An auxiliary acquisition method and apparatus for a frequency hopping communication system

Abstract

This application discloses an auxiliary acquisition method and apparatus for a frequency-hopping communication system, relating to the field of wireless communication technology. The destination node acquires the signal frame transmitted by the source node at the start of the TDMA time slot, obtaining an initial acquisition correlation peak. If the peak is greater than a threshold, its time position is used as the initial timing synchronization position, and the initial signal arrival time is calculated. A time tracking filter is set to track and filter the initial signal arrival time and calculate the predicted signal arrival time. At other times in the TDMA time slot, subsequent acquisition correlation peaks are acquired. If they are greater than a threshold, their time position is used as the final timing synchronization position for processing data pulses, and the subsequent signal arrival time is calculated to update the time tracking filter; if they are less than or equal to the threshold, the predicted signal arrival time is used as the final timing synchronization position for processing data pulses. This solves the problems of high hardware cost, susceptibility to interference, and rapid reduction in transmission rate over long distances in existing technologies.

Description

Technical Field

[0001] This application relates to the field of wireless communication technology, and in particular to an auxiliary acquisition method and apparatus for a frequency hopping communication system. Background Technology

[0002] In unmanned node communication scenarios, transmission rate, anti-interference capability, and low cost are usually the main factors of concern in communication system design. In complex electromagnetic environments, unmanned communication nodes often face interference from other unknown or even malicious signals. Anti-interference capabilities are typically achieved using high-speed frequency hopping transmission that varies with the pulse signal frequency, but its anti-interference performance is often limited by the signal acquisition process. Currently, commonly used signal acquisition methods include multi-channel parallel reception and single-channel serial reception.

[0003] Multi-channel parallel reception requires multiple hardware receiving channels to receive signals simultaneously, and the baseband digital processing resources must also support multi-channel signal acquisition and processing, thereby improving the anti-interference capability of the received signal acquisition process. However, this method will increase the hardware cost of the node communication equipment significantly. Single-channel serial reception does not require multiple hardware receiving channels, and only processes the single-channel received signal acquisition and processing corresponding to a single frequency point instantaneously. It is susceptible to interference signals. If multiple pulse signals at multiple frequencies are to be acquired, the signal frame needs to reserve a long signal acquisition ratio. As the communication distance increases, the signal acquisition overhead during transmission will increase significantly, resulting in a rapid decrease in transmission rate.

[0004] Therefore, existing unmanned node communication signal acquisition technologies suffer from problems such as high hardware costs for multi-channel parallel reception methods and susceptibility to interference and rapid reduction in transmission rate over long distances for single-channel serial reception methods. Summary of the Invention

[0005] This application provides an auxiliary acquisition method for a frequency-hopping communication system, which solves the problems in existing unmanned node communication signal acquisition technologies, such as high hardware costs for multi-channel parallel reception methods and susceptibility to interference and rapid reduction in transmission rate over long distances for single-channel serial reception methods. This application eliminates the need for multiple hardware reception channels and does not significantly increase the signal acquisition ratio during transmission, while also improving the anti-interference capability of the frequency-hopping communication system.

[0006] In a first aspect, embodiments of this application provide an auxiliary acquisition method for a frequency-hopping communication system, applied to unmanned node communication. The unmanned node communication employs a synchronous TDMA access method. The method includes: a source node sending a signal frame to the communication channel at the start of the TDMA time slot; a destination node receiving the signal frame from the source node via the communication channel and performing signal acquisition processing, using the sum of the multiplication of the local PN sequence and the conjugate of the received signal as the initial acquisition correlation peak; when the initial acquisition correlation peak is less than or equal to a threshold, it is considered an invalid acquisition, and the destination node continues searching for acquisition in the communication channel; when the initial acquisition correlation peak is greater than the threshold, acquisition is considered successful, the time position of the initial acquisition correlation peak is used as the initial timing synchronization position of the signal frame, and the time difference between the time position of the initial acquisition correlation peak and the start of the TDMA time slot is obtained, with the time difference used as the initial signal arrival time of the signal frame sent by the source node; the destination node sets a time tracking filter for the source node, which is used to track and filter changes in signal arrival time. In the initial stage, after three successful acquisitions, this... The initial signal arrival times acquired from three captures are used to establish the state matrix and error matrix of the time tracking filter. The time tracking filter is then used to calculate the predicted signal arrival times of the source node at other times in the TDMA time slot. At other times in the TDMA time slot, the destination node performs signal capture processing again on the signal frame sent by the source node and obtains the subsequent capture correlation peak. The method for obtaining the subsequent capture correlation peak is the same as that for obtaining the initial capture correlation peak. When the subsequent capture correlation peak is greater than the threshold, the time position of the subsequent capture correlation peak is used as the final timing synchronization position of the signal frame. Data pulse processing is performed on the signal frame based on the final timing synchronization position of the signal frame. The time difference between the time position of this subsequent capture correlation peak and the start time of the TDMA time slot is re-acquired to obtain the subsequent signal arrival time. The state matrix and error matrix of the time tracking filter are then updated using the subsequent signal arrival time. When the subsequent capture correlation peak is less than or equal to the threshold, the predicted signal arrival time is used as the final timing synchronization position of the signal frame. Data pulse processing is performed on the signal frame based on the final timing synchronization position of the signal frame.

[0007] In one possible implementation, the signal frame includes sequentially arranged synchronization acquisition pulses and data pulses, with one pulse corresponding to one frequency hopping point; the synchronization acquisition pulses are used for receiving signal acquisition and timing synchronization; and the data pulses are used for data transmission.

[0008] In one possible implementation, the result of multiplying and accumulating the local PN sequence with the conjugate of the received signal is based on... Obtain; among which, Indicates the location of the received signal. At this point, the result of multiplying and summing the local PN sequence and the received signal (conjugate), specifically represents the initial acquisition correlation peak. This represents the signal received by the destination node after power normalization. For the index of the received signal, Let j represent the local PN sequence, and j represent the index of the local PN sequence. is the length of the PN sequence.

[0009] In one possible implementation, when the initial capture correlation peak is greater than a threshold, the capture is considered successful. The time position of the initial capture correlation peak is used as the initial timing synchronization position of the signal frame. The time difference between the time position of the initial capture correlation peak and the start time of the TDMA time slot is obtained, and the time difference is used as the initial signal arrival time of the source node's transmitted signal frame. This includes: the threshold is based on... Determined; among them, For the threshold, As the first engineering constant, The length of the PN sequence; the time difference is quantified using the local clock cycle.

[0010] In one possible implementation, the destination node sets a time tracking filter for the source node. This time tracking filter tracks and filters changes in signal arrival time. In the initial stage, after three successful acquisitions, the initial signal arrival times obtained from these three acquisitions are used to establish the state matrix and error matrix of the time tracking filter. The state matrix is ​​represented as follows: ;in, The state matrix, The initial signal arrival time of the first measured source node transmitted signal frame. The initial signal arrival time of the source node's transmitted signal frame measured for the second time. The initial signal arrival time of the source node's transmitted signal frame measured for the third time. For measurement At that moment, For measurement At that moment, For measurement At the time; the error matrix is ​​represented as: ;in, Here is the error matrix. For the second engineering constant, The standard deviation of the initial signal arrival time measurement error is given; the time tracking filter uses a Kalman filter based on a uniform acceleration model to track and filter changes in the signal arrival time; the state transition matrix in the Kalman filter is given. Measurement matrix Process noise matrix The expressions are as follows: , and ;in, The time interval between two consecutive measurements of the arrival time of the initial signal. For transpose operation; determine whether the measured arrival time of subsequent signals meets the preset conditions; if the preset conditions are not met, the arrival time of subsequent signals is discarded; if the preset conditions are not met three times in a row, reset the time tracking filter and then measure the initial signal arrival time of the source node's transmitted signal frames three more times to re-establish the state matrix and error matrix of the time tracking filter; if the preset conditions are met, use the arrival time of subsequent signals to update the state matrix and error matrix of the time tracking filter to track and filter the changes in signal arrival time.

[0011] In one possible implementation, the preset conditions include: ;in, For the first The arrival time of subsequent signals after the source node transmits a signal frame. For the first The estimated arrival time of subsequent signals measured in the first measurement. For the measurement matrix, For the first Error matrix of subsequent signal arrival times measured in the second measurement The estimated value, For subsequent signal arrival time measurement error matrix, , This is the normalized threshold value.

[0012] In one possible implementation, the step of using a time tracking filter to estimate the predicted signal arrival time of the source node at other times in the TDMA time slot includes: ;in, For the predicted signal arrival time of the source node at other times in the TDMA time slot, The first row of the state matrix represents the signal arrival time. The second row component in the state matrix represents the rate of change over time. The third row component in the state matrix represents the time-varying acceleration. This is the difference between other times in the TDMA time slot and the most recent update time of the time tracking filter.

[0013] Secondly, embodiments of this application provide an auxiliary acquisition device for a frequency hopping communication system. The device includes: a signal arrival time acquisition module, used by a source node to send a signal frame to a communication channel at the start of a TDMA time slot; after receiving the signal frame from the source node via the communication channel, the destination node performs signal acquisition processing, using the sum of the multiplication of the local PN sequence and the conjugate of the received signal as the initial acquisition correlation peak; when the initial acquisition correlation peak is less than or equal to a threshold, it is considered an invalid acquisition, and the destination node continues to search for acquisition in the communication channel; when the initial acquisition correlation peak is greater than the threshold, it is considered a successful acquisition, and the time position of the initial acquisition correlation peak is used as the initial timing synchronization position of the signal frame, and the time difference between the time position of the initial acquisition correlation peak and the start of the TDMA time slot is obtained, with the time difference used as the initial signal arrival time of the signal frame sent by the source node; and a setting module, used by the destination node to set a time tracking filter for the source node. The time tracking filter is used to track and filter changes in the signal arrival time. In the initial stage, after three successful acquisitions, the initial signal arrival time is used... The arrival time is used to establish the state matrix and error matrix of the time tracking filter. The time tracking filter is used to calculate the predicted signal arrival time of the source node at other times in the TDMA time slot. The data pulse processing module is used by the destination node to re-acquire the signal frame sent by the source node at other times in the TDMA time slot and obtain the subsequent acquisition correlation peak. The method of obtaining the subsequent acquisition correlation peak is the same as that of obtaining the initial acquisition correlation peak. When the subsequent acquisition correlation peak is greater than the threshold, the time position of the subsequent acquisition correlation peak is used as the final timing synchronization position of the signal frame. Data pulse processing is performed on the signal frame based on the final timing synchronization position of the signal frame. The time difference between the time position of the subsequent acquisition correlation peak and the start time of the TDMA time slot is re-obtained to obtain the subsequent signal arrival time. The state matrix and error matrix of the time tracking filter are updated using the subsequent signal arrival time. When the subsequent acquisition correlation peak is less than or equal to the threshold, the predicted signal arrival time is used as the final timing synchronization position of the signal frame. Data pulse processing is performed on the signal frame based on the final timing synchronization position of the signal frame.

[0014] Thirdly, embodiments of this application provide an auxiliary acquisition server for a frequency hopping communication system, including a memory and a processor; the memory is used to store computer-executable instructions; the processor is used to execute the computer-executable instructions to implement the method described in the first aspect or any possible implementation of the first aspect.

[0015] Fourthly, embodiments of this application provide a computer-readable storage medium storing executable instructions, which, when executed by a computer, enable the method described in the first aspect or any possible implementation thereof.

[0016] One or more technical solutions provided in this application embodiment have at least the following technical effects: This application embodiment provides an auxiliary acquisition method for a frequency hopping communication system. The source node transmits a signal frame at the start of the TDMA time slot. After receiving the frame, the destination node performs signal acquisition and multiplies the local PN sequence with the conjugate of the received signal to obtain the initial acquisition correlation peak. If the peak is greater than a threshold, its time position is used as the initial timing synchronization position, and the initial signal arrival time is calculated. The destination node sets a time tracking filter for the source node. The time tracking filter is used to track and filter changes in the signal arrival time. In the initial stage, after three successful acquisitions, the initial signal arrival times obtained from these three acquisitions are used to establish the state matrix and error matrix of the time tracking filter. The time tracking filter is used to calculate the predicted signal arrival time of the source node at other times in the TDMA time slot. In other times within the TDMA time slot, the signal is captured again to obtain subsequent capture correlation peaks. When the subsequent capture correlation peak is greater than a threshold, the time position of the subsequent capture correlation peak is used as the final timing synchronization position of the signal frame. Based on the final timing synchronization position of the signal frame, data pulse processing is performed on the signal frame. The time difference between the time position of this subsequent capture correlation peak and the start time of the TDMA time slot is re-acquired to obtain the subsequent signal arrival time, and the state matrix and error matrix of the time tracking filter are updated using the subsequent signal arrival time. If it is less than or equal to the threshold, the predicted signal arrival time is used as the final timing synchronization position for data pulse processing. This solves the problems in existing unmanned node communication signal acquisition technologies, such as the high hardware cost of multi-channel parallel reception methods and the susceptibility to interference and rapid reduction in transmission rate during long-distance transmission of single-channel serial reception methods. This application eliminates the need for multiple hardware reception channels and does not significantly increase the signal acquisition ratio during transmission, while also improving the anti-interference capability of the frequency hopping communication system. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments of this application or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A flowchart of an auxiliary acquisition method for a frequency hopping communication system provided in this application embodiment.

[0019] Figure 2 This is a schematic diagram of the TDMA time slot allocation period provided in an embodiment of this application.

[0020] Figure 3 This is a schematic diagram illustrating the correspondence between signal frames and frequency hopping points provided in an embodiment of this application.

[0021] Figure 4 This is a schematic diagram of an auxiliary acquisition device for a frequency hopping communication system provided in an embodiment of this application.

[0022] Figure 5 This is a schematic diagram of an auxiliary capture server for a frequency hopping communication system provided in an embodiment of this application.

[0023] Icons: 400 - An auxiliary acquisition device for a frequency hopping communication system; 401 - Signal arrival time acquisition module; 402 - Setting module; 403 - Data pulse processing module; 501 - Memory; 502 - Processor. Detailed Implementation

[0024] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0025] The following description of some technologies involved in the embodiments of this application is provided to aid understanding and should be considered merely exemplary. Therefore, those skilled in the art should recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of this application. Similarly, for clarity and brevity, some descriptions of well-known functions and structures are omitted in the following description.

[0026] This application provides an auxiliary acquisition method for a frequency hopping communication system, such as... Figure 1 As shown, the method includes steps S101 to S108. Wherein, Figure 1 This is merely one execution order shown in the embodiments of this application and does not represent the only execution order of an auxiliary acquisition method for a frequency hopping communication system. Where the final result can be achieved, Figure 1 The steps shown can be performed in parallel or in reverse order.

[0027] This application discloses an auxiliary acquisition method for a frequency-hopping communication system, applicable to unmanned node communication, which employs synchronous TDMA access. Unmanned nodes include drones, autonomous vehicles, etc.

[0028] S101: The source node sends a signal frame to the communication channel at the start of the TDMA time slot.

[0029] Specifically, TDMA is a communication technology that divides communication time into time slots. Different users or nodes occupy the communication channel for data transmission in different time slots. In this way, multiple users or nodes can share the same communication channel, effectively avoiding mutual interference and improving channel utilization.

[0030] Figure 2 This is a schematic diagram of the TDMA time slot allocation period provided in an embodiment of this application. Figure 2 As shown, each node's communication equipment is configured with only a single receiving channel. The signal frame consists of sequentially arranged synchronization acquisition pulses and data pulses. One pulse corresponds to one frequency hopping point, which changes with each pulse. The number of synchronization acquisition pulses is 1, while the number of data pulses is greater than 1. The synchronization acquisition pulses are used for receiving signal acquisition and timing synchronization. The data pulses are used for data transmission. Figure 2 In this context, N represents the number of time slots contained in a complete TDMA cycle.

[0031] Figure 3 This diagram illustrates the correspondence between signal frames and frequency hopping points provided in an embodiment of this application. The frequency hopping point sequence varies randomly in different TDMA time slots, exhibiting strong anti-interference capabilities. Figure 3 f1, f2, f3, f4, ..., fM represent different frequency modulation points.

[0032] S102: After the destination node receives the signal frame from the source node from the communication channel, it performs signal acquisition processing and uses the result of multiplying the local PN sequence with the conjugate of the received signal as the initial acquisition correlation peak.

[0033] Specifically, a local PN sequence refers to a pseudo-random noise sequence generated at the receiving end of a communication system that is exactly the same as the one at the transmitting end.

[0034] The result of multiplying and accumulating the local PN sequence and the received signal conjugate is based on Obtain. Among them, Indicates the location of the received signal. At this point, the result of multiplying and summing the local PN sequence and the received signal (conjugate), specifically represents the initial acquisition correlation peak. This represents the signal received by the destination node after power normalization. For the index of the received signal, Let j represent the local PN sequence, and j represent the index of the local PN sequence. is the length of the PN sequence.

[0035] S103: When the initial capture correlation peak is less than or equal to the threshold, it is considered an invalid capture, and the destination node continues to search for capture in the communication channel.

[0036] S104: When the initial capture correlation peak is greater than the threshold, the capture is considered successful. The time position of the initial capture correlation peak is taken as the initial timing synchronization position of the signal frame. The time difference between the time position of the initial capture correlation peak and the start time of the TDMA time slot is obtained. The time difference is taken as the initial signal arrival time of the source node's transmitted signal frame.

[0037] Threshold based on Confirmed. Among them, For the threshold, As the first engineering constant, is the length of the PN sequence.

[0038] Specifically, the first engineering constant The value range is from 0.3 to 0.5.

[0039] The time difference is quantified using local clock cycles.

[0040] Specifically, the time difference can be quantified by the local clock cycle and can be understood as the number of local clock slices that pass between the start time of the TDMA time slot and the time position of the initial capture correlation peak, which is used as the initial signal arrival time of the source node's transmitted signal frame.

[0041] S105: The destination node sets the time tracking filter of the source node. The time tracking filter is used to track and filter the changes in signal arrival time. In the initial stage, after three successful acquisitions, the initial signal arrival times obtained from these three acquisitions are used to establish the state matrix and error matrix of the time tracking filter. The time tracking filter is used to calculate the predicted signal arrival time of the source node at other times in the TDMA time slot.

[0042] The state matrix is ​​represented as follows: .in, The state matrix, The initial signal arrival time of the first measured source node transmitted signal frame. The initial signal arrival time of the source node's transmitted signal frame measured for the second time. The initial signal arrival time of the source node's transmitted signal frame measured for the third time. For measurement At that moment, For measurement At that moment, For measurement At that moment.

[0043] The error matrix is ​​represented as follows: .in, Here is the error matrix. For the second engineering constant, This represents the standard deviation of the measurement error for the initial signal arrival time.

[0044] Specifically, the value range of the second engineering constant is 2 to 4.

[0045] The time tracking filter uses a Kalman filter based on a uniform acceleration model to track and filter changes in the signal arrival time.

[0046] Specifically, the uniform acceleration model assumes that the change in signal arrival time conforms to the law of uniform acceleration motion, and continuously updates the state estimate through the Kalman filter algorithm to improve the tracking accuracy of changes in signal arrival time.

[0047] State transition matrix in a Kalman filter Measurement matrix Process noise matrix The expressions are as follows: , and .in, The time interval between two consecutive measurements of the arrival time of the initial signal. This is a transpose operation.

[0048] Specifically, the state transition matrix The state at the current moment can be estimated and predicted based on the state at the previous moment. Measurement matrix. Used to map the system's state variables to the observation space, that is, to extract the part related to the actual observations from the state estimate so as to compare and update with the actual measurements. Process noise matrix The influence of system model uncertainties and external disturbances on state estimation is considered. By modeling process noise, the Kalman filter can better adapt to changes in the actual system and improve the robustness of tracking filtering.

[0049] Through the Kalman filtering process based on the uniform acceleration model, the time tracking filter can continuously update the estimate of the signal arrival time and its changing state, thereby achieving accurate tracking filtering of the initial signal arrival time change, and providing a reliable basis for subsequent calculation of the predicted signal arrival time of the source node at other times in the TDMA time slot.

[0050] Determine whether the arrival time of the measured subsequent signal meets the preset conditions.

[0051] The preset conditions include: .in, For the first The arrival time of subsequent signals after the source node transmits a signal frame. For the first The estimated arrival time of subsequent signals measured in the first measurement. For the measurement matrix, For the first Error matrix of subsequent signal arrival times measured in the second measurement The estimated value, For subsequent signal arrival time measurement error matrix, , This is the normalized threshold value.

[0052] Specifically, normalized threshold value The empirical value range is 9 to 25, which is used to define a reasonable range of difference between the measured value and the estimated value.

[0053] If the preset conditions are not met, the arrival time of subsequent signals will be discarded.

[0054] Specifically, after obtaining an initial signal arrival time measurement, it is substituted into the aforementioned preset conditions for judgment. If the measurement value does not meet the preset conditions, i.e. This indicates that the measured value deviates too much from the theoretically calculated value, which may be due to measurement error or interference. In this case, the measured value of the initial signal arrival time is determined to be an outlier and is discarded, and will not be used for subsequent time tracking filtering.

[0055] If the preset conditions are not met three times in a row, the time tracking filter is reset and the initial signal arrival time of the source node's transmitted signal frames is measured three more times to re-establish the state matrix and error matrix of the time tracking filter.

[0056] Specifically, if the initial signal arrival times obtained from three consecutive measurements do not meet the preset conditions, it means that the time tracking filter may have a state deviation or malfunction due to multiple abnormal measurement data. In this case, the time tracking filter needs to be reset to its initial state. After resetting, the initial signal arrival times of the signal frames transmitted by the source node are measured three more times. Based on these three valid measurements, the state matrix and error matrix of the time tracking filter are re-established.

[0057] If the preset conditions are met, the state matrix and error matrix of the time tracking filter are updated using the subsequent signal arrival time to track and filter changes in signal arrival time.

[0058] Specifically, if the arrival time of the measured initial signal meets the preset condition, i.e. This indicates that the measurement value is reliable and valid. At this point, the state matrix and error matrix of the time tracking filter are updated using this initial signal arrival time. In this way, the time tracking filter can continuously adjust its state based on the latest valid measurement data, thereby more accurately tracking and filtering changes in signal arrival time, providing a reliable basis for subsequently accurately estimating the predicted signal arrival time of the source node at other times in the TDMA time slot.

[0059] The time-tracking filter employs a Kalman filter based on a uniform acceleration model, which assumes that the signal arrival time follows a uniformly accelerated motion. Under this model, the signal arrival time not only changes linearly with time (determined by the rate of time change), but is also subject to a quadratic change due to the influence of acceleration.

[0060] The predicted signal arrival time of the source node at other times in the TDMA time slot is estimated using a time tracking filter, including: .in, For the predicted signal arrival time of the source node at other times in the TDMA time slot, The first row of the state matrix represents the signal arrival time. The second row component in the state matrix represents the rate of change over time. The third row component in the state matrix represents the time-varying acceleration. This is the difference between other times in the TDMA time slot and the most recent update time of the time tracking filter.

[0061] Specifically, the difference It is a key time parameter for calculating the arrival time of the predicted signal. It represents the length of time elapsed from the moment when the time tracking filter last updates the state matrix to the other moment of the TDMA time slot that needs to be predicted.

[0062] In this way, the time tracking filter can make relatively accurate predictions of the signal arrival time of the source node at other times in the TDMA time slot based on historical signal arrival time information and a uniform acceleration model. This provides a reliable timing synchronization basis for data pulse processing of the signal frame when synchronization pulse acquisition fails, effectively improving the performance and stability of the frequency hopping communication system under interference environments.

[0063] S106: At other times in the TDMA time slot, the destination node performs signal acquisition processing again on the signal frame sent by the source node and obtains the subsequent acquisition correlation peak. The method for obtaining the subsequent acquisition correlation peak is the same as that for obtaining the initial acquisition correlation peak.

[0064] Specifically, the destination node uses the locally stored PN sequence to perform conjugate multiplication and accumulation with the received signal. This process involves sliding the received signal, sequentially multiplying and accumulating the local PN sequence with the received signal at different positions to obtain a series of accumulation results, which constitute the subsequent capture correlation peak.

[0065] S107: When the subsequent capture correlation peak is greater than the threshold, the time position of the subsequent capture correlation peak is taken as the final timing synchronization position of the signal frame. Based on the final timing synchronization position of the signal frame, the signal frame is processed into data pulses. The time difference between the time position of the subsequent capture correlation peak and the start time of the TDMA time slot is re-acquired to obtain the arrival time of the subsequent signal. The state matrix and error matrix of the time tracking filter are updated using the arrival time of the subsequent signal.

[0066] Specifically, when the subsequent captured correlation peak exceeds the threshold, this final timing synchronization position can more accurately reflect the arrival time of the signal frame, providing an accurate time reference for subsequent data pulse processing. Based on this final timing synchronization position, the destination node can accurately determine the start and end positions of the data pulses in the signal frame, thereby correctly demodulating and processing the data pulses, extracting the valid information transmitted within, and ensuring the accuracy and reliability of communication.

[0067] S108: When the subsequent captured correlation peak is less than or equal to the threshold, the predicted signal arrival time is used as the final timing synchronization position of the signal frame, and the signal frame is processed into data pulses based on the final timing synchronization position of the signal frame.

[0068] Specifically, when the subsequent captured correlation peak is less than or equal to the threshold, it means that the signal capture result at the current moment is not ideal, possibly due to interference or other factors that prevented the successful capture of a valid signal correlation peak. In this case, the destination node will not blindly wait or make uncertain attempts, but will use the predicted signal arrival time obtained from the time tracking filter as the final timing synchronization position of the signal frame. The time tracking filter is a Kalman filter based on a uniform acceleration model. By tracking and filtering the previously acquired signal arrival time, it can calculate the signal arrival time of the source node at the current moment in the TDMA time slot and at other moments in the TDMA time slot.

[0069] This application embodiment also provides an auxiliary acquisition device 400 for a frequency hopping communication system, such as Figure 4 As shown, the device includes: a signal arrival time acquisition module 401, a setting module 402, and a data pulse processing module 403.

[0070] The signal arrival time acquisition module 401 is used by the source node to send a signal frame to the communication channel at the start of the TDMA time slot. After receiving the signal frame from the source node from the communication channel, the destination node performs signal acquisition processing, and uses the sum of the product of the local PN sequence and the conjugate of the received signal as the initial acquisition correlation peak. If the initial acquisition correlation peak is less than or equal to a threshold, it is considered an invalid acquisition, and the destination node continues to search for acquisition in the communication channel. If the initial acquisition correlation peak is greater than the threshold, it is considered a successful acquisition, and the time position of the initial acquisition correlation peak is used as the initial timing synchronization position of the signal frame. The time difference between the time position of the initial acquisition correlation peak and the start of the TDMA time slot is obtained, and the time difference is used as the initial signal arrival time of the signal frame sent by the source node.

[0071] The setting module 402 is used by the destination node to set the time tracking filter of the source node. The time tracking filter is used to track and filter the changes in signal arrival time. In the initial stage, after three successful captures, the initial signal arrival times obtained from these three captures are used to establish the state matrix and error matrix of the time tracking filter. The time tracking filter is used to calculate the predicted signal arrival time of the source node at other times in the TDMA time slot.

[0072] The data pulse processing module 403 is used by the destination node to re-acquire the signal frame sent by the source node at other times in the TDMA time slot and obtain the subsequent acquisition correlation peak. The method for obtaining the subsequent acquisition correlation peak is the same as that for obtaining the initial acquisition correlation peak. When the subsequent acquisition correlation peak is greater than a threshold, the time position of the subsequent acquisition correlation peak is used as the final timing synchronization position of the signal frame. Based on the final timing synchronization position of the signal frame, data pulse processing is performed on the signal frame. The time difference between the time position of this subsequent acquisition correlation peak and the start time of the TDMA time slot is re-acquired to obtain the subsequent signal arrival time, and the state matrix and error matrix of the time tracking filter are updated using the subsequent signal arrival time. When the subsequent acquisition correlation peak is less than or equal to the threshold, the predicted signal arrival time is used as the final timing synchronization position of the signal frame, and data pulse processing is performed on the signal frame based on the final timing synchronization position of the signal frame.

[0073] Some modules in the apparatus described in this application can be described in the general context of computer-executable instructions that are executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, classes, etc., that perform a specific task or implement a specific abstract data type. This application can also be practiced in distributed computing environments where tasks are performed by remote processing devices connected via a communication network. In distributed computing environments, program modules can reside in local and remote computer storage media, including storage devices.

[0074] The apparatus or module described in the above embodiments can be implemented by a computer chip or physical entity, or by a product with a certain function. For ease of description, the above apparatus is described by dividing it into various modules according to their functions. When implementing the embodiments of this application, the functions of each module can be implemented in one or more software and / or hardware. Of course, a module that implements a certain function can also be implemented by combining multiple sub-modules or sub-units.

[0075] The methods, apparatus, or modules described in this application can be implemented in a computer-readable program code manner. The controller can be implemented in any suitable manner, for example, as a microprocessor or processor and a computer-readable medium storing computer-readable program code (e.g., software or firmware) executable by the (micro)processor, logic gates, switches, application-specific integrated circuits (ASICs), programmable logic controllers, and embedded microcontrollers. Examples of controllers include, but are not limited to, the following microcontrollers: ARC 625D, Atmel AT91SAM, Microchip PIC18F26K20, and Silicon Labs C8051F320. A memory controller can also be implemented as part of the control logic of a memory. Those skilled in the art will also recognize that, in addition to implementing the controller in purely computer-readable program code manner, the same functionality can be achieved by logically programming the method steps to make the controller take the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers. Therefore, such a controller can be considered a hardware component, and the means included within it for implementing various functions can also be considered as structures within the hardware component. Alternatively, the device used to implement various functions can be viewed as either a software module that implements the method or a structure within a hardware component.

[0076] like Figure 5 As shown in the figure, this application embodiment also provides an auxiliary acquisition server for a frequency hopping communication system, including a memory 501 and a processor 502; the memory 501 is used to store computer-executable instructions; the processor 502 is used to execute the computer-executable instructions to implement the auxiliary acquisition method for a frequency hopping communication system described above in this application embodiment.

[0077] This application also provides a computer-readable storage medium storing executable instructions, which, when executed by a computer, can implement the auxiliary acquisition method of a frequency hopping communication system described above in this application.

[0078] As can be seen from the above description of the embodiments, those skilled in the art can clearly understand that this application can be implemented by means of software plus necessary hardware. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product, or it can be embodied in the process of data migration. The computer software product can be stored in a storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, mobile terminal, server, or network device, etc.) to execute the methods described in the embodiments of this application.

[0079] The various embodiments described in this specification are presented in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on its differences from other embodiments. All or part of this application can be used in numerous general-purpose or special-purpose computer system environments or configurations.

[0080] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of this application.

Claims

1. An auxiliary acquisition method for a frequency hopping communication system, characterized in that, This is applied to unmanned node communication, which employs a synchronous TDMA access method, including: The source node sends a signal frame to the communication channel at the start of the TDMA time slot; After the destination node receives the signal frame from the source node from the communication channel, it performs signal acquisition processing and uses the result of multiplying and accumulating the local PN sequence with the conjugate of the received signal as the initial acquisition correlation peak. When the initial capture correlation peak is less than or equal to the threshold, it is considered an invalid capture, and the destination node continues to search for capture in the communication channel; When the initial capture correlation peak is greater than the threshold, the capture is considered successful. The time position of the initial capture correlation peak is taken as the initial timing synchronization position of the signal frame, and the time difference between the time position of the initial capture correlation peak and the start time of the TDMA time slot is obtained. The time difference is taken as the initial signal arrival time of the source node's transmitted signal frame. The destination node sets the time tracking filter of the source node. The time tracking filter is used to track and filter the changes in signal arrival time. In the initial stage, after three successful captures, the initial signal arrival times obtained from these three captures are used to establish the state matrix and error matrix of the time tracking filter. The time tracking filter is used to calculate the predicted signal arrival time of the source node at other times in the TDMA time slot. At other times in the TDMA time slot, the destination node performs signal acquisition processing on the signal frame sent by the source node again and obtains the subsequent acquisition correlation peak; the method of obtaining the subsequent acquisition correlation peak is the same as that of obtaining the initial acquisition correlation peak. When the subsequent capture correlation peak is greater than the threshold, the time position of the subsequent capture correlation peak is taken as the final timing synchronization position of the signal frame. Based on the final timing synchronization position of the signal frame, the signal frame is processed into data pulses. The time difference between the time position of the subsequent capture correlation peak and the start time of the TDMA time slot is re-acquired to obtain the arrival time of the subsequent signal. The state matrix and error matrix of the time tracking filter are updated using the arrival time of the subsequent signal. When the subsequent captured correlation peak is less than or equal to the threshold, the predicted signal arrival time is used as the final timing synchronization position of the signal frame, and the signal frame is processed into data pulses based on the final timing synchronization position of the signal frame.

2. The auxiliary acquisition method for a frequency hopping communication system according to claim 1, characterized in that, The signal frame includes sequentially arranged synchronization acquisition pulses and data pulses, with one pulse corresponding to one frequency hopping point; The synchronization capture pulse is used for receiving signal capture and timing synchronization; The data pulses are used for data transmission.

3. The auxiliary acquisition method for a frequency hopping communication system according to claim 1, characterized in that, The result of multiplying and accumulating the local PN sequence and the received signal conjugate is based on Obtain; among which, Indicates the location of the received signal. At this point, the result of multiplying and summing the local PN sequence and the received signal (conjugate), specifically represents the initial acquisition correlation peak. This represents the signal received by the destination node after power normalization. For the index of the received signal, Let j represent the local PN sequence, and j represent the index of the local PN sequence. is the length of the PN sequence.

4. The auxiliary acquisition method for a frequency hopping communication system according to claim 3, characterized in that, When the initial acquisition correlation peak is greater than the threshold, the acquisition is considered successful. The time position of the initial acquisition correlation peak is used as the initial timing synchronization position of the signal frame. The time difference between the time position of the initial acquisition correlation peak and the start time of the TDMA time slot is obtained, and the time difference is used as the initial signal arrival time of the source node's transmitted signal frame. This includes: Threshold based on Determined; among them, For the threshold, As the first engineering constant, The length of the PN sequence; The time difference is quantified using local clock cycles.

5. The auxiliary acquisition method for a frequency hopping communication system according to claim 4, characterized in that, The destination node sets the time tracking filter of the source node. The time tracking filter is used to track and filter changes in signal arrival time. In the initial stage, after three successful acquisitions, the initial signal arrival times obtained from these three acquisitions are used to establish the state matrix and error matrix of the time tracking filter, including: The state matrix is ​​represented as follows: ;in, The state matrix, The initial signal arrival time of the first measured source node transmitted signal frame. The initial signal arrival time of the source node's transmitted signal frame measured for the second time. The initial signal arrival time of the source node's transmitted signal frame, measured for the third time. For measurement At that moment, For measurement At that moment, For measurement The moment; The error matrix is ​​represented as follows: ;in, Here is the error matrix. For the second engineering constant, The standard deviation of the initial signal arrival time measurement error; The time tracking filter uses a Kalman filter based on a uniform acceleration model to track and filter changes in the signal arrival time; State transition matrix in a Kalman filter Measurement matrix Process noise matrix The expressions are as follows: , and ;in, The time interval between two consecutive measurements of the arrival time of the initial signal. This is a transpose operation; Determine whether the arrival time of the measured subsequent signal meets the preset conditions; If the preset conditions are not met, the arrival time of subsequent signals will be discarded. If the preset conditions are not met three times in a row, the time tracking filter is reset and the initial signal arrival time of the source node's transmitted signal frames is measured three more times to re-establish the state matrix and error matrix of the time tracking filter. If the preset conditions are met, the state matrix and error matrix of the time tracking filter are updated using the subsequent signal arrival time to track and filter changes in signal arrival time.

6. The auxiliary acquisition method for a frequency hopping communication system according to claim 5, characterized in that, The preset conditions include: ;in, For the first The arrival time of subsequent signals after the source node transmits a signal frame. For the first The estimated arrival time of subsequent signals measured in the first measurement. For the measurement matrix, For the first Error matrix of subsequent signal arrival times measured in the second measurement The estimated value, For subsequent signal arrival time measurement error matrix, , This is the normalized threshold value.

7. The auxiliary acquisition method for a frequency hopping communication system according to claim 6, characterized in that, The method of using a time tracking filter to calculate the predicted signal arrival time of the source node at other times in the TDMA time slot includes: ;in, For the predicted signal arrival time of the source node at other times in the TDMA time slot, The first row of the state matrix represents the signal arrival time. The second row component in the state matrix represents the rate of change over time. The third row component in the state matrix represents the time-varying acceleration. This is the difference between other times in the TDMA time slot and the most recent update time of the time tracking filter.

8. An auxiliary acquisition device for a frequency hopping communication system, characterized in that, The device performs the assisted acquisition method for a frequency-hopping communication system as described in any one of claims 1 to 7, comprising: The signal arrival time acquisition module is used by the source node to send a signal frame to the communication channel at the start of the TDMA time slot. After the destination node receives the signal frame from the source node from the communication channel, it performs signal acquisition processing, and the result of multiplying and accumulating the local PN sequence and the conjugate of the received signal is used as the initial acquisition correlation peak. When the initial acquisition correlation peak is less than or equal to the threshold, it is considered an invalid acquisition, and the destination node continues to search for acquisition in the communication channel. When the initial acquisition correlation peak is greater than the threshold, it is considered a successful acquisition. The time position of the initial acquisition correlation peak is used as the initial timing synchronization position of the signal frame, and the time difference between the time position of the initial acquisition correlation peak and the start of the TDMA time slot is obtained. The time difference is used as the initial signal arrival time of the signal frame sent by the source node. The setting module is used by the destination node to set the time tracking filter of the source node. The time tracking filter is used to track and filter the changes in signal arrival time. In the initial stage, after three successful captures, the initial signal arrival times obtained from these three captures are used to establish the state matrix and error matrix of the time tracking filter. The time tracking filter is used to calculate the predicted signal arrival time of the source node at other times in the TDMA time slot. The data pulse processing module is used by the destination node to re-acquire the signal frame sent by the source node at other times in the TDMA time slot and obtain the subsequent acquisition correlation peak. The method for obtaining the subsequent acquisition correlation peak is the same as that for obtaining the initial acquisition correlation peak. When the subsequent acquisition correlation peak is greater than the threshold, the time position of the subsequent acquisition correlation peak is used as the final timing synchronization position of the signal frame. Data pulse processing is performed on the signal frame based on the final timing synchronization position of the signal frame. The time difference between the time position of this subsequent acquisition correlation peak and the start time of the TDMA time slot is re-obtained to obtain the subsequent signal arrival time. The state matrix and error matrix of the time tracking filter are updated using the subsequent signal arrival time. When the subsequent acquisition correlation peak is less than or equal to the threshold, the predicted signal arrival time is used as the final timing synchronization position of the signal frame. Data pulse processing is performed on the signal frame based on the final timing synchronization position of the signal frame.

9. An auxiliary acquisition server for a frequency hopping communication system, characterized in that, Including memory and processor; The memory is used to store computer-executable instructions; The processor is used to execute the computer-executable instructions to implement the auxiliary acquisition method of the frequency hopping communication system according to any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores executable instructions, which, when executed by a computer, enable the auxiliary acquisition method of the frequency hopping communication system as described in any one of claims 1-7.

Images