A photonic frequency-hopping digital signal matching receiver and method

Abstract

This invention discloses a photonic frequency-hopping digital signal matching and receiving device and method, belonging to the field of signal processing technology. The device includes a configurable optical pulse sequence generation module, a fast tunable optical shaping module, an orthogonal basis generation module, an electro-optic sampling module, a photoelectric conversion module, an analog-to-digital conversion module, a signal processing module, and a synchronization extraction module. The configurable optical pulse shaping module generates an optical pulse sequence; the fast tunable optical shaping module shapes the temporal shape of the optical pulses; the orthogonal basis generation module phase-shifts the shaped optical pulses to generate two mutually orthogonal optical sequences; the electro-optic sampling module, photoelectric conversion module, and analog-to-digital conversion module process the two optical sequences into digital signals; and the signal processing module performs parallel-to-serial conversion on the digital signals to recover binary digital codes. This invention achieves matched reception of frequency-hopping digital signals with complex modulation formats by rapidly adjusting the receiving frequency in the optical domain and matching it with the shape of the digital signal to be received.

Description

Technical Field

[0001] This invention relates to a photonic frequency hopping digital signal matching and receiving device and method, belonging to the field of signal processing technology. Background Technology

[0002] With the continuous development of satellite communication technology, the next generation of satellite communication systems will evolve from low Earth orbit to high Earth orbit, from narrowband to broadband, and from single-function to multi-functional integration. As electronic information technology advances, spectrum resources are becoming increasingly congested, and the potential sources and power of interference faced by satellite communications are constantly increasing. Simultaneously, due to the long distance between satellite and ground, the complex electromagnetic environment of space, and the long propagation distance, satellite communication signals experience significant attenuation during transmission, resulting in lower signal power compared to noise and interference. This necessitates that improved satellite communication systems possess both broadband anti-interference capabilities and broadband noise suppression capabilities.

[0003] Currently, electronic frequency-hopping receiver systems are limited by "electronic bottlenecks," restricting the achievable reception range and making it difficult for the operating bandwidth of frequency-hopping receivers to meet current and future application needs. Furthermore, the tuning speed of electronic components limits the frequency-hopping speeds that these systems can support, hindering the development and application of frequency-hopping communication systems with stronger anti-interception, anti-reconnaissance, and anti-interference capabilities. Photonics technology possesses advantages such as ultra-wideband and ultra-high speed, which are not available in electronic technology, effectively overcoming its shortcomings. Frequency-hopping receiver schemes incorporating photonics technology have already been reported. Photonic agile frequency sources have expanded the frequency bands supported by frequency hopping communication (Wei, J., et al. (2018). Ultralow-Noise and Agile Microwave Synthesizer Based on a Femtosecond Mode-Locked FiberLaser. cleo.). However, schemes based on direct frequency synthesis (DDS) are limited by the output bandwidth of DDS and can only achieve frequency hopping in the range of less than 2 GHz. Agile frequency sources based on injected optical semiconductor lasers can support 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)). However, due to the rate limitation of frequency offset control by adjusting power, the frequency hopping speed that can be achieved by the scheme is less than 107 hops / s. Frequency hopping receivers based on fast tunable microwave photonic filters have fast tuning speeds and support a large frequency hopping range, thus having broad research potential.A 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.) achieves high-speed frequency hopping signal reception by rapidly introducing an electrical phase shift. However, due to the periodicity of the FIR filter response, the supported frequency hopping range is smaller than the filter's free spectrum region (FSR), which is no greater than 10 GHz in the proposed scheme. Furthermore, due to the presence of multiple passbands, the anti-interference performance needs to be improved. A 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.) By adjusting the carrier frequency using an electro-optic intensity modulator and combining it with the extremely narrow passband of the FBG, fast passband adjustment is achieved. However, the supported frequency hopping range is limited by the response of the FBG, which is 12 GHz in this scheme. Furthermore, due to the temperature sensitivity of the FBG, the system stability needs to be improved. A frequency hopping reception scheme based on the rapid tuning of the receiver response of an integrated microwave photonic signal processing and digitizing system achieves ultra-wideband frequency hopping reception covering a range of 6-40 GHz through rapid 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 reception scheme can avoid broadband interference and significantly reduce the possibility of malicious interference to communication. At this point, 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, none of the above solutions can suppress noise located in the receiving passband. When receiving satellite communication signals with low signal power, the signal-to-noise ratio is still low, making it difficult to achieve low bit error rate digital communication.

[0004] To suppress in-band noise and improve the reliability of digital communication, numerous research institutions both domestically and internationally have proposed schemes that utilize the differences in waveform and spectral structure between interference and signals for suppression. Interference suppression schemes can be broadly categorized into three types based on their methods: spatial anti-interference techniques, frequency domain interference cancellation techniques, and time domain interference cancellation techniques. Spatial anti-interference techniques increase the signal's receiving gain while suppressing interference by adjusting the gain direction of the receiving antenna. However, this method is not suitable for satellite communication systems where the signal's arrival direction is variable or the interference source direction may overlap with the signal. Frequency domain interference cancellation techniques digitize the received signal, perform spectral analysis using Fourier transform, apply relevant interference suppression algorithms to suppress the spectral components of the interference, and finally restore the interference-cancelled signal to its original time domain form using an 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 constraint between the bandwidth of the electronic analog-to-digital converter and the sampling accuracy limits 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 receiving criterion. By adjusting the tap coefficients of the transverse filter, the receiving response is matched with the shape of the digital signal, achieving 25dB real-time cancellation 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, due to the limitations of the operating bandwidth of analog-to-digital converters / digital-to-analog converters, these methods cannot adjust the tap coefficients when processing broadband signals and are not suitable for interference suppression in next-generation broadband satellite communications.To achieve interference suppression for broadband signals, microwave photonics technology offers interference cancellation schemes with large bandwidth and high tuning accuracy. Combined with optimization algorithms, adaptive interference cancellation in the Ku band can be achieved (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 scheme requires the interference signal to be used as a reference signal and processed together with the received signal in the optical domain. Information such as the frequency, shape, and phase of the interference must be obtained in advance, making it unsuitable for eliminating non-cooperative channel noise. In summary, the above-mentioned in-band noise suppression schemes cannot achieve in-band noise suppression for high-bandwidth, fast-tuning frequency-hopping receiver systems.

[0005] Therefore, existing frequency hopping reception and in-band interference suppression schemes cannot meet the requirements of next-generation satellite communication systems to simultaneously possess broadband anti-interference and broadband noise suppression capabilities. Summary of the Invention

[0006] The technical problem solved by this invention is to overcome the shortcomings of the prior art and propose a photonic frequency hopping digital signal matching and receiving device and method. By rapidly adjusting the receiving frequency in the optical domain and matching it with the shape of the digital signal to be received, the matching and receiving of frequency hopping digital signals with complex modulation formats is effectively realized.

[0007] The technical solution of this invention is:

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

[0009] The configurable optical pulse shaping and generating module generates an optical pulse sequence based on 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 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 time.

[0011] The orthogonal basis generation module performs phase shifting 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-optic sampling module modulates two optical sequences with the frequency-hopping digital signal to be received, and performs sampling processing in the optical domain.

[0013] The photoelectric conversion module and the analog-to-digital conversion module perform photoelectric conversion on the electrical signals after processing the two optical sequences, sample and convert them into electrical signals, and then sample the two electrical signals 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 pattern agreed upon by both communicating parties in advance. It 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 operation, it receives digital signals and performs spectrum analysis. Based on the analysis results, it sends instructions to the synchronization extraction module to perform parallel-to-serial conversion and recover the binary digital code.

[0015] The synchronization extraction module generates an optical pulse clock signal, a frequency hopping sequence, and a sampling clock signal based on the frequency hopping pattern, the code rate of the digital signal to be received, the modulation format, the transmission code pattern, and the clock phase difference. After receiving instructions from the signal processing module, the synchronization extraction module regenerates the frequency hopping 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 analog-to-digital conversion module, respectively.

[0016] Furthermore, the temporal shape p of the optical pulse sequence s (t) and the transmission time-domain code s of the codeword to be received digital signal i (t) matches, satisfying relation 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 reciprocal 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. Based on the analysis results, it sends a command to the synchronization extraction module. If the analysis results indicate that the digital signal contains only a DC component, the signal processing module sends an update command to the synchronization extraction module. The synchronization extraction module changes the start position of the frequency hopping pattern and generates a new frequency hopping sequence. This continues until the digital signal contains an AC component at any position in the time domain, meaning that the center frequency of the Fourier transform of the optical pulse time domain shape is the same as the carrier frequency of the digital frequency hopping signal to be received at the corresponding time, thus achieving frequency hopping synchronization.

[0018] Furthermore, the signal processing module receives the digital signal and performs spectrum analysis. Based on the analysis results, it sends an instruction to the synchronization extraction module. If the analysis results show that the digital signal contains an AC component at any point in the time domain, it sends a clock fine-tuning instruction. 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 analog-to-digital converter module. That is, the analog-to-digital converter module samples at the peak value to achieve clock synchronization.

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

[0020] Furthermore, the bandwidth of both the photoelectric conversion module and the analog-to-digital conversion module is not less than the reciprocal 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 with the same frequency as the digital signal code rate based on the code rate of the digital signal to be received. This clock signal serves as the initial optical pulse clock signal and the sampling clock signal.

[0022] A method for matching and receiving photonic frequency hopping digital signals includes:

[0023] S1: The photonic frequency hopping digital signal matching receiver as described in claim 1 is calibrated to obtain the clock phase difference used for matching reception;

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

[0025] S3: The synchronization extraction module selects a random start position in the frequency hopping pattern and generates a frequency hopping frequency sequence according to the frequency hopping pattern; it generates an optical pulse clock signal and an electrical sampling clock signal with the same frequency as the digital signal code rate according to the communication digital signal code 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 shape of the optical pulse according to the code rate, modulation format and transmission code of the communication digital signal, and generates a sampled 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 sequence and outputs the sampled optical pulse sequence;

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

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

[0030] S8: The photoelectric conversion module and the 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 from the analog-to-digital converter 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 one frequency hopping duration from the current frequency hopping start position as the new frequency hopping start position and returns to step S3.

[0033] If the digital signal contains an AC component at any point in the time domain, the signal processing module sends a clock fine-tuning command to the synchronization extraction module. After receiving the clock fine-tuning command, the synchronization extraction module simultaneously introduces a fine-tuning amount of less than one symbol 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 conversion module, and sends the adjusted clock signal as the 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. After returning to execute steps S4 to S8, step S10 is then executed.

[0034] S10: The signal processing module uses the average amplitude of all recorded digital signals as the decision threshold to make a decision on the current digital signal output by the analog-to-digital converter module, and performs parallel-to-serial conversion on the decision result according to the pre-agreed digital vector signal modulation format to recover the transmitted 01 digital code.

[0035] Further, in step S1, the photon frequency-hopping digital signal matching receiver is calibrated. The calibration method is as follows:

[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, initially set to 0;

[0037] S1.2: The synchronization extraction module sets an arbitrary clock period to generate an optical pulse clock signal and an electrical sampling clock signal with a fixed clock period. 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 a narrow optical pulse sequence according to the clock signal. The fast tunable optical shaping module is set as an all-pass system. After the narrow optical pulse sequence passes through the orthogonal basis generation module, it is modulated and digitized by the RF calibration signal of arbitrary frequency in the electro-optic sampling module, photoelectric conversion module, and analog-to-digital conversion module, respectively. The digitization 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 increments 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 digitization results, and select the clock phase difference corresponding to the test with the largest amplitude as the clock phase difference for the receiving test.

[0042] Further, in step S8, after receiving the clock fine-tuning command, the synchronization extraction module simultaneously introduces a fine-tuning amount of less than one symbol period into the optical pulse clock and the electrical sampling clock to find the delay fine-tuning amount with the largest output amplitude of the electrical analog-to-digital converter module. The specific method is as follows: the set single fine-tuning amount is introduced in stages, and after each introduction, steps S4 to S7 are executed to obtain the amplitude of the digital signal output by the electrical analog-to-digital converter module under the corresponding cumulative fine-tuning amount, until the fine-tuning amount accumulates to one symbol period; the digital signal with the largest amplitude is found, and the cumulative fine-tuning amount corresponding to the digital signal is the delay fine-tuning amount.

[0043] The advantages of this invention compared to the prior art are:

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

[0045] (2) Thanks to the wide bandwidth of microwave photonics technology, the operating frequency range is greatly expanded. This invention can support low signal-to-noise ratio reception of broadband frequency-agile frequency-hopping digital signals, and can meet the requirements of improving the anti-interference capability of next-generation satellite communication systems. Attached Figure Description

[0046] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

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

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

[0049] Figure 3 This is a schematic diagram of the structure of the photon frequency hopping vector digital signal receiving device according to an embodiment of the present invention. Detailed Implementation

[0050] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0051] This invention proposes a photonic frequency hopping digital signal matching and receiving device, such as... Figure 1 As shown, the system includes a configurable optical pulse sequence generation module 1. Along the signal output direction of the configurable optical pulse sequence generation module 1, the following modules are arranged in sequence: a fast tunable optical shaping module 2, an orthogonal basis generation module 3, an electro-optic sampling module 4, a photoelectric converter 5, an analog-to-digital converter 6, a signal processing module 7, and a synchronization extraction module 8. The output of the signal processing module 7 is connected to the configurable optical pulse sequence generation module 1 and the synchronization extraction module 8. The output of the synchronization extraction module 8 is connected to the control terminals of the configurable optical pulse shaping module 1, the fast tunable optical shaping module 2, and the analog-to-digital converter 5.

[0052] The configurable optical pulse shaping and generation module 1 is controlled by the signal processing module 7 and the synchronization extraction module 8. Based on the bit rate, bandwidth, modulation format information of the digital signal to be received, and the clock information provided by the synchronization extraction module 8, it generates an optical pulse sequence. The optical pulse time-domain shape p generated by the configurable optical pulse sequence generation module 1... s (t) and the transmission time-domain code s of the codeword to be received digital signal i (t) matches, satisfying relation p s (t)=K·s i (t), where K is a constant, and the optical pulse is in phase with the received digital signal. The time interval of the optical pulse sequence generated by the configurable optical pulse sequence generation module 1 is equal to the reciprocal 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 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 time.

[0054] The orthogonal basis generation module 3 performs phase shifting 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-optic sampling modules 4 are electro-optic sampling modules 4-1 and 4-2, which respectively use two optical sequences and frequency-hopping digital signals to perform sampling processing in the optical domain.

[0056] The two photoelectric converters 5 are photoelectric converters 5-1 and 5-2, respectively. The bandwidths of photoelectric converters 5-1 and 5-2 and the analog-to-digital converter module 6 are all no less than the bandwidth of the shaped light pulses generated by the fast tunable light shaping module 2. The analog-to-digital converter module 6 is controlled by the synchronous extraction module 8, and its sampling period is the same as the time interval of the light pulses generated by the configurable light pulse sequence generation module 1. It samples at the peak value of the electrical pulses output by photoelectric converters 5-1 and 5-2.

[0057] The synchronous extraction module 8 generates an optical pulse clock signal, a frequency hopping frequency sequence, and a sampling clock signal based on the frequency hopping pattern, the code rate of the digital signal to be received, and the transmitted waveform provided by the signal processing module 7. At the same time, it 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 analog-to-digital conversion module 6, respectively.

[0058] The method for matching and receiving photonic frequency-hopping digital signals using the device proposed in this invention includes the following steps:

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

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

[0061] 1.2) The synchronous extraction module 8 sets an arbitrary clock period to generate an optical pulse clock signal and an electrical sampling clock signal with a fixed clock period. 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 clock signals for 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 a narrow optical pulse sequence according to the clock signal. The fast tunable optical shaping module 2 is set as an all-pass system. After the narrow optical pulse sequence passes through the orthogonal basis generation module 3, it is modulated by the radio frequency calibration signal of arbitrary frequency in the electro-optic sampling modules 4-1 and 4-2 respectively. After being detected by the photoelectric converters 5-1 and 5-2, it is sent to the analog-to-digital converter module 6 for digitization. The digitization result is sent to the signal processing module 7.

[0063] 1.4) 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 increments 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 amplitude of the digitization 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 for the receiving test.

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

[0067] S3. The synchronization extraction module 8 selects a random start position in the frequency hopping pattern and generates a frequency hopping frequency sequence according to the frequency hopping pattern; it generates an optical pulse clock signal and an electrical sampling clock signal with the same frequency as the digital signal code rate according to the communication digital signal code 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 generation module 1 configures the optical pulse shape according to the communication code information sent by the signal processing module 7, and simultaneously generates a sampled 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 generation module 1 is equal to the reciprocal of the code rate of the frequency hopping digital signal to be received; the optical pulse time domain shape p s (t) and the transmission time-domain code s of the codeword to be received digital signal i (t) matches, satisfying relation 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 sequence sent by the synchronization extraction module 7, such as... Figure 2As shown in signal (f), the center frequency of the Fourier transform of the optical pulse output by the fast tunable optical shaping module 2 is 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 90° phase difference, such as... Figure 2 Shown by the signal in (g).

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

[0072] S8. Signal processing module 7 performs spectrum analysis on the digital signal input by analog-to-digital converter module 6: When the input digital signal contains only DC component, signal processing module 6 sends an update command to synchronization extraction module 7. Synchronization extraction module 7 takes the position after the current frequency hopping start position as the new frequency hopping start position and returns to step S2.

[0073] S9. When the digital signal received by the signal processing module 7 contains an AC component at any point in the time domain, the signal processing module 7 sends a clock fine-tuning command to the synchronization extraction module 8. After receiving the clock fine-tuning command, the synchronization extraction module 7 simultaneously introduces a fine-tuning amount of less than one symbol 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 electrical sampling clock to the configurable optical pulse sequence generation module 1 and the electrical analog-to-digital converter 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. They are then modulated by the frequency hopping digital signal to be received through the electro-optic sampling modules 4-1 and 4-2, respectively, and converted into electrical signals through the photoelectric converters 5-1 and 5-2. In the electrical analog-to-digital conversion module 6, they are converted into digital signals according to the electrical sampling clock provided by the synchronization extraction module 8, and then input to the signal processing module 7.

[0075] S11, the signal processing module 7 sets a decision threshold based on the average of the input sampling results, makes a decision on the sampling signal output by the analog-to-digital converter module 6, and performs parallel-to-serial conversion on the decision result according to the pre-agreed digital vector signal modulation format to recover 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 and a programmable optical filter 1-2, such as... Figure 3 As shown, along the signal output direction of the fast tunable optical filter 2, the sequence includes a 90° optical bridge 3, electro-optic modulators 4-1 and 4-2, photoelectric converters 5-1 and 5-2, and an analog-to-digital converter module 6 comprising electrical filters 6-1 and 6-2 and an analog-to-digital converter 6-3. The output of the signal processing module 7 is connected to the control terminal of the programmable optical filter 1-2 and the input terminal of the synchronization extraction module 8. The output of the synchronization extraction module 8 is connected to the mode-locked laser 1-1, the fast tunable optical filter 2, and the analog-to-digital converter 6-3. The bandwidths of the photoelectric converters 5-1 and 5-2 and the analog-to-digital converter module 6 are all not less than the reciprocal of the time-domain period of the optical pulse sequence generated by the configurable optical pulse sequence generation module 1.

[0077] The synchronous extraction module 8 is connected to both the mode-locked laser 1-1 and the analog-to-digital converter 6-3, ensuring that the sampling rate of the 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, and equal to the reciprocal of the bit rate of the digital signal to be received. Furthermore, the 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] The method for matching and receiving data after calibration using the device described in this embodiment is as follows:

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

[0080] 2) The synchronous extraction module 8 generates a clock signal with a period equal to the reciprocal of the code rate based on the digital signal code rate and modulation format, and sends it as a clock signal to the mode-locked laser 1-1 and the analog-to-digital converter 6-3 respectively.

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

[0082] 4) The synchronous extraction module 8 randomly selects a starting position in the frequency hopping pattern, generates a frequency hopping frequency sequence that is consistent with the frequency hopping pattern, sends the frequency hopping frequency sequence into 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 that of the frequency hopping frequency sequence, and after passing through the 90° optical bridge 3, outputs an optical pulse sequence with two channels that are orthogonal to each other and whose center frequency of the Fourier transform of the time-domain shape is the same as that of 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-optic modulators 4-1 and 4-2 respectively. The signals are converted into electrical signals by photoelectric converters 5-1 and 5-2, and after being filtered by anti-aliasing filters 6-1 and 6-2, they are sent to the electrical analog-to-digital converter 6-3. According to the electrical sampling clock provided by the synchronization extraction module 8, the signals are converted into digital signals and input to the signal processing module 7.

[0084] 6) Signal processing module 7 performs spectrum analysis on the digital signal input from analog-to-digital converter 6-3: When the input digital signal contains only a DC component, signal processing module 7 sends an update command to synchronization extraction module 8. Synchronization extraction module 8 selects the new position after the current frequency hopping start position 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 command to the synchronization extraction module 8. After receiving the clock fine-tuning command, the synchronization extraction module 8 introduces a fine-tuning amount of less than one clock cycle into the optical pulse clock and the electrical sampling clock to satisfy that the electrical sampling clock is in phase with the received electrical signal and the electrical analog-to-digital converter 6 samples at the highest point of the electrical pulse. The adjusted clock signal is then sent as the 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 the process returns to step 5).

[0086] 8) The signal processing module 7 sets a decision threshold based on 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 recover the transmitted 0 1 information.

[0087] The embodiments described above are merely preferred embodiments of the present invention. Ordinary variations and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included within the protection scope of the present invention.

Claims

1. A photonic frequency-hopping digital signal matching and 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-optic sampling module, a photoelectric conversion module, an analog-to-digital conversion module, a signal processing module, and a synchronization extraction module; The configurable optical pulse shaping and generating module generates an optical pulse sequence based on 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 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 time. The orthogonal basis generation module performs phase shifting 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-optic sampling module modulates two optical sequences with the frequency-hopping digital signal to be received, and performs sampling processing in the optical domain. The photoelectric conversion module and the analog-to-digital conversion module perform photoelectric conversion on the electrical signals after processing the two optical sequences, sample and convert them into electrical signals, and then sample the two electrical signals 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 pattern agreed upon by both communicating parties in advance. It 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 operation, it receives digital signals and performs spectrum analysis. Based on the analysis results, it sends instructions to the synchronization extraction module to perform parallel-to-serial conversion and recover the binary digital code. The synchronization extraction module generates an optical pulse clock signal, a frequency hopping sequence, and a sampling clock signal based on the frequency hopping pattern, the code rate of the digital signal to be received, the modulation format, the transmission code pattern, and the clock phase difference. After receiving instructions from the signal processing module, the synchronization extraction module regenerates the frequency hopping 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 analog-to-digital conversion module, respectively.

2. The photon frequency hopping digital signal matching and receiving device according to claim 1, characterized in that, Temporal shape p of a light pulse sequence s (t) and the transmission time-domain code s of the codeword to be received digital signal i (t) matches, satisfying relation 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 reciprocal of the code rate of the frequency hopping digital signal to be received.

3. The photon frequency hopping digital signal matching and receiving device according to claim 1, characterized in that, The signal processing module receives the digital signal and performs spectrum analysis. Based on the analysis results, it sends a command to the synchronization extraction module. If the analysis results show that the digital signal contains only a DC component, the signal processing module sends an update command to the synchronization extraction module. The synchronization extraction module changes the start position of the frequency hopping pattern and generates a new frequency hopping sequence. This continues until the digital signal contains an AC component at any position in the time domain, that is, the center frequency of the Fourier transform of the optical pulse time domain shape is the same as the carrier frequency of the digital frequency hopping signal to be received at the corresponding time, thus achieving frequency hopping synchronization.

4. The photon frequency hopping digital signal matching and receiving device according to claim 1, characterized in that, The signal processing module receives the digital signal and performs spectrum analysis. Based on the analysis results, it sends a command to the synchronization extraction module. If the analysis results show that the digital signal contains an AC component at any point in the time domain, it sends a clock fine-tuning command. 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 analog-to-digital converter module. That is, the analog-to-digital converter module samples at the peak value to achieve clock synchronization.

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

6. The photon frequency hopping digital signal matching and receiving device according to claim 5, characterized in that, The bandwidth of both the photoelectric conversion module and the analog-to-digital conversion module is not less than the reciprocal of the period of the optical pulse sequence generated by the configurable optical pulse generator module.

7. The photon frequency hopping digital signal matching and receiving device according to claim 1, characterized in that, The synchronization extraction module generates a clock signal with the same frequency as the digital signal bit rate based on the bit rate of the digital signal to be received. The clock signal serves as the initial optical pulse clock signal and the sampling clock signal.

8. A method for matching and receiving photonic frequency hopping digital signals, characterized in that, include: S1: The photonic frequency hopping digital signal matching receiver as described in claim 1 is calibrated to obtain the clock phase difference used for matching reception; S2: The signal processing module sends the frequency hopping pattern, communication digital signal code rate, modulation format and transmission code pattern agreed upon by both parties in advance, as well as the clock phase difference obtained from calibration, to the synchronization extraction module. S3: The synchronization extraction module selects a random start position in the frequency hopping pattern and generates a frequency hopping frequency sequence according to the frequency hopping pattern; it generates an optical pulse clock signal and an electrical sampling clock signal with the same frequency as the digital signal code rate according to the communication digital signal code 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 shape of the optical pulse according to the code rate, modulation format and transmission code of the communication digital signal, and generates a sampled 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 sequence and outputs the sampled optical pulse sequence; S6: The orthogonal basis generation module processes the optical pulses and outputs two orthogonal optical pulse sequences with a 90° phase difference. S7: The electro-optic sampling module modulates the frequency-hopping digital signal with two orthogonal sampling optical pulse sequences to complete the frequency-hopping digital signal sampling processing in the optical domain; S8: The photoelectric conversion module and the 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 from the analog-to-digital converter 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 one frequency hopping duration from the current frequency hopping start position as the new frequency hopping start position and returns to step S3. If the digital signal contains an AC component at any point in the time domain, the signal processing module sends a clock fine-tuning command to the synchronization extraction module. After receiving the clock fine-tuning command, the synchronization extraction module simultaneously introduces a fine-tuning amount of less than one symbol 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 conversion module, and sends the adjusted clock signal as the 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. After returning to execute steps S4 to S8, step S10 is then executed. S10: The signal processing module uses the average amplitude of all recorded digital signals as the decision threshold to make a decision on the current digital signal output by the analog-to-digital converter module, and performs parallel-to-serial conversion on the decision result according to the pre-agreed digital vector signal modulation format to recover the transmitted 01 digital code.

9. A photonic frequency hopping digital signal matching and receiving method according to claim 8, characterized in that, In step S1, the photon frequency hopping digital signal matching receiver is calibrated. The calibration method is as follows: 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, initially set to 0; S1.2: The synchronization extraction module sets an arbitrary clock period to generate an optical pulse clock signal and an electrical sampling clock signal with a fixed clock period. 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 a narrow optical pulse sequence according to the clock signal. The fast tunable optical shaping module is set as an all-pass system. After the narrow optical pulse sequence passes through the orthogonal basis generation module, it is modulated and digitized by the RF calibration signal of arbitrary frequency in the electro-optic sampling module, photoelectric conversion module, and analog-to-digital conversion module, respectively. The digitization 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 increments 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 digitization results, and select the clock phase difference corresponding to the test with the largest amplitude as the clock phase difference for the receiving test.

10. A photonic frequency hopping digital signal matching and receiving method according to claim 8, characterized in that, In step S8, after receiving the clock fine-tuning command, the synchronization extraction module simultaneously introduces a fine-tuning amount of less than one symbol period into the optical pulse clock and the electrical sampling clock to find the delay fine-tuning amount with the largest output amplitude of the electrical analog-to-digital converter module. The specific method is as follows: the set single fine-tuning amount is introduced in stages, and after each introduction, steps S4 to S7 are executed to obtain the amplitude of the digital signal output by the electrical analog-to-digital converter module under the corresponding cumulative fine-tuning amount, until the fine-tuning amount accumulates to one symbol period; the digital signal with the largest amplitude is found, and the cumulative fine-tuning amount corresponding to the digital signal is the delay fine-tuning amount.

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