技术领域Technical field
本发明涉及导航技术领域，尤其是涉及一种地基导航信号接收的锁频环方法及系统。The present invention relates to the field of navigation technology, and in particular to a frequency-locked loop method and system for receiving ground-based navigation signals.
背景技术Background technique
为了克服“远近效应”问题，地基导航系统在信号体制上采用了跳时/直序-码分多址信号(TH/DS-CDMA)，通过划分时隙，不同伪卫星在不同时隙发射扩频信号，即时分的扩频通信体制，它既能克服“远近效应”，也能具有扩频信号的测距能力。In order to overcome the "far and near effect" problem, the ground-based navigation system adopts time hopping/direct sequence code division multiple access signal (TH/DS-CDMA) in the signal system. By dividing the time slots, different pseudolites transmit spreaded signals in different time slots. Frequency signal, that is, a split-spectrum communication system, which can not only overcome the "far and near effect", but also have the ranging capability of spread spectrum signals.
TH/DS-CDMA不是一种连续播发的信号，系统中的伪卫星都有自己的信号发射时间窗口，只在特定的时隙发送导航信号，一般某个时隙只有一个伪卫星的发射窗口是打开的，多个伪卫星之间是分时播发信号的。在地基导航系统中，一个跳时图案使用超帧、子帧和时隙来描述。跳时图案的一个周期称为超帧，一个超帧包含了M个子帧，每个子帧中划分了N个时隙，每个时隙时间为Ts，一般与测距码周期相同，一个子帧的时间Tf即为N·Ts。具体应用中，地基伪卫星部署数量的上限取决于N，即在一个子帧内，每一个时隙只允许一个伪卫星发射信号，且伪卫星在子帧内的发射时隙并不固定。TH/DS-CDMA is not a continuously broadcast signal. The pseudolites in the system have their own signal transmission time windows, and navigation signals are only sent in specific time slots. Generally, the emission window of only one pseudolite in a certain time slot is When turned on, multiple pseudolites broadcast signals in a time-sharing manner. In ground-based navigation systems, a time-hopping pattern is described using superframes, subframes, and time slots. One cycle of the time hopping pattern is called a superframe. A superframe contains M subframes. Each subframe is divided into N time slots. The time of each time slot is Ts . Generally, it is the same as the ranging code period. A subframe The frame time Tf is N·Ts . In specific applications, the upper limit of the number of ground-based pseudolites deployed depends on N, that is, within a subframe, only one pseudolite is allowed to transmit signals in each time slot, and the pseudolite's transmission time slot within a subframe is not fixed.
在无线信号的接收处理中，一般使用锁频环在信号的捕获阶段进行频率的牵引、捕获，或者在信号的跟踪阶段对频率连续跟踪，跳时信号体制的引入使得传统的锁频环技术不能完全适用。锁频环结构是由鉴频器、滤波器构成的负反馈系统，鉴频器的作用是计算信号的频率误差，通过观测两个时刻(t1、t2)的信号相位变化()来推算：滤波器的作用是抑制噪声，同时滤波器的带宽和阶数也决定了锁频环对信号动态的响应能力。在地基导航系统中，由于信号不是连续播发，不能形成对信号相位的连续观测，只能获取到信号发射时隙时刻的相位，并且两个观测时刻的时间间隔Δt并不固定；另外，由于地基导航信号的较强接收功率，可按一个发射时隙TS的时间对信号进行积分检测，考虑因频率偏差带来的可容忍的功率损耗，信号可检测的频率范围可达但是，对于信号相位的观测周期被限定在两个信号发射时隙的时间间隔，可能的时间间隔范围Δt∈[2TS,(2N-1)TS]，可被观测的频率偏差最大范围/>最小范围/>平均时间间隔为Tf，可被观测的平均频率偏差范围为/>其范围只有捕获带宽范围的/>有可能会出现信号检测到但却无法正确锁定频率的情况。In the reception and processing of wireless signals, frequency-locked loops are generally used to pull and capture the frequency in the signal acquisition phase, or to continuously track the frequency in the signal tracking phase. The introduction of the time-hopping signal system makes the traditional frequency-locked loop technology unable to Totally applicable. The frequency locked loop structure is a negative feedback system composed of a frequency discriminator and a filter. The function of the frequency discriminator is to calculate the frequency error of the signal by observing the signal phase changes at two moments (t1 , t2 ) ( ) to calculate: The function of the filter is to suppress noise. At the same time, the bandwidth and order of the filter also determine the response ability of the frequency locked loop to signal dynamics. In the ground-based navigation system, since the signal is not broadcast continuously, continuous observation of the signal phase cannot be formed. Only the phase at the signal transmission time slot moment can be obtained, and the time interval Δt between the two observation moments is not fixed; in addition, due to the ground-based The strong received power of the navigation signal can be integrated and detected according to the time of one transmission time slot TS. Taking into account the tolerable power loss caused by the frequency deviation, the signal can be detected in a frequency range of up to However, the observation period for the signal phase is limited to the time interval between two signal transmission time slots, the possible time interval range Δt∈[2TS , (2N-1)TS ], and the maximum range of frequency deviation that can be observed/ > Minimum range/> The average time interval is Tf , and the observable average frequency deviation range is/> Its range is only within the capture bandwidth range/> There may be situations where the signal is detected but the frequency cannot be locked correctly.
因此，对于地基导航信号接收使用的锁频环需要根据其跳时信号的特点，在信号相位观测不连续、观测时间间隔不固定以及可观测的频率偏差范围小于信号可检测频率范围等问题下，寻找如何准确计算鉴频误差、对频率进行快速牵引和精确跟踪的技术方案。Therefore, the frequency-locked loop used for ground-based navigation signal reception needs to be based on the characteristics of the time-hopping signal. When the signal phase observation is discontinuous, the observation time interval is not fixed, and the observable frequency deviation range is smaller than the signal detectable frequency range, etc., Looking for technical solutions on how to accurately calculate the frequency identification error, quickly pull the frequency and accurately track the frequency.
发明内容Contents of the invention
本发明所要解决的技术问题，在于提供一种地基导航信号接收的锁频环方法及系统，适用于跳时体制信号，以实现地基导航信号捕获阶段频率的快速牵引、精确捕获，以及跟踪阶段的频率精确跟踪。The technical problem to be solved by the present invention is to provide a frequency-locked loop method and system for ground-based navigation signal reception, which is suitable for time-hopping system signals to achieve rapid traction and accurate acquisition of frequencies in the ground-based navigation signal acquisition phase, as well as tracking phase Precise frequency tracking.
为了解决上述技术问题，本发明提供了一种地基导航信号接收的锁频环方法，该方法包括以下步骤：In order to solve the above technical problems, the present invention provides a frequency-locked loop method for ground-based navigation signal reception. The method includes the following steps:
步骤一，产生本地载波，将输入的地基导航数字采样信号正交下变频至基带I/Q信号；Step 1: Generate a local carrier and orthogonally down-convert the input ground-based navigation digital sampling signal to a baseband I/Q signal;
步骤二，产生与输入信号伪码同步的本地伪码，对基带I/Q信号进行伪码解扩、累加处理，获得存在信号时的前半时隙时间积分值Ikh、Qkh和完整时隙TS时间积分值Ik、Qk；Step 2: Generate local pseudocode synchronized with the pseudocode of the input signal, perform pseudocode despreading and accumulation processing on the baseband I/Q signal, and obtain the first half of the time slot when the signal exists Time integration values Ikh , Qkh and complete time slotTS time integration values Ik , Qk ;
步骤三，依据积分值计算锁频环的输入鉴频误差Step 3: Calculate the input frequency discrimination error of the frequency locked loop based on the integral value
步骤四，对频率误差进行滤波处理，更新本地载波的频率。Step 4: Filter the frequency error and update the frequency of the local carrier.
优选的，该方法还包括：Preferably, the method also includes:
在地基导航信号的捕获阶段，分为粗捕环和精捕环两个先后作用的锁频环，粗捕环鉴频误差计算方法为：精捕环鉴频误差计算方法为：/>In the acquisition stage of the ground-based navigation signal, it is divided into two frequency-locked loops, the coarse acquisition loop and the fine acquisition loop, which work successively. The frequency discrimination error calculation method of the coarse acquisition loop is: The calculation method of precision capture ring frequency identification error is:/>
其中，Tk是地基导航信号跳时图案相邻的时隙k和时隙k-1之间的时间间隔；所述粗捕环和精捕环的带宽Ba1、Ba2，满足Ba2≤Ba1的关系。Among them, Tk is the time interval between the adjacent time slot k and the time slot k-1 of the ground-based navigation signal time hopping pattern; the bandwidths Ba1 and Ba2 of the rough capture loop and the fine capture loop satisfy Ba2 ≤ Ba1 relationship.
优选的，所述粗捕环和精捕环两个先后作用的锁频环的切换条件是：Preferably, the switching conditions of the two frequency-locked loops, the coarse trapping loop and the fine trapping loop, which act sequentially, are:
粗捕环计算的鉴频误差满足/>Frequency identification error in rough capture loop calculation Satisfied/>
其中，Tmax是地基导航信号跳时图案中相邻时隙时间间隔Tk的最大值。Among them, Tmax is the maximum value of the time interval Tk between adjacent time slots in the time hopping pattern of the ground-based navigation signal.
优选的，该方法还包括：Preferably, the method also includes:
在地基导航信号的跟踪阶段，使用锁频环跟踪信号频率时，鉴频误差的计算方法为：In the tracking stage of ground-based navigation signals, when using a frequency-locked loop to track the signal frequency, the frequency identification error is calculated as:
其中，Tk是地基导航信号跳时图案相邻的时隙k和时隙k-1之间的时间间隔。Among them, Tk is the time interval between the adjacent time slot k and the time slot k-1 of the ground-based navigation signal time hopping pattern.
为了解决上述技术问题，本发明还提供了一种地基导航信号接收的锁频环系统，该系统包括：In order to solve the above technical problems, the present invention also provides a frequency-locked loop system for ground-based navigation signal reception, which system includes:
载波振荡器，产生本地的正交载波信号；Carrier oscillator, which generates local orthogonal carrier signals;
正交下变频器，与所述载波振荡器相连，用于将输入信号与本地正交载波信号混频，产生基带I/Q信号；An orthogonal downconverter, connected to the carrier oscillator, used to mix the input signal with the local orthogonal carrier signal to generate a baseband I/Q signal;
码产生器，产生与输入信号调制伪码同步的本地伪码，以及输出半时隙指示信号；A code generator that generates a local pseudo code synchronized with the input signal modulation pseudo code, and outputs a half time slot indication signal;
伪码解扩模块，与所述正交下变频器、码产生器相连，用于将基带I/Q信号与本地伪码进行解扩、累加处理，输出前半时隙I/Q积分值和完整时隙I/Q积分值；The pseudo code despreading module is connected to the orthogonal down converter and the code generator, and is used to despread and accumulate the baseband I/Q signal and the local pseudo code, and output the I/Q integral value of the first half time slot and the complete Time slot I/Q integral value;
所述载波振荡器，输出载波信号的频率可编程更新；所述半时隙指示信号，是一个占空比为50％的信号，在地基导航信号划分时隙的前半个周期时间电平为低，后半个周期/>时间电平为高。The frequency of the carrier oscillator outputting the carrier signal can be updated programmably; the half-time slot indication signal is a signal with a duty cycle of 50%, and is used in the first half cycle of the ground-based navigation signal divided time slot The time level is low, the second half cycle/> time level is high.
优选的，所述伪码解扩模块包括：Preferably, the pseudocode despreading module includes:
乘法器，输入所述正交下变频器输出的基带I/Q信号和码产生器输出的本地同步伪码，用于信号的解扩；A multiplier that inputs the baseband I/Q signal output by the quadrature downconverter and the local synchronization pseudo code output by the code generator for despreading the signal;
上升沿检测器，输入所述码产生器输出的半时隙指示信号，用于检测该信号的上升沿，输出半时隙脉冲信号；A rising edge detector, which inputs the half-time slot indication signal output by the code generator, is used to detect the rising edge of the signal, and outputs a half-time slot pulse signal;
下降沿检测器，输入所述码产生器输出的半时隙指示信号，用于检测该信号的下降沿，输出完整时隙脉冲信号；A falling edge detector, which inputs the half time slot indication signal output by the code generator, is used to detect the falling edge of the signal, and outputs a complete time slot pulse signal;
累加器，与所述乘法器、下降沿检测器相连，用于对解扩后的信号在一个时隙内连续累加，并在完整时隙脉冲信号来临时清零；An accumulator, connected to the multiplier and the falling edge detector, is used to continuously accumulate the despread signal within a time slot, and clear it when the complete time slot pulse signal arrives;
半时隙积分值锁存器，与所述累加器、上升沿检测器相连，在半时隙脉冲信号驱动下，锁存累加器输出的积分值；A half-time slot integral value latch is connected to the accumulator and the rising edge detector, and is driven by the half-time slot pulse signal to latch the integral value output by the accumulator;
完整时隙积分值锁存器，与所述累加器、下降沿检测器相连，在完整时隙脉冲信号驱动下，锁存累加器输出的积分值。The complete time slot integrated value latch is connected to the accumulator and the falling edge detector, and is driven by the complete time slot pulse signal to latch the integrated value output by the accumulator.
本发明实现的地基导航信号接收的锁频环方法和系统的主要优点：The main advantages of the frequency-locked loop method and system for ground-based navigation signal reception implemented by the present invention are:
(1)依据信号发射时隙，动态计算实际的信号相位观测的时间间隔，以此计算锁频环鉴频误差；(1) Based on the signal transmission time slot, dynamically calculate the actual signal phase observation time interval to calculate the frequency-locked loop frequency discrimination error;
(2)利用地基导航信号的相对强功率接收条件，通过对一个时隙的等半划分，在一个时隙内就能计算鉴频误差，并且可被观测的频率误差范围为覆盖了信号可被检测的频率范围，并通过粗捕环和精捕环不同的鉴频误差计算方式、带宽，确保信号的频率能被准确牵引、精确捕获；(2) Taking advantage of the relatively strong power reception conditions of ground-based navigation signals, by dividing a time slot into equal halves, the frequency identification error can be calculated within a time slot, and the observable frequency error range is It covers the frequency range in which the signal can be detected, and uses different frequency identification error calculation methods and bandwidths of the coarse capture loop and the fine capture loop to ensure that the frequency of the signal can be accurately pulled and accurately captured;
(3)通过半时隙指示信号，获取一个时隙内的两个等半积分值，相比较于传统锁频环的实现，在资源上只是增加了若干个寄存器。(3) Through the half-time slot indication signal, two equal and half integral values in one time slot are obtained. Compared with the implementation of the traditional frequency-locked loop, only a few registers are added in terms of resources.
附图说明Description of drawings
附图用于提供对本发明的进一步理解，并且构成本申请的一部分，与本发明实施例一起用于解释本发明，并不构成对本发明的不当限定。在附图中：The drawings are used to provide a further understanding of the present invention and constitute a part of the present application. They are used to explain the present invention together with the embodiments of the present invention and do not constitute an improper limitation of the present invention. In the attached picture:
图1为本发明地基导航信号接收锁频环方法实施例的流程示意图；Figure 1 is a schematic flow chart of an embodiment of a ground-based navigation signal receiving frequency-locked loop method according to the present invention;
图2为本发明锁频环频率响应图；Figure 2 is a frequency response diagram of the frequency locked loop of the present invention;
图3为本发明地基导航信号接收锁频环系统实施例的组成示意图；Figure 3 is a schematic diagram of the composition of an embodiment of a frequency-locked loop system for receiving ground-based navigation signals according to the present invention;
图4为本发明伪码解扩模块的组成示意图；Figure 4 is a schematic diagram of the composition of the pseudocode despreading module of the present invention;
图5为本发明半时隙指示信号、上升沿检测信号和下降沿检测信号的时序关系图。Figure 5 is a timing relationship diagram of the half-time slot indication signal, rising edge detection signal and falling edge detection signal according to the present invention.
具体实施方式Detailed ways
为了使本发明的目的、技术方案及优点更加清楚明白，以下结合实施例，对本发明进行进一步详细说明。应当理解，此处所描述的具体实施例仅仅用以解释本发明，并不用于限定本发明。In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with examples. It should be understood that the specific embodiments described here are only used to explain the present invention and are not intended to limit the present invention.
实施例1Example 1
图1为本发明地基导航信号接收锁频环方法实施例的流程示意图。图1所示的方法实施例包括以下步骤：Figure 1 is a schematic flow chart of an embodiment of a ground-based navigation signal receiving frequency-locked loop method according to the present invention. The method embodiment shown in Figure 1 includes the following steps:
S101，产生本地载波，将输入的地基导航数字采样信号正交下变频至基带I/Q信号；S101, generate a local carrier and orthogonally down-convert the input ground-based navigation digital sampling signal to a baseband I/Q signal;
S102，产生与输入信号伪码同步的本地伪码，对基带I/Q信号进行伪码解扩、累加处理，获得存在信号时的前半时隙时间积分值Ikh、Qkh和完整时隙Ts时间积分值Ik、Qk；S102, generate local pseudo code synchronized with the input signal pseudo code, perform pseudo code despreading and accumulation processing on the baseband I/Q signal, and obtain the first half time slot when the signal exists Time integrated values Ikh , Qkh and complete time slot Ts time integrated values Ik , Qk ;
S103，依据积分值计算锁频环的输入鉴频误差S103, calculate the input frequency discrimination error of the frequency locked loop based on the integral value
S104，对频率误差进行滤波处理，更新本地载波的频率。S104: Filter the frequency error and update the frequency of the local carrier.
其中，在地基导航信号的捕获阶段，为达到更好的牵引效果，可以分为粗捕环和精捕环两个锁频环，两个锁频环的结构形式是一致的，但是采取的鉴频误差计算方法和带宽不一样，锁频环阶数为一阶或二阶，其选择取决于接收信号的动态条件。Among them, in the capture stage of ground-based navigation signals, in order to achieve better traction effect, it can be divided into two frequency-locked loops, a coarse capture loop and a fine capture loop. The structural forms of the two frequency-locked loops are the same, but the identification method adopted The frequency error calculation method is different from the bandwidth. The frequency-locked loop order is first-order or second-order. The choice depends on the dynamic conditions of the received signal.
粗捕环鉴频误差计算方法为：The calculation method of frequency identification error of coarse capture loop is:
精捕环鉴频误差计算方法为：The calculation method of precision capture ring frequency identification error is:
Tk是地基导航信号跳时图案相邻的时隙k和时隙k-1之间的时间间隔。Tk is the time interval between the adjacent time slot k and time slot k-1 of the ground-based navigation signal time hopping pattern.
粗捕环和精捕环在时间上先后作用，粗捕环具有很宽的线性牵引范围，能够快速将频率牵引至较小范围，而精捕环则更一步地准确捕获频率，以便交接到后续的锁相环。粗捕环和精捕环的带宽Ba1、Ba2，满足Ba2≤Ba1的关系。粗捕环和精捕环的切换条件是粗捕环计算的鉴频误差满足/>其中，Tmax是地基导航信号跳时图案中相邻时隙时间间隔Tk的最大值，切换条件实际上是要保证在粗捕环的作用下，频率误差落入精捕环的线性牵引范围，精捕环的最小牵引范围是/>The coarse capture ring and the fine capture ring work one after another in time. The coarse capture ring has a wide linear traction range and can quickly pull the frequency to a smaller range, while the fine capture ring accurately captures the frequency for subsequent handover. of phase locked loop. The bandwidths Ba1 and Ba2 of the coarse capturing ring and the fine capturing ring satisfy the relationship of Ba2 ≤ Ba1 . The switching condition between the coarse capture loop and the fine capture loop is the frequency identification error calculated by the coarse capture loop. Satisfied/> Among them, Tmax is the maximum value of the time interval Tk between adjacent time slots in the time-hopping pattern of the ground-based navigation signal. The switching condition is actually to ensure that under the action of the coarse capture ring, the frequency error falls into the linear traction range of the fine capture ring. , the minimum traction range of the fine catching ring is/>
其中，在地基导航信号的跟踪阶段，在一些情况下也有可能使用锁频环跟踪信号频率，譬如接收信号微弱时，此时鉴频误差的计算方法为：Among them, during the tracking stage of ground-based navigation signals, it is possible to use a frequency-locked loop to track the signal frequency in some cases. For example, when the received signal is weak, the calculation method of the frequency identification error is:
其中，Tk是地基导航信号跳时图案相邻的时隙k和时隙k-1之间的时间间隔。Among them, Tk is the time interval between the adjacent time slot k and the time slot k-1 of the ground-based navigation signal time hopping pattern.
依据本发明提供的方法，图2是锁频环的仿真结果图，展示了锁频环在信号的捕获阶段对频率快速牵引的效果，仿真条件：地基导航系统发射时隙TS＝0.1ms，一个子帧Tf内包含10个时隙；初始频率偏差-4000Hz；锁频环为2阶，平均闭环时间为Tf＝1ms，带宽为5Hz和10Hz。从仿真图可见，在很大初始频率偏差的条件下，虽然环路的平均闭环时间为1ms，但是依然能够成功牵引和捕获频率。According to the method provided by the present invention, Figure 2 is a simulation result diagram of the frequency-locked loop, showing the effect of the frequency-locked loop on the rapid pulling of frequency during the signal acquisition phase. Simulation conditions: ground-based navigation system transmission time slot TS =0.1ms, One subframe Tf contains 10 time slots; the initial frequency deviation is -4000Hz; the frequency-locked loop is 2nd order, the average closed loop time is Tf =1ms, and the bandwidth is 5Hz and 10Hz. It can be seen from the simulation diagram that under the condition of large initial frequency deviation, although the average closed loop time of the loop is 1ms, it can still successfully pull and capture the frequency.
实施例2Example 2
图3为本发明地基导航信号接收锁频环系统实施例的组成示意图。图3所示的系统实施例包括：载波振荡器200、正交下变频器(210、220)、码产生器230和伪码解扩模块240。Figure 3 is a schematic diagram of the composition of an embodiment of a frequency-locked loop system for receiving ground-based navigation signals according to the present invention. The system embodiment shown in Figure 3 includes: a carrier oscillator 200, a quadrature downconverter (210, 220), a code generator 230 and a pseudo code despreading module 240.
载波振荡器200，产生本地的正交载波信号205、206，输入正交下变频器210、220，将输入信号201正交下变频，产生基带I/Q信号207、208。码产生器230，产生与输入信号调制伪码同步的本地伪码202，以及输出半时隙指示信号203，伪码解扩模块240，将基带I/Q信号207、208与本地伪码202进行解扩、累加处理，在半时隙指示信号203的控制下，输出前半时隙I/Q积分值211、214和完整时隙I/Q积分值212、213。The carrier oscillator 200 generates local orthogonal carrier signals 205 and 206, which are input to the quadrature down-converters 210 and 220, which orthogonally down-convert the input signal 201 to generate baseband I/Q signals 207 and 208. The code generator 230 generates the local pseudo code 202 synchronized with the input signal modulation pseudo code, and outputs the half time slot indication signal 203. The pseudo code despreading module 240 performs the baseband I/Q signals 207 and 208 with the local pseudo code 202. The despreading and accumulation processing, under the control of the half time slot indication signal 203, outputs the first half time slot I/Q integrated values 211, 214 and the complete time slot I/Q integrated values 212, 213.
图4是伪码解扩模块240的组成示意图。如图4所示，伪码解扩模块240包括：乘法器(310、320)、上升沿检测器390、下降沿检测器400、累加器(330、340)、半时隙积分值锁存器(350、380)和完整时隙积分值锁存器(360、370)。FIG. 4 is a schematic diagram of the composition of the pseudocode despreading module 240. As shown in Figure 4, the pseudocode despreading module 240 includes: a multiplier (310, 320), a rising edge detector 390, a falling edge detector 400, an accumulator (330, 340), and a half-slot integral value latch (350, 380) and full slot integrated value latches (360, 370).
正交下变频器210、220输出的基带I/Q信号207、208和码产生器230输出的本地同步伪码202，输入乘法器310、320，完成信号的解扩，输出信号335、336。上升沿检测器390，检测半时隙指示信号203的上升沿，输出半时隙脉冲信号341；下降沿检测器400，检测半时隙指示信号203的下降沿，输出完整时隙脉冲信号342。累加器330、340，对解扩后的信号335、336在一个时隙内连续累加，并在完整时隙脉冲信号342来临时清零。半时隙积分值锁存器350、380，在半时隙脉冲信号341驱动下，锁存累加器330、340输出的积分值；完整时隙积分值锁存器360、370，在完整时隙脉冲信号342驱动下，锁存累加器330、340输出的积分值。The baseband I/Q signals 207 and 208 output by the quadrature downconverters 210 and 220 and the local synchronization pseudo code 202 output by the code generator 230 are input to the multipliers 310 and 320 to complete signal despreading and output signals 335 and 336. The rising edge detector 390 detects the rising edge of the half time slot indication signal 203 and outputs the half time slot pulse signal 341; the falling edge detector 400 detects the falling edge of the half time slot indication signal 203 and outputs the complete time slot pulse signal 342. The accumulators 330 and 340 continuously accumulate the despread signals 335 and 336 within a time slot and clear them when the complete time slot pulse signal 342 arrives. The half-time slot integrated value latches 350 and 380, driven by the half-time slot pulse signal 341, latch the integrated values output by the accumulators 330 and 340; the complete time slot integrated value latches 360 and 370, in the complete time slot Driven by the pulse signal 342, the integrated values output by the accumulators 330 and 340 are latched.
图5展示了半时隙指示信号203与上升沿检测信号341、下降沿检测信号342的时序关系。半时隙指示信号203是一个占空比为50％的信号，在地基导航信号划分时隙的前半个周期时间电平为低，后半个周期/>时间电平为高。FIG. 5 shows the timing relationship between the half-slot indication signal 203 and the rising edge detection signal 341 and the falling edge detection signal 342. The half-time slot indication signal 203 is a signal with a duty cycle of 50%, and is used in the first half cycle of the ground-based navigation signal divided time slot. The time level is low, the second half cycle/> time level is high.
本发明所提供锁频环系统的方案，与传统锁频环比较，只增加了半时隙积分值锁存器350、380，以及产生半时隙指示信号203的相应逻辑。Compared with the traditional frequency-locked loop, the solution of the frequency-locked loop system provided by the present invention only adds half-time slot integral value latches 350 and 380 and the corresponding logic for generating the half-time slot indication signal 203.
最后说明的是，以上实施例仅用以说明本发明的技术方案而非限制，尽管参照较佳实施例对本发明进行了详细说明，本领域的普通技术人员应当理解，可以对本发明的技术方案进行修改或者等同替换，而不脱离本发明技术方案的宗旨和范围，其均应涵盖在本发明的权利要求范围当中。Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified. Modifications or equivalent substitutions without departing from the spirit and scope of the technical solution of the present invention shall be included in the scope of the claims of the present invention.
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| CN202310695945.9ACN116744234A (en) | 2023-06-13 | 2023-06-13 | A frequency-locked loop method and system for ground-based navigation signal reception |
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| CN202310695945.9ACN116744234A (en) | 2023-06-13 | 2023-06-13 | A frequency-locked loop method and system for ground-based navigation signal reception |
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