CN105188129A - Synchronization acquisition and tracking method based on multi-angle fractional order related coordination - Google Patents

Synchronization acquisition and tracking method based on multi-angle fractional order related coordination Download PDF

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CN105188129A
CN105188129A CN201510607613.6A CN201510607613A CN105188129A CN 105188129 A CN105188129 A CN 105188129A CN 201510607613 A CN201510607613 A CN 201510607613A CN 105188129 A CN105188129 A CN 105188129A
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CN105188129B (en
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沙学军
史军
韩墨
李卓明
白旭
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Harbin Institute of Technology Shenzhen
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    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04WWIRELESS COMMUNICATION NETWORKS
    • H04W56/00Synchronisation arrangements
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Abstract

基于多角度分数阶相关协同的同步捕获与跟踪方法,涉及无线通信领域。是为了实现同步码的快速同步捕获和精确同步跟踪。本发明基于不同旋转角度下分数阶自相关函数的峰值相同、尖锐程度不同的特点,根据系统信号参数和性能指标通过旋转角度来选择尖锐程度不同的分数阶自相关函数用于通信信号同步码的同步捕获和跟踪,即通过旋转角度选择峰值相对较宽的分数阶相关函数进行同步码的快速捕获,然后再利用旋转角度对应的峰值较尖锐的分数阶相关函数来实现同步码的精确跟踪。本发明使用于无线通信中同步码的同步捕获与跟踪。

The invention relates to a synchronous acquisition and tracking method based on multi-angle fractional correlation cooperation, which relates to the field of wireless communication. It is to realize fast synchronization acquisition and precise synchronization tracking of synchronization code. The present invention is based on the characteristics of the same peak value and different sharpness of the fractional autocorrelation function at different rotation angles, and selects the fractional autocorrelation function with different sharpness through the rotation angle according to the system signal parameters and performance indicators for the synchronization code of the communication signal Synchronous capture and tracking, that is, select a fractional correlation function with a relatively wide peak value through the rotation angle to quickly capture the synchronization code, and then use a fractional correlation function with a sharper peak value corresponding to the rotation angle to achieve precise tracking of the synchronization code. The invention is used for synchronous capture and tracking of synchronous codes in wireless communication.

Description

基于多角度分数阶相关协同的同步捕获与跟踪方法Synchronous Acquisition and Tracking Method Based on Multi-angle Fractional Correlation Synergy

技术领域technical field

本发明涉及无线通信领域。The invention relates to the field of wireless communication.

背景技术Background technique

同步是移动通信的关键技术之一,其目的是实现收发两端的信号在时间上步调一致,它直接影响着通信的质量。因此,如何实现稳定、可靠、准确的同步是通信系统中首要解决的问题。在数字通信中,信息流往往是以一个或几个码元组成一帧来传送。接收端必须知道这些帧的起止时刻,否则无法正确恢复信息。同步的目的就是给出帧的开头和结尾的标记,在接收端根据这些标记来设别出这一帧。这些标记往往用一些特殊的码组来表示,例如巴克码、PN序列、Zadoff-Chu序列等。Synchronization is one of the key technologies of mobile communication. Its purpose is to realize the time synchronization of the signals at both ends of the transceiver, which directly affects the quality of communication. Therefore, how to realize stable, reliable and accurate synchronization is the primary problem to be solved in the communication system. In digital communication, the information flow is often transmitted in a frame composed of one or several symbols. The receiving end must know the start and end moments of these frames, otherwise the information cannot be recovered correctly. The purpose of synchronization is to mark the beginning and end of the frame, and the frame is identified at the receiving end according to these marks. These marks are often represented by some special code groups, such as Barker codes, PN sequences, Zadoff-Chu sequences, etc.

现有同步方法通常基于传统相关运算,实际工程应用中通常是利用设定检测门限的方法来寻找相关函数的峰值以获取同步信息。为了提高检测概率和降低虚警概率,往往要求同步信号的相关函数具有精锐的特性。然而,在检测过程中由于信道的影响,计算得到的同步信号的相关函数并不是如预期的是一个尖锐的峰值,所以很难准确找到同步。此外,若欲提高同步精度需要提高信号的采样频率,这样会大大增加系统的计算开销。Existing synchronization methods are usually based on traditional correlation calculations. In practical engineering applications, the method of setting detection thresholds is usually used to find the peak of the correlation function to obtain synchronization information. In order to improve the detection probability and reduce the false alarm probability, it is often required that the correlation function of the synchronous signal has a sharp characteristic. However, due to the influence of the channel during the detection process, the calculated correlation function of the synchronization signal is not a sharp peak as expected, so it is difficult to find the synchronization accurately. In addition, if the synchronization accuracy is to be improved, the sampling frequency of the signal needs to be increased, which will greatly increase the computational overhead of the system.

发明内容Contents of the invention

本发明是为了实现同步码的快速同步捕获和精确同步跟踪,从而提供一种基于多角度分数阶相关协同的同步捕获与跟踪方法。The present invention aims to realize fast synchronization capture and precise synchronization tracking of synchronization codes, thereby providing a synchronization capture and tracking method based on multi-angle fractional correlation cooperation.

基于多角度分数阶相关协同的同步捕获与跟踪方法,它由以下步骤实现:A synchronous acquisition and tracking method based on multi-angle fractional correlation synergy, which is realized by the following steps:

步骤一、接收端确定同步捕获参数,所述捕获参数包括分数阶相关器的旋转角度αacq、比较器的检测门限Vth和相位搜索控制模块输出同步码相位的变化量△τacqStep 1. The receiving end determines the synchronization acquisition parameters, which include the rotation angle α acq of the fractional order correlator, the detection threshold V th of the comparator, and the variation Δτ acq of the phase of the synchronization code output by the phase search control module;

同时,接收端确定同步跟踪参数,所述同步跟踪参数包括分数阶相关器的旋转角度αtra、相位搜索控制模块输出同步码相位的变化量△τtra和本地同步码的超前和滞后量τtra,且2τtra≤Tc;Tc为码元宽度;At the same time, the receiving end determines the synchronization tracking parameters, which include the rotation angle α tra of the fractional order correlator, the change amount Δτ tra of the synchronization code phase output by the phase search control module, and the leading and lagging amounts τ tra of the local synchronization code , and 2τ tra ≤ T c ; T c is the symbol width;

同步捕获过程:Synchronous capture process:

步骤二、采用捕获参数控制模块根据步骤一中所确定捕获参数,将接收信号r(t)与本地同步码通过分数阶相关器,计算出两者在旋转角度为αacq的分数阶相关函数峰值VacqStep 2: Use the capture parameter control module to pass the received signal r(t) and the local synchronization code through the fractional order correlator according to the capture parameters determined in step 1, and calculate the peak value of the fractional order correlation function between the two at a rotation angle of α acq Vacq ;

步骤三、将步骤二中分数阶相关器的输出值Vacq送给门限比较器,并判断分数阶相关器的输出值Vacq是否小于检测门限VthStep 3, sending the output value V acq of the fractional order correlator in step 2 to the threshold comparator, and judging whether the output value V acq of the fractional order correlator is less than the detection threshold V th ;

当Vacq小于检测门限Vth时,则本地同步码的相位和接收到的同步码的相位不同,门限比较器输出一个信号给同步码相位搜索控制模块,在相位搜索控制模块的控制下,本地同步码产生器改变输出同步码的相位状态,同步码相位的变化量为△τacq;若改变后的本地同步码的相位状态仍与接收同步码的相位状态不同,门限比较器继续输出一个信号给相位搜索控制模块,使相位搜索控制模块再一次改变本地参考同步码的相位;When V acq is less than the detection threshold V th , the phase of the local synchronous code is different from the phase of the received synchronous code, and the threshold comparator outputs a signal to the synchronous code phase search control module. Under the control of the phase search control module, the local The synchronous code generator changes the phase state of the output synchronous code, and the variation of the synchronous code phase is △τ acq ; if the changed phase state of the local synchronous code is still different from the phase state of the received synchronous code, the threshold comparator continues to output a signal Give the phase search control module to make the phase search control module change the phase of the local reference synchronization code again;

直至本地参考同步码的相位状态趋近于接收同步码的相位状态时,分数阶相关器的输出Vacq超过检测门限Vth,即完成同步码的同步捕获,转入同步跟踪过程;Until the phase state of the local reference synchronous code approaches the phase state of the received synchronous code, the output V acq of the fractional order correlator exceeds the detection threshold V th , that is, the synchronous capture of the synchronous code is completed, and the synchronous tracking process is transferred to;

同步跟踪过程:Synchronous tracking process:

步骤四、将接收信号分成三路,跟踪参数控制模块根据步骤一中所确定的跟踪参数,将其中两路信号分别与本地参考同步码的超前码c(t-τ′dtra)和滞后码c(t-τ′dtra)进行旋转角度为αtra的分数阶相关运算;Step 4, the received signal is divided into three paths, and the tracking parameter control module, according to the tracking parameters determined in step 1, combines the signals of two paths with the leading code c(t-τ′ dtra ) and the local reference synchronization code respectively Lag code c( t -τ′d-τ tra ) carries out the fractional order correlation operation whose rotation angle is α tra ;

将另一路信号与本地参考同步码c(t-τ′d)进行旋转角度为αtra的分数阶相关运算,其中τ′d是对接收同步码未知时延量τd的估计值,经包络检波后送给判决器用于信息数据恢复;Carry out the fractional order correlation operation with the rotation angle of α tra between the other signal and the local reference synchronization code c(t-τ′ d ), where τ′ d is the estimated value of the unknown time delay τ d of receiving the synchronization code. After network detection, it is sent to the decision device for information data recovery;

步骤五、将步骤四中超前和滞后相关支路的输出经包络检波送给加法器,产生误差信号;并将该误差信号经过一个低通滤波器进行滤波,以平滑噪声对同步跟踪的影响;Step 5. Send the output of the leading and lagging related branches in step 4 to the adder through envelope detection to generate an error signal; and filter the error signal through a low-pass filter to smooth the influence of noise on synchronous tracking ;

并判断该误差信号是否为正,如判断结果为是,则执行步骤五一;如果判断结果为否,则执行步骤五二;And judge whether the error signal is positive, if the judgment result is yes, then execute step 51; if the judgment result is no, then execute step 52;

步骤五一、则本地同步码的超前码的相位状态比滞后码的相位状态更趋近接收同步码的相位状态,则在相位搜索控制模块的控制下,使本地同步码产生器输出同步码的相位状态进行超前调整,相位调整的变化量为△τtraStep 51, then the phase state of the leading code of the local synchronizing code is closer to the phase state of receiving the synchronizing code than the phase state of the lagging code, then under the control of the phase search control module, the local synchronizing code generator is output to the phase state of the synchronizing code The phase state is adjusted in advance, and the change amount of the phase adjustment is △τ tra ;

若调整后误差信号仍为正,相位搜索控制模块再一次超前调整本地参考同步码的相位,直到本地参考同步码的相位状态趋近接收同步码的相位状态,则实现了同步码的同步跟踪;If the adjusted error signal is still positive, the phase search control module adjusts the phase of the local reference synchronization code in advance again until the phase state of the local reference synchronization code approaches the phase state of the received synchronization code, then the synchronization tracking of the synchronization code is realized;

步骤五二、则本地同步码的滞后码的相位状态比超前码的相位状态更接近接收同步码的相位状态,相位搜索控制模块将滞后调整本地参考同步码的相位,直到本地参考同步码的相位状态趋近接收同步码的相位状态,则实现了同步码的同步跟踪。Step 52, then the phase state of the delayed code of the local synchronous code is closer to the phase state of the received synchronous code than the phase state of the advanced code, and the phase search control module will adjust the phase of the local reference synchronous code laggingly until the phase of the local reference synchronous code The state is close to the phase state of receiving the synchronization code, and the synchronization tracking of the synchronization code is realized.

本发明基于不同旋转角度下分数阶自相关函数的峰值相同、尖锐程度不同的特点,根据系统信号参数和性能指标通过旋转角度来选择尖锐程度不同的分数阶自相关函数用于通信信号同步码的同步捕获和跟踪,即通过旋转角度选择峰值相对较宽的分数阶相关函数进行同步码的快速捕获,然后再利用旋转角度对应的峰值较尖锐的分数阶相关函数来实现同步码的精确跟踪。与传统基于经典相关的同步方法相比,该方法时钟抖动减小,对定位等信号处理有贡献。此外,对系统误码性能有一定的改善。The present invention is based on the characteristics of the same peak value and different sharpness of the fractional autocorrelation function at different rotation angles, and selects the fractional autocorrelation function with different sharpness through the rotation angle according to the system signal parameters and performance indicators for the synchronization code of the communication signal Synchronous capture and tracking, that is, select a fractional correlation function with a relatively wide peak value through the rotation angle to quickly capture the synchronization code, and then use a fractional correlation function with a sharper peak value corresponding to the rotation angle to achieve precise tracking of the synchronization code. Compared with the traditional synchronization method based on classical correlation, this method reduces clock jitter and contributes to signal processing such as positioning. In addition, the bit error performance of the system is improved to a certain extent.

附图说明Description of drawings

图1是不同旋转角度下矩形脉冲信号的分数阶自相关函数仿真示意图;Figure 1 is a schematic diagram of the simulation of the fractional autocorrelation function of the rectangular pulse signal at different rotation angles;

图2是不同旋转角度下巴克码的分数阶自相关函数仿真示意图;Fig. 2 is a schematic diagram of the simulation of the fractional autocorrelation function of the Barker code under different rotation angles;

图3是在k=-1,ω0=4的情况下,不同旋转角度下线性调频信号的分数阶自相关函数仿真示意图;Fig. 3 is in the case of k=-1, ω 0 =4, the fractional order autocorrelation function simulation schematic diagram of chirp signal under different rotation angles;

图4是在q=4,NZC=7,l=0的情况下,不同旋转角度下Zadoff-Chu序列的分数阶自相关函数仿真示意图;Fig. 4 is in the case of q=4, N ZC =7, l=0, the fractional order autocorrelation function simulation schematic diagram of Zadoff-Chu sequence under different rotation angles;

图5是同步捕获系统原理示意图;Fig. 5 is a schematic diagram of the principle of the synchronous capture system;

图6是同步跟踪系统原理示意图;Fig. 6 is a schematic diagram of the principle of the synchronous tracking system;

图7是基于经典相关和分数阶相关同步方法的误码率比较仿真示意图;Fig. 7 is a schematic diagram of bit error rate comparison simulation based on classical correlation and fractional order correlation synchronization methods;

图8是基于分数阶相关和经典相关的同步抖动比较仿真示意图;Fig. 8 is a schematic diagram of a comparison simulation of synchronous jitter based on fractional order correlation and classical correlation;

图9中基于分数阶相关和经典相关的同步跟踪抖动的方差比较仿真示意图;Schematic diagram of variance comparison simulation of synchronous tracking jitter based on fractional order correlation and classical correlation in Fig. 9;

具体实施方式Detailed ways

具体实施方式一、基于多角度分数阶相关协同的同步捕获与跟踪方法,它由以下步骤实现:The specific embodiment one, based on the multi-angle fractional order correlation synchronous acquisition and tracking method, it is realized by the following steps:

步骤一、接收端,根据系统性能指标及所选同步码的参数确定同步捕获过程中分数阶相关器的旋转角度αacq、比较器的检测门限Vth和相位搜索控制模块输出同步码相位的变化量△τacq;同时,确定同步跟踪过程中分数阶相关器的旋转角度αtra、相位搜索控制模块输出同步码相位的变化量△τtra和本地同步码的超前和滞后量τtra,且2τtra≤TcStep 1. The receiving end determines the rotation angle α acq of the fractional correlator, the detection threshold V th of the comparator, and the phase change of the synchronization code output by the phase search control module during the synchronization acquisition process according to the system performance index and the parameters of the selected synchronization code. Δτ acq ; at the same time, determine the rotation angle α tra of the fractional correlator in the process of synchronous tracking, the change amount Δτ tra of the output synchronization code phase of the phase search control module, and the lead and lag τ tra of the local synchronization code, and 2τ tra ≤ T c .

步骤二、在捕获参数控制模块根据步骤一中所确定捕获参数的作用下,将接收信号r(t)与本地同步码通过分数阶相关器,计算出它们角度为αacq的分数阶相关函数峰值VacqStep 2. Under the action of the capture parameter control module determined in step 1, the received signal r(t) and the local synchronization code are passed through the fractional order correlator to calculate the peak value of the fractional order correlation function whose angle is α acq V acq .

步骤三、将步骤二中分数阶相关器的输出Vacq送给门限比较器。当Vacq小于检测门限Vth时,说明本地同步码的相位和接收到的同步码的相位不同,门限比较器输出一信号给同步码相位搜索控制模块,在相位搜索控制模块的作用下,本地同步码产生器改变输出同步码的相位状态,相位的变化量为△τacq。若改变后的本地同步码的相位状态仍与接收同步码的相位状态不同,门限比较器继续输出一信号给相位搜索控制模块,使它再一次改变本地参考同步码的相位,直到本地参考同步码的相位状态很接近接收同步码的相位状态时,分数阶相关器的输出Vacq超过检测门限Vth,即认为实现了同步码的同步捕获,从而转入同步跟踪。Step 3: Send the output V acq of the fractional-order correlator in step 2 to the threshold comparator. When V acq is less than the detection threshold V th , it means that the phase of the local synchronous code is different from the phase of the received synchronous code, and the threshold comparator outputs a signal to the synchronous code phase search control module. Under the action of the phase search control module, the local The synchronous code generator changes the phase state of the output synchronous code, and the variation of the phase is Δτ acq . If the phase state of the changed local synchronous code is still different from the phase state of the received synchronous code, the threshold comparator continues to output a signal to the phase search control module to make it change the phase of the local reference synchronous code again until the local reference synchronous code When the phase state of the phase state is very close to the phase state of the received synchronous code, the output V acq of the fractional order correlator exceeds the detection threshold V th , which means that the synchronous capture of the synchronous code has been realized, and then it turns into synchronous tracking.

步骤四、待步骤三完成同步捕获后,将接收信号分成三路,在跟踪参数控制模块根据步骤一中所确定跟踪参数的作用下,其中两路分别与本地参考同步码的超前码c(t-τ′dtra)和滞后码c(t-τ′dtra)进行αtra角度的分数阶相关运算;另一路与本地参考同步码c(t-τ′d)进行角度为αtra的分数阶相关运算,其中τ′d是对接收同步码未知时延量τd的估计,经包络检波后送给判决器用于信息数据恢复。Step 4, after step 3 completes the synchronous capture, the received signal is divided into three paths, and under the action of the tracking parameter determined in the step 1 by the tracking parameter control module, two of them are respectively with the leading code c(t of the local reference synchronization code -τ′ dtra ) and the lagging code c(t-τ′ dtra ) carry out the fractional correlation operation of the α tra angle; the other way and the local reference synchronous code c(t-τ′ d ) carry out an angle of The fractional order correlation operation of α tra , where τ′ d is the estimate of the unknown time delay τ d of the received synchronization code, which is sent to the decision device for information data recovery after envelope detection.

步骤五、将步骤四中超前和滞后相关支路的输出经包络检波送给加法器,产生误差信号。将误差信号经过一个低通滤波器以平滑噪声对同步跟踪的影响。若误差信号为正,说明本地同步码的超前码的相位状态比滞后码的相位状态更接近接收同步码的相位状态,于是在相位搜索控制模块的作用下,本地同步码产生器将输出同步码的相位状态进行超前调整,相位调整的变化量为△τtra。若调整后误差信号仍为正,相位搜索控制模块再一次超前调整本地参考同步码的相位,直到本地参考同步码的相位状态很接近接收同步码的相位状态。相反,若误差信号为负,说明本地同步码的滞后码的相位状态比超前码的相位状态更接近接收同步码的相位状态,相位搜索控制模块将滞后调整本地参考同步码的相位,直到本地参考同步码的相位状态很接近接收同步码的相位状态,即认为实现了同步码的同步跟踪。Step 5: Send the output of the leading and lagging related branches in step 4 to the adder through envelope detection to generate an error signal. Pass the error signal through a low-pass filter to smooth out the effect of noise on synchronous tracking. If the error signal is positive, it means that the phase state of the leading code of the local synchronization code is closer to the phase state of the receiving synchronization code than the phase state of the lagging code, so under the action of the phase search control module, the local synchronization code generator will output the synchronization code The phase state of the phase is adjusted in advance, and the amount of change of the phase adjustment is △τ tra . If the error signal is still positive after adjustment, the phase search control module adjusts the phase of the local reference synchronization code in advance again until the phase state of the local reference synchronization code is very close to the phase state of the received synchronization code. On the contrary, if the error signal is negative, it means that the phase state of the lagging code of the local synchronization code is closer to the phase state of the receiving synchronization code than the phase state of the leading code, and the phase search control module will adjust the phase of the local reference synchronization code laggingly until the local reference The phase state of the synchronization code is very close to the phase state of the received synchronization code, which means that the synchronization tracking of the synchronization code is realized.

具体实施方式二、本具体实施方式是具体实施方式一所述的基于多角度分数阶相关协同的同步捕获与跟踪方法的进一步限定,同步捕获过程中,接收信号与本地同步码进行分数阶相关运算时,分数阶相关输出脉冲的宽度随旋转角度的变化而变化。Specific embodiment 2. This specific embodiment is a further limitation of the synchronous acquisition and tracking method based on multi-angle fractional correlation cooperation described in specific embodiment 1. During the synchronous acquisition process, the received signal and the local synchronization code are subjected to fractional correlation operations When , the width of the fractional correlation output pulse varies with the rotation angle.

具体实施方式三、本具体实施方式是具体实施方式一所述的基于多角度分数阶相关协同的同步捕获与跟踪方法的进一步限定,同步跟踪过程中,接收信号与本地同步码进行分数阶相关运算时,分数阶相关输出脉冲的宽度随旋转角度的变化而变化。Specific Embodiment 3. This specific embodiment is a further limitation of the synchronous acquisition and tracking method based on multi-angle fractional correlation coordination described in specific embodiment 1. During the synchronous tracking process, the received signal and the local synchronization code are subjected to fractional correlation operations When , the width of the fractional correlation output pulse varies with the rotation angle.

具体实施方式四、本具体实施方式是具体实施方式一所述的基于多角度分数阶相关协同的同步捕获与跟踪方法的进一步限定,同步捕获过程与同步跟踪过程,分数阶相关运算的旋转角度不同。Embodiment 4. This embodiment is a further limitation of the synchronous acquisition and tracking method based on multi-angle fractional correlation collaboration described in Embodiment 1. The rotation angles of the fractional correlation operations are different in the synchronous acquisition process and the synchronous tracking process. .

具体实施方式五、本具体实施方式是具体实施方式二所述的基于多角度分数阶相关协同的同步捕获与跟踪方法的进一步限定,分数阶相关运算的旋转角度是根据系统信号参数与性能指标计算得到。Specific Embodiment Five. This specific embodiment is a further limitation of the synchronous acquisition and tracking method based on multi-angle fractional-order correlation cooperation described in specific embodiment 2. The rotation angle of the fractional-order correlation operation is calculated according to the system signal parameters and performance indicators get.

具体实施方式六、本具体实施方式是具体实施方式三所述的基于多角度分数阶相关协同的同步捕获与跟踪方法的进一步限定,分数阶相关运算的旋转角度是根据系统信号参数与性能指标计算得到。Specific Embodiment 6. This specific embodiment is a further limitation of the synchronous acquisition and tracking method based on multi-angle fractional-order correlation cooperation described in specific embodiment 3. The rotation angle of the fractional-order correlation operation is calculated according to the system signal parameters and performance indicators get.

相关函数与傅里叶变换定义的频率功率谱密度互为傅里叶变换对,它是传统信号处理中描述信号时域特征的一种重要方法。近年来,随着信号处理理论研究的不断深入和应用范围的不断扩展,在传统傅里叶变换基础上涌现出一系列新型信号处理技术,极大地丰富了传统信号处理方法和技术的内涵与外延。其中,分数傅里叶变换作为傅里叶变换的广义形式,它突破了傅里叶变换只能在单一的时域或频域范围内进行信号分析的局限,能够在介于时域和频域之间的分数域分析和处理信号。与傅里叶变换相比,分数傅里叶变换多了一个旋转角度的自由参数,随着角度从0连续增长到π/2,它能够展示出信号从时域逐渐变化到频域的所有特征。相应地,分数傅里叶变换下的相关函数(通常称为分数阶相关函数)也呈现出与传统相关函数不同的表达形式,具有一个旋转角度的自由参数,它能够展示出信号在不同旋转角度下的相关特性。两函数x(t)和y(t)的分数阶互相关函数的定义为The correlation function and the frequency power spectral density defined by Fourier transform are a Fourier transform pair, which is an important method to describe the time-domain characteristics of signals in traditional signal processing. In recent years, with the continuous deepening of signal processing theory research and the continuous expansion of application scope, a series of new signal processing technologies have emerged on the basis of traditional Fourier transform, which has greatly enriched the connotation and extension of traditional signal processing methods and technologies. . Among them, the fractional Fourier transform is a generalized form of the Fourier transform, which breaks through the limitation that the Fourier transform can only perform signal analysis in a single time domain or frequency domain. between fractional domain analysis and processing signals. Compared with the Fourier transform, the fractional Fourier transform has one more free parameter of the rotation angle. As the angle increases continuously from 0 to π/2, it can show all the characteristics of the signal gradually changing from the time domain to the frequency domain. . Correspondingly, the correlation function under the fractional Fourier transform (usually called the fractional order correlation function) also presents a different form of expression from the traditional correlation function, with a free parameter of the rotation angle, which can show the signal at different rotation angles related features below. The fractional cross-correlation function of two functions x(t) and y(t) is defined as

RR xx ythe y αα (( ττ )) == ee -- jτjτ 22 cotcot αα ∫∫ -- ∞∞ ++ ∞∞ xx (( tt )) ythe y ** (( tt -- ττ )) ee jj tt ττ cotcot αα dd tt -- -- -- (( 11 ))

式中,α对应于分数傅里叶变换的旋转角度。特别地,当x(t)=y(t)时,便可得到分数阶自相关函数的定义,即where α corresponds to the rotation angle of the fractional Fourier transform. In particular, when x(t)=y(t), the definition of the fractional autocorrelation function can be obtained, namely

RR xx xx αα (( ττ )) == ee -- jτjτ 22 cotcot αα ∫∫ -- ∞∞ ++ ∞∞ xx (( tt )) xx ** (( tt -- ττ )) ee jj tt ττ cotcot αα dd tt -- -- -- (( 22 ))

当角度α=π/2时,分数阶互(自)相关函数便退化为常规互(自)相关函数,即When the angle α=π/2, the fractional-order mutual (auto)correlation function degenerates into a conventional mutual (auto)correlation function, namely

RR xx ythe y (( ττ )) == ∫∫ -- ∞∞ ++ ∞∞ xx (( tt )) ythe y ** (( tt -- ττ )) dd tt -- -- -- (( 33 ))

RR xx xx (( ττ )) == ∫∫ -- ∞∞ ++ ∞∞ xx (( tt )) xx ** (( tt -- ττ )) dd tt -- -- -- (( 44 ))

因此,常规相关函数可以看成分数阶相关函数在角度α=π/2时的特例。Therefore, the conventional correlation function can be regarded as a special case of the fractional correlation function at the angle α=π/2.

从信号设计的角度看,同步码主要可以归为二进制码和恒幅零自相关序列两类。例如巴克码、PN码都属于二进制码,可以看成是矩形脉冲的叠加;而恒幅零自相关序列则主要有Zadoff-Chu序列,Chirp-like序列和Frank序列等,它们实质上是满足一定参数约束条件的线性调频序列。基于此,为得到一般化结果,将信号建模为:From the point of view of signal design, synchronization codes can be classified into binary codes and constant-amplitude zero-autocorrelation sequences. For example, Barker codes and PN codes belong to binary codes, which can be regarded as the superposition of rectangular pulses; while constant-amplitude zero-autocorrelation sequences mainly include Zadoff-Chu sequences, Chirp-like sequences and Frank sequences, etc., which essentially satisfy a certain Chirp sequence for parameter constraints. Based on this, in order to obtain generalized results, the signal is modeled as:

xx (( tt )) == 11 ττ 00 rr ee cc tt (( tt ττ 00 )) ee (( jj // 22 )) ktkt 22 ++ jωjω 00 tt -- -- -- (( 55 ))

式中,τ0>0,k和ω0为任意常数,rect(t/τ0)表示矩形脉冲信号,其表达式为where τ 0 >0, k and ω 0 are arbitrary constants, rect(t/τ 0 ) represents a rectangular pulse signal, and its expression is

根据前述分数阶自相关函数的定义,可得信号x(t)的分数阶自相关函数为According to the definition of the aforementioned fractional autocorrelation function, the fractional autocorrelation function of the signal x(t) can be obtained as

RR xx xx αα (( ττ )) == ee -- (( jj // 22 )) ττ 22 cotcot αα ++ jωjω 00 ττ (( 11 -- || ττ || ττ 00 )) sinsin cc [[ ττ (( kk ++ cotcot αα )) ττ 00 22 ππ (( 11 -- || ττ || ττ 00 )) ]] -- -- -- (( 77 ))

式中,|τ|≤τ0,sinc(·)=sinπ(·)/π(·)。In the formula, |τ|≤τ 0 , sinc(·)=sinπ(·)/π(·).

当α=-arccot(k)+nπ(n为整数)时,信号x(t)的自相关函数可以化简为When α=-arccot(k)+nπ (n is an integer), the autocorrelation function of signal x(t) can be simplified as

RR xx xx αα (( ττ )) == (( 11 -- || ττ || ττ 00 )) ee -- (( jj // 22 )) ττ 22 cotcot αα ++ jωjω 00 ττ ,, || ττ || ≤≤ ττ 00 -- -- -- (( 88 ))

可以看出,在此条件下信号x(t)的自相关函数是一个初始频率为ω0,调频斜率为-cotα的线性调频信号,其包络调制函数是宽度为2τ0的三角脉冲信号,因此x(t)的自相关函数的宽度为2τ0It can be seen that under this condition, the autocorrelation function of the signal x(t) is a linear frequency modulation signal with an initial frequency of ω 0 and a frequency modulation slope of -cotα, and its envelope modulation function is a triangular pulse signal with a width of 2τ 0 , Therefore the width of the autocorrelation function of x(t) is 2τ 0 .

当α≠-arccot(k)+nπ时,信号x(t)的自相关函数仍是一个初始频率为ω0,调频斜率为-cotα的线性调频信号,但其包络调制函数为When α≠-arccot(k)+nπ, the autocorrelation function of the signal x(t) is still a chirp signal with an initial frequency of ω 0 and a frequency modulation slope of -cotα, but its envelope modulation function is

(( 11 -- || ττ || ττ 00 )) sinsin cc [[ ττ (( kk ++ cotcot αα )) ττ 00 22 ππ (( 11 -- || ττ || ττ 00 )) ]] -- -- -- (( 99 ))

当|τ|<<τ0时,包络近似为sinc函数,即When |τ|<<τ 0 , the envelope is approximately a sinc function, namely

sinsin cc &lsqb;&lsqb; &tau;&tau; (( kk ++ cotcot &alpha;&alpha; )) &tau;&tau; 00 22 &pi;&pi; &rsqb;&rsqb; -- -- -- (( 1010 ))

当x=π/2时,sinc[x/π]=2/π,接近-4dB。于是,令τ′(k+cotα)τ0/2=π/2,得到τ′=π/(k+cotα)τ0,即信号x(t)的自相关函数-4dB时宽为2|τ′|=2π/(|k+cotα|τ0)<<τ0When x=π/2, sinc[x/π]=2/π, close to -4dB. Then, let τ′(k+cotα)τ 0 /2=π/2, and get τ′=π/(k+cotα)τ 0 , that is, the autocorrelation function of signal x(t) has a -4dB duration of 2| τ′|=2π/(|k+cotα|τ 0 )<<τ 0 .

若k=ω0=0,信号x(t)为矩形脉冲信号;当α=π/2时,它的分数阶自相关函数是初始频率为0,调频斜率为-cotα、包络调制函数为三角脉冲的线性调频信号,时宽为2τ0;而在其他α≠π/2角度下,包络调制函数则变为sinc函数,此时-4dB时宽为2π/(|cotα|τ0)且在角度α主值区间(0,π/2)上随着α增大而增大,而在[π/2,π)上随着α增大而减小,如图1所示。由于二进制码可以看成是矩形脉冲的叠加,因此其分数阶自相关函数也具备这一特性,如图2所示。此外,若k≠0,信号x(t)为线性调频信号,其分数阶自相关函数在α=-arccot(k)+nπ(n为整数)时是初始频率为ω0,调频斜率为-cotα,包络调制函数为三角脉冲的线性调频信号,时宽为2τ0;而在其他α≠-arccot(k)+nπ角度下,包络调制函数变为sinc函数,-4dB时宽为2π/(|k+cotα|τ0)且在角度α主值区间(0,-arccot(k))上随着α增大而增大,而在[-arccot(k),π)上随着α增大而减小,如图3所示。由于恒幅零自相关序列可以看成是满足特定参数条件的离散线性调频信号,因此它的分数阶自相关函数也具有这样的性质,如图4所示。If k=ω 0 =0, the signal x(t) is a rectangular pulse signal; when α=π/2, its fractional autocorrelation function is that the initial frequency is 0, the frequency modulation slope is -cotα, and the envelope modulation function is The linear frequency modulation signal of the triangular pulse has a duration of 2τ 0 ; while at other angles of α≠π/2, the envelope modulation function becomes a sinc function, and the duration of -4dB is 2π/(|cotα|τ 0 ) And it increases with the increase of α in the main value range of angle α (0, π/2), and decreases with the increase of α in [π/2, π), as shown in Fig. 1 . Since the binary code can be regarded as a superposition of rectangular pulses, its fractional autocorrelation function also has this characteristic, as shown in Figure 2. In addition, if k≠0, the signal x(t) is a linear frequency modulation signal, and its fractional autocorrelation function is when α=-arccot(k)+nπ (n is an integer), the initial frequency is ω 0 , and the frequency modulation slope is - cotα, the envelope modulation function is a linear FM signal of a triangular pulse, and the time width is 2τ 0 ; while at other α≠-arccot(k)+nπ angles, the envelope modulation function becomes a sinc function, and the -4dB time width is 2π /(|k+cotα|τ 0 ) and increases with the increase of α in the main value interval of angle α (0,-arccot(k)), while in [-arccot(k),π) with α increases and decreases, as shown in Figure 3. Since the constant-amplitude zero-autocorrelation sequence can be regarded as a discrete chirp signal satisfying certain parameter conditions, its fractional-order autocorrelation function also has such properties, as shown in Figure 4.

综上分析,一个信号的不同旋转角度的分数阶自相关函数的峰值相同,但峰值之外的相关值衰减速度不同,即分数阶自相关函数的尖锐程度不同。基于这一特点,根据系统信号参数和性能指标通过选择适当的旋转角度可以先基于相关峰相对较宽的分数阶相关函数实现快速同步捕获,然后再利用相关峰较尖锐的分数阶相关函数实现精确同步跟踪。In summary, the peak value of the fractional autocorrelation function of different rotation angles of a signal is the same, but the decay speed of the correlation value outside the peak is different, that is, the sharpness of the fractional autocorrelation function is different. Based on this feature, by selecting an appropriate rotation angle according to the system signal parameters and performance indicators, fast synchronization can be achieved based on the fractional-order correlation function with a relatively wide correlation peak, and then the accurate Sync tracking.

同步捕获的目的是使本地同步码与接收信号中同步码的相位之差小于Tc/2n,其中Tc为码元宽度,n为正整数且其具体取值视系统检测精度来确定。根据扩频通信理论可知,滑动相关检测是一种最简单、最实用的同步捕获方法。在基于常规相关运算的滑动相关检测中,为了减小噪声,提高检测概率,受系统带宽的限制相关后的带宽要窄;从缩短捕获时间来看,应加快滑动速度,即加大收发时钟频率差,又要求相关后的带宽要宽,这两者相互矛盾。考虑到不同旋转角度分数阶自相关函数具有峰值相同、尖锐程度不同的特点,可以通过旋转角度αacq来控制分数阶相关器输出相关脉冲的宽度。也就是说,当滑动快时,可以选择合适的角度αacq以使得相关后的带宽满足系统要求。鉴于此,图5给出了基于分数阶相关运算的滑动相关同步捕获原理框图。The purpose of synchronous acquisition is to make the phase difference between the local synchronous code and the synchronous code in the received signal less than T c /2 n , where T c is the symbol width, n is a positive integer and its specific value depends on the detection accuracy of the system. According to spread spectrum communication theory, sliding correlation detection is the simplest and most practical synchronization acquisition method. In sliding correlation detection based on conventional correlation operations, in order to reduce noise and increase detection probability, the bandwidth after correlation is limited by the system bandwidth; from the perspective of shortening the capture time, the sliding speed should be accelerated, that is, the frequency of the transceiver clock should be increased Poor, and requires a wider bandwidth after correlation, the two contradict each other. Considering that the fractional autocorrelation function with different rotation angles has the same peak value but different sharpness, the width of the correlation pulse output by the fractional order correlator can be controlled by the rotation angle α acq . That is to say, when the sliding is fast, an appropriate angle α acq can be selected so that the correlated bandwidth meets the system requirements. In view of this, Fig. 5 shows the block diagram of sliding correlation synchronous capture based on fractional order correlation operation.

一旦接收机实现了同步捕获后,本地参考同步码必须尽可能精确地跟踪接收信号的变化,使本地同步码的相位与接收同步码相位的差别尽可能的小,以期分数阶相关器获得最大的相关输出,这一过程称为同步跟踪。设观测信号模型为r(t)=Ac(t;τd)+n(t),0≤t≤T,其中n(t)为零均值,功率谱密度为N0/2的高斯白噪声;c(t;τd)表示接收信号中归一化的同步码信号分量,其中τd为待估计的未知时延,A为信号幅度。先讨论无噪声干扰及信道时延情况,以期从中得到某些启发。根据分数傅里叶变换域的信号检测理论,分数域匹配滤波器对同步码信号的输出co(t)是c(t)的分数阶自相关函数,且在t=T时达到最大值。也就是说,分数域匹配滤波器输出达到最大的抽样时刻t=T,即在分数阶相关函数的峰值点。在噪声背景下,对相关峰值的辨识一般比较困难。假定不在峰值点进行抽样,而在t=T-τtra时早抽样,在t=T+τtra时迟抽样,这两个抽样点间的延时量2τtra≤Tc。从统计平均的意义上,早抽样的绝对值和迟抽样的绝对值比峰值样值小。因为分数阶自相关函数相对最佳抽样时刻t=T是偶函数,所以在t=T-τtra和t=T+τtra时刻的分数阶自相关函数的绝对值相等。在此条件下,适当的抽样时刻是在t=T-τtra和t=T+τtra之间的中点。基于此,图6给出了同步跟踪的原理框图。Once the receiver achieves synchronization acquisition, the local reference synchronization code must track the changes of the received signal as accurately as possible, so that the difference between the phase of the local synchronization code and the phase of the received synchronization code is as small as possible, so that the fractional order correlator can obtain the maximum Correlation output, this process is called synchronous tracking. Suppose the observed signal model is r(t)=Ac(t;τ d )+n(t), 0≤t≤T, where n(t) is Gaussian white noise with zero mean and power spectral density of N 0 /2 ; c(t; τ d ) represents the normalized synchronous code signal component in the received signal, where τ d is the unknown time delay to be estimated, and A is the signal amplitude. Discuss the noise-free interference and channel delay first, in order to get some inspiration from it. According to the signal detection theory in the fractional Fourier transform domain, the output c o (t) of the fractional domain matched filter to the synchronous code signal is a fractional autocorrelation function of c(t), and reaches the maximum value when t=T. That is to say, the sampling time t=T at which the output of the fractional-domain matched filter reaches the maximum, that is, at the peak point of the fractional-order correlation function. In the background of noise, it is generally difficult to identify the correlation peak. Assuming that sampling is not performed at the peak point, early sampling is performed when t=T-τ tra , and late sampling is performed when t=T+τ tra , the delay between these two sampling points is 2τ tra ≤ T c . In the sense of statistical average, the absolute value of the early sample and the absolute value of the late sample are smaller than the peak sample value. Because the fractional autocorrelation function is an even function relative to the optimal sampling time t=T, the absolute values of the fractional autocorrelation functions at the time t=T-τ tra and t=T+τ tra are equal. Under this condition, the appropriate sampling instant is the midpoint between t=T-τ tra and t=T+τ tra . Based on this, Figure 6 shows a functional block diagram of synchronous tracking.

在图6中,分数阶相关器取代了等效的分数域匹配滤波器。三个分数阶相关器在符号间隔T上积分,其中两个分数阶相关器分别比所估计的最佳抽样时刻提早τtra和延迟τtra开始积分,它们输出的绝对值之差形成误差信号。为了平滑噪声对跟踪性能的影响,将误差信号通过一个低通滤波器。如果定时偏离最佳抽样时刻,则低通滤波器输出的平均误差信号非零,误差的正负号则决定了相位搜索控制模块输出同步码的相位是迟后还是提前。下面给出数值分析结果。In Figure 6, a fractional-order correlator replaces the equivalent fractional-domain matched filter. The three fractional correlators are integrated on the symbol interval T, and two of the fractional correlators start integrating earlier than the estimated optimal sampling time τ tra and delayed τ tra respectively, and the difference between the absolute values of their outputs forms an error signal. To smooth the effect of noise on tracking performance, the error signal is passed through a low-pass filter. If the timing deviates from the best sampling moment, the average error signal output by the low-pass filter is non-zero, and the sign of the error determines whether the phase of the synchronization code output by the phase search control module is late or advanced. The numerical analysis results are given below.

基于前述分析,以13位巴克码作为同步码,后面紧跟经过13位巴克码扩频的数据信息位,信息调制方式采用双极性调制。仿真中每个码片进行4倍采样,仿真信道为高斯白噪信道。图7给出了基于分数阶相关和经典相关方法的同步算法的误码性能比较。可以看出,基于分数阶相关的同步误码性能略优于传统基于经典相关的同步误码性能,但相差不大,这是因为巴克码经典相关函数的相关峰本身就非常尖锐的缘故。图8给出了信噪比为8dB时,两种同步方法的同步跟踪抖动情况,图中横坐标为0表示,未发生同步抖动,由于每个码片进行了4倍采样,所以1表示抖动了四分之一个码片,2表示抖动了二分之一码片;而横坐标的正负号则分别表示向滞后和提前方向抖动。进一步地,图9以采样间隔为基本单位,给出了基于分数阶相关和经典相关的同步跟踪抖动方差随信噪比的变化曲线。可以看出,尽管基于分数阶相关和经典相关的同步误码性能相差不大,但是前者具有更好的同步跟踪性能,即其同步抖动较小。Based on the above analysis, the 13-bit Barker code is used as the synchronization code, followed by the data information bits spread by the 13-bit Barker code, and the information modulation method adopts bipolar modulation. In the simulation, each chip is sampled 4 times, and the simulation channel is a Gaussian white noise channel. Figure 7 shows the bit error performance comparison of synchronization algorithms based on fractional correlation and classical correlation methods. It can be seen that the synchronous bit error performance based on fractional correlation is slightly better than the traditional synchronous bit error performance based on classical correlation, but the difference is not large, because the correlation peak of the classical correlation function of Barker code itself is very sharp. Figure 8 shows the synchronization tracking jitter of the two synchronization methods when the signal-to-noise ratio is 8dB. The abscissa in the figure is 0, indicating that no synchronization jitter occurs. Since each chip is sampled by 4 times, 1 indicates jitter 1/4 chip, 2 means 1/2 chip jitter; and the positive and negative signs of the abscissa represent jitter in the direction of lag and advance respectively. Further, Fig. 9 shows the variation curve of the jitter variance of the synchronous tracking based on the fractional order correlation and the classical correlation with the signal-to-noise ratio, taking the sampling interval as the basic unit. It can be seen that although the synchronization bit error performance based on fractional correlation and classical correlation is not much different, the former has better synchronization tracking performance, that is, its synchronization jitter is smaller.

本发明基于不同旋转角度下分数阶自相关函数的峰值相同、尖锐程度不同的特点,根据系统信号参数和性能指标通过旋转角度来选择尖锐程度不同的分数阶自相关函数用于通信信号同步码的同步捕获和跟踪,即通过旋转角度选择峰值相对较宽的分数阶相关函数进行同步码的快速捕获,然后再利用旋转角度对应的峰值较尖锐的分数阶相关函数来实现同步码的精确跟踪。与传统基于经典相关的同步方法相比,该方法时钟抖动减小,对定位等信号处理有贡献。此外,对系统误码性能有一定的改善。The present invention is based on the characteristics of the same peak value and different sharpness of the fractional autocorrelation function at different rotation angles, and selects the fractional autocorrelation function with different sharpness through the rotation angle according to the system signal parameters and performance indicators for the synchronization code of the communication signal Synchronous capture and tracking, that is, select a fractional correlation function with a relatively wide peak value through the rotation angle to quickly capture the synchronization code, and then use a fractional correlation function with a sharper peak value corresponding to the rotation angle to achieve precise tracking of the synchronization code. Compared with the traditional synchronization method based on classical correlation, this method reduces clock jitter and contributes to signal processing such as positioning. In addition, the bit error performance of the system is improved to a certain extent.

Claims (7)

1.基于多角度分数阶相关协同的同步捕获与跟踪方法,其特征是:它由以下步骤实现:1. The synchronous acquisition and tracking method based on multi-angle fractional order correlation collaboration is characterized in that: it is realized by the following steps: 步骤一、接收端确定同步捕获参数,所述捕获参数包括分数阶相关器的旋转角度αacq、比较器的检测门限Vth和相位搜索控制模块输出同步码相位的变化量ΔτacqStep 1. The receiving end determines the synchronous acquisition parameters, and the acquisition parameters include the rotation angle α acq of the fractional order correlator, the detection threshold V th of the comparator, and the variation Δτ acq of the phase of the synchronous code output by the phase search control module; 同时,接收端确定同步跟踪参数,所述同步跟踪参数包括分数阶相关器的旋转角度αtra、相位搜索控制模块输出同步码相位的变化量Δτtra和本地同步码的超前和滞后量τtra,且2τtra≤Tc;Tc为码元宽度;At the same time, the receiving end determines the synchronous tracking parameters, the synchronous tracking parameters include the rotation angle α tra of the fractional order correlator, the variation Δτ tra of the phase of the synchronization code output by the phase search control module, and the lead and lag τ tra of the local synchronization code, And 2τ tra ≤ T c ; T c is the symbol width; 同步捕获过程:Synchronous capture process: 步骤二、采用捕获参数控制模块根据步骤一中所确定捕获参数,将接收信号r(t)与本地同步码通过分数阶相关器,计算出两者在旋转角度为αacq的分数阶相关函数峰值VacqStep 2: Use the capture parameter control module to pass the received signal r(t) and the local synchronization code through the fractional order correlator according to the capture parameters determined in step 1, and calculate the peak value of the fractional order correlation function between the two at a rotation angle of α acq Vacq ; 步骤三、将步骤二中分数阶相关器的输出值Vacq送给门限比较器,并判断分数阶相关器的输出值Vacq是否小于检测门限VthStep 3, sending the output value V acq of the fractional order correlator in step 2 to the threshold comparator, and judging whether the output value V acq of the fractional order correlator is less than the detection threshold V th ; 当Vacq小于检测门限Vth时,则本地同步码的相位和接收到的同步码的相位不同,门限比较器输出一个信号给同步码相位搜索控制模块,在相位搜索控制模块的控制下,本地同步码产生器改变输出同步码的相位状态,同步码相位的变化量为Δτacq;若改变后的本地同步码的相位状态仍与接收同步码的相位状态不同,门限比较器继续输出一个信号给相位搜索控制模块,使相位搜索控制模块再一次改变本地参考同步码的相位;When V acq is less than the detection threshold V th , the phase of the local synchronous code is different from the phase of the received synchronous code, and the threshold comparator outputs a signal to the synchronous code phase search control module. Under the control of the phase search control module, the local The synchronous code generator changes the phase state of the output synchronous code, and the variation of the synchronous code phase is Δτ acq ; if the phase state of the changed local synchronous code is still different from the phase state of the received synchronous code, the threshold comparator continues to output a signal to The phase search control module makes the phase search control module change the phase of the local reference synchronization code again; 直至本地参考同步码的相位状态趋近于接收同步码的相位状态时,分数阶相关器的输出Vacq超过检测门限Vth,即完成同步码的同步捕获,转入同步跟踪过程;Until the phase state of the local reference synchronous code approaches the phase state of the received synchronous code, the output V acq of the fractional order correlator exceeds the detection threshold V th , that is, the synchronous capture of the synchronous code is completed, and the synchronous tracking process is transferred to; 同步跟踪过程:Synchronous tracking process: 步骤四、将接收信号分成三路,跟踪参数控制模块根据步骤一中所确定的跟踪参数,将其中两路信号分别与本地参考同步码的超前码c(t-τ′dtra)和滞后码c(t-τ′dtra)进行旋转角度为αtra的分数阶相关运算;Step 4, the received signal is divided into three paths, and the tracking parameter control module, according to the tracking parameters determined in step 1, combines the signals of two paths with the leading code c(t-τ′ dtra ) and the local reference synchronization code respectively Lag code c( t -τ′d-τ tra ) carries out the fractional order correlation operation whose rotation angle is α tra ; 将另一路信号与本地参考同步码c(t-τ′d)进行旋转角度为αtra的分数阶相关运算,其中τ′d是对接收同步码未知时延量τd的估计值,经包络检波后送给判决器用于信息数据恢复;Carry out the fractional order correlation operation with the rotation angle of α tra between the other signal and the local reference synchronization code c(t-τ′ d ), where τ′ d is the estimated value of the unknown time delay τ d of receiving the synchronization code. After network detection, it is sent to the decision device for information data recovery; 步骤五、将步骤四中超前和滞后相关支路的输出经包络检波送给加法器,产生误差信号;并将该误差信号经过一个低通滤波器进行滤波,以平滑噪声对同步跟踪的影响;Step 5. Send the output of the leading and lagging related branches in step 4 to the adder through envelope detection to generate an error signal; and filter the error signal through a low-pass filter to smooth the influence of noise on synchronous tracking ; 并判断该误差信号是否为正,如判断结果为是,则执行步骤五一;如果判断结果为否,则执行步骤五二;And judge whether the error signal is positive, if the judgment result is yes, then execute step 51; if the judgment result is no, then execute step 52; 步骤五一、则本地同步码的超前码的相位状态比滞后码的相位状态更趋近接收同步码的相位状态,则在相位搜索控制模块的控制下,使本地同步码产生器输出同步码的相位状态进行超前调整,相位调整的变化量为ΔτtraStep 51, then the phase state of the leading code of the local synchronizing code is closer to the phase state of receiving the synchronizing code than the phase state of the lagging code, then under the control of the phase search control module, the local synchronizing code generator is output to the phase state of the synchronizing code The phase state is adjusted in advance, and the change amount of the phase adjustment is Δτ tra ; 若调整后误差信号仍为正,相位搜索控制模块再一次超前调整本地参考同步码的相位,直到本地参考同步码的相位状态趋近接收同步码的相位状态,则实现了同步码的同步跟踪;If the adjusted error signal is still positive, the phase search control module adjusts the phase of the local reference synchronization code in advance again until the phase state of the local reference synchronization code approaches the phase state of the received synchronization code, then the synchronization tracking of the synchronization code is realized; 步骤五二、则本地同步码的滞后码的相位状态比超前码的相位状态更接近接收同步码的相位状态,相位搜索控制模块将滞后调整本地参考同步码的相位,直到本地参考同步码的相位状态趋近接收同步码的相位状态,则实现了同步码的同步跟踪。Step 52, then the phase state of the delayed code of the local synchronous code is closer to the phase state of the received synchronous code than the phase state of the advanced code, and the phase search control module will adjust the phase of the local reference synchronous code laggingly until the phase of the local reference synchronous code The state is close to the phase state of receiving the synchronization code, and the synchronization tracking of the synchronization code is realized. 2.根据权利要求1所述的基于多角度分数阶相关协同的同步捕获与跟踪方法,其特征在于步骤一中接收端确定同步捕获参数是根据系统性能指标及所选同步码的参数确定的。2. The synchronous acquisition and tracking method based on multi-angle fractional correlation coordination according to claim 1, characterized in that in step 1, the receiving end determines that the synchronous acquisition parameters are determined according to the system performance index and the parameters of the selected synchronous code. 3.根据权利要求1所述的基于多角度分数阶相关协同的同步捕获与跟踪方法,其特征在于同步捕获过程中,接收信号与本地同步码进行分数阶相关运算时,分数阶相关输出脉冲的宽度随旋转角度的变化而变化。3. The synchronous acquisition and tracking method based on multi-angle fractional correlation coordination according to claim 1, wherein in the synchronous acquisition process, when the received signal and the local synchronization code carry out the fractional correlation operation, the fractional correlation output pulse The width changes with the rotation angle. 4.根据权利要求1所述的基于多角度分数阶相关协同的同步捕获与跟踪方法,其特征在于同步跟踪过程中,接收信号与本地同步码进行分数阶相关运算时,分数阶相关输出脉冲的宽度随旋转角度的变化而变化。4. The synchronous capture and tracking method based on multi-angle fractional correlation coordination according to claim 1, characterized in that in the synchronous tracking process, when the received signal and the local synchronization code carry out the fractional correlation operation, the fractional correlation output pulse The width changes with the rotation angle. 5.根据权利要求1所述的基于多角度分数阶相关协同的同步捕获与跟踪方法,其特征在于同步捕获过程与同步跟踪过程,分数阶相关运算的旋转角度不同。5. The synchronous acquisition and tracking method based on multi-angle fractional correlation collaboration according to claim 1, characterized in that the rotation angles of the fractional correlation operations are different in the synchronous acquisition process and the synchronous tracking process. 6.根据权利要求3所述的基于多角度分数阶相关协同的同步捕获与跟踪方法,其特征在于,分数阶相关运算的旋转角度是根据系统信号参数与性能指标计算得到。6. The synchronous acquisition and tracking method based on multi-angle fractional correlation coordination according to claim 3, characterized in that the rotation angle of the fractional correlation operation is calculated according to system signal parameters and performance indicators. 7.根据权利要求4所述的基于多角度分数阶相关协同的同步捕获与跟踪方法,其特征在于,分数阶相关运算的旋转角度是根据系统信号参数与性能指标计算得到。7. The synchronous acquisition and tracking method based on multi-angle fractional correlation coordination according to claim 4, characterized in that the rotation angle of the fractional correlation operation is calculated according to system signal parameters and performance indicators.
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106647786A (en) * 2016-11-24 2017-05-10 西北工业大学 Fractional order differential-based staged space tethered capture device attitude stabilization control method
CN106647786B (en) * 2016-11-24 2019-08-13 西北工业大学 Utilize the system of the space rope stage by stage catching device pose stabilization control method of fractional order differential

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