Complex scene-oriented multi-mode signal real-time adaptive identification and extraction method

Abstract

The invention discloses a multi-mode signal real-time self-adaptive recognition and extraction method for a complex scene, solves the problem that an existing interference suppression and signal extraction algorithm cannot adapt to gravitational wave measurement requirements, belongs to the technical field of digital signal processing, and adopts a fixed sequence of main carrier clock sideband pseudo code signals to perform signal extraction and separation. According to the sequence, the processing efficiency is optimized, the weak signal is prevented from being covered by the strong signal, and the interference of subsequent processing is remarkably reduced. Compared with parallel or disordered processing in the background technology, the method provided by the invention has the advantages that strong interference components are stripped in sequence, so that rapid convergence in real-time operation is ensured, and the robustness and precision of overall signal extraction are improved.

Description

A Real-Time Adaptive Recognition and Extraction Method for Multi-Mode Signals in Complex Scenarios Technical Field

[0001] This invention relates to a real-time adaptive recognition and extraction method for multi-mode signals in complex scenarios, belonging to the field of digital signal processing technology. Background Technology

[0002] In space gravitational wave detection, the displacement measurement accuracy of laser interferometry is required to be on the order of 10 picometers. Among these, laser source frequency noise and clock frequency noise are the two main types of noise.

[0003] To eliminate clock noise, the clock signal is multiplied to GHz and then applied to the inter-satellite laser link via phase modulation. Clock noise is then extracted from the clock sideband beat frequency signal and eliminated from the TDI data assembly. Simultaneously, laser noise is effectively eliminated during TDI data post-processing, relaxing frequency stability requirements by several orders of magnitude. TDI is considered a systematic strategy to suppress the main noise in laser interferometry. To achieve time delay processing in TDI, accurate measurement of the inter-satellite absolute distance is required. Therefore, in the TDI mechanism, the inter-satellite laser link needs to simultaneously perform three functions: displacement measurement, clock sideband modulation, and absolute distance measurement.

[0004] The receiver receives a mixed beat frequency signal that includes an optical carrier signal, a clock sideband signal, and a pseudo-code ranging communication signal. Due to the unique nature of gravitational wave measurements, the beat frequency signal also contains the pseudo-code ranging communication signal from the local satellite's optical path. The system focuses on different aspects of each signal, therefore, it is necessary to study extraction methods for various signal types and reduce mutual coupling and interference.

[0005] In the field of optical signal processing in complex environments, especially for mixed beat frequency signals that include optical carrier signals, clock sideband signals and pseudocode ranging communication signals, existing technologies typically employ traditional signal separation methods.

[0006] (1) The scientific literature "Broadband Signal Channelization Based on Critical Sampling Polyphase Filter Banks" adopts a signal separation method based on filter banks. By designing multiple bandpass filters with fixed bandwidths, different frequency components are extracted from the mixed signal. This method is common in early optical communication and radar systems, but the fixed filter bandwidth makes it difficult to adapt to dynamically changing signal environments and easily introduces phase distortion, leading to a decrease in signal extraction accuracy. Although it can handle multi-frequency signals, it cannot effectively solve the problem of strong signals masking weak signals, and its performance is limited, especially in scenarios with high real-time requirements.

[0007] (2) Chinese patents CN120724171A and CN105162740B employ blind source separation technology to separate mixed signals through statistical characteristics. These methods are widely used in biomedical signal processing and speech separation, but they rely on the assumption of statistical independence of signal sources and have high computational complexity, making real-time processing difficult. In optical signal processing, due to the strong correlation and power differences between carrier, sideband, and pseudocode signals, blind source separation methods are prone to slow convergence or incomplete separation.

[0008] (3) The scientific literature "Phase Tracking Algorithm for Satellite QPSK Carrier Modulation Signal Based on PLL Loop" adopts phase-locked loop (PLL) technology. Digital PLLs are commonly used to track single-frequency signals, such as carrier recovery, and are a standard application in communication systems. However, existing PLL technologies are mostly designed for single signal components, and when applied to mixed signals, they lack a collaborative processing mechanism for multi-mode signals. Although the PLL-based carrier tracking scheme in "Phase Tracking Algorithm for Satellite QPSK Carrier Modulation Signal Based on PLL Loop" can accurately track the main carrier, it does not consider the interference of clock sideband and pseudocode signals, resulting in performance degradation when extracting weak signals.

[0009] (4) Chinese patent CN120009917A employs adaptive filtering techniques, such as least mean square (LMS) or recursive least squares (RLS) algorithms, to cancel known interference signals. In pseudocode ranging systems, adaptive filtering is often used to suppress self-interference, but it usually requires prior knowledge and the characteristics of the interference signal. However, existing methods often treat adaptive filtering as an independent module, without integrating it with carrier and sideband processing, resulting in difficulty in convergence of the adaptive filter and poor real-time performance when a strong carrier is present. Summary of the Invention

[0010] The technical problem to be solved by this invention is to overcome the shortcomings of the prior art and solve the problem that the existing interference suppression and signal extraction algorithms cannot meet the requirements of gravitational wave measurement.

[0011] The objective of this invention is achieved through the following technical solution: a real-time adaptive identification and extraction method for multi-mode signals in complex scenarios. Based on the sequential processing strategy of "step-by-step stripping, from strong to weak, and from easy to difficult", combined with the collaborative signal processing mechanism of frequency domain analysis (FFT) and digital phase-locked loop (PLL), the method completes digital domain signal reconstruction and real-time subtraction filtering, and uses adaptive filtering to cancel the local satellite pseudocode signal. Finally, it realizes the identification, extraction and separation of the main carrier signal, clock sideband signal, local satellite pseudocode signal and pseudocode ranging communication signal.

[0012] A real-time adaptive recognition and extraction method for multi-mode signals in complex scenarios includes: S1, from mixed signals Extracting the main carrier signal and will From mixed signal After filtering, the signal is obtained. S2, from the signal Extracting clock sideband signals and will From signal After filtering, the signal is obtained. S3, from the signal The pseudo-code signal emitted by the satellite itself is filtered out.

[0013] Compared with the prior art, the present invention has the following advantages: (1) In terms of the signal processing sequence strategy of step-by-step stripping: the present invention is the first to propose the "main carrier" Clock sideband The "pseudo-code signal" is extracted and separated in a fixed order, based on the principle of "from strong to weak, from easy to difficult". This order optimizes processing efficiency, avoids strong signals masking weak signals, and significantly reduces interference in subsequent processing. Compared with parallel or disordered processing in the prior art, this invention ensures rapid convergence in real-time operation by sequentially stripping away strong interference components, thereby improving the robustness and accuracy of the overall signal extraction.

[0014] (2) In terms of the synergistic application of frequency domain analysis and digital phase-locked loop (PLL): This invention combines frequency domain analysis (FFT) and digital phase-locked loop (PLL) to achieve coarse acquisition and precise tracking of the main carrier. Based on the tracked phase and estimated amplitude, a "clean" carrier signal is reconstructed in the digital domain and then directly subtracted from the original mixed signal. This synergistic mechanism of FFT and PLL overcomes the problem of traditional PLLs easily losing lock in mixed signals, while improving the accuracy of carrier filtering. Compared with the use of PLL or FFT alone in the background technology, this invention achieves more efficient initial signal acquisition and tracking.

[0015] (3) Regarding the integrated optimization of clock sideband processing: This invention utilizes bandpass filtering (based on FFT) and two PLLs working together to reconstruct a "clean" clock sideband signal in the digital domain based on the tracked phase and estimated amplitude, and then directly subtracts it from the remaining signal. This method seamlessly integrates sideband processing with carrier filtering, avoiding interference from residual carriers in the sideband signal and improving the accuracy of sideband phase measurement. Compared with the methods of processing sidebands independently in the prior art, this invention reduces the cross-influence between signals.

[0016] (4) Regarding adaptive cancellation and local satellite pseudocode signal filtering: This invention utilizes known local satellite pseudocode sequences (including spreading sequences and modulation schemes) to reconstruct the reference signal at the receiver and employs an adaptive filter for cancellation. This design places pseudocode filtering after carrier and sideband processing, ensuring that the adaptive filter operates in a low-interference environment and improving convergence speed and suppression effect. Compared with the direct application of adaptive filtering in the background technology, this invention solves the problem of performance degradation of the adaptive filter under strong interference by filtering out strong signals beforehand. Attached Figure Description

[0017] Figure 1 is a block diagram of the overall scheme for a real-time adaptive recognition and extraction method for multi-mode signals in complex scenarios.

[0018] Figure 2 is a schematic diagram of the algorithm for real-time adaptive recognition and extraction of multi-mode signals. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0020] A real-time adaptive identification and extraction method for multi-mode signals in complex scenarios, as shown in Figures 1 and 2, includes: S1, identification, extraction and filtering of the main carrier. The function of this step is to extract the main carrier signal (for optical carrier interferometry) from the mixed signal and filter it out from the mixed signal to reduce the interference effect on subsequent processing.

[0021] S11. Carrier Identification and Tracking (Phase-Locked Loop (PLL)): The carrier signal is usually the strongest component in the beat spectrum. A narrow-bandwidth digital phase-locked loop (PLL) is used to lock onto and track the phase of the primary carrier. .

[0022] Frequency domain analysis (FFT) is used to find the frequency components with the highest energy concentration in the signal, and the carrier frequency is determined by power spectrum peak detection (coarse carrier frequency acquisition); the numerically controlled oscillator (NCO) of the PLL generates a sine / cosine reference signal; the phase detector compares the input signal. The phase difference between the NCO output signal and the NCO output signal generates an error signal; the loop filter filters out high-frequency noise in the error signal and controls the frequency and phase of the NCO to keep it synchronized with the input carrier, thereby outputting an accurate carrier phase.

[0023] S12. Carrier signal reconstruction and filtering: Using the phase and amplitude information accurately tracked by the PLL, a "clean" carrier signal is reconstructed in the digital domain.

[0024] Reconstructed signal: (1) Among them It can be obtained by estimating the signal amplitude after the PLL is locked.

[0025] The reconstructed carrier signal is directly subtracted from the original mixed signal: (2) The signal mainly includes clock sideband signal, pseudocode modulation signal, local pseudocode signal and noise, while the main carrier component is greatly suppressed.

[0026] Output: Carrier phase information ; Main carrier signal; The signal remaining after filtering out the main carrier.

[0027] S2. Clock Sideband Identification, Extraction, and Filtering: This step aims to identify, extract, and filter the remaining signal. The clock sideband signal is extracted for clock sideband frequency measurement and filtered out from the mixed signal to reduce interference to subsequent processing.

[0028] S21. Sideband Identification and Extraction (Bandpass Filtering + PLL): Clock sidebands are located at the main carrier frequency in the spectrum. On both sides, the offset is the clock modulation frequency (known), at a distance from the main carrier. The position of (frequency). Since the carrier has been filtered out, the sideband signal becomes... The dominant component in.

[0029] Frequency domain bandpass filtering: for Perform a Fast Fourier Transform (FFT) at the frequency point and frequency A bandpass filter is placed near each of the components to extract the sideband signal components. .

[0030] Sideband phase tracking: for Precise phase tracking is performed using a second PLL to obtain the sideband phase. The clock sideband signal is a single-frequency signal, so narrowband tracking technology is used.

[0031] S22. Sideband signal reconstruction and filtering: Similar to the carrier wave, the sideband signal is reconstructed using the tracked sideband phase and the estimated amplitude.

[0032] Reconstructed signal: (3) From Subtract the reconstructed sideband signal from the middle: (4) It mainly contains pseudocode modulation signal, local pseudocode signal and noise.

[0033] Output: Instantaneous sideband phase Clock sideband signal; the signal remaining after filtering out the main carrier and clock sideband signal.

[0034] S3. Filter out local satellite pseudo-code signals. The purpose of this step is to filter out the remaining signals. The pseudo-code signal (i.e., self-interference signal) emitted by the satellite itself is filtered out to reduce the interference to subsequent processing.

[0035] S31. Local satellite pseudocode signal reconstruction: Given the pseudocode sequence (including its spread spectrum sequence, modulation method, etc.) transmitted by the local satellite, a reference signal that is as consistent as possible with the coupled signal can be reconstructed at the receiving end, and then this reference signal is subtracted from the received signal.

[0036] S32. Adaptive cancellation uses an adaptive filter to filter the residual signal using the reconstructed local pseudocode signal as a reference signal, thereby canceling the local pseudocode signal.

[0037] The adaptive filter adjusts the weights to minimize the correlation between the output signal and the local pseudocode signal.

[0038] Output: The residual signal after filtering out the pseudocode from the local satellite, mainly containing the pseudocode ranging signal from neighboring satellites. Major coherent interference (carrier, sidebands) has been eliminated.

[0039] The contents not described in detail in this specification are common knowledge to those skilled in the art.

[0040] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A method for real-time adaptive recognition and extraction of multi-mode signals in complex scenarios, characterized in that, include: S1, from the mixed signal Extracting the main carrier signal and will From mixed signal After filtering, the signal is obtained. S2, from the signal Extracting clock sideband signals and will From signal After filtering, the signal is obtained. ； S3, from signal The pseudo-code signal emitted by the satellite itself is filtered out.

2. The multi-mode signal real-time adaptive recognition and extraction method according to claim 1, characterized in that, In S1, a digital phase-locked loop is used to lock onto and track the phase of the main carrier. 。 3. The multi-mode signal real-time adaptive recognition and extraction method according to claim 1, characterized in that, Frequency domain analysis is used to find the frequency components with the most concentrated energy in the signal, and the carrier frequency is determined by power spectrum peak detection; a digital phase-locked loop (PLL) with a numerically controlled oscillator generates a sine / cosine reference signal; a phase detector compares the input signal. The phase difference between the output signal and the CNC oscillator signal generates an error signal; the loop filter filters out high-frequency noise in the error signal and controls the frequency and phase of the CNC oscillator to keep it synchronized with the input carrier, thereby outputting a precise carrier phase.

4. The multi-mode signal real-time adaptive recognition and extraction method according to claim 1, characterized in that, In S1, a carrier signal is reconstructed in the digital domain using the phase and amplitude information accurately tracked by the digital phase-locked loop.

5. The multi-mode signal real-time adaptive recognition and extraction method according to claim 1, characterized in that, In S2, the clock sideband is located at the main carrier frequency in the spectrum. On both sides, the offset is the clock modulation frequency. Since the carrier has been filtered out, the sideband signal becomes... The dominant component in.

6. The multi-mode signal real-time adaptive recognition and extraction method according to claim 5, characterized in that, In S2, for Perform a Fast Fourier Transform and extract the sideband signal components by setting a bandpass filter. ,right Precise phase tracking is performed using a second digital phase-locked loop to obtain the sideband phase. The sideband signal is reconstructed using the tracked sideband phase and the estimated amplitude.

7. The multi-mode signal real-time adaptive recognition and extraction method according to claim 1, characterized in that, In S3, the local satellite pseudocode signal is reconstructed. An adaptive filter is used with the reconstructed local satellite pseudocode signal as a reference signal to filter the residual signal, thereby canceling out the local satellite pseudocode signal.

8. The multi-mode signal real-time adaptive recognition and extraction method according to claim 7, characterized in that, The adaptive filter adjusts the weights to minimize the correlation between the output signal and the local pseudocode signal.

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