Photon frequency hopping digital signal matching receiving device and method

Abstract

The invention discloses a photon frequency hopping digital signal matching receiving device and method, and belongs to the technical field of signal processing. The device comprises a configurable optical pulse sequence generation module, a fast tunable optical shaping module, an orthogonal basis generation module, an electro-optical sampling module, a photoelectric conversion module, an electric analog-to-digital conversion module, a signal processing module and a synchronous extraction module. The configurable optical pulse shaping generation module generates an optical pulse sequence, the fast tunable optical shaping module shapes the optical pulse time domain appearance, and the orthogonal basis generation module shifts the phase of the shaped optical pulse to generate two paths of mutually orthogonal optical sequences. The electro-optical sampling module, the photoelectric conversion module and the electric analog-to-digital conversion module process the two paths of optical sequences into digital signals, and the signal processing module performs parallel-to-serial conversion on the digital signals to recover binary digital codes. According to the invention, the receiving frequency is quickly adjusted on the optical domain and is matched with the appearance of the digital signal to be received, so that the matched receiving of the frequency hopping digital signal in a complex modulation format is realized.

Description

Technical Field

[0001] The invention relates to a photon frequency hopping digital signal matching receiving device and method, belonging to the technical field of signal processing. Background Art

[0002] With the continuous development of satellite communication technology, the next generation of satellite communication systems will develop from low orbit to high orbit, from narrowband to broadband, and from single function to multi-functional integration. With the development of electronic information technology, spectrum resources are becoming increasingly crowded, and the potential interference sources and interference power faced by satellite communications are increasing; at the same time, due to the long distance between the satellite and the ground, the complex electromagnetic environment in space, and the long propagation distance, the satellite communication signal attenuates greatly during the transmission process, and the signal power is lower than that of noise and interference. This requires the satellite communication system to have both broadband anti-interference capabilities and broadband noise suppression capabilities.

[0003] At present, in the electrical frequency hopping receiving system, due to the limitation of "electronic bottleneck", the achievable receiving range is limited, and the working bandwidth of the frequency hopping receiver is difficult to meet the existing and future application requirements; at the same time, due to the tuning speed of electrical devices, the frequency hopping speed that the electrical frequency hopping receiving system can support is limited, which restricts the development and application of frequency hopping communication systems with stronger anti-interception, anti-detection and anti-interference capabilities. Photonic technology has the advantages of ultra-wideband and ultra-high speed that electronic technology does not have, which can effectively overcome the shortcomings of electronic technology. At present, frequency hopping receiving schemes combined with photonic technology have been reported. The agile frequency source based on photonic technology has improved the frequency band supported by frequency hopping communication (Wei, J., et al. (2018). Ultralow-Noise and Agile Microwave Synthesizer Based on a Femtosecond Mode-Locked FiberLaser. cleo.), but the scheme based on direct frequency synthesis (DDS) is limited by the output bandwidth of DDS and can only achieve frequency hopping within a range of less than 2 GHz; the agile frequency source scheme based on injected optical semiconductor lasers supports a frequency hopping range of more than 8 GHz (Zhou, P., et al. (2016). Agile frequency-hopping microwave waveform generation by a semiconductor laser subject to optical injection. 2016 25th Wireless and Optical Communication Conference (WOCC)), but due to the rate limit of frequency offset controlled by adjusting power, the scheme can achieve a frequency hopping speed of less than 107 hops / s; the frequency hopping receiver based on fast tunable microwave photonic filters has fast tuning speed and supports a large frequency hopping range, so it has broad research potential.The tunable microwave photonic filter based on finite impulse response (FIR) (Kim, H.-J., et al. (2016). "Rapidly Tunable Dual-Comb RF Photonic Filter for Ultrabroadband RF Spread Spectrum Applications." IEEE Transactions on Microwave Theory and Techniques 64 (10): 3351-3362.) realizes the reception of high-speed frequency-hopping signals by quickly introducing electrical phase shift. However, due to the periodicity of the FIR filter response, the supported frequency-hopping range is smaller than the free spectrum region (FSR) of the filter, which is no more than 10 GHz in the scheme. In addition, due to the existence of multiple passbands, the anti-interference performance needs to be improved. The tunable microwave photonic filter based on fiber Bragg grating (FBG) (Li, P., et al. (2018). "Fast Tunable Photonic Single-bandpass RF Filter with Multiple Arbitrary Switching Flat-top Passbands." Journal of Lightwave Technology:1-1.) The carrier frequency is adjusted by an electro-optical intensity modulator, and fast passband adjustment is achieved in combination with the extremely narrow passband of FBG. However, the supported frequency hopping range is limited by the response of FBG, which is 12GHz in the scheme. At the same time, due to the temperature sensitivity of FBG, the stability of the system needs to be improved. The frequency hopping receiving scheme based on the fast tuning of the receiving response of the integrated microwave photonic signal processing and digitization system realizes ultra-wideband frequency hopping reception with a frequency hopping range of 6-40GHz by fast shaping of optical pulses (Sun, Y., et al (2021). "Fast and large-range frequency hopping receiving based on simultaneous photonic filtering and digitizing" Optics Letters: 46-4). The above microwave photonic frequency hopping receiving scheme can avoid broadband interference and greatly reduce the possibility of malicious interference to communication. At this time, the main factor affecting communication changes from malicious interference to the deterioration of weak communication signals by in-band noise overlapping with the communication frequency band. However, the above solutions are unable to suppress the noise within the receiving passband. When receiving satellite communication signals with relatively low signal power, the signal-to-noise ratio is still low, making it difficult to achieve low-error digital communication.

[0004] In order to suppress in-band noise and improve the reliability of digital communications, many research institutions at home and abroad have proposed solutions that use the differences between interference and signals in waveform, spectrum and other structures to suppress interference. There are three main types of interference suppression schemes according to the method classification: spatial anti-interference technology, frequency domain interference elimination technology and time domain interference elimination technology. Spatial anti-interference technology is to increase the receiving gain of the signal while suppressing the receiving gain of the interference by adjusting the gain direction of the receiving antenna. However, this method is not suitable for satellite communication systems where the signal arrival direction is variable and the interference source direction may overlap with the signal. Frequency domain interference elimination technology is to digitize the received signal and perform spectrum analysis through Fourier transform, use the interference suppression related algorithm to suppress the spectral components of the interference, and finally restore the interference-eliminated signal to the interference-eliminated time domain signal through inverse Fourier transform. Using this method, the University of Electronic Science and Technology of China achieved interference suppression with a bandwidth of 20MHz (Liu Y., et al, (2017) A full-duplex transceiver with two-stage analog cancellations for multipath self-interference, IEEE Transactions on Microwave Theory and Techniques). However, this method requires high-precision analog-to-digital conversion of the broadband received signal first. The mutual constraints of the bandwidth and sampling accuracy of the analog-to-digital converter limit the working bandwidth of this scheme. Time domain interference cancellation technology is a widely studied technology. Its principle is to construct an adaptive transverse filter at the receiving end according to the optimal reception criterion, and to match the receiving response with the shape of the digital signal by adjusting the tap coefficient of the transverse filter, so as to achieve 25dB real-time elimination of interference with a bandwidth not exceeding 500MHz (Venkatakrishnan SB, et al, (2018), Wideband RF self-interference cancellation circuit for phased array simultaneous transmit and receive system, IEEE Access). However, limited by the operating bandwidth of the analog-to-digital converter / digital-to-analog converter, this type of method cannot adjust the tap coefficient when processing broadband signals and is not suitable for interference suppression in the next generation of broadband satellite communications.In order to achieve interference suppression of broadband signals, microwave photonic technology provides an interference elimination solution with large bandwidth and high tuning accuracy. Combined with the optimization algorithm, it can achieve adaptive interference cancellation in the Ku band (Zhang Y., et al, (2015), self-interference cancellation using dual-drive Mach-Zehnder modulator for in-band full-duplex radio-over-fiber system, Optics Express). However, this solution requires the interference signal to be used as a reference signal and to be processed in the optical domain together with the received signal. The frequency, shape, phase and other information of the interference must be obtained in advance, which is not suitable for eliminating non-cooperative channel noise. In summary, the above-mentioned in-band noise suppression scheme cannot achieve in-band noise suppression for large bandwidth, fast tuning frequency hopping receiving systems.

[0005] Therefore, the existing frequency hopping reception and in-band interference suppression schemes cannot meet the requirements of the next generation satellite communication system for both broadband anti-interference and broadband noise suppression capabilities. Summary of the invention

[0006] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art and propose a photonic frequency-hopping digital signal matching receiving device and method, which effectively realizes the matching reception of complex modulation format frequency-hopping digital signals by quickly adjusting the receiving frequency in the optical domain and matching the shape of the digital signal to be received.

[0007] The technical solution of the present invention is:

[0008] A photon frequency-hopping digital signal matching receiving device comprises a configurable optical pulse sequence generation module, a fast tunable optical shaping module, an orthogonal basis generation module, an electro-optical sampling module, an optoelectronic conversion module, an electrical analog-to-digital conversion module, a signal processing module and a synchronization extraction module;

[0009] The configurable optical pulse shaping generation module generates an optical pulse sequence according to the optical pulse clock signal provided by the synchronization extraction module and the code rate, bandwidth and modulation format information of the digital signal to be received provided by the signal processing module;

[0010] The fast tunable optical shaping module shapes the time domain shape of the optical pulse generated by the configurable optical pulse sequence generation module according to the frequency hopping frequency sequence provided by the synchronization extraction module, so that the center frequency of the Fourier transform of the time domain shape of the optical pulse is the same as the carrier frequency of the digital frequency hopping signal to be received at the corresponding moment;

[0011] The orthogonal base generation module performs phase shift processing on the optical pulse sequence output by the fast tunable optical shaping module to generate two mutually orthogonal optical sequences with a phase difference of 90°;

[0012] The electro-optical sampling module uses two optical sequences to modulate the frequency-hopping digital signal to be received and performs sampling processing in the optical domain;

[0013] The photoelectric conversion module and the electrical analog-to-digital conversion module respectively perform photoelectric conversion on the electrical signals processed by the two optical sequences, sample and convert them into electrical signals, and then sample the two electrical signals respectively according to the sampling clock signal output by the synchronization extraction module to obtain digital signals;

[0014] The signal processing module stores the frequency hopping pattern, the code rate of the digital signal to be received, the modulation format and the transmission code type agreed upon in advance by the communicating parties, sends the above data to the synchronization extraction module and the configurable optical pulse shaping generation module, and sends the clock phase difference to the synchronization extraction module; during the working process, it receives the digital signal and performs spectrum analysis, sends instructions to the synchronization extraction module according to the analysis results, performs parallel-serial conversion, and recovers the binary digital code;

[0015] The synchronization extraction module generates an optical pulse clock signal, a frequency hopping frequency sequence and a sampling clock signal according to the frequency hopping pattern, the code rate of the digital signal to be received, the modulation format, the transmission code type and the clock phase difference; after receiving the instruction from the signal processing module, the synchronization extraction module regenerates the frequency hopping frequency sequence or adjusts the phase of the sampling clock signal and the optical pulse clock signal, and sends them to the configurable optical pulse sequence generation module, the fast tunable optical shaping module and the electrical analog-to-digital conversion module respectively.

[0016] Furthermore, the time domain shape of the optical pulse train p s (t) and the transmitted time domain code pattern s of the digital signal codeword to be received i (t) matches, satisfying the relationship p s (t) = K·s i (t), where K is a constant; at the same time, the time domain signal of the optical pulse sequence is in phase with the digital signal to be received, and the time interval of the optical pulse sequence is equal to the inverse of the code rate of the frequency hopping digital signal to be received.

[0017] Furthermore, the signal processing module receives the digital signal and performs spectrum analysis, and sends instructions to the synchronization extraction module according to the analysis results. If the analysis result shows that the digital signal contains only DC components, the signal processing module sends an update command to the synchronization extraction module, and the synchronization extraction module changes the frequency hopping start position in the frequency hopping pattern to generate a new frequency hopping frequency sequence; until the digital signal contains AC components at any position in the time domain, that is, the center frequency of the Fourier transform of the time domain shape of the optical pulse is the same as the carrier frequency of the digital frequency hopping signal to be received at the corresponding moment, thereby achieving frequency hopping synchronization.

[0018] Furthermore, the signal processing module receives the digital signal and performs spectrum analysis, and sends instructions to the synchronization extraction module based on the analysis results. If the analysis result shows that the digital signal contains an AC component at any position in the time domain, a clock fine-tuning instruction is sent, and the synchronization extraction module adjusts the phase of the sampling clock signal and the optical pulse clock signal to maximize the amplitude of the digital signal output by the electrical analog-to-digital conversion module, that is, the electrical analog-to-digital conversion module samples at the peak value to achieve clock synchronization.

[0019] Furthermore, the electrical analog-to-digital conversion module is controlled by a synchronous extraction module, the sampling period is the same as the optical pulse time interval generated by the configurable optical pulse sequence generation module, and sampling is performed at the peak of the electrical pulses output by the two photoelectric conversion modules to obtain a digital signal.

[0020] Furthermore, the bandwidths of the photoelectric conversion module and the electrical analog-to-digital conversion module are not less than the inverse of the period of the optical pulse sequence generated by the configurable optical pulse generation module.

[0021] Furthermore, the synchronization extraction module generates a clock signal having the same frequency as the code rate of the digital signal to be received according to the code rate of the digital signal to be received, and the clock signal is used as the initial optical pulse clock signal and the sampling clock signal.

[0022] A photon frequency hopping digital signal matching receiving method, comprising:

[0023] S1: calibrating the photon frequency hopping digital signal matching receiving device according to claim 1 to obtain a clock phase difference for matching reception;

[0024] S2: The signal processing module sends the frequency hopping pattern, communication digital signal code rate, modulation format and transmission code type agreed upon by both parties in advance, as well as the calibrated clock phase difference to the synchronization extraction module;

[0025] S3: The synchronization extraction module selects a random starting position in the frequency hopping pattern and generates a frequency hopping frequency sequence according to the frequency hopping pattern; generates an optical pulse clock signal and an electrical sampling clock signal with the same frequency as the digital signal rate according to the communication digital signal rate and the clock phase difference, and sends them to the configurable optical pulse sequence generation module and the electrical analog-to-digital conversion module respectively;

[0026] S4: The configurable optical pulse sequence generation module configures the optical pulse shape according to the communication digital signal code rate, modulation format and transmission code type, and generates a sampling optical pulse sequence according to the optical pulse clock signal;

[0027] S5: The fast tunable optical shaping module shapes the optical pulse sequence according to the frequency hopping frequency sequence and outputs a sampling optical pulse sequence;

[0028] S6: The orthogonal basis generation module processes the optical pulses and outputs two orthogonal optical pulse sequences with a phase difference of 90°;

[0029] S7: The electro-optical sampling module modulates the frequency-hopping digital signal with two orthogonal sampling optical pulse sequences, and completes the frequency-hopping digital signal sampling processing in the optical domain;

[0030] S8: The photoelectric conversion module and the electrical analog-to-digital conversion module convert the modulated optical signal into an electrical digital signal;

[0031] S9: The signal processing module performs spectrum analysis on any digital signal output by the electrical analog-to-digital conversion module:

[0032] If the digital signal contains only a DC component, the signal processing module records the received digital signal and sends an update command to the synchronization extraction module. The synchronization extraction module moves a frequency hopping frequency duration from the current frequency hopping start position as a new frequency hopping start position and returns to step S3.

[0033] If the digital signal contains an AC component at any position in the time domain, the signal processing module sends a clock fine-tuning instruction to the synchronization extraction module. After receiving the clock fine-tuning instruction, the synchronization extraction module simultaneously introduces a fine-tuning amount less than one symbol period in the optical pulse clock and the electrical sampling clock, finds the delay fine-tuning amount with the largest output amplitude of the electrical analog-to-digital conversion module, and sends the adjusted clock signal as a new optical pulse clock and electrical sampling clock to the configurable optical pulse sequence generation module and the electrical analog-to-digital conversion module respectively, and returns to execute steps S4 to S8, and then executes step S10;

[0034] S10: The signal processing module uses the mean value of all recorded digital signal amplitudes as the decision threshold, makes a decision on the current digital signal output by the electrical analog-to-digital conversion module, and performs parallel-to-serial conversion on the decision result according to the pre-agreed digital vector signal modulation format to restore the transmitted 01 digital code.

[0035] Furthermore, in step S1, the photon frequency hopping digital signal matching receiving device is calibrated, and the calibration method is:

[0036] S1.1: The signal processing module sends a calibration start command to the configurable optical pulse sequence generation module and the synchronization extraction module, and sends a clock phase difference to the synchronization extraction module, which is initially set to 0;

[0037] S1.2: The synchronization extraction module sets an arbitrary clock cycle to generate an optical pulse clock signal and an electrical sampling clock signal with a fixed clock cycle. The phase difference between the two is determined by the clock phase difference sent by the signal processing module, and they are used as clock signals for the configurable optical pulse sequence generation module and the electrical analog-to-digital conversion module respectively;

[0038] S1.3: The configurable optical pulse sequence generation module generates an optical narrow pulse sequence according to the clock signal, and the fast tunable optical shaping module is set as an all-pass system. After the optical narrow pulse sequence passes through the orthogonal basis generation module, it is modulated and digitized with the radio frequency calibration signal of any frequency in the electro-optical sampling module, the photoelectric conversion module, and the electrical analog-to-digital conversion module, and the digitized result is sent to the signal processing module;

[0039] S1.4: The signal processing module records the amplitude of the digitized result of the received calibration signal;

[0040] S1.5: The signal processing module linearly increases the current clock phase difference and sends it to the synchronization extraction module as the updated clock phase difference;

[0041] S1.6: Repeat steps 1.2 to 1.5 until the clock phase difference reaches 2π; compare the amplitudes of all recorded digitized results, and select the clock phase difference corresponding to the test with the largest amplitude as the clock phase difference of the receiving test.

[0042] Further, in step S8, after receiving the clock fine-tuning instruction, the synchronization extraction module simultaneously introduces a fine-tuning amount less than one code element period in the optical pulse clock and the electrical sampling clock, and searches for the delay fine-tuning amount with the largest output amplitude of the electrical analog-to-digital conversion module. The specific method is: introducing the set single fine-tuning amount in batches, executing steps S4 to S7 after each introduction, obtaining the digital signal amplitude output by the electrical analog-to-digital conversion module under the corresponding cumulative fine-tuning amount, until the accumulated fine-tuning amount reaches one code element period; finding the digital signal with the largest amplitude, and the cumulative fine-tuning amount corresponding to the digital signal is the delay fine-tuning amount.

[0043] The advantages of the present invention compared with the prior art are:

[0044] (1) The present invention effectively realizes the matching reception of frequency-hopping digital signals with complex modulation formats by quickly adjusting the receiving frequency in the optical domain and matching the shape of the digital signal to be received, thereby suppressing the noise in the receiving passband and reducing the receiving demodulation signal-to-noise ratio threshold.

[0045] (2) Thanks to the large bandwidth characteristics of microwave photonic technology, the operating frequency range is greatly expanded. The present invention can support the low signal-to-noise ratio reception of broadband frequency-agile frequency-hopping digital signals, and can meet the requirements for improving the anti-interference capability of the next generation satellite communication system. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0047] Figure 1 It is a structural schematic diagram of the photon frequency hopping vector digital signal receiving device of the present invention;

[0048] Figure 2 It is a schematic diagram of signal processing in the photon frequency hopping vector digital signal receiving method of the present invention;

[0049] Figure 3 The figure is a schematic diagram of the structure of a photon frequency hopping vector digital signal receiving device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0050] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0051] The present invention proposes a photon frequency hopping digital signal matching receiving device, such as Figure 1 As shown, it includes a configurable optical pulse sequence generating module 1, and along the signal output direction of the configurable optical pulse sequence generating module 1, there are a fast tunable optical shaping module 2, an orthogonal basis generating module 3, an electro-optical sampling module 4, a photoelectric converter 5, an electrical analog-to-digital conversion module 6, a signal processing module 7 and a synchronization extraction module 8. Among them, the output end of the signal processing module 7 is connected to the configurable optical pulse sequence generating module 1 and the synchronization extraction module 8, and the output end of the synchronization extraction module 8 is connected to the control end of the configurable optical pulse shaping generating module 1, the fast tunable optical shaping generating module 2 and the electrical analog-to-digital conversion module 5.

[0052] The configurable optical pulse shaping generation module 1 is controlled by the signal processing module 7 and the synchronization extraction module 8, and generates an optical pulse sequence according to the code rate, bandwidth, modulation format information of the digital signal to be received and the clock information provided by the synchronization extraction module 8. The time domain shape of the optical pulse generated by the configurable optical pulse sequence generation module 1 is p s (t) and the transmitted time domain code pattern s of the digital signal codeword to be received i (t) matches, satisfying the relationship p s (t) = K·s i (t), where K is a constant. The optical pulse is in phase with the received digital signal. The time interval of the optical pulse sequence generated by the optical pulse sequence generating module 1 can be configured to be equal to the inverse of the code rate of the frequency hopping digital signal to be received.

[0053] The fast tunable optical shaping module 2 shapes the time domain shape of the optical pulse generated by the configurable optical pulse sequence generating module 1 according to the frequency hopping frequency sequence output by the synchronization extraction module 8, so that the center frequency of the Fourier transform of the time domain shape of the optical pulse is the same as the carrier frequency of the digital frequency hopping signal to be received at the corresponding moment.

[0054] The orthogonal basis generation module 3 performs phase shift processing on the optical pulse sequence output by the fast tunable optical shaping module 2 to generate two mutually orthogonal optical sequences with a phase difference of 90°.

[0055] The two electro-optical sampling modules 4 are electro-optical sampling modules 4-1 and 4-2, respectively, which use two optical sequences and frequency-hopping digital signal modulation to perform sampling processing in the optical domain.

[0056] The two photoelectric converters 5 are photoelectric converters 5-1 and 5-2 respectively, and the bandwidths of the photoelectric converters 5-1, 5-2 and the electrical analog-to-digital conversion module 6 are not less than the bandwidth of the shaped optical pulses generated by the fast tunable optical shaping module 2. The electrical analog-to-digital conversion module 6 is controlled by the synchronization extraction module 8, and the sampling period is the same as the optical pulse time interval generated by the configurable optical pulse sequence generation module 1, and the sampling is performed at the peak of the electrical pulses output by the photoelectric converters 5-1 and 5-2.

[0057] The synchronization extraction module 8 generates an optical pulse clock signal, a frequency hopping frequency sequence and a sampling clock signal according to the frequency hopping pattern, the code rate of the digital signal to be received, the transmission waveform and other information provided by the signal processing module 7, and adjusts the phase of the sampling clock signal and the optical pulse clock signal according to the received signal of the signal processing module 7, and sends them to the configurable optical pulse sequence generation module 1, the fast tunable optical shaping module 2 and the electrical analog-to-digital conversion module 6 respectively.

[0058] The method for matching and receiving photon frequency hopping digital signals using the device proposed by the present invention comprises the following steps:

[0059] S1. Perform system calibration. The calibration method is:

[0060] 1.1) The signal processing module 7 sends a calibration start command to the configurable optical pulse sequence generation module 1 and the synchronization extraction module 8, and sends a clock phase difference to the synchronization extraction module 8, which is initially set to 0;

[0061] 1.2) The synchronization extraction module 8 sets an arbitrary clock cycle to generate an optical pulse clock signal and an electrical sampling clock signal with a fixed clock cycle. The phase difference between the two is determined by the clock phase difference sent by the signal processing module 7, and they are used as the clock signals of the configurable optical pulse sequence generation module 1 and the electrical analog-to-digital conversion module 6 respectively;

[0062] 1.3) The configurable optical pulse sequence generation module 1 generates an optical narrow pulse sequence according to a clock signal, and the fast tunable optical shaping module 2 is set as an all-pass system. After the optical narrow pulse sequence passes through the orthogonal basis generation module 3, it is modulated with a radio frequency calibration signal of any frequency in the electro-optical sampling modules 4-1 and 4-2 respectively, and then sent to the electrical analog-to-digital conversion module 6 for digitization after being detected by the photoelectric converters 5-1 and 5-2, and the digitized result is sent to the signal processing module 7;

[0063] 1.4) The signal processing module 7 records the amplitude of the digitized result of the received calibration signal;

[0064] 1.5) The signal processing module 7 linearly increases the original clock phase difference and sends it to the synchronization extraction module 8 as the updated clock phase difference;

[0065] 1.6) Repeat steps 1.2 to 1.5 until the clock phase difference reaches 2π, compare the amplitudes of the digitized results recorded by the signal processing module 7 in multiple tests, and select the clock phase difference corresponding to the test with the largest amplitude as the clock phase difference of the receiving test.

[0066] S2. The signal processing module 7 sends the frequency hopping pattern, communication digital signal code rate, modulation format and transmission code type agreed upon in advance by the communicating parties, as well as the clock phase difference obtained by system calibration to the synchronization extraction module 8.

[0067] S3, the synchronization extraction module 8 selects a random starting position in the frequency hopping pattern, and generates a frequency hopping frequency sequence according to the frequency hopping pattern; generates an optical pulse clock signal and an electrical sampling clock signal with the same frequency as the digital signal bit rate according to the communication digital signal bit rate and the clock phase difference, and sends them to the configurable optical pulse sequence generation module 1 and the electrical analog-to-digital conversion module 6 respectively.

[0068] S4, the configurable optical pulse sequence generating module 1 configures the optical pulse shape according to the communication code type information sent by the signal processing module 7, and generates a sampling optical pulse sequence according to the optical pulse clock signal provided by the synchronization extraction module 8; the time interval of the optical pulse sequence generated by the configurable optical pulse sequence generating module 1 is equal to the inverse of the code rate of the frequency hopping digital signal to be received; the optical pulse time domain shape p s (t) and the transmitted time domain code pattern s of the digital signal codeword to be received i (t) matches, satisfying the relationship p s (t) = K·s i (t), where K is a constant.

[0069] S5, the fast tunable optical shaping module 2 shapes the optical pulses generated by the configurable optical pulse sequence generating module 1 according to the frequency hopping frequency sequence sent by the synchronization extraction module 7, such as Figure 2As shown in the signal (f), the center frequency of the Fourier transform of the optical pulse output by the fast tunable optical shaping module 2 is made the same as the frequency specified by the corresponding time-hopping frequency sequence.

[0070] S6, the orthogonal basis generation module 3 processes the optical pulse sequence output by the fast tunable optical shaping module 2, and outputs two orthogonal optical pulse sequences with a phase difference of 90°, such as Figure 2 Shown by the signal in (g).

[0071] S7, the two optical pulse sequences generated by the orthogonal basis generation module 3 are modulated by the frequency hopping digital signal to be received through the electro-optical sampling modules 4-1, 4-2, and converted into electrical signals through the photoelectric converters 5-1, 5-2, such as Figure 2 The signal (h) is converted into a digital signal in the electrical analog-to-digital conversion module 6 and input into the signal processing module 7.

[0072] S8. The signal processing module 7 performs spectrum analysis on the digital signal input by the electrical analog-to-digital conversion module 6: When the input digital signal contains only a DC component, the signal processing module 6 sends an update command to the synchronization extraction module 7. The synchronization extraction module 7 uses the position after the start position of this frequency hopping as the new start position of the frequency hopping and returns to step S2.

[0073] S9. When the digital signal received by the signal processing module 7 contains an AC component at any position in the time domain, the signal processing module 7 sends a clock fine-tuning instruction to the synchronization extraction module 8. After receiving the clock fine-tuning instruction, the synchronization extraction module 7 simultaneously introduces a fine-tuning amount less than one code element period into the optical pulse clock and the electrical sampling clock, finds the delay fine-tuning amount with the largest output amplitude of the electrical analog-to-digital converter 6, and sends the adjusted clock signal as the new optical pulse clock and the electrical sampling clock to the configurable optical pulse sequence generation module 1 and the electrical analog-to-digital conversion module 6 respectively.

[0074] S10, the optical pulses generated by the configurable optical pulse sequence generation module 1 according to the optical pulse clock are sent to the fast tunable optical shaping module 2 for shaping, and are converted into mutually orthogonal optical pulse sequences by the orthogonal basis generation module 3, and are modulated with the frequency-hopping digital signals to be received by the electro-optical sampling modules 4-1 and 4-2 respectively, and are converted into electrical signals by the photoelectric converters 5-1 and 5-2, and are converted into digital signals in the electrical analog-to-digital conversion module 6 according to the electrical sampling clock provided by the synchronization extraction module 8, and are input into the signal processing module 7.

[0075] S11, the signal processing module 7 sets the decision threshold according to the mean value of the input sampling result, and makes a decision on the sampling signal output by the electrical analog-to-digital conversion module 6, and performs parallel-to-serial conversion on the decision result according to the pre-agreed digital vector signal modulation format, and recovers the transmitted 0 1 digital code, such as Figure 2 Shown by the signal in (h).

[0076] In one embodiment of the present invention, the configurable optical pulse sequence generation module 1 includes a mode-locked laser 1-1, a programmable optical filter 1-2, such as Figure 3 As shown, along the signal output direction of the fast tunable optical filter 2 are the 90° optical bridge 3, the electro-optical modulators 4-1, 4-2, the photoelectric converters 5-1, 5-2, and the electrical analog-to-digital conversion module 6 including the electrical filters 6-1, 6-2 and the electrical analog-to-digital converter 6-3. The output end of the signal processing module 7 is connected to the control end of the programmable optical filter 1-2 and the input end of the synchronization extraction module 8, and the output end of the synchronization extraction module 8 is connected to the mode-locked laser 1-1, the fast tunable optical filter 2 and the electrical analog-to-digital converter 6-3. The bandwidths of the photoelectric converters 5-1, 5-2 and the electrical analog-to-digital conversion module 6 are not less than the inverse of the time domain period of the optical pulse sequence generated by the configurable optical pulse sequence generation module 1.

[0077] The synchronization extraction module 8 is connected to the mode-locked laser 1-1 and the electrical analog-to-digital converter 6-3 respectively, so that the sampling rate of the electrical analog-to-digital converter 6-3 is the same as the repetition frequency of the optical pulse sequence output by the mode-locked laser 1-1, which is equal to the inverse of the bit rate of the digital signal to be received, and the electrical analog-to-digital converter 6-3 samples at the peak of the electrical pulse. The signal processing module 7 is connected to the programmable optical filter 1-2.

[0078] After calibration, the device provided in the embodiment performs matching reception as follows:

[0079] 1) The signal processing module 7 sends the agreed frequency hopping pattern, digital signal code rate, modulation format and transmission code type to the synchronization extraction module 8;

[0080] 2) The synchronization extraction module 8 generates a clock signal with a period equal to the inverse of the code rate according to the digital signal code rate and modulation format, and sends it to the mode-locked laser 1-1 and the electrical analog-to-digital converter 6-3 as a clock signal;

[0081] 3) The signal processing module 7 sends the time domain shape of the transmitted codeword of the digital signal to be received to the programmable optical filter 1-2, so that the impulse response p of the programmable optical filter 1-2 s (t) and the time domain code pattern s of the digital signal codeword to be received i (t) matches, satisfying the relationship p s (t) = K·s i (t), where K is a constant;

[0082] 4) The synchronization extraction module 8 randomly selects a starting position in the frequency hopping pattern, generates a frequency hopping frequency sequence consistent with the frequency hopping pattern, and sends the frequency hopping frequency sequence to the fast tunable optical filter 2, controls it to generate an optical pulse sequence whose center frequency of the Fourier transform of the time domain shape is equal to the frequency hopping frequency sequence, and after passing through the 90° optical bridge 3, outputs an optical pulse sequence whose two channels are mutually orthogonal and whose center frequency of the Fourier transform of the time domain shape is the same as the frequency hopping frequency sequence;

[0083] 5) The two orthogonal optical pulse sequences generated by the orthogonal basis generation module 3 are optically sampled in the electro-optical modulators 4-1 and 4-2 for the received frequency-hopping digital vector signals, respectively. The signals are converted into electrical signals through the photoelectric converters 5-1 and 5-2, and then sent to the electrical analog-to-digital converter 6-3 after anti-aliasing filtering through the electrical filters 6-1 and 6-2. The signals are converted into digital signals according to the electrical sampling clock provided by the synchronization extraction module 8 and input into the signal processing module 7;

[0084] 6) The signal processing module 7 performs spectrum analysis on the digital signal input by the analog-to-digital converter 6-3: When the input digital signal contains only a DC component, the signal processing module 7 sends an update command to the synchronization extraction module 8, and the synchronization extraction module 8 selects the new position after the start position of this frequency hopping as the updated frequency hopping start position, and returns to step 4)

[0085] 7) When the digital signal received by the signal processing module 7 contains an AC component at any sampling time, the signal processing module 7 sends a clock fine-tuning instruction to the synchronization extraction module 8. After receiving the clock fine-tuning instruction, the synchronization extraction module 8 introduces a fine-tuning amount less than one clock cycle into the optical pulse clock and the electrical sampling clock to ensure that the electrical sampling clock is in phase with the received electrical signal and the electrical analog-to-digital conversion module 6 samples at the highest point of the electrical pulse, and sends the adjusted clock signal as a new optical pulse clock and electrical sampling clock to the mode-locked laser 1-1 and the electrical analog-to-digital converter 6-3 respectively, and returns to step 5);

[0086] 8) The signal processing module 7 sets the decision threshold according to the mean of the received sampling results, makes a decision on the digital signal output by the analog-to-digital converter 6-3, and performs parallel-to-serial conversion on the decision result according to the pre-agreed digital vector signal modulation format to restore the sent 0 1 information.

[0087] The above-described embodiments are only preferred specific implementations of the present invention. Common changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included in the protection scope of the present invention.

Claims

1. A photon frequency hopping digital signal matching receiving device, characterized in that: It includes a configurable optical pulse sequence generation module, a fast tunable optical shaping module, an orthogonal basis generation module, an electro-optical sampling module, an optoelectronic conversion module, an electrical analog-to-digital conversion module, a signal processing module and a synchronization extraction module; The configurable optical pulse shaping generation module generates an optical pulse sequence according to the optical pulse clock signal provided by the synchronization extraction module and the code rate, bandwidth and modulation format information of the digital signal to be received provided by the signal processing module; The fast tunable optical shaping module shapes the time domain shape of the optical pulse generated by the configurable optical pulse sequence generation module according to the frequency hopping frequency sequence provided by the synchronization extraction module, so that the center frequency of the Fourier transform of the time domain shape of the optical pulse is the same as the carrier frequency of the digital frequency hopping signal to be received at the corresponding moment; The orthogonal base generation module performs phase shift processing on the optical pulse sequence output by the fast tunable optical shaping module to generate two mutually orthogonal optical sequences with a phase difference of 90°; The electro-optical sampling module uses two optical sequences to modulate the frequency-hopping digital signal to be received and performs sampling processing in the optical domain; The photoelectric conversion module and the electrical analog-to-digital conversion module respectively perform photoelectric conversion on the electrical signals processed by the two optical sequences, sample and convert them into electrical signals, and then sample the two electrical signals respectively according to the sampling clock signal output by the synchronization extraction module to obtain digital signals; The signal processing module stores the frequency hopping pattern, the code rate of the digital signal to be received, the modulation format and the transmission code type agreed upon in advance by the communicating parties, sends the above data to the synchronization extraction module and the configurable optical pulse shaping generation module, and sends the clock phase difference to the synchronization extraction module; during the working process, it receives the digital signal and performs spectrum analysis, sends instructions to the synchronization extraction module according to the analysis results, performs parallel-serial conversion, and recovers the binary digital code; The synchronization extraction module generates an optical pulse clock signal, a frequency hopping frequency sequence and a sampling clock signal according to the frequency hopping pattern, the code rate of the digital signal to be received, the modulation format, the transmission code type and the clock phase difference; after receiving the instruction from the signal processing module, the synchronization extraction module regenerates the frequency hopping frequency sequence or adjusts the phase of the sampling clock signal and the optical pulse clock signal, and sends them to the configurable optical pulse sequence generation module, the fast tunable optical shaping module and the electrical analog-to-digital conversion module respectively.

2. The photon frequency hopping digital signal matching receiving device according to claim 1, characterized in that: The time domain profile of the optical pulse train s (t) and the transmitted time domain code pattern s of the digital signal codeword to be received i (t) matches, satisfying the relationship p s (t) = K·s i (t), where K is a constant; at the same time, the time domain signal of the optical pulse sequence is in phase with the digital signal to be received, and the time interval of the optical pulse sequence is equal to the inverse of the code rate of the frequency hopping digital signal to be received.

3. The photon frequency hopping digital signal matching receiving device according to claim 1, characterized in that: The signal processing module receives the digital signal and performs spectrum analysis, and sends instructions to the synchronization extraction module according to the analysis results. If the analysis result shows that the digital signal contains only DC components, the signal processing module sends an update command to the synchronization extraction module, and the synchronization extraction module changes the frequency hopping start position in the frequency hopping pattern to generate a new frequency hopping frequency sequence; until the digital signal contains AC components at any position in the time domain, that is, the center frequency of the Fourier transform of the time domain shape of the optical pulse is the same as the carrier frequency of the digital frequency hopping signal to be received at the corresponding moment, thereby achieving frequency hopping synchronization.

4. The photon frequency hopping digital signal matching receiving device according to claim 1, characterized in that: The signal processing module receives the digital signal and performs spectrum analysis, and sends instructions to the synchronization extraction module based on the analysis results. If the analysis result shows that the digital signal contains an AC component at any position in the time domain, a clock fine-tuning instruction is sent, and the synchronization extraction module adjusts the phase of the sampling clock signal and the optical pulse clock signal to maximize the amplitude of the digital signal output by the electrical analog-to-digital conversion module, that is, the electrical analog-to-digital conversion module samples at the peak value to achieve clock synchronization.

5. The photon frequency hopping digital signal matching receiving device according to claim 1, characterized in that: The electrical analog-to-digital conversion module is controlled by the synchronous extraction module, the sampling period is the same as the optical pulse time interval generated by the configurable optical pulse sequence generation module, and the peak values ​​of the electrical pulses output by the two photoelectric conversion modules are sampled to obtain digital signals.

6. The photon frequency hopping digital signal matching receiving device according to claim 5, characterized in that: The bandwidths of the photoelectric conversion module and the electrical analog-to-digital conversion module are not less than the inverse of the period of the optical pulse sequence generated by the configurable optical pulse generation module.

7. The photon frequency hopping digital signal matching receiving device according to claim 1, characterized in that: The synchronization extraction module generates a clock signal having the same frequency as the code rate of the digital signal to be received according to the code rate of the digital signal to be received, and the clock signal is used as the initial optical pulse clock signal and the sampling clock signal.

8. A photon frequency hopping digital signal matching receiving method, characterized in that: include: S1: calibrating the photon frequency hopping digital signal matching receiving device according to claim 1 to obtain a clock phase difference for matching reception; S2: The signal processing module sends the frequency hopping pattern, communication digital signal code rate, modulation format and transmission code type agreed upon by both parties in advance, as well as the calibrated clock phase difference to the synchronization extraction module; S3: The synchronization extraction module selects a random starting position in the frequency hopping pattern and generates a frequency hopping frequency sequence according to the frequency hopping pattern; generates an optical pulse clock signal and an electrical sampling clock signal with the same frequency as the digital signal rate according to the communication digital signal rate and the clock phase difference, and sends them to the configurable optical pulse sequence generation module and the electrical analog-to-digital conversion module respectively; S4: The configurable optical pulse sequence generation module configures the optical pulse shape according to the communication digital signal code rate, modulation format and transmission code type, and generates a sampling optical pulse sequence according to the optical pulse clock signal; S5: The fast tunable optical shaping module shapes the optical pulse sequence according to the frequency hopping frequency sequence and outputs a sampling optical pulse sequence; S6: The orthogonal basis generation module processes the optical pulses and outputs two orthogonal optical pulse sequences with a phase difference of 90°; S7: The electro-optical sampling module modulates the frequency-hopping digital signal with two orthogonal sampling optical pulse sequences, and completes the frequency-hopping digital signal sampling processing in the optical domain; S8: The photoelectric conversion module and the electrical analog-to-digital conversion module convert the modulated optical signal into an electrical digital signal; S9: The signal processing module performs spectrum analysis on any digital signal output by the electrical analog-to-digital conversion module: If the digital signal contains only a DC component, the signal processing module records the received digital signal and sends an update command to the synchronization extraction module. The synchronization extraction module moves a frequency hopping frequency duration from the current frequency hopping start position as a new frequency hopping start position and returns to step S3. If the digital signal contains an AC component at any position in the time domain, the signal processing module sends a clock fine-tuning instruction to the synchronization extraction module. After receiving the clock fine-tuning instruction, the synchronization extraction module simultaneously introduces a fine-tuning amount less than one symbol period in the optical pulse clock and the electrical sampling clock, finds the delay fine-tuning amount with the largest output amplitude of the electrical analog-to-digital conversion module, and sends the adjusted clock signal as a new optical pulse clock and electrical sampling clock to the configurable optical pulse sequence generation module and the electrical analog-to-digital conversion module respectively, and returns to execute steps S4 to S8, and then executes step S10; S10: The signal processing module uses the mean value of all recorded digital signal amplitudes as the decision threshold, makes a decision on the current digital signal output by the electrical analog-to-digital conversion module, and performs parallel-to-serial conversion on the decision result according to the pre-agreed digital vector signal modulation format to restore the transmitted 01 digital code.

9. A photon frequency hopping digital signal matching receiving method according to claim 8, characterized in that: In step S1, the photon frequency hopping digital signal matching receiving device is calibrated, and the calibration method is: S1.1: The signal processing module sends a calibration start command to the configurable optical pulse sequence generation module and the synchronization extraction module, and sends a clock phase difference to the synchronization extraction module, which is initially set to 0; S1.2: The synchronization extraction module sets an arbitrary clock cycle to generate an optical pulse clock signal and an electrical sampling clock signal with a fixed clock cycle. The phase difference between the two is determined by the clock phase difference sent by the signal processing module, and they are used as clock signals for the configurable optical pulse sequence generation module and the electrical analog-to-digital conversion module respectively; S1.3: The configurable optical pulse sequence generation module generates an optical narrow pulse sequence according to the clock signal, and the fast tunable optical shaping module is set as an all-pass system. After the optical narrow pulse sequence passes through the orthogonal basis generation module, it is modulated and digitized with the radio frequency calibration signal of any frequency in the electro-optical sampling module, the photoelectric conversion module, and the electrical analog-to-digital conversion module, and the digitized result is sent to the signal processing module; S1.4: The signal processing module records the amplitude of the digitized result of the received calibration signal; S1.5: The signal processing module linearly increases the current clock phase difference and sends it to the synchronization extraction module as the updated clock phase difference; S1.6: Repeat steps 1.2 to 1.5 until the clock phase difference reaches 2π; compare the amplitudes of all recorded digitized results, and select the clock phase difference corresponding to the test with the largest amplitude as the clock phase difference of the receiving test.

10. A photon frequency hopping digital signal matching receiving method according to claim 8, characterized in that: In step S8, after receiving the clock fine-tuning instruction, the synchronization extraction module simultaneously introduces a fine-tuning amount less than one code element period in the optical pulse clock and the electrical sampling clock, and searches for the delay fine-tuning amount with the largest output amplitude of the electrical analog-to-digital conversion module. The specific method is: introducing the set single fine-tuning amount in batches, executing steps S4 to S7 after each introduction, obtaining the digital signal amplitude output by the electrical analog-to-digital conversion module under the corresponding cumulative fine-tuning amount, until the accumulated fine-tuning amount reaches one code element period; finding the digital signal with the largest amplitude, and the cumulative fine-tuning amount corresponding to the digital signal is the delay fine-tuning amount.

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