Multi-channel fast blind acquisition and demodulation method, system and device for VDE-SAT system, and medium

Abstract

The invention discloses a VDE-SAT system multi-channel fast blind capture and demodulation method, system and device and a medium. The method comprises the steps of broadband radio frequency signal preprocessing and shunt storage, delay optimization and broadband coarse capture of an asymmetric threshold, on-demand scheduling and data extraction of a trigger index, narrow-band fine detection and target channel locking, and load data extraction and shared core demodulation. The system, the equipment and the medium are used for implementing the method. According to the method, a hierarchical scheduling architecture in which broadband coarse capture and narrowband time division precision processing are coordinated is constructed, so that bottom layer computing power multiplexing is realized; differential delay parameter homonymous optimization aiming at a frequency division multiple access scene and an asymmetric false alarm judgment threshold mechanism are combined; a complete solution for multi-channel fast blind acquisition and demodulation of the VDE-SAT system, which has the advantages of low hardware static resource consumption, fast multi-user concurrent response, strong detection robustness in a severe space electromagnetic environment and the like, is provided for a low earth orbit satellite platform with extremely limited size, power consumption and computing resources.

Description

A method, system, device and medium for multi-channel fast blind acquisition and demodulation in VDE-SAT system Technical Field

[0001] This invention belongs to the field of satellite communication and signal processing technology, specifically relating to a method, system, device and medium for fast blind acquisition and demodulation of multiple channels in a VDE-SAT system. Background Technology

[0002] In VDE-SAT (VHF Data Exchange System via Satellite) satellite communication systems, the uplink typically employs Frequency Division Multiple Access (FDMA) and random access mechanisms. Low Earth Orbit (LEO) satellite receivers, when dealing with a massive number of maritime terminals, must simultaneously monitor asynchronously arriving user signals across multiple frequency division channels. Due to the Doppler frequency offset in the satellite-ship link and the randomness of user access, the onboard terminal receiver module not only needs high-precision signal acquisition and demodulation capabilities but also faces extremely high real-time requirements.

[0003] Currently, for multi-channel blind acquisition and demodulation, existing technologies mainly employ the following two receiver architectures, but both have significant limitations: 1. Fully Parallel Acquisition and Demodulation Architecture: The traditional fully parallel architecture uses a streaming processing mechanism that completely replicates the physical link. In this architecture, after the broadband received signal undergoes digital down-conversion and is decomposed into multiple independent sub-channels, the system configures each sub-channel with a dedicated and completely independent differential correlation acquisition module, multi-mode demodulation module, and decoder pipeline. Its advantage is that the streaming processing mechanism eliminates cross-channel buffering and queuing, and its signal acquisition latency depends only on the physical transmission time of the synchronization header (approximately 0.8 milliseconds), resulting in extremely high real-time acquisition performance. The disadvantage is that to support multi-mode systems, the core hardware resources of the fully parallel architecture (including DSP, lookup table (LUT), and triggers (FF)) increase linearly with the number of concurrent sub-channels. Furthermore, because the sub-channel baseband sampling rate is much lower than the system's underlying operating frequency, a massive number of computing units remain idle for most clock cycles. On spaceborne platforms where size, power consumption, and FPGA chip capacity are extremely limited, this architecture would result in severe static area redundancy, making it unsuitable for use in lightweight terminals.

[0004] 2. Time-Division Polling (TDM) Architecture: To address the excessive hardware overhead of fully parallel architectures, existing technologies often introduce a Time-Division Polling (TDM) architecture. This architecture leverages the significant clock difference between the signal baseband sampling rate and the underlying system's main frequency. After bandwidth decomposition at the front end, it forcibly introduces a large-scale sub-channel data buffer pool, while only one shared acquisition and multi-mode demodulation core is instantiated at the back end. A high-speed clock drives the state machine to blindly poll and scan each channel buffer on a time-slice basis. This architecture successfully decouples the back-end computing power scale from the number of sub-channels, significantly reducing the static computation area and basic logic overhead in multi-channel concurrent scenarios. The problem is that this "time-for-space" multiplexing strategy completely disrupts the real-time signal processing mechanism. The single acquisition time is affected by the combined effects of physical writing, cross-frame queuing scheduling, and frame header alignment waiting. As the system's concurrent channel load increases, the invalid scanning of idle channels and the queuing of busy channels lead to a sharp increase in average acquisition latency. In the VDE-SAT system, this frame-level response delay can easily cause signaling to exceed the protocol layer threshold, thereby triggering timeout retransmission and channel congestion.

[0005] Existing multi-channel receiver architectures suffer from an inherent contradiction when handling sparse and bursty services such as VDE-SAT: excessive static hardware resource consumption and insufficient real-time acquisition response capability. How to eliminate cross-channel queuing lag time and achieve an effective balance between low hardware overhead and fast response without significantly increasing the system's static logic area is a pressing technical challenge in current satellite communication physical layer receiver design.

[0006] Patent application CN111464228A discloses a "Multi-channel VDES transceiver preprocessing system based on spaceborne DBF," which employs multiplexing or independent single-channel burst detection logic and optimizes filter design and single-channel demodulation. However, this technology still relies on traditional single-channel independent monitoring or simple time-division polling architectures, failing to address the complex scenarios unique to VDE-SAT systems, such as multi-channel concurrency, extremely weak signals, and large frequency offset random access. This results in an inherent contradiction when dealing with multi-user concurrent access: excessive static hardware resource consumption and insufficient real-time acquisition response capability. If independent fully parallel monitoring logic is used, the underlying logic resources such as DSP and lookup tables increase linearly with the number of channels, leading to severe area redundancy and extremely high static power consumption. If simple time-division polling multiplexing is introduced, the real-time signal processing mechanism is completely disrupted, causing severe cross-channel queuing and scheduling delays. This has resulted in existing systems being unable to effectively balance extremely low hardware resource overhead with sub-millisecond-level high acquisition real-time performance on spaceborne platforms where size and power consumption are extremely limited. Summary of the Invention

[0007] To overcome the problems of high static resource consumption, high polling delay, and insufficient weak signal detection capability in existing multi-channel spaceborne receivers under multi-user concurrent scenarios, this invention aims to provide a method, system, device, and medium for fast blind acquisition and demodulation of multiple channels in a VDE-SAT system. This method performs real-time monitoring of the entire frequency band signal through wideband coarse acquisition. After trigger detection, it completes wideband buffer data backtracking based on the synchronization signal trigger index, and uses narrowband time-division fine processing to perform fine confirmation of sub-channels within the target frequency band, followed by physical frame extraction and demodulation decoding. This invention combines wideband global monitoring capability with narrowband high-precision time-division multiplexing processing. Through a wideband and narrowband hierarchical processing architecture and a buffer backtracking scheduling mechanism, it achieves on-demand allocation and reuse of backend narrowband processing resources; simultaneously, it incorporates differential delay sampling point parameter optimization design. or In addition, an asymmetric joint detection threshold mechanism enhances the broadband triggering capability and narrowband confirmation reliability under multi-user concurrency conditions, thereby achieving low-overhead, low-latency, and high-reliability blind acquisition and demodulation of multi-channel signals.

[0008] To achieve the above objectives, the technical solution adopted by this invention is: a method for fast blind acquisition and demodulation of multiple channels in a VDE-SAT system, comprising the following steps: Step 1: The onboard terminal receiving module receives the original VDE-SAT frequency division multiple channel signal and performs analog-to-digital conversion, digital down-conversion, anti-aliasing filtering, and downsampling, and then separates it into two independent upper-frequency band data streams in the frequency domain. With lower frequency band data stream Step 2: and The process is divided into two parts: the first part continuously writes data to the corresponding broadband data cache module for storage; the second part sends data to the corresponding broadband coarse acquisition module for differential delay multiplication and performs sliding correlation operation with the local broadband reference synchronization sequence. The resulting magnitude value is compared with the pre-configured broadband judgment threshold to obtain the acquisition success flag signal and the synchronization signal trigger index, which are then output to the time-division scheduling controller. Step 3: The time-division scheduling controller is activated upon receiving the acquisition success flag signal and triggers the synchronization signal based on the synchronization signal trigger index. Execute data scheduling to obtain the broadband synchronization header sequence to be processed and output it to the narrowband time-division fine processing module; Step 4: The narrowband time-division fine processing module is internally configured with a sub-channel down-conversion decimation unit and a narrowband fine detection unit. It performs time-division multiplexing on each sub-channel in the currently triggered frequency band to obtain a set of effective users that includes the effective sub-channels and their corresponding fine synchronization positions, as well as the frequency band type to which the effective sub-channels belong; Step 5: The time-division scheduling controller determines whether there are signals to be processed in the upper and lower frequency bands based on the set of effective users, and accesses the data streams continuously written to the upper frequency band in step 2. and lower frequency band data stream The broadband data buffer module; the time-division scheduling controller extracts the complete physical frame data segment containing the signal to be processed from the broadband data buffer module corresponding to the frequency band where the signal to be processed exists. The complete physical frame data segment contains the payload and synchronization sequence, and sends the complete physical frame data segment to the narrowband time-division fine processing module and demodulation decoding module to perform time-division fine processing and demodulation decoding; when all the signals to be processed are processed, the time-division scheduling controller resets the system receiving state.

[0009] In step 2, for the upper frequency band, the broadband coarse acquisition module targets the input upper frequency band data stream. The following processing flow is executed sequentially: Step 2.1: The broadband coarse acquisition module, based on the optimized differential delay sampling points, performs processing on the upper frequency band data stream. Perform differential delay multiplication to obtain the differential result sequence. The calculation method is as follows: in, The broadband coarse acquisition module selects a fixed number of delay sampling points to match the set differential delay sampling points. Alternatively, perform extraction and delay multiplication operations when D=9; Step 2.2: The broadband coarse acquisition module will process the difference result sequence generated in Step 2.1. Synchronization sequence with local broadband reference Perform the sliding correlation operation and calculate the output result of the sliding correlation operation at the corresponding time. The calculation method is as follows: in, This represents the complex conjugate operation. The effective accumulated length of the local broadband reference synchronization sequence; Step 2.3: The broadband coarse acquisition module extracts the output results of the sliding correlation operation. modulus and modulus Broadband determination threshold Perform amplitude comparison; if the magnitude of the sliding correlation operation output at the current time satisfies... If the acquisition is successful, the wideband coarse acquisition module records the current time as the trigger index and outputs a successful acquisition flag signal and a synchronization signal trigger index to the time-division scheduling controller. If the modulus of the output result of the sliding correlation operation at the current moment satisfies If the broadband coarse acquisition fails, the module will discard the current data and continue to perform sliding correlation operations on subsequent input data streams for detection; lower frequency band data stream With upper frequency band data stream The processing flow is the same.

[0010] The broadband determination threshold in step 2.3 Broadband determination threshold ,in The set broadband false alarm rate, The standard deviation of the equivalent noise of the output of the broadband sliding correlation operation in the absence of a signal is given. It is determined by the product of the self-power of the local broadband reference synchronization sequence and the channel background noise power.

[0011] The data scheduling process in step 3 includes: Step 3.1: The time-division scheduling controller triggers the index using the synchronization signal obtained in step 2.3. Using the time base and combining the effective accumulated length of the local broadband reference synchronization sequence. Calculate the target data index range Step 3.2: The time-division scheduling controller accurately extracts the corresponding data segments from the broadband data cache module that is continuously stored in Step 2, based on the target data index range obtained in Step 3.1. Step 3.3: The time-division scheduling controller uses the data segments extracted in Step 3.2 as the broadband synchronization header sequence to be processed and outputs them to the narrowband time-division fine processing module.

[0012] The narrowband determination threshold in step 4.3 for ,in The equivalent noise standard deviation of the narrowband sliding correlation operation output in a pure noise background; narrowband decision threshold. It is based on the preset narrowband false alarm rate. The derivation is confirmed, and it satisfies the condition that the narrowband false alarm rate is much smaller than the broadband false alarm rate, i.e. .

[0013] Step 4, for the first For each sub-channel, the narrowband time-division processing module sequentially executes the following narrowband fine detection process: Step 4.1: Using the sub-channel down-conversion decimation unit of the narrowband time-division fine processing module, the broadband synchronization header sequence to be processed output by the time-division scheduling controller in step 3 is compared with the first sub-channel... The local reference zero intermediate frequency center frequency sequence corresponding to each sub-channel is multiplied to complete the sub-channel digital down-conversion independently of the front-end receiving link; then, the down-converted signal is input into a low-pass anti-aliasing filter and downsampled to output the first sub-channel. Downsampled synchronization header sequence of each sub-channel Step 4.2: Utilize the narrowband fine detection unit of the narrowband time-division fine processing module, combined with the set differential delay sampling after downsampling. With the downsampled local reference synchronization sequence For the first generated in step 4.1 Downsampled synchronization header sequence of each sub-channel Perform differential delay multiplication and correlation accumulation operations to calculate the downsampled correlation peak magnitude. The calculation formula is as follows: in, To eliminate the narrowband differential result sequence after eliminating the time-varying carrier phase, This represents the complex conjugate operation. The effective accumulation length of the local narrowband reference synchronization sequence; Step 4.3: The narrowband fine detection unit of the narrowband time-division fine processing module will calculate the downsampled correlation peak magnitude value obtained in step 4.2. With pre-configured narrowband decision threshold Perform amplitude comparison; if the comparison result satisfies... Then confirm the first With valid user access in each sub-channel, the narrowband time-division fine processing module extracts the fine synchronization position at that moment and assigns it to the first sub-channel. Each sub-channel and its corresponding fine synchronization position are updated to the set of valid users. The set of valid users contains information on all sub-channels that are determined to have valid signals, including the frequency band type, sub-channel number, and corresponding fine synchronization position of each valid sub-channel. If the comparison result satisfies... Then determine the first If no valid user access is found on a subchannel, the narrowband time-division fine processing module will skip that subchannel and continue to perform traversal detection on the next subchannel.

[0014] The specific method of step 5 includes: Step 5.1: The time-division scheduling controller accesses the upper frequency band data streams continuously written in step 2 according to the frequency band type, sub-channel number and corresponding fine synchronization position recorded in the effective user set obtained in step 4.3. and lower frequency band data stream The broadband data buffer module; subsequently, the time-division scheduling controller accurately extracts the complete physical frame data segment from the broadband data buffer module corresponding to the frequency band containing the signal to be processed, according to the fine synchronization position, and schedules the complete physical frame data segment to the narrowband time-division fine processing module; Step 5.2: The narrowband time-division fine processing module receives the complete physical frame data segment output in step 5.1, and uses the internally configured sub-channel down-conversion decimation unit to perform digital down-conversion, low-pass filtering, and downsampling decimation processing on the complete physical frame data segment according to the sub-channel number recorded in the effective user set, to obtain the narrowband complete physical frame data segment of the corresponding sub-channel, and outputs the narrowband complete physical frame data segment to the demodulation decoding module; Step 5.3: The demodulation decoding module receives the narrowband complete physical frame data segment output in step 5.2, and based on the VDE-SAT specified in ITU-R M.2092 Recommendation. The signal system performs demodulation and decoding operations on the complete physical frame data segment of the narrowband, and finally outputs the source bit stream of the corresponding sub-channel in the effective user set; Step 5.4: After completing the narrowband time-division fine processing, demodulation and decoding and source bit stream output of all signals to be processed in the effective user set, the time-division scheduling controller clears the current effective user set, releases the processing resources occupied by the narrowband time-division fine processing module and the demodulation and decoding module, and resets the system reception state, so that the system returns to the reception process that relies on the wideband coarse acquisition module for global monitoring.

[0015] This invention also provides a VDE-SAT system multi-channel fast blind acquisition and demodulation system, comprising: a broadband radio frequency signal preprocessing and splitting storage module, used to enable the onboard terminal receiving module to receive the original VDE-SAT frequency division multi-channel signal and perform analog-to-digital conversion, digital down-conversion, anti-aliasing filtering and downsampling, and then separate it into two independent upper-band data streams in the frequency domain. With lower frequency band data stream A broadband coarse acquisition module with optimized latency and asymmetric threshold is used to... and The process is divided into two parts: the first part continuously writes data to the corresponding broadband data cache module for storage; the second part sends data to the corresponding broadband coarse acquisition module for differential delay multiplication and performs sliding correlation with the local broadband reference synchronization sequence. The resulting magnitude is compared with a pre-configured broadband determination threshold to obtain a successful acquisition flag signal and a synchronization signal trigger index, which are then output to the time-division scheduling controller. The on-demand scheduling and data extraction module for the trigger index is used to activate the time-division scheduling controller upon receiving the successful acquisition flag signal and trigger the index based on the synchronization signal. The system performs data scheduling to obtain the broadband synchronization header sequence to be processed and outputs it to the narrowband time-division fine processing module. The narrowband fine detection and target channel locking module is used to implement the sub-channel down-conversion decimation unit and narrowband fine detection unit configured within the narrowband time-division fine processing module. It traverses and processes each sub-channel within the currently triggered frequency band in a time-division multiplexing manner to obtain a set of valid users containing valid sub-channels, their corresponding fine synchronization positions, and the frequency band type to which the valid sub-channels belong. The payload data extraction and shared core demodulation module determines whether there are signals to be processed in the upper and lower frequency bands based on the set of valid users and accesses the continuously written upper frequency band data streams. and lower frequency band data stream The broadband data buffer module; the time-division scheduling controller extracts the complete physical frame data segment containing the signal to be processed from the broadband data buffer module corresponding to the frequency band where the signal to be processed exists. The complete physical frame data segment contains the payload and synchronization sequence, and sends the complete physical frame data segment to the narrowband time-division fine processing module and demodulation decoding module to perform time-division fine processing and demodulation decoding; when all the signals to be processed are processed, the time-division scheduling controller resets the system receiving state.

[0016] The present invention also provides a VDE-SAT system multi-channel fast blind acquisition and demodulation device, comprising: a memory: storing a computer program for the above-mentioned VDE-SAT system multi-channel fast blind acquisition and demodulation method, which is a computer-readable device; and a processor: used to implement the VDE-SAT system multi-channel fast blind acquisition and demodulation method when executing the computer program.

[0017] The present invention also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, enables the implementation of the aforementioned VDE-SAT system multi-channel fast blind acquisition and demodulation method.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The present invention innovatively introduces a hierarchical processing strategy of "broadband coarse detection - narrowband fine detection". By using a broadband coarse acquisition module to perform real-time sliding correlation detection on the full-band signal, when a suspected target is detected, a successful acquisition flag signal and a synchronization signal trigger index are output; combined with a time-division scheduling controller using the synchronization signal trigger index as a time reference, the target data segment is accurately backtracked and extracted from the broadband data buffer module, and finally the target data segment is scheduled to a single instantiated narrowband time-division fine processing module and demodulation decoding module, and fine detection and physical frame demodulation processing are performed sequentially on the sub-channels of the effective user set in a time-division multiplexing manner.

[0019] The resulting technical benefits are: enabling full-band, all-weather macroscopic monitoring using low-complexity broadband modules; activating high-precision narrowband computing power only after a suspected target is detected; constructing a collaborative processing flow between the broadband coarse acquisition module, time-division scheduling controller, narrowband time-division fine processing module, and demodulation / decoding module; completely breaking the strict linear superposition relationship between the number of concurrent channels and the underlying baseband computing power in the traditional fully parallel architecture; and providing efficient support for resource scheduling in a highly dynamic, multi-concurrency environment on spacecraft.

[0020] 2. This invention utilizes a wideband coarse acquisition module to select optimized differential delay sampling point parameters when performing differential delay multiplication operations on the upper-band and lower-band data streams respectively. or And by finding the optimal differential delay sampling point factor at the physical level (optimal) The differential phase rotation characteristics of multi-channel concurrent signals caused by the inherent frequency band spacing are optimized in the same direction.

[0021] The resulting technical effect is that, in frequency division multiple access (FDMA) scenarios with multiple users and random concurrent access, the parameters of the specifically selected differential delay sampling points... or It can strictly constrain the additional phase offset generated by the differential delay multiplication of multiple user signals with different center frequencies within the same phase sector of the complex plane, and make the rotation vectors of multiple frequency signals in the complex plane in the same quadrant, achieving constructive superposition in the same direction. This effectively avoids the "phase vector cancellation" problem caused by blindly setting differential delay parameters in the conventional way, and completely eliminates the risk of missed detection caused by phase reversal of weak signals in the VDE-SAT system under full load and concurrent conditions. It significantly improves the system's global trigger sensitivity, overall capture rate and robustness under full load and concurrent conditions.

[0022] 3. Low asymmetric joint detection threshold design: This invention configures the broadband coarse acquisition module based on the broadband false alarm rate. The broadband decision threshold is derived, and the narrowband time-division fine processing module is configured based on the narrowband false alarm rate. The derived narrowband detection threshold is set with the narrowband false alarm rate being much smaller than the broadband false alarm rate. An asymmetric threshold detection mechanism was constructed.

[0023] The resulting technical benefits are as follows: During the broadband full-band monitoring phase, the broadband coarse acquisition module effectively offsets the broadband signal-to-noise ratio dilution effect caused by the large amount of in-band thermal noise introduced by the full-band digital reception by utilizing the lower broadband decision threshold corresponding to the relaxed broadband false alarm rate. This maximizes the high trigger pass rate of weak burst signals in the harsh environment of extremely low signal-to-noise ratio VDE-SAT. Subsequently, during the narrowband fixed-point verification phase, the narrowband time-division fine processing module utilizes the high narrowband decision threshold corresponding to the stringent narrowband false alarm rate to accurately intercept and completely eliminate occasional false alarm signals caused by the relaxed threshold during the broadband phase. This achieves an organic combination of broadband high-sensitivity triggering and narrowband high-reliability verification, achieving the best engineering balance between "eliminating detection blind spots" and "suppressing invalid dynamic power consumption," ensuring that the system has an extremely low total false alarm rate and strong detection robustness in complex space electromagnetic environments.

[0024] This invention achieves underlying computing power reuse by constructing a hierarchical scheduling architecture that coordinates "broadband coarse acquisition - narrowband time-division fine processing". Combined with differential delay parameter optimization in the same direction for frequency division multiple access scenarios and an asymmetric false alarm judgment threshold mechanism, it completely breaks through the inherent performance bottlenecks of traditional multi-channel spaceborne receivers in terms of "static logic area overhead", "cross-channel acquisition queuing delay" and "sensitivity to extremely weak signal detection". It provides a complete solution for VDE-SAT system multi-channel fast blind acquisition and demodulation with the advantages of low hardware static resource consumption, fast multi-user concurrent response and strong detection robustness in harsh space electromagnetic environment for low-Earth orbit satellite platforms with extremely limited size, power consumption and computing resources. Attached Figure Description

[0025] Figure 1 is a diagram of the architecture of the wide and narrow band hierarchical blind acquisition and demodulation system of the present invention.

[0026] Figure 2 is a flowchart of the wide and narrow band joint blind acquisition and demodulation processing according to an embodiment of the present invention.

[0027] Figure 3 is a comparison of the power consumption of three digital signal processing unit (DSP) architectures.

[0028] Figure 4 is a comparison chart of the consumption of three lookup table (LUT) architectures.

[0029] Figure 5 is a comparison chart of the consumption of three trigger (FF) architectures.

[0030] Figure 6 is a comparison of the absolute time dimension capture latency of the three architectures.

[0031] Figure 7 is a comparison of the equivalent symbol dimension capture latency for the three architectures. Detailed Implementation

[0032] The technical solution adopted by the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0033] This invention combines the advantages of broadband energy sensing and narrowband high-precision processing, aiming to solve the contradiction between high static power consumption and insufficient real-time acquisition caused by hardware resource constraints in VDE-SAT (VHF Data Exchange System via Satellite) satellite receivers when facing frequency division multiple access (FDMA) multi-user random access. It provides a new physical layer receiver architecture and signal processing method for achieving low-overhead, low-latency, and highly reliable satellite-to-ground data transmission.

[0034] As shown in Figures 1 and 2, a method for fast blind acquisition and demodulation of multiple channels in a VDE-SAT system includes the following steps: Step 1: The onboard terminal receiving module receives the original VDE-SAT frequency division multiple channel signal and performs analog-to-digital conversion, digital down-conversion, anti-aliasing filtering, and downsampling. Then, it separates the signal into two independent upper-band data streams in the frequency domain. With lower frequency band data stream Regarding step 1 above, this method first receives a weak analog signal superimposed with Doppler frequency shift, channel fading and Gaussian white noise from the radio frequency front end of the spaceborne terminal. After sampling and digitizing the baseband received signal through an analog-to-digital converter (ADC), it is sent to a digital downconverter (DDC) to shift the carrier frequency to zero intermediate frequency.

[0035] To reduce the complexity of subsequent multi-channel digital signal processing algorithms and the computational resource area of ​​the underlying FPGA / DSP chip, the sampled signal needs to pass through a low-pass anti-aliasing filter to suppress high-frequency signals and out-of-band interference from adjacent frequency bands. After filtering, downsampling and decimation processing is performed, which significantly reduces the system's operating clock frequency without affecting the recovery of effective information.

[0036] Based on the physical characteristics of frequency band allocation in the VDE-SAT protocol, the preprocessing module precisely separates the downsampled broadband signal into two independent data streams—a lower frequency band and an upper frequency band—in the frequency domain. At this point, the sampling rate of the output broadband signal is 12 times that of the narrowband baseband symbol rate.

[0037] Step 2: Transfer the upper frequency band data stream With lower frequency band data stream The process is divided into two parts: the first part continuously writes data to the corresponding broadband data buffer module for storage; the second part sends data to the corresponding broadband coarse acquisition module for differential delay multiplication and performs sliding correlation with the local broadband reference synchronization sequence. The resulting magnitude is compared with the pre-configured broadband judgment threshold to obtain the acquisition success flag signal and the synchronization signal trigger index, which are then output to the time-division scheduling controller. The core purpose of step 2 is to perform macroscopic "coarse triggering" of the signal energy across the entire frequency band, without needing to demodulate specific sub-channels at this stage. Taking the upper frequency band as an example, the broadband coarse acquisition module targets the input upper frequency band data stream... The following processing flow is executed sequentially: Step 2.1: The broadband coarse acquisition module, based on the optimized differential delay sampling points, performs processing on the upper frequency band data stream. Perform differential delay multiplication to obtain the differential result sequence. The calculation method is as follows: in, The sequence of difference results. For upper frequency band data stream, In this embodiment, the broadband coarse acquisition module selects a fixed number of differential delay sampling points to determine the set number of differential delay sampling points. Perform extraction and delay multiplication operations.

[0038] In practical VDE-SAT multi-channel concurrent scenarios, there is an inherent frequency difference between user signals of different frequencies. Conventional differential delay designs are prone to causing the complex vectors of each channel to cancel each other out, resulting in serious missed detections in multi-user concurrent scenarios. To solve this technical problem, this method optimizes the differential phase rotation characteristics at the physical level and selects the delay sampling point. or Decimation and delay multiplication are performed. By using this optimized parameter, the component vectors of the signals from each concurrent user are confined to the same phase sector in the complex plane, exhibiting optimal unidirectionality. This enables constructive energy interference during multi-user concurrent superposition, completely overcoming the risk of destructive phases in concurrent signals.

[0039] Step 2.2: The wideband coarse acquisition module processes the difference result sequence generated in step 2.1. Synchronization sequence with local broadband reference Perform the sliding correlation operation and calculate the output result of the sliding correlation operation at the corresponding time. The calculation method is as follows: in, For a moment The output results of the sliding correlation calculation, This represents the complex conjugate operation. The effective accumulated length of the local broadband reference synchronization sequence; Step 2.3: The broadband coarse acquisition module extracts the output results of the sliding correlation operation. modulus and modulus Broadband determination threshold Amplitude comparison and broadband determination threshold are performed. Broadband determination threshold ,in The set broadband false alarm rate, The standard deviation of the equivalent noise of the output of the broadband sliding correlation operation in the absence of a signal is given. It is determined by the product of the self-power of the local broadband reference synchronization sequence and the channel background noise power; if the magnitude of the output result of the sliding correlation operation at the current time satisfies If the acquisition is successful, the wideband coarse acquisition module records the current time as the trigger index and outputs a successful acquisition flag signal and a synchronization signal trigger index to the time-division scheduling controller. If the modulus of the output result of the sliding correlation operation at the current moment satisfies If the current data is not successfully captured, the broadband coarse capture module will discard the current data and continue to perform sliding correlation operations on the subsequent input data stream for detection.

[0040] Lower band data stream With upper frequency band data stream The processing flow is the same.

[0041] This invention innovatively introduces an "asymmetric threshold design" mechanism, that is, using a relaxed broadband false alarm rate. Determine the broadband decision threshold for the reference parameters. By moderately tolerating false alarms in the broadband phase, the amplitude attenuation caused by the signal-to-noise ratio dilution effect is effectively offset, significantly improving the trigger pass rate of weak signals under extremely low signal-to-noise ratios. If the detected modulus value at the current moment satisfies... The system then determines that wideband coarse acquisition has been completed within the frequency band and records the current time as a trigger index. The system then outputs a successful capture flag signal and its index to the time-division scheduling controller. Any occasional false alarms generated during this process will be eliminated by a subsequent, more stringent narrowband fine-tuning detection step.

[0042] Step 3: The time-division scheduling controller is activated upon receiving the successful acquisition flag signal and triggers the index based on the synchronization signal. Data scheduling is performed to obtain the broadband synchronization header sequence to be processed and output to the narrowband time-division fine processing module. Regarding step 3 above, once the broadband coarse acquisition module is successfully triggered, the system immediately shifts its focus from full-band streaming blind search to on-demand extraction and subsequent processing of the target signal. The time-division scheduling controller, as the central hub of the entire hierarchical processing architecture, is activated. The time-division scheduling controller first determines the broadband data buffer module that matches the frequency band identifier generated in step 2 based on the frequency band identifier generated by the trigger. Subsequently, the time-division scheduling controller triggers the index using the synchronization signal obtained in step 2.3. Using the time base and combining the effective accumulated length of the local broadband reference synchronization sequence. Calculate the target data index range In the corresponding broadband data caching module, precise address backtracking is performed to extract the effective accumulated length of the local broadband reference synchronization sequence, with a length strictly equal to the protocol's preset length. The historical data segment is output as a broadband synchronization header sequence to the narrowband time-division fine processing module.

[0043] Step 4: The narrowband time-division fine processing module is internally configured with a sub-channel down-conversion decimation unit and a narrowband fine detection unit. It uses time-division multiplexing to traverse each sub-channel within the currently triggered frequency band, obtaining a set of valid users including valid sub-channels, their corresponding fine synchronization positions, and the frequency band type to which the valid sub-channels belong. Regarding Step 4, the core of this step lies in utilizing the "time prior information" provided by the broadband trigger position to perform high-precision fixed-point verification of the target sub-channel using concentrated computing resources. Specifically, it includes the following sub-steps: Step 4.1: Sub-channel digital down-conversion and narrowband decimation: Driven by a high-speed clock, the sub-channel down-conversion decimation unit performs time-division traversal of multiple sub-channels within the target frequency band. For the first... Each sub-channel will extract the broadband synchronization header sequence to be processed. With the The local reference zero intermediate frequency center frequency sequences corresponding to each sub-channel are multiplied together, and then fed into a low-pass anti-aliasing filter (LPF) for further processing. Downsampling processing. Its discrete mathematical expression as a physical process can be represented as: in, For the first The center frequency of each sub-channel For broadband sampling period, This indicates a downsampling operation. This step is independent of the front-end broadband receiver link. Through secondary mixing and decimation in the digital domain, out-of-band interference from adjacent sub-channels is eliminated, and the sampling rate is adapted to the narrowband baseband symbol rate, outputting a clean downsampled synchronization header sequence. .

[0044] Step 4.2: Utilize the narrowband fine detection unit of the narrowband time-division fine processing module, combined with the set differential delay sampling after downsampling. With the downsampled local reference synchronization sequence For the first generated in step 4.1 Downsampled synchronization header sequence of each sub-channel Perform differential delay multiplication and correlation accumulation operations to calculate the downsampled correlation peak magnitude. The calculation formula is as follows: in, To eliminate the narrowband differential result sequence after eliminating the time-varying carrier phase, This represents the complex conjugate operation. This is the effective accumulated length of the local narrowband reference synchronization sequence; unlike the "sliding correlation" in the wideband phase, the time-division scheduling controller has already triggered the index based on the synchronization signal. After completing the frame header alignment of the data segment, the narrowband processing here no longer requires time-domain sliding search, but can be performed directly within the interval. The system performs single-block accumulation within the unit. This "fixed-point accumulation" mechanism greatly reduces the computational complexity of the backend.

[0045] Step 4.3: The narrowband fine detection unit of the narrowband time-division fine processing module will process the downsampled correlation peak magnitude value obtained in step 4.2. With pre-configured narrowband decision threshold Amplitude comparison is performed, and the narrowband determination threshold is set. for ,in The equivalent noise standard deviation of the narrowband correlation operation output in a pure noise background; the narrowband decision threshold for constructing an asymmetric threshold detection mechanism. It is based on the preset narrowband false alarm rate. The derivation is confirmed, and it satisfies the condition that the narrowband false alarm rate is much smaller than the broadband false alarm rate, i.e. If the comparison results satisfy Then confirm the first With valid user access in each sub-channel, the narrowband time-division fine processing module extracts the fine synchronization position at that moment and assigns it to the first sub-channel. Each sub-channel and its corresponding fine synchronization position are updated to the set of valid users; if the comparison result satisfies Then determine the first If no valid user access is found on a subchannel, the narrowband time-division fine processing module will skip that subchannel and continue to perform traversal detection on the next subchannel.

[0046] Specifically, since the narrowband processing branch does not suffer from the signal-to-noise ratio dilution effect introduced by bandwidth expansion, its probability density distribution of superimposed noise has a significant statistical distance from the pure noise distribution. Therefore, to ensure an extremely low false alarm probability for the system, the system operates with a stringent narrowband false alarm rate. As a benchmark (e.g., set as) (or lower orders of magnitude) Derivation to determine the setpoint threshold By ensuring that the false alarm rate in narrowband is much lower than that in broadband, thus satisfying the requirement... This tiered detection mechanism cleverly resolves the system's contradictions: weak false alarm signals that are allowed through the low bandwidth threshold will now face strict interception and be eliminated by the high threshold; while genuine weak user signals can successfully pass the double verification. If the comparison results meet the requirements... The system then officially confirms the number. Each sub-channel completes fine acquisition, and the channel status and precise synchronization position index are registered in the set of valid users, awaiting subsequent demodulation processing.

[0047] Step 5: The time-division scheduling controller determines whether there are any signals to be processed in the upper and lower frequency bands based on the set of valid users, and accesses the data streams continuously written to the upper frequency band in Step 2. and lower frequency band data stream The broadband data buffer module; the time-division scheduling controller extracts the complete physical frame data segment containing the signal to be processed from the broadband data buffer module corresponding to the frequency band where the signal to be processed exists. The complete physical frame data segment contains the payload and synchronization sequence, and sends the complete physical frame data segment to the narrowband time-division fine processing module and demodulation decoding module to perform time-division fine processing and demodulation decoding; when all the signals to be processed are processed, the time-division scheduling controller resets the system receiving state.

[0048] Regarding step 5 above, this step aims to complete the final decoding output of the target user data and achieve a closed-loop state for the entire hierarchical scheduling system. Specifically, this implementation phase includes the following core operational processes and technical advantages: complete physical frame data segment extraction and front-end hardware multiplexing: the time-division scheduling controller, based on the fine synchronization position of the corresponding sub-channel in the effective user set obtained in step 4, revisits the continuously written upper-band data streams from step 2. and lower frequency band data stream The broadband data cache module, using the precise synchronization position confirmed in step 4 as the starting address, is accessed again by the time-division scheduling controller to accurately extract the complete physical frame data segment of the currently accessing user. Subsequently, the complete physical frame data segment is scheduled and output to the narrowband time-division fine processing module; this data segment is then sent to the configured sub-channel down-conversion decimation unit. In this stage, the system directly reuses the digital down-conversion (DDC) and downsampling decimation physical logic from step 4, thereby avoiding the redundant instantiation of front-end digital signal processing (DSP) resources and further improving chip area utilization.

[0049] Based on the shared core, the computing power is replaced and demodulated: the clean, narrowband, complete physical frame data segments, after frequency conversion and extraction, are sequentially input into the "shared VDE-SAT multi-mode demodulation core" inside the system. Based on the VDE-SAT signal standard specified in ITU-R M.2092 Recommendation, this demodulation core performs standard demodulation and decoding baseband processing operations on the data stream.

[0050] System state closure and reset: After demodulating all channel data in the effective user set and outputting all source bit streams to the downstream router, the time-division scheduling controller will actively clear the effective user set and status flags in the current memory, releasing the occupied narrowband processing resource time slices. At this point, the system processing pipeline is completely emptied and automatically restores to the initial streaming reception state that relies on the wideband coarse acquisition module for global energy monitoring.

[0051] The application prospects of this invention are as follows: With its extremely low hardware resource consumption and excellent parallel acquisition real-time performance, this invention perfectly matches the extremely power-constrained, size-and-weight (SWaP) low-Earth orbit (LEO) satellite payload platform, and is particularly suitable for VDE-SAT (Very High Frequency Data Exchange System) and ocean-wide broadband network scenarios for global maritime communications. Specific application prospects include: 1. Next-generation VDE-SAT satellite payload design: As an upgrade to the traditional Automatic Identification System (AIS), VDE-SAT faces enormous pressure on its uplink from the extremely large-scale frequency division multiple access (FDMA) and random asynchronous access of ship terminals on a wide-area sea surface. This invention can be directly used as the core physical layer receiving architecture of the VDE-SAT satellite communication payload, enabling high-concurrency, low-miss-alarm reception of short bursts of maritime data in multiple sub-channels with minimal FPGA static physical resource noise, thus resolving the contradiction between the computing power bottleneck of the satellite payload and the multiple access capacity from the underlying architecture.

[0052] 2. Maritime Emergency Search and Rescue and GMDSS Modernization Network: In Global Maritime Distress and Safety System (GMDSS) and ocean-going emergency rescue scenarios, distress signals sent by ships (such as delay-sensitive signals in the VDE-SAT protocol) have extremely high real-time reception requirements. Traditional time-division polling architectures can lead to frame-level queuing delays of tens of milliseconds, easily causing signaling timeouts and retransmissions. This invention utilizes digital domain high-speed scheduling to eliminate cross-channel queuing delays, achieving sub-millisecond instantaneous response. Even under conditions of Doppler frequency offset and low signal-to-noise ratio caused by severe sea states, it can quickly locate weak distress signals from ships.

[0053] 3. Maritime IoT and Unmanned Equipment Networking: This addresses the data transmission needs of marine hydrological monitoring buoys, offshore wind power platforms, and unmanned surface vessels (USVs) deployed in vast and deep sea areas. This type of maritime IoT service exhibits typical "sparse and bursty" characteristics. The "broadband triggering, on-demand scheduling" mechanism of this invention perfectly matches these characteristics, enabling seamless 24 / 7 monitoring of the entire frequency band of the sea area while minimizing ineffective dynamic power consumption of the spaceborne platform, thus achieving efficient space-to-ground IoT data interaction.

[0054] Experimental Analysis 1. Simulation Conditions To verify the effectiveness of the proposed "broadband and narrowband hierarchical blind acquisition and demodulation architecture" in resolving the contradiction between high static resource consumption and high acquisition delay in multi-channel concurrent processing, the following simulation parameters were set in the context of low-Earth orbit satellite-to-ground communication: Communication system parameters: The satellite operating frequency band was set to VHF (156~163 MHz), and the system's underlying hardware operating frequency was 189.504 MHz. The total signal sampling bandwidth of the frequency division multi-channel was 94.752 Msps, the baseband sampling rate of each sub-channel was 134.4 Ksps, the information symbol rate was 33.6 Ksps, QPSK modulation was used, the physical interval between the center frequencies of adjacent sub-channels was 50 KHz, the original protocol synchronization header length was 27 symbols, and the single-slot data burst length was 627 symbols.

[0055] Concurrency scenario settings: Set the number of sub-channels that the system can monitor concurrently. The scanning range is 1 to 6 to simulate the actual load conditions of multiple terminals randomly and asynchronously accessing in a typical high-dynamic maritime scenario.

[0056] The underlying resource quantization model employs FPGA core physical resources, namely the Digital Signal Processing Unit (DSP), Lookup Table (LUT), and Flip-Flop (FF), as the quantization benchmark. In resource allocation, the demodulation and decoding module serves as the primary resource overhead module (e.g., DSP = 120, LUT = 42000); the narrowband time-division fine processing module includes sub-channel down-conversion decimation units and narrowband fine detection units (e.g., DSP = 14, LUT = 4500); the newly added wideband coarse acquisition module in the hierarchical architecture has a relatively simple algorithm and consumes almost no high-order multiplexing multiplier resources (e.g., DSP = 42, LUT = 13000); the time-division scheduling controller mainly provides logic control overhead (DSP = 0, LUT = 3000). In the fully parallel architecture, the processing resources of subsequent stages increase with the number of channels. It exhibits linear multiplication; the hierarchical architecture achieves global single-set dynamic reuse of the computing power of subsequent processing through a time-division scheduling controller, a narrowband time-division fine processing module, and a demodulation and decoding module.

[0057] Hardware processing time estimation: Considering the underlying hardware state switching and pipeline overhead, the scheduler's time consumption when scanning idle channels is set to 0.2 ms, while the single execution time when processing busy channels is set to 0.8 ms.

[0058] 2. Simulation Content: Single-Channel Basic Overhead Assessment: Observation of single-channel ( Under extreme conditions, the hierarchical processing architecture, due to the additional introduction of broadband coarse detection branches and on-demand scheduler logic, exhibits different overhead characteristics in its initial logical resources (DSP, LUT, FF) compared to the fully parallel architecture and the pure time-division polling (TDM) architecture.

[0059] Multi-channel concurrent resource growth trend analysis: Comparison with the growth trend of concurrent sub-channels The core hardware resource inflation curves for three different architectures were observed as the number of core hardware resources was gradually increased to six. The focus was on observing the significant linear growth disadvantage of the fully parallel architecture due to the complete replication of physical links, and the evolution trend of the broadband-narrowband hierarchical architecture in suppressing resource inflation.

[0060] Validation of architecture performance under full load: Quantification under multi-user full load conditions Under this architecture, the extreme pressure drop ratio of the core physical resources of the system (especially the expensive DSP computing nodes and the huge LUT / FF logic gate array) is demonstrated. This verifies the theoretical expectation that it can successfully break the linear coupling between the underlying computing power and the number of sub-channels through the dual reuse mechanism of "broadband triggering and on-demand scheduling", thereby reducing the hardware implementation threshold of the spaceborne FPGA.

[0061] System absolute acquisition latency comparison analysis (millisecond level): Observe the changes in the physical time of the average acquisition latency of the three architectures under different numbers of concurrent sub-channels (as shown in Figure 6). Focus on observing the significant linear lag caused by the large-scale buffer and queuing polling mechanism in the pure time-division polling (TDM) architecture, and how the broadband and narrowband hierarchical processing architecture controls the latency to near the physical theoretical lower limit of 0.8 milliseconds for the fully parallel architecture through ultra-fast underlying scheduling.

[0062] Equivalent Symbol Delay Cost Quantization (Symbol Level): Evaluate the equivalent symbol length of different architectures when processing delays are converted to baseband symbol rates (as shown in Figure 7). Verify whether the acquisition delay of the pure TDM architecture increases dramatically to 802 symbols (even exceeding the physical total length of a single-slot data burst) when fully loaded with 6 sub-channels. Simultaneously, quantify and verify the real-time response performance of the proposed wide-narrowband hierarchical architecture under full load, proving that its average acquisition delay per acquisition remains constant at approximately 27.65 equivalent symbols, thus completely eliminating cross-frame queuing lag. 3. Simulation Results Figure 3 is a comparison of the overhead of the digital signal processing unit (DSP) with the number of concurrent sub-channels under the fully parallel architecture, the traditional time-division polling (TDM) architecture, and the wide-narrowband joint hierarchical architecture. Simulation results show that the overhead of the digital signal processing unit (DSP) in the fully parallel architecture increases linearly with the increase of the number of concurrent sub-channels. The broadband-narrowband joint hierarchical architecture significantly reduces the growth rate of DSP resources through broadband on-demand triggering and back-end demodulation computing power pooling strategies. The DSP consumption level of the broadband-narrowband joint hierarchical architecture is close to that of the traditional time-division polling (TDM) architecture, with only an increase in broadband front-end monitoring logic overhead.

[0063] Figure 4 compares the overhead of the lookup table (LUT) under the three architectures as the number of concurrent sub-channels changes. Simulation results show that the overhead of the lookup table (LUT) in the fully parallel architecture increases linearly with the number of concurrent sub-channels; the broadband-narrowband joint hierarchical architecture also reduces the growth slope of the lookup table (LUT) resources, and the LUT overhead level of the broadband-narrowband joint hierarchical architecture is close to that of the traditional time-division polling (TDM) architecture.

[0064] Figure 5 is a comparison of the overhead of triggers (FFs) under the three architectures as the number of concurrent sub-channels changes. Simulation results show that the overhead of triggers (FFs) in the fully parallel architecture also increases linearly with the increase of the number of concurrent sub-channels; the broadband and narrowband joint hierarchical architecture also reduces the growth slope of trigger (FF) resources, and the trigger (FF) consumption level of the broadband and narrowband joint hierarchical architecture is close to that of the traditional time-division polling (TDM) architecture.

[0065] The simulation results comparing hardware resource consumption in Figures 3, 4, and 5 show that the wideband and narrowband joint hierarchical architecture avoids the cross-channel queuing delay of the traditional time-division polling (TDM) architecture while perfectly preserving the computing power reuse characteristics, achieving the optimal trade-off between hardware area and logic overhead and extremely high real-time response performance for multi-channel satellite receivers.

[0066] Figures 6 and 7 present the quantitative comparison results of the average acquisition delay of the fully parallel architecture, the traditional time-division polling (TDM) architecture, and the broadband-narrowband joint hierarchical architecture from the two dimensions of absolute time and equivalent symbol count, respectively. Simulation results show that the acquisition delay of the traditional TDM architecture, affected by the periodic polling mechanism, increases linearly with the increase of the number of concurrent sub-channels; the acquisition delay of the fully parallel architecture does not change with the number of concurrent sub-channels; the broadband-narrowband joint hierarchical architecture, through broadband triggering and on-demand scheduling mechanisms, completely eliminates scan waiting and cross-channel queuing delays, and the delay performance of the broadband-narrowband joint hierarchical architecture is highly close to that of the fully parallel architecture.

[0067] The simulation results comparing Figures 6 and 7 show that the combined wideband and narrowband hierarchical architecture, while reusing underlying computing resources, still possesses high real-time response capabilities, effectively balancing the trade-off between hardware area overhead and acquisition latency in multi-channel satellite receivers. Specifically, while maintaining a detection and acquisition latency highly consistent with the fully parallel architecture (approximately 0.823 ms), this architecture successfully avoids the high queuing latency (over 23 ms) caused by blindly scanning idle channels in the Time Division Polling (TDM) architecture, and significantly reduces the static resource overhead of satellite equipment. For example, under full load conditions, DSP resource consumption is reduced by approximately 82% compared to the fully parallel architecture (from 831 to 161). Therefore, this invention can simultaneously achieve extremely low hardware logic overhead and high real-time acquisition response capabilities on low-Earth orbit satellite platforms with extremely limited size and power consumption.

[0068] As shown in Figure 2, the present invention also provides a VDE-SAT system multi-channel fast blind acquisition and demodulation system, including: a broadband radio frequency signal preprocessing and splitting storage module, used to realize that after the on-board terminal receiving module receives the original VDE-SAT frequency division multi-channel signal in step 1 and performs analog-to-digital conversion, digital down-conversion, anti-aliasing filtering and downsampling, it is separated into two independent upper-band data streams in the frequency domain. With lower frequency band data stream A broadband coarse acquisition module with optimized delay and asymmetric threshold is used to implement the upper frequency band data stream in step 2. With lower frequency band data stream The process is divided into two parts: the first part continuously writes data to the corresponding broadband data cache module for storage; the second part sends data to the corresponding broadband coarse acquisition module for differential delay multiplication and performs sliding correlation operation with the local broadband reference synchronization sequence. The resulting magnitude value is compared with the pre-configured broadband determination threshold to obtain a successful acquisition flag signal and a synchronization signal trigger index, which are then output to the time-division scheduling controller. The on-demand scheduling and data extraction module for the trigger index is used to activate the time-division scheduling controller in step 3 after receiving the successful acquisition flag signal and trigger the index based on the synchronization signal. The data scheduling is executed to obtain the broadband synchronization header sequence to be processed and output to the narrowband time-division fine processing module; the narrowband fine detection and target channel locking module is used to implement the sub-channel down-conversion decimation unit and narrowband fine detection unit configured in the narrowband time-division fine processing module in step 4, and to traverse and process each sub-channel in the currently triggered frequency band in a time-division multiplexing manner to obtain a set of effective users including effective sub-channels and their corresponding fine synchronization positions and the frequency band types to which the effective sub-channels belong; the payload data extraction and shared core demodulation module is used to implement the time-division scheduling controller in step 5 to determine whether there are signals to be processed in the upper and lower frequency bands based on the set of effective users, and to access the data streams continuously written to the upper frequency band respectively. and lower frequency band data stream The broadband data buffer module; the time-division scheduling controller extracts the complete physical frame data segment containing the signal to be processed from the broadband data buffer module corresponding to the frequency band where the signal to be processed exists. The complete physical frame data segment contains the payload and synchronization sequence, and sends the complete physical frame data segment to the narrowband time-division fine processing module and demodulation decoding module to perform time-division fine processing and demodulation decoding; when all the signals to be processed are processed, the time-division scheduling controller resets the system receiving state.

[0069] The present invention also provides a VDE-SAT system multi-channel fast blind acquisition and demodulation device, comprising: a memory: storing a computer program for the above-mentioned VDE-SAT system multi-channel fast blind acquisition and demodulation method, which is a computer-readable device; and a processor: used to implement the VDE-SAT system multi-channel fast blind acquisition and demodulation method when executing the computer program.

[0070] The present invention also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, enables the implementation of the aforementioned VDE-SAT system multi-channel fast blind acquisition and demodulation method.

Claims

1. A method for fast blind acquisition and demodulation of multiple channels in a VDE-SAT system, characterized in that, The process includes the following steps: Step 1: The onboard terminal receiving module receives the original VDE-SAT frequency division multiple channel signal and performs analog-to-digital conversion, digital down-conversion, anti-aliasing filtering, and downsampling. Then, it separates the signal into two independent upper-band data streams in the frequency domain. With lower frequency band data stream Step 2: and The process is divided into two parts: the first part continuously writes data to the corresponding broadband data cache module for storage; the second part sends data to the corresponding broadband coarse acquisition module for differential delay multiplication and performs sliding correlation operation with the local broadband reference synchronization sequence. The resulting magnitude value is compared with the pre-configured broadband judgment threshold to obtain the acquisition success flag signal and the synchronization signal trigger index, which are then output to the time-division scheduling controller. Step 3: The time-division scheduling controller is activated upon receiving the acquisition success flag signal and triggers the synchronization signal based on the synchronization signal trigger index. Perform data scheduling to obtain the broadband synchronization header sequence to be processed and output it to the narrowband time-division fine processing module; Step 4: The narrowband time-division fine processing module is internally configured with a sub-channel down-conversion decimation unit and a narrowband fine detection unit. It performs time-division multiplexing on each sub-channel within the currently triggered frequency band to obtain a set of valid users containing the valid sub-channels, their corresponding fine synchronization positions, and the frequency band type to which the valid sub-channels belong. Step 5: The time-division scheduling controller determines whether there are signals to be processed in the upper and lower frequency bands based on the set of valid users, and accesses the data streams continuously written to the upper frequency band in Step 2. and lower frequency band data stream The broadband data buffer module; the time-division scheduling controller extracts the complete physical frame data segment containing the signal to be processed from the broadband data buffer module corresponding to the frequency band where the signal to be processed exists. The complete physical frame data segment contains the payload and synchronization sequence, and sends the complete physical frame data segment to the narrowband time-division fine processing module and demodulation decoding module to perform time-division fine processing and demodulation decoding; when all the signals to be processed are processed, the time-division scheduling controller resets the system receiving state.

2. The method for fast blind acquisition and demodulation of multiple channels in a VDE-SAT system according to claim 1, characterized in that, In step 2, for the upper frequency band, the broadband coarse acquisition module targets the input upper frequency band data stream. The following processing flow is executed sequentially: Step 2.1: The broadband coarse acquisition module, based on the optimized differential delay sampling points, performs processing on the upper frequency band data stream. Perform differential delay multiplication to obtain the differential result sequence. The calculation method is as follows: in, The broadband coarse acquisition module selects a fixed number of delay sampling points to match the set differential delay sampling points. Alternatively, perform extraction and delay multiplication operations when D=9; Step 2.2: The broadband coarse acquisition module will process the difference result sequence generated in Step 2.

1. Synchronization sequence with local broadband reference Perform the sliding correlation operation and calculate the output result of the sliding correlation operation at the corresponding time. The calculation method is as follows: in, This represents the complex conjugate operation. The effective accumulated length of the local broadband reference synchronization sequence; Step 2.3: The broadband coarse acquisition module extracts the output results of the sliding correlation operation. modulus and modulus Broadband determination threshold Perform amplitude comparison; if the magnitude of the sliding correlation operation output at the current time satisfies... If the acquisition is successful, the wideband coarse acquisition module records the current time as the trigger index and outputs a successful acquisition flag signal and a synchronization signal trigger index to the time-division scheduling controller. If the modulus of the output result of the sliding correlation operation at the current moment satisfies If the broadband coarse acquisition fails, the module will discard the current data and continue to perform sliding correlation operations on subsequent input data streams for detection; lower frequency band data stream With upper frequency band data stream The processing flow is the same.

3. The method for fast blind acquisition and demodulation of multiple channels in a VDE-SAT system according to claim 2, characterized in that, The broadband determination threshold in step 2.3 Broadband determination threshold ,in The set broadband false alarm rate, The standard deviation of the equivalent noise of the output of the broadband sliding correlation operation in the absence of a signal is given. It is determined by the product of the self-power of the local broadband reference synchronization sequence and the channel background noise power.

4. The method for fast blind acquisition and demodulation of multiple channels in a VDE-SAT system according to claim 2, characterized in that, The data scheduling process in step 3 includes: Step 3.1: The time-division scheduling controller triggers the index using the synchronization signal obtained in step 2.

3. Using the time base and combining the effective accumulated length of the local broadband reference synchronization sequence. Calculate the target data index range Step 3.2: The time-division scheduling controller accurately extracts the corresponding data segments from the broadband data cache module that is continuously stored in Step 2, based on the target data index range obtained in Step 3.

1. Step 3.3: The time-division scheduling controller uses the data segments extracted in Step 3.2 as the broadband synchronization header sequence to be processed and outputs them to the narrowband time-division fine processing module.

5. The method for fast blind acquisition and demodulation of multiple channels in a VDE-SAT system according to claim 4, characterized in that, The narrowband determination threshold in step 4.3 for ,in The equivalent noise standard deviation of the narrowband sliding correlation operation output in a pure noise background; Narrowband decision threshold It is based on the preset narrowband false alarm rate. The derivation is confirmed, and it satisfies the condition that the narrowband false alarm rate is much smaller than the broadband false alarm rate, i.e. 。 6. The method for fast blind acquisition and demodulation of multiple channels in a VDE-SAT system according to claim 1, characterized in that, Step 4, for the first For each sub-channel, the narrowband time-division processing module sequentially executes the following narrowband fine detection process: Step 4.1: Using the sub-channel down-conversion decimation unit of the narrowband time-division fine processing module, the broadband synchronization header sequence to be processed output by the time-division scheduling controller in step 3 is compared with the first sub-channel... The local reference zero intermediate frequency center frequency sequence corresponding to each sub-channel is multiplied to complete the sub-channel digital down-conversion independently of the front-end receiving link; Subsequently, the down-converted signal is input to a low-pass anti-aliasing filter and downsampled, outputting the first... Downsampled synchronization header sequence of each sub-channel Step 4.2: Utilize the narrowband fine detection unit of the narrowband time-division fine processing module, combined with the set differential delay sampling after downsampling. With the downsampled local reference synchronization sequence For the first generated in step 4.1 Downsampled synchronization header sequence of each sub-channel Perform differential delay multiplication and correlation accumulation operations to calculate the downsampled correlation peak magnitude. The calculation formula is as follows: in, To eliminate the narrowband differential result sequence after eliminating the time-varying carrier phase, This represents the complex conjugate operation. The effective accumulation length of the local narrowband reference synchronization sequence; Step 4.3: The narrowband fine detection unit of the narrowband time-division fine processing module will calculate the downsampled correlation peak magnitude value obtained in step 4.

2. With pre-configured narrowband decision threshold Perform amplitude comparison; if the comparison result satisfies... Then confirm the first With valid user access in each sub-channel, the narrowband time-division fine processing module extracts the fine synchronization position at that moment and assigns it to the first sub-channel. Each sub-channel and its corresponding fine synchronization position are updated to the set of valid users. The set of valid users contains information on all sub-channels that are determined to have valid signals, including the frequency band type, sub-channel number, and corresponding fine synchronization position of each valid sub-channel. If the comparison result satisfies... Then determine the first If no valid user access is found on a subchannel, the narrowband time-division fine processing module will skip that subchannel and continue to perform traversal detection on the next subchannel.

7. The method for fast blind acquisition and demodulation of multiple channels in a VDE-SAT system according to claim 6, characterized in that, The specific method of step 5 includes: Step 5.1: The time-division scheduling controller accesses the upper frequency band data streams continuously written in step 2 according to the frequency band type, sub-channel number and corresponding fine synchronization position recorded in the effective user set obtained in step 4.

3. and lower frequency band data stream The broadband data buffer module; subsequently, the time-division scheduling controller accurately extracts the complete physical frame data segment from the broadband data buffer module corresponding to the frequency band containing the signal to be processed, according to the fine synchronization position, and schedules the complete physical frame data segment to the narrowband time-division fine processing module; Step 5.2: The narrowband time-division fine processing module receives the complete physical frame data segment output in step 5.1, and uses the internally configured sub-channel down-conversion decimation unit to perform digital down-conversion, low-pass filtering, and downsampling decimation processing on the complete physical frame data segment according to the sub-channel number recorded in the effective user set, to obtain the narrowband complete physical frame data segment of the corresponding sub-channel, and outputs the narrowband complete physical frame data segment to the demodulation decoding module; Step 5.3: The demodulation decoding module receives the narrowband complete physical frame data segment output in step 5.2, and based on the VDE-SAT specified in ITU-RM.2092 Recommendation. The signal system performs demodulation and decoding operations on the complete physical frame data segment of the narrowband, and finally outputs the source bit stream of the corresponding sub-channel in the effective user set; Step 5.4: After completing the narrowband time-division fine processing, demodulation and decoding and source bit stream output of all signals to be processed in the effective user set, the time-division scheduling controller clears the current effective user set, releases the processing resources occupied by the narrowband time-division fine processing module and the demodulation and decoding module, and resets the system reception state, so that the system returns to the reception process that relies on the wideband coarse acquisition module for global monitoring.

8. A VDE-SAT system multi-channel fast blind acquisition and demodulation system based on the method of claim 1, characterized in that, include: The broadband RF signal preprocessing and splitting storage module is used to enable the onboard terminal receiving module to receive the raw VDE-SAT frequency division multichannel signal, perform analog-to-digital conversion, digital down-conversion, anti-aliasing filtering, and downsampling, and then separate it into two independent upper-band data streams in the frequency domain. With lower frequency band data stream A broadband coarse acquisition module with optimized latency and asymmetric threshold is used to... and The process is divided into two parts: the first part continuously writes data to the corresponding broadband data cache module for storage; the second part sends data to the corresponding broadband coarse acquisition module for differential delay multiplication and performs sliding correlation with the local broadband reference synchronization sequence. The resulting magnitude is compared with a pre-configured broadband determination threshold to obtain a successful acquisition flag signal and a synchronization signal trigger index, which are then output to the time-division scheduling controller. The on-demand scheduling and data extraction module for the trigger index is used to activate the time-division scheduling controller upon receiving the successful acquisition flag signal and trigger the index based on the synchronization signal. Perform data scheduling to obtain the broadband synchronization header sequence to be processed and output it to the narrowband time-division fine processing module; The narrowband fine detection and target channel locking module is used to implement the narrowband time-division fine processing module, which is internally configured with a sub-channel down-conversion decimation unit and a narrowband fine detection unit. It performs time-division multiplexing on each sub-channel within the currently triggered frequency band to obtain a set of effective users containing valid sub-channels, their corresponding fine synchronization positions, and the frequency band type to which the valid sub-channels belong. The payload data extraction and shared core demodulation module, based on the valid user set, determines whether there are signals to be processed in the upper and lower frequency bands, and accesses the continuously written upper frequency band data streams. and lower frequency band data stream The broadband data buffer module; the time-division scheduling controller extracts the complete physical frame data segment containing the signal to be processed from the broadband data buffer module corresponding to the frequency band where the signal to be processed exists. The complete physical frame data segment contains the payload and synchronization sequence, and sends the complete physical frame data segment to the narrowband time-division fine processing module and demodulation decoding module to perform time-division fine processing and demodulation decoding; when all the signals to be processed are processed, the time-division scheduling controller resets the system receiving state.

9. A VDE-SAT system multi-channel fast blind acquisition and demodulation device, characterized in that, include: Memory: A computer program for a VDE-SAT system multi-channel fast blind acquisition and demodulation method as described in any one of claims 1-7, which is a computer-readable device; Processor: Used to implement the VDE-SAT system multi-channel fast blind acquisition and demodulation method according to any one of claims 1-7 when executing the computer program.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, enables the implementation of a VDE-SAT system multi-channel fast blind acquisition and demodulation method as described in any one of claims 1-7.

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