A photon-assisted microwave spectrum detection device and method based on single-bit compressed sensing

Abstract

The application discloses a kind of photonic-assisted microwave spectrum detection device and method based on single-bit compressed sensing, its device includes continuous wave laser, first and second optical coupler, phase modulator, Mach-Zehnder modulator, double parallel Mach-Zehnder modulator, electrical comb generator, optical isolator, single-mode optical fiber, antenna, electrical filter, 90 ° electrical mixer, erbium-doped fiber amplifier, optical circulator, pseudo-random sequence generator and photodetector;Its method is to utilize stimulated Brillouin scattering effect to construct the optical notch filter corresponding to the frequency of the signal to be measured, and to act on the optical frequency comb to produce spectral holes, then utilize the random demodulator assisted by photon and single-bit compressed sensing technology to reconstruct the position information of spectral hole with high probability to realize the spectrum estimation of the signal to be measured.The scheme converts the spectrum detection of the signal to be measured into the detection of the frequency-domain sparse electrical comb, and avoids the use of high-speed analog-to-digital converter through single-bit compressed sensing.

Description

Technical Field

[0001] This invention belongs to the field of microwave signal measurement technology, specifically relating to a photon-assisted microwave spectrum detection device and method based on single-bit compressed sensing. Background Technology

[0002] In electronic warfare environments, to protect our equipment from enemy electromagnetic attacks and interference and ensure its safe and normal operation, it is necessary to detect the complex electromagnetic environment in real time. Therefore, microwave spectrum detection systems play an important role in modern electronic warfare. The reception of broadband microwave signals is an important part of microwave spectrum detection. The acquisition of microwave signals usually needs to follow the Nyquist sampling theorem, that is, the sampling frequency must be greater than twice the highest frequency of the signal in order to recover the original signal without distortion. Therefore, the acquisition of high-frequency, broadband signals places high demands on the performance of analog-to-digital converters. Compressed sensing technology has attracted widespread attention due to its unique advantages. Compressed sensing technology utilizes the sparsity structure of signals and can acquire signals at a low sampling rate much lower than the Nyquist sampling rate, which can greatly reduce the system's requirements for the sampling rate of analog-to-digital converters and significantly reduce system costs (IEEE Trans. Inf. Theory, 52(4), 1289-1306, 2006). Combining compressed sensing technology with spectrum sensing systems is expected to significantly reduce the processing complexity of microwave spectrum detection systems at the receiving end.

[0003] Currently, the research and implementation of compressed sensing systems based on traditional electronic technologies are relatively mature (IEEE J.Emerg. Sel. Topics Circuits Syst., 2(3), 516-529, 2012). However, electronic systems face problems such as limited frequency measurement range and real-time performance, large size, high power consumption, and susceptibility to electromagnetic interference. In recent years, microwave photonics has been widely studied as a promising emerging interdisciplinary field. Microwave photonics technology has advantages such as large instantaneous bandwidth, low transmission loss, and resistance to electromagnetic interference (J. Lightw. Technol., 27(3), 314-335, 2009). Microwave spectrum detection systems based on microwave photonics technology are expected to solve the problems faced by traditional electronic spectrum detection systems and are of great research value.

[0004] Commonly used photon-assisted compressed sensing systems mainly employ a random demodulator structure. Some researchers, based on this random demodulator structure, have used cascaded modulators to significantly reduce the sampling rate while potentially extending the operating bandwidth to tens of GHz (Opt. Exp., 19(8): 7339-7348, 2011). In addition, another structure for compressed sensing systems is the modulation broadband converter, which has also been implemented using microwave photonic systems (IEEE Photon. Technol. Lett., 23(2), 67-69, 2011). Although it can reconstruct broadband signals, its structure is relatively complex, posing many difficulties for practical applications. In the above schemes, signal acquisition typically employs multi-bit quantization, resulting in a large amount of data obtained from sampling and requiring subsequent processing. Single-bit quantization, as an extreme form of quantization, can effectively reduce the number of quantization bits. Single-bit compressed sensing technology based on single-bit quantization can reconstruct sparse signals using only the symbol information of the measured values ​​(IEEE Trans. Signal. Process., 60(7), 3868-3875, 2012). Since single-bit quantization only requires quantizing the signal to +1 or −1, the single-bit quantization process can be implemented by a simple and efficient comparator, which can effectively reduce the system complexity. Currently, some scholars have combined single-bit compressed sensing technology with microwave photonics technology (Opt. Exp., 31(11):7339-7348, 2023), demonstrating the unique advantages of microwave photonic single-bit compressed sensing technology. Therefore, researching a photonics-assisted microwave spectrum detection system based on single-bit compressed sensing technology, which can achieve broadband microwave signal spectrum detection while further reducing the number of quantization bits and the amount of sampling data using single-bit compressed sensing technology, is of great significance and value. Summary of the Invention

[0005] To address the technical problems existing in the background art, this invention proposes a photon-assisted spectrum detection device and method based on single-bit compressed sensing. By rationally setting the sideband modulation mode and the frequency position of the stimulated Brillouin loss spectrum, high-resolution frequency measurement of broadband microwave signals can be performed without the need for a high-speed analog-to-digital converter. This invention reduces the overall system cost while increasing the system's tunability and feasibility, and has significant research significance and application value.

[0006] The present invention adopts the following solution to solve its technical problem:

[0007] A photon-assisted microwave spectrum detection device based on single-bit compressed sensing is characterized in that the device comprises a continuous-wave laser, a first optical coupler, a Mach-Zehnder modulator, an electrical frequency comb generator, an optical isolator, a single-mode fiber, an optical circulator, a dual-parallel Mach-Zehnder modulator, an antenna, an electrical filter, a 90° electrical mixer, an erbium-doped fiber amplifier, a phase modulator, a pseudo-random sequence generator, a second optical coupler, and a photodetector; the output port of the continuous-wave laser is connected to the input port of the first optical coupler, and the three output ports of the first optical coupler are respectively connected to the optical input ports of the Mach-Zehnder modulator, the dual-parallel Mach-Zehnder modulator, and the phase modulator; the output port of the electrical frequency comb generator is connected to the radio frequency input port of the Mach-Zehnder modulator, the optical output port of the Mach-Zehnder modulator is connected to the input port of the optical isolator, the output port of the optical isolator is connected to one end of the single-mode fiber, and the other end of the single-mode fiber is connected to port II of the optical circulator. The signal under test is received by an antenna. The output port of the antenna is connected to the input port of an electrical filter. The output port of the electrical filter is connected to the input port of a 90° electrical mixer. The two output ports of the 90° electrical mixer are respectively connected to the two RF input ports of a dual parallel Mach-Zehnder modulator. The optical output port of the dual parallel Mach-Zehnder modulator is connected to the input port of an erbium-doped fiber amplifier. The output port of the erbium-doped fiber amplifier is connected to port I of an optical circulator. Port III of the optical circulator is connected to one input port of a second optical coupler. The output port of the pseudo-random sequence generator is connected to the RF input port of a phase modulator. The optical output port of the phase modulator is connected to the other input port of the second optical coupler. The output port of the second optical coupler is connected to the input port of a photodetector. After low-pass filtering, undersampling, and single-bit quantization of the electrical signal output by the photodetector, the spectral information of the signal under test can be obtained by further processing the data using a single-bit compressed sensing recovery algorithm.

[0008] In the device, an electrical frequency comb generator outputs an electrical frequency comb, which is injected into a Mach-Zehnder modulator to generate an optical frequency comb. An optical notch filter, whose frequency response corresponds to the frequency of the signal under test, is constructed using stimulated Brillouin scattering. This filter is then applied to the optical frequency comb output from the Mach-Zehnder modulator to generate spectral holes. The spectrum of the signal under test is estimated using the location information of these spectral holes. Theoretically, the measurement error is related to the frequency interval of the optical frequency comb. Δf Positive correlation.

[0009] In the device, the frequency range of the electrical frequency comb and the magnitude of the Stokes shift due to stimulated Brillouin scattering jointly determine the measurable frequency range of the system. Assuming the constructed optical notch filter is applied to the positive first-order optical sideband of the suppressed carrier double-sideband signal output by the Mach-Zehnder modulator, the measurable signal frequency range is: ,in, This refers to the number of teeth on an electric frequency comb. For Stokes shift, This is the starting frequency of the electric frequency comb. Δf The frequency interval of the comb teeth.

[0010] In the aforementioned device, if the signal to be measured is directly input into the 90° electrical mixer, it is impossible to determine, based on the reconstruction results, which optical sideband of the Mach-Zehnder modulator's output suppressed carrier double-sideband signal the constructed optical notch filter applies to. Therefore, it is necessary to use an electrical filter with a passband identical to the frequency range of the measurable signal to limit the frequency range of the signal to be measured, preventing out-of-band signals from entering the modulator. This would cause the optical notch filter, generated by stimulated Brillouin scattering, to apply to an undesirable optical sideband, interfering with the frequency measurement results.

[0011] In the device, the low-frequency component of the mixed signal generated by the photodetector contains all the information of the filtered optical / electric frequency comb, which is then completely recovered using a single-bit compressed sensing recovery algorithm. The mixed signal generated by the photodetector, after low-pass filtering, can be acquired at a lower sampling rate, avoiding the use of a high-speed analog-to-digital converter. Furthermore, the use of single-bit compressed sensing technology can reduce the number of quantization bits, thus reducing the amount of sampled data and the required storage space.

[0012] A microwave signal spectrum detection method using the above-mentioned device includes the following steps:

[0013] 1) The output frequency of the continuous wave laser is The optical signal is split into three optical signals on an average basis after passing through an optical coupler, and then injected into a phase modulator, a Mach-Zehnder modulator and a dual parallel Mach-Zehnder modulator, respectively.

[0014] 2) The electric frequency comb generator produces a starting frequency of... Frequency interval is Δf An electrical frequency comb is injected into a Mach-Zehnder modulator. The modulator bias voltage is adjusted so that the Mach-Zehnder modulator operates at the minimum bias point. Then, the Mach-Zehnder modulator outputs a suppressed carrier double-sideband signal corresponding to the electrical frequency comb, i.e., an optical frequency comb signal.

[0015] 3) The optical signal output from the Mach-Zehnder modulator is injected into a single-mode fiber after passing through an optical isolator as the probe light for stimulated Brillouin scattering.

[0016] 4) The center frequency received by the antenna is The signal under test is split into two orthogonal signals after passing through an electrical filter and a 90° electrical mixer. These two orthogonal signals are used to drive the two sub-modulators of a dual parallel Mach-Zehnder modulator. By adjusting the modulator bias voltage so that both sub-modulators operate at their minimum bias points and the main modulator operates at its quadrature bias point, the dual parallel Mach-Zehnder modulator outputs a suppressed carrier single-sideband signal corresponding to the signal under test, i.e., generating a center frequency of... The negative first-order light edge band;

[0017] 5) The suppressed carrier single-sideband signal output from the dual parallel Mach-Zehnder modulator is input into an erbium-doped fiber amplifier for power amplification. The amplified optical signal is then injected back into a single-mode fiber as pump light for stimulated Brillouin scattering, and the frequency is shifted upwards. The position generates the Brillouin loss spectrum as an optical notch filter, with a center frequency of . ;

[0018] 6) The pseudo-random binary sequence (PRBS) generated by the pseudo-random sequence generator is loaded onto the phase modulator. The optical signal output by the phase modulator and the optical signal after the stimulated Brillouin scattering effect are combined into a single optical signal after passing through the second optical coupler and input into the photodetector. The electrical signal output by the photodetector is low-pass filtered, undersampled and quantized by a single bit, and the spectrum information of the signal under test is obtained by using a single-bit compressed sensing recovery algorithm.

[0019] This invention proposes a photon-assisted spectrum detection device and method based on single-bit compressed sensing, which transforms the spectrum detection of the signal under test into the detection of a frequency-domain sparse electrical frequency comb. The use of single-bit compressed sensing avoids the use of a high-speed analog-to-digital converter, reducing system costs. At the same time, the system has good tunability and can realize spectrum detection of wide-range broadband signals, showing good application prospects. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the device structure of the present invention;

[0021] Figure 2 The spectrum of the optical frequency comb after filtering and the spectrum of the electrical frequency comb signal reconstructed by the single-bit recovery algorithm are given when the signal under test is a linear frequency modulated signal with a center frequency of 9.7 GHz and a bandwidth of 0.12 GHz, and the comb tooth spacing of the optical frequency comb is 100 MHz.

[0022] Figure 3The spectrum of the optical frequency comb after filtering and the spectrum of the electrical frequency comb signal reconstructed by the single-bit recovery algorithm are given when the signal under test consists of a linear frequency modulated signal with a center frequency of 9.7 GHz and a bandwidth of 0.12 GHz and a binary phase shift keying (BPSK) signal with a carrier frequency of 9.3 GHz and a rate of 100 Mb / s, and the comb tooth spacing of the optical frequency comb is 100 MHz.

[0023] Figure 4 The spectrum of the optical frequency comb after filtering and the spectrum of the electrical frequency comb signal reconstructed by the single-bit recovery algorithm are given when the signal under test is a linear frequency modulated signal with a center frequency of 9.7 GHz and a bandwidth of 0.12 GHz, and the optical frequency comb tooth spacing is 50 MHz and 20 MHz respectively. Detailed Implementation

[0024] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0025] See Figure 1 The device of the present invention includes: a continuous wave laser 1, a first optical coupler 2, an electric frequency comb generator 3, a Mach-Zehnder modulator 4, an optical isolator 5, a single-mode fiber 6, an antenna 7, an electrical filter 8, a 90° electrical mixer 9, a dual parallel Mach-Zehnder modulator 10, an erbium-doped fiber amplifier 11, an optical circulator 12, a pseudo-random sequence generator 13, a phase modulator 14, a second optical coupler 15, and a photodetector 16.

[0026] The output port of the continuous wave laser 1 is connected to the input port of the first optical coupler 2. The three output ports of the first optical coupler 2 are respectively connected to the optical input ports of the Mach-Zehnder modulator 4, the dual parallel Mach-Zehnder modulator 10, and the phase modulator 14. The output port of the electric frequency comb generator 3 is connected to the radio frequency input port of the Mach-Zehnder modulator 4. The optical output port of the Mach-Zehnder modulator 4 is connected to the input port of the optical isolator 5. The output port of the optical isolator 5 is connected to one end of the single-mode fiber 6, and the other end of the single-mode fiber 6 is connected to port II of the optical circulator 12. The signal under test is received by the antenna 7. The output port of the antenna 7 is connected to the input port of the electric filter 8, and the output port of the electric filter 8 is connected to the input port of the electric filter 8. The input port of the 90° electric mixer 9 is connected to the input port of the 90° electric mixer 9. The two output ports of the 90° electric mixer 9 are respectively connected to the two RF input ports of the dual parallel Mach-Zehnder modulator 10. The optical output port of the dual parallel Mach-Zehnder modulator 10 is connected to the input port of the erbium-doped fiber amplifier 11. The output port of the erbium-doped fiber amplifier 11 is connected to port I of the optical circulator 12. Port III of the optical circulator 12 is connected to one input port of the second optical coupler 15. The output port of the pseudo-random sequence generator 13 is connected to the RF input port of the phase modulator 14. The optical output port of the phase modulator 14 is connected to the other input port of the second optical coupler 15. The output port of the second optical coupler 15 is connected to the input port of the photodetector 16.

[0027] The present invention performs photon-assisted microwave spectrum detection, and the specific steps are as follows:

[0028] Step 1: The output frequency of the continuous wave laser is... The optical signal is split into three optical signals on an average basis after passing through an optical coupler, and then injected into a phase modulator, a Mach-Zehnder modulator and a dual parallel Mach-Zehnder modulator, respectively.

[0029] Step 2: The electric frequency comb generator produces the starting frequency as follows: Frequency interval is Δf An electrical frequency comb is injected into a Mach-Zehnder modulator. The modulator bias voltage is adjusted so that the Mach-Zehnder modulator operates at the minimum bias point. Then, the Mach-Zehnder modulator outputs a suppressed carrier double-sideband signal corresponding to the electrical frequency comb, i.e., an optical frequency comb signal.

[0030] Step 3: The optical signal output from the Mach-Zehnder modulator is injected into a single-mode fiber after passing through an optical isolator as the probe light for stimulated Brillouin scattering.

[0031] Step 4: The center frequency received by the antenna is... The signal under test is split into two orthogonal signals after passing through an electrical filter and a 90° electrical mixer. These two orthogonal signals are used to drive the two sub-modulators of a dual parallel Mach-Zehnder modulator. By adjusting the modulator bias voltage so that both sub-modulators operate at their minimum bias points and the main modulator operates at its quadrature bias point, the dual parallel Mach-Zehnder modulator outputs a suppressed carrier single-sideband signal corresponding to the signal under test, i.e., generating a center frequency of... The negative first-order light edge band;

[0032] Step 5: The suppressed carrier single-sideband signal output from the dual parallel Mach-Zehnder modulator is input into an erbium-doped fiber amplifier for power amplification. The amplified optical signal is then injected back into a single-mode fiber as pump light for stimulated Brillouin scattering, and the frequency is shifted upwards. The position generates the Brillouin loss spectrum as an optical notch filter, with a center frequency of . ;

[0033] Step Six: The PRBS signal generated by the pseudo-random sequence generator is loaded onto the phase modulator. The optical signal output from the phase modulator and the optical signal after stimulated Brillouin scattering are combined into a single optical signal by the second optical coupler and input into the photodetector. The waveform output from the photodetector is processed according to the following principles:

[0034] 1. The attenuation spectrum of the stimulated Brillouin scattering effect excited by the optical signal modulated by the signal under test is used as an optical notch filter. This filter acts on the optical frequency comb generated by the modulation of the electrical frequency comb signal. The optical frequency comb output by the Mach-Zehnder modulator is filtered by the optical notch filter whose frequency response corresponds to the frequency of the signal under test, generating spectral holes. The spectrum of the signal under test can be estimated by the position information of the spectral holes. Theoretically, its measurement error is related to the frequency interval of the optical frequency comb. Δf They are positively correlated.

[0035] 2. After the electrical signal output by the photodetector undergoes low-pass filtering, undersampling, and single-bit quantization, the quantized data is processed using a single-bit compressed sensing recovery algorithm to reconstruct the filtered electrical frequency comb, thereby determining the location of spectral holes. Finally, based on the location information of the spectral holes, i.e., the position of the filtered-out electrical frequency comb teeth, the frequency range of the signal under test is calculated, thus completing the frequency estimation of the unknown microwave signal.

[0036] Example

[0037] The specific implementation process of this embodiment is as follows:

[0038] Step 1: A continuous wave laser generates a single-frequency optical signal with a wavelength of 1553.349 nm. This optical signal is then split into three optical signals by an optical coupler and injected into a phase modulator, a Mach-Zehnder modulator, and a dual parallel Mach-Zehnder modulator, respectively.

[0039] Step 2: The electrical frequency comb generator produces an electrical frequency comb with a starting frequency of 0.05 GHz, a frequency interval of 100 MHz, and 10 comb teeth. This electrical frequency comb is injected into a Mach-Zehnder modulator. By adjusting the modulator's bias voltage to make the Mach-Zehnder modulator operate at its minimum bias point, the Mach-Zehnder modulator outputs a suppressed carrier double-sideband signal corresponding to this electrical frequency comb, i.e., an optical frequency comb signal, such as... Figure 2 As shown in (a), the power of the carrier differs from that of the sideband by 16 dB;

[0040] Step 3: The optical signal output from the Mach-Zehnder modulator is injected into the single-mode fiber through the optical isolator and then through port II of the optical circulator as the probe light for stimulated Brillouin scattering.

[0041] Step 4: A linear frequency modulated signal with a center frequency of 9.7 GHz, a bandwidth of 0.12 GHz, and a pulse width and pulse period of 0.512 μs and 1.024 μs, respectively, is used as the signal under test. After being input into a 90° electric mixer through an electric filter, it is split into two orthogonal signals. These two orthogonal signals are respectively loaded onto the two RF ports of a dual parallel Mach-Zehnder modulator. The bias voltage is adjusted so that its modulation mode is suppressed carrier single sideband and generates negative first-order optical sideband.

[0042] Step 5: Input the suppressed carrier single-sideband signal output from the dual parallel Mach-Zehnder modulator into the erbium-doped fiber amplifier for power amplification. The amplified optical signal is then injected into the single-mode fiber via optical circulator port I as pump light for stimulated Brillouin scattering effect, and a Brillouin loss spectrum is generated at a frequency shifted up by 10 GHz as an optical notch filter.

[0043] Step Six: The PRBS signal with an output rate of 2 Gb / s from the output port of the pseudo-random sequence generator is loaded onto the phase modulator. The optical signal output from the phase modulator and the optical signal output from port III of the optical circulator are combined into a single optical signal after passing through the second optical coupler and input into the photodetector. After photoelectric conversion, the electrical signal from the photodetector is sampled at a sampling rate of 16 GSa / s, obtaining 16384 sampling points. Then, low-pass filtering, undersampling, and single-bit sampling quantization are performed in the digital domain to obtain 512 observations. At this point, the equivalent sampling rate of the system is 500 MHz, which is lower than the Nyquist sampling rate (1.9 GHz) of the electrical frequency comb signal. The collected observations are reconstructed and recovered using the Binary Iterative Hard Thresholding (BIHT) algorithm. Figure 2 Spectral information in (a). Figure 2(b) is the spectrum diagram of the reconstructed frequency comb signal. The frequency range of the introduced spectral holes is 150 ~ 450 MHz, and the frequency range of the signal under test can be estimated to be 9.55 ~ 9.85 GHz. At this time, the error of spectrum detection is less than 90 MHz.

[0044] Adjusting the operating frequency band and signal format of the signal under test can verify the system's ability to detect the spectrum of signals of different formats or frequency bands. When the signal under test consists of a linear frequency modulated signal with a center frequency of 9.7 GHz and a bandwidth of 0.12 GHz and a BPSK signal with a carrier frequency of 9.3 GHz and a data rate of 100 Mb / s, with other settings remaining the same as above... Figure 3 (a) and (b) show the spectrum of the optical frequency comb after filtering and the spectrum of the electrical frequency comb signal reconstructed by the single-bit recovery algorithm, respectively. Figure 3 In (b), the frequency range of the spectral holes is 0.15 ~ 0.45 GHz and 0.55 ~ 0.85 GHz, respectively. Therefore, the operating frequency of the signal under test can be estimated to be 9.15 ~ 9.45 GHz and 9.55 ~ 9.85 GHz, and the spectrum detection error is less than 90 MHz.

[0045] By further reducing Δf This can improve the spectrum detection accuracy of the microwave spectrum detection device. At this point, the signal under test is a linear frequency modulated signal with a center frequency of 9.7 GHz and a bandwidth of 0.12 GHz. First, Δf If the frequency is set to 50 MHz, the starting frequency is set to 0.12 GHz, and the number of teeth of the electric frequency comb is set to 10, then the frequency coverage range of the electric frequency comb signal is 0.12 ~ 0.57 GHz, and its digital processing is the same as above. Figure 4 (a) and (b) show the spectrum of the optical frequency comb after filtering and the spectrum of the electrical frequency comb signal reconstructed by the single-bit recovery algorithm, respectively. Figure 4 The glitches in (b) are due to the suboptimal recovery results of the recovery algorithm. Given the known frequency range of the electronic frequency comb, frequencies exceeding 0.12 ~ 0.57 GHz can be ignored and do not affect the actual measurement results. Figure 4 In (b), the location of the spectral holes is 0.22 ~ 0.37 GHz, thus estimating the frequency range of the signal under test to be 9.63 ~ 9.78 GHz, with a frequency detection error of less than 50 MHz. Then, Δf If the frequency is set to 20 MHz, the starting frequency is set to 0.21 GHz, and the number of teeth on the electronic frequency comb is set to 10, then the frequency coverage range of the electronic frequency comb is 0.21 ~ 0.39 GHz. Figure 4(c) and (d) show the spectrum of the optical frequency comb after filtering and the spectrum of the electrical frequency comb signal reconstructed by the single-bit recovery algorithm, respectively. Figure 4 In (d), the spectral hole is 0.23 ~ 0.37 GHz, and the frequency range of the signal under test is estimated to be 9.63 ~ 9.77 GHz. At this time, the frequency detection error is less than 20 MHz.

[0046] In summary, we proposed a photon-assisted microwave spectrum detection method based on single-bit compressed sensing technology. By combining stimulated Brillouin scattering effect with single-bit compressed sensing technology, we successfully completed spectrum sensing of unknown microwave signals, achieving microwave spectrum detection with an error of less than 20 MHz. The above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. It should be noted that those skilled in the art can make several equivalent modifications and substitutions based on the content disclosed in this invention. For example, when the recovery effect is good, the measurement error is determined by the frequency interval of the optical frequency comb, which can be further reduced. Δf To reduce system measurement errors. In practical applications, one can first use... Δf A 100 MHz optical frequency comb is used to roughly estimate the signal under test over a wide frequency range, and then... Δf The 20 MHz optical frequency comb is used to accurately estimate the signal under test in a small frequency range to further reduce the spectrum detection error. In addition, the spectrum detection range of the signal can be expanded by shifting the frequency of the optical carrier of the input dual parallel Mach-Zehnder modulator. These equivalent modifications and substitutions, as well as the adjustment of the frequency range, should also be considered within the scope of protection of this invention.

Claims

1. A photon-assisted microwave spectrum detection device based on single-bit compressed sensing, characterized in that, The device includes a continuous-wave laser, a first optical coupler, a Mach-Zehnder modulator, an electrical frequency comb generator, an optical isolator, a single-mode fiber, an optical circulator, a dual-parallel Mach-Zehnder modulator, an antenna, an electrical filter, a 90° electrical mixer, an erbium-doped fiber amplifier, a phase modulator, a pseudo-random sequence generator, a second optical coupler, and a photodetector. The output port of the continuous-wave laser is connected to the input port of the first optical coupler. The three output ports of the first optical coupler are respectively connected to the optical input ports of the Mach-Zehnder modulator, the dual-parallel Mach-Zehnder modulator, and the phase modulator. The output port of the electrical frequency comb generator is connected to the radio frequency input port of the Mach-Zehnder modulator. The optical output port of the Mach-Zehnder modulator is connected to the input port of the optical isolator. The output port of the optical isolator is connected to one end of the single-mode fiber, and the other end of the single-mode fiber is connected to port II of the optical circulator. The signal to be tested is received by an antenna. The output port of the antenna is connected to the input port of an electrical filter. The output port of the electrical filter is connected to the input port of a 90° electrical mixer. The two output ports of the 90° electrical mixer are respectively connected to the two RF input ports of a dual parallel Mach-Zehnder modulator. The optical output port of the dual parallel Mach-Zehnder modulator is connected to the input port of an erbium-doped fiber amplifier. The output port of the erbium-doped fiber amplifier is connected to port I of an optical circulator. Port III of the optical circulator is connected to one input port of a second optical coupler. The output port of the pseudo-random sequence generator is connected to the RF input port of a phase modulator. The optical output port of the phase modulator is connected to the other input port of the second optical coupler. The output port of the second optical coupler is connected to the input port of a photodetector. The spectrum information of the signal to be tested can be obtained by digitally processing the waveform output by the photodetector.

2. The photon-assisted microwave spectrum detection device based on single-bit compressed sensing according to claim 1, characterized in that, An electrical frequency comb generator outputs an electrical frequency comb, which is injected into a Mach-Zehnder modulator to generate an optical frequency comb. An optical notch filter, whose frequency response corresponds to the frequency of the signal under test, is constructed using stimulated Brillouin scattering. This filter is then applied to the optical frequency comb output from the Mach-Zehnder modulator to generate spectral holes. The spectrum of the signal under test is estimated using the location information of these spectral holes. Theoretically, the measurement error is related to the frequency interval of the optical frequency comb. Δf They are positively correlated.

3. The photon-assisted microwave spectrum detection device based on single-bit compressed sensing according to claim 1, characterized in that, The range of the electrical frequency comb and the magnitude of the Stokes shift due to stimulated Brillouin scattering jointly determine the measurable frequency range of the system.

4. The photon-assisted microwave spectrum detection device based on single-bit compressed sensing according to claim 1, characterized in that, The passband of the electrical filter is the same as the frequency range of the measurable signal, which avoids out-of-band signals from entering the modulator and causing stimulated Brillouin scattering. The optical notch filter, which produces an undesirable optical frequency comb, interferes with the frequency measurement results.

5. The photon-assisted microwave spectrum detection device based on single-bit compressed sensing according to claim 1, characterized in that, The low-frequency components of the mixed signal generated by the photodetector contain all the information of the filtered optical / electric frequency comb, which can be completely recovered using a single-bit compressed sensing recovery algorithm.

6. A microwave spectrum detection method using the apparatus as described in claim 1, characterized in that, The method includes the following steps: 1) The output frequency of the continuous wave laser is The optical signal is split into three optical signals on an average basis after passing through an optical coupler, and then injected into a phase modulator, a Mach-Zehnder modulator and a dual parallel Mach-Zehnder modulator, respectively. 2) The electric frequency comb generator produces a starting frequency of... Frequency interval is Δf An electrical frequency comb is injected into a Mach-Zehnder modulator. The modulator bias voltage is adjusted so that the Mach-Zehnder modulator operates at the minimum bias point. Then, the Mach-Zehnder modulator outputs a suppressed carrier double-sideband signal corresponding to the electrical frequency comb, i.e., an optical frequency comb signal. 3) The optical signal output from the Mach-Zehnder modulator is injected into a single-mode fiber after passing through an optical isolator as the probe light for stimulated Brillouin scattering. 4) The center frequency received by the antenna is The signal under test is split into two orthogonal signals after passing through an electrical filter and a 90° electrical mixer. These two orthogonal signals are used to drive the two sub-modulators of a dual parallel Mach-Zehnder modulator. By adjusting the modulator bias voltage so that both sub-modulators operate at their minimum bias points and the main modulator operates at its quadrature bias point, the dual parallel Mach-Zehnder modulator outputs a suppressed carrier single-sideband signal corresponding to the signal under test, i.e., generating a center frequency of... The negative first-order light edge band; 5) The suppressed carrier single-sideband signal output from the dual parallel Mach-Zehnder modulator is input into an erbium-doped fiber amplifier for power amplification. The amplified optical signal is then injected back into a single-mode fiber as pump light for stimulated Brillouin scattering, and the frequency is shifted upwards. The position generates the Brillouin loss spectrum as an optical notch filter, with a center frequency of . ; 6) The pseudo-random binary sequence (PRBS) generated by the pseudo-random sequence generator is loaded onto the phase modulator. The optical signal output by the phase modulator and the optical signal after the stimulated Brillouin scattering effect are combined into a single optical signal after passing through the second optical coupler and input into the photodetector. The electrical signal output by the photodetector is low-pass filtered, undersampled and quantized by a single bit, and the spectrum information of the signal under test is obtained by using a single-bit compressed sensing recovery algorithm.

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