated incident signal through the output terminal; the signal detection device is used for acquiring the frequency of the estimated incident signal through the input end and generating an optical carrier signal; generating a chaotic photoelectric oscillator radio frequency signal according to the estimated frequency of the incident signal and the optical carrier signal; and detecting a target signal by using the radio frequency signal of the chaotic photoelectric oscillator. The embodiment can be implemented by utilizing the environment to estimate the frequency of an incident signal and an optical carrier signal to generate a chaotic photoelectric oscillator radio-frequency signal and then utilizing the chaotic photoelectric oscillator radio-frequency signal to implement target signal (namely microwave photon weak signal) detection.
It should be noted that, in this specification, each embodiment is described in a progressive manner, and the same and similar parts between the embodiments are referred to each other, and each embodiment focuses on differences from other embodiments. The above-described apparatus and system embodiments are merely illustrative, in that elements described as separate components may or may not be physically separate. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
The above description is only for the preferred embodiment, but the scope of the present disclosure is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present disclosure should be covered within the scope of the present disclosure. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (10)
1. A signal detection system, the system comprising: frequency estimation means and signal detection means; the output end of the frequency pre-estimating device is connected with the input end of the signal detection device;
the frequency estimation device is used for generating a plurality of optical carrier signals; obtaining the frequency of an estimated incident signal according to the radio frequency signals; outputting the estimated frequency of the incident signal through the output end;
the signal detection device is used for acquiring the frequency of the estimated incident signal through the input end and generating an optical carrier signal; generating a chaotic photoelectric oscillator radio frequency signal according to the estimated frequency of the incident signal and the optical carrier signal; and detecting a target signal by using the radio frequency signal of the chaotic photoelectric oscillator.
2. The system of claim 1, wherein the frequency pre-estimating device comprises a laser, a radio frequency signal generating unit and a digital-to-analog converter; the signal output end of the laser is connected with the input end of the radio frequency signal generating unit, the output end of the radio frequency signal generating unit is connected with the input end of the digital-to-analog converter, and the output end of the digital-to-analog converter is connected with the input end of the signal detection device;
the laser is used for generating a plurality of optical carrier signals;
the radio frequency signal generating unit is used for determining a plurality of radio frequency signals according to the plurality of beams of optical carrier signals;
the digital-to-analog converter is used for obtaining the frequency of the estimated incident signal according to the radio frequency signals.
3. The system of claim 2, wherein the laser comprises two lasers, each laser producing an optical carrier signal.
4. The system of claim 3, wherein the radio frequency signal generation unit comprises: the device comprises a wavelength division multiplexer, a polarization controller, a Mach-Zehnder modulator, a filter, a wavelength division demultiplexer and a photoelectric detector; the input end of the wavelength division multiplexer is connected with the signal output end of the laser, the output end of the wavelength division multiplexer is connected with the input end of the polarization controller, the output end of the polarization controller is connected with the input end of the Mach-Zehnder modulator, the output end of the Mach-Zehnder modulator is connected with the input end of the filter, the output end of the filter is connected with the input end of the wavelength division demultiplexer, the output end of the wavelength division demultiplexer is connected with the input end of the photoelectric detector, and the output end of the photoelectric detector is connected with the input end of the signal detection device;
the wavelength division multiplexer is used for mixing the two beams of optical carrier signals to obtain a beam of optical carrier signal;
the polarization controller is used for adjusting the polarization state of the optical carrier signal to obtain an optical carrier signal with the adjusted polarization state;
the Mach-Zehnder modulator is used for modulating the optical carrier signal after the polarization state adjustment to obtain a modulated optical signal;
the filter is used for filtering the modulated optical signal to obtain a carrier-suppressed optical signal;
the wavelength division multiplexer is used for performing wavelength division multiplexing processing on the optical signals subjected to carrier suppression to obtain two optical signals;
and the photoelectric detector is used for carrying out beat frequency processing on the two beams of optical signals to obtain two radio frequency signals.
5. The system of claim 4, wherein the photo detector comprises two photo detectors, and each photo detector is configured to receive a beam of optical signals and perform beat processing on the beam of optical signals to obtain a radio frequency signal corresponding to the beam of optical signals.
6. The system of claim 1, wherein the signal detection device comprises: the device comprises a laser, a signal generating unit and a signal detecting unit; the output end of the laser is connected with the input end of the signal generation unit, and the input end of the signal generation unit is connected with the output end of the frequency estimation device; the output end of the signal generating unit is connected with the input end of the signal detecting unit; the output end of the signal detection unit is connected with the input end of the signal generation unit;
the laser is used for generating an optical carrier signal;
the signal generating unit is used for generating a radio frequency signal of the chaotic photoelectric oscillator according to the frequency of the estimated incident signal and the optical carrier signal;
and the signal detection unit is used for detecting a target signal by using the radio frequency signal of the chaotic photoelectric oscillator.
7. The system of claim 6, wherein the signal generation unit comprises: the device comprises a polarization controller, a Mach-Zehnder modulator, a single-mode optical fiber and a tunable optical fiber Bragg grating; the input end of the polarization controller is connected with the signal output end of the laser, the output end of the polarization controller is connected with the input end of the Mach-Zehnder modulator, the output end of the Mach-Zehnder modulator is connected with the input end of the single-mode optical fiber, and the output end of the single-mode optical fiber is connected with the input end of the tunable optical fiber Bragg grating;
the polarization controller is used for adjusting the polarization state of the optical carrier signal to obtain an optical carrier signal with the adjusted polarization state;
the Mach-Zehnder modulator is used for modulating the optical carrier signal after the polarization state adjustment to obtain a modulated optical signal;
the single-mode fiber is used for carrying out time delay processing on the modulated optical signal to obtain a time-delayed optical signal;
and the tunable fiber Bragg grating is used for generating a radio frequency signal of the chaotic photoelectric oscillator according to the frequency of the estimated incident signal and the delayed optical signal.
8. The system of claim 7, wherein the signal detection unit comprises: the device comprises a coupler, a spectrum analyzer, a photoelectric detector, a frequency-adjustable radio frequency amplifier, a radio frequency beam splitter, a radio frequency analyzer and a low noise amplifier;
the input end of the coupler is connected with the output end of the tunable fiber Bragg grating, the output end of the coupler is connected with the input end of the spectrum analyzer, the output end of the coupler is connected with the input end of the photoelectric detector, the output end of the photoelectric detector is connected with the input end of the frequency-adjustable radio frequency amplifier, the output end of the frequency-adjustable radio frequency amplifier is connected with the input end of the radio frequency beam splitter, the output end of the radio frequency beam splitter is connected with the input end of the radio frequency analyzer, the output end of the radio frequency beam splitter is connected with the input end of the low noise amplifier, and the output end of the low noise amplifier is connected with the input end of the Mach-Zehnder modulator;
the coupler is used for dividing the chaotic photoelectric oscillator radio frequency signal into two chaotic photoelectric oscillator radio frequency signals;
the spectrum analyzer is used for analyzing the signal state of the radio frequency signal of the chaotic photoelectric oscillator;
the photoelectric detector is used for carrying out beat frequency processing on the radio frequency signal of the chaotic photoelectric oscillator to obtain a radio frequency signal;
the frequency-adjustable radio frequency amplifier is used for amplifying the radio frequency signal to obtain an amplified radio frequency signal;
the radio frequency beam splitter is used for splitting the amplified radio frequency signal to obtain two beams of amplified radio frequency signals;
the radio frequency analyzer is used for observing the amplified radio frequency signal to obtain a target signal;
the low noise amplifier is used for amplifying a target signal in the amplified radio frequency signal.
9. The system according to claim 7, wherein the tunable fiber bragg grating further comprises a reflection end, the input end of the tunable fiber bragg grating inputs the delay optical signal, the delay optical signal enters from the reflection end, and after the delay optical signal is reflected by the fiber bragg grating according to the estimated frequency of the incident signal, a chaotic optoelectronic oscillator radio frequency signal is obtained, and the chaotic optoelectronic oscillator radio frequency signal enters from the reflection end to the output end.
10. The system of claim 9, wherein the tunable fiber bragg grating is provided with a knob, and when the knob is adjusted, the length of the grating is changed, and the wavelength of the reflected light is changed.
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