CN106338748A - Kalman filtering based GPS receiver tracking loop - Google Patents

Kalman filtering based GPS receiver tracking loop Download PDF

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Publication number
CN106338748A
CN106338748A CN201610781828.4A CN201610781828A CN106338748A CN 106338748 A CN106338748 A CN 106338748A CN 201610781828 A CN201610781828 A CN 201610781828A CN 106338748 A CN106338748 A CN 106338748A
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kalman filter
signal
carrier
code
loop
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CN201610781828.4A
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魏冰然
严余伟
张又鑫
宋天阳
傅晓宇
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电子科技大学
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01SRADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/01Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/13Receivers
    • G01S19/24Acquisition or tracking or demodulation of signals transmitted by the system
    • G01S19/29Acquisition or tracking or demodulation of signals transmitted by the system carrier, including Doppler, related
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01SRADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/01Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/13Receivers
    • G01S19/24Acquisition or tracking or demodulation of signals transmitted by the system
    • G01S19/30Acquisition or tracking or demodulation of signals transmitted by the system code related

Abstract

The invention discloses a Kalman filtering based GPS receiver tracking loop. One path of carrier signals is correlated with an input intermediate frequency signal to obtain in-phase branch data I; the other path of carrier signals is coupled for 90 degrees and then correlated with the input intermediate frequency signal to obtain orthogonal branch data Q; an advanced signal E, an instant signal P and a lagged signal L are correlated with the I and are also correlated with the Q to obtain in-phase branch accumulation data IE, IP and IL and orthogonal branch accumulation data QE, QP and QL via an integration accumulation module; the IE, IP, IL, QE, QP and QL are connected with the input end of a code ring Kalman filter, and the output end of the code ring Kalman filter is connected with a local C/A code generator; and the IP and QP are connected with the input end of a carrier ring Kaman filter, and the output end of the carrier ring Kaman filter is connected with an NCO carrier wave generator. The GPS receiver tracking loop can track signals whose carrier-to-noise ratio is as low as 19dB-Hz, the tracking error for signals whose carrier-to-noise ratio is 13dB-Hz can be controlled within 10m, and the performance is improved greatly.

Description

基于卡尔曼滤波的GPS接收机跟踪环路 GPS receiver tracking loops based on Kalman Filter

技术领域 FIELD

[0001] 本发明属于定位导航技术领域,特别涉及一种基于卡尔曼滤波的GPS接收机跟踪环路。 [0001] The present invention belongs to positioning and navigation technology, and particularly relates to a GPS receiver tracking loop based on Kalman filtering.

背景技术 Background technique

[0002] 现代军事中,飞行路线、导弹轨迹、作战路线等长距离远程控制的活动都离不开对定位和导航的需求,特别是对于远程无人机、洲际导弹等,必须依靠全球性的卫星定位来实现目标的准确到达或打击。 [0002] In the modern military, flight path, the trajectory missiles, combat routes long-distance remote control activities are inseparable from the need for positioning and navigation, especially for remote unmanned aircraft, ICBMs, etc., we must rely on global satellite positioning to achieve the goal of accurately reach or strike. 发展最全面、应用最广泛的GPS系统接收机在高功率噪声下的信号跟踪环节是本发明的重点研究对象。 The development of the most comprehensive, the most widely used GPS receiver system noise at high power signal tracking link is the focus of the research object of the present invention.

[0003] 这一方面使因为在一些场景中,卫星信号的强度十分微弱。 [0003] Because this will allow in some scenarios, the strength of the satellite signal is very weak. 例如无线设备工作在在茂密的森林中或者在封闭性很好的操作室内时,载噪比(carrier-to-noise ratio)的一个典型值是25分贝-赫兹(dB-Hz)。 For example in a wireless device is operating in dense forest or in a closed interior of a good operation, a typical value of the carrier to noise ratio (carrier-to-noise ratio) is 25 db - Hertz (dB-Hz). 另一个例子是,地球同步轨道卫星所运行的高度是高于GPS卫星的轨道高度的,而GPS卫星上发射信号的天线是朝向地球的,信号虽然可以传播到天线背向的另一侧空间中并被侦测使用,但是地球同步轨道卫星视野内的可见卫星通常很少,并且可视时间都及其短暂。 As another example, the height of geostationary satellites that orbit operation is above the height of the GPS satellites and the antenna on the GPS satellites transmitting signals towards the earth, although the signal can be propagated to the other side facing away from the space of the antenna and detecting use, but visible satellites in geosynchronous orbit satellite vision usually small, and visual and short time.

[0004] 传统的GPS接收机包括下变频并采样接收到的无线信号、搜索并捕获视野内的GPS 可见卫星、对捕获信号的C/A码和载波进行跟踪、解调出导航数据,以及解算出位置坐标。 [0004] The conventional GPS receiver comprising sampling and downconverts the received wireless signal, search and acquisition of GPS satellites in the field of view of the C / A code and carrier tracking of the captured signal, demodulates the navigation data, and de calculate position coordinates.

[0005] 捕获环节获得信号及其参数的粗略估计值后,跟踪环节对信号的码相位、载波相位和多普勒频移进行精确估计。 [0005] After obtaining a rough estimate of signal capture and link parameters, the tracking code phase part of the signal, the carrier phase and Doppler frequency shift accurately estimated. 对载波的估计用于剥离接收信号中的载波并解调出导航比特,对码延迟的估计用于剥离C/A码,计算伪距和位置坐标。 Estimate of the carrier for release of the carrier signal receiving and demodulating navigation bits, of the code delay estimation for stripping C / A code is calculated pseudoranges and the position coordinates.

[0006] 在噪声的影响下,接收机无法准确判断C/A码码相位,码相位误差被放大成伪距误差,进一步影响定位精度,在连续求解位置的过程中坐标值波动较大;噪声也会使鉴相器不能准确输出本地参数误差,造成接收信号与复现信号相关值衰减,剥离载波和C/A码不彻底,无法判别导航数据;或者由于鉴相器的错误输出,彻底失去对接收信号的跟踪。 [0006] Under the influence of noise, the receiver can not accurately determine the C / A code phase of the code, the code phase error is amplified into pseudorange error, further positioning accuracy, coordinate values ​​during continuous fluctuations solving location; Noise also causes the output of the phase detector can not accurately local error parameters, resulting in a received signal and a reproduced signal related to the attenuation values, and peeling the carrier C / a code is not complete, the navigation data can not be determined; or by an error output of the phase detector, completely lost tracking the received signal. 定位精度会随着噪声功率的增大而下降,以至于完全失去对信号的识别,无法给出定位结果。 Positioning precision will increase as the noise power decreases, so that the identification signal is completely lost, positioning result can not be given.

[0007] 另一方面,对微弱信号下提高接收机性能的研究通常有助于提高一般情况下接收机的性能。 [0007] On the other hand, studies for improving the performance of the receiver under weak signal usually increases the performance of the receiver under normal circumstances. 适用于低信噪比下定位算法用于普通的接收机,通常在常规的信号强度下,接收机将得到更加准确的定位结果。 For low SNR positioned at an algorithm for normal receiver, typically at a conventional signal strength, receiver positioning will be more accurate results.

发明内容 SUMMARY

[0008] 本发明的目的在于克服现有技术的不足,提供一种可以跟踪载噪比低至19dB_Hz 的信号,而载噪比低至13dB_Hz时使用两个卡尔曼滤波的跟踪环路仍能保持对信号的跟踪并且跟踪误差在l〇m以内,相比于传统的跟踪方法性能大大提高的于卡尔曼滤波的GPS接收机跟踪环路。 [0008] The object of the present invention is to overcome the disadvantages of the prior art, to provide a low signal to noise ratio tracking 19dB_Hz carrier, and carrier to noise ratio as low as two 13dB_Hz using Kalman filter tracking loop can maintain and the tracking of the tracking error signal is within l〇m compared to conventional methods in greatly improved performance tracking Kalman filter tracking loop of GPS receivers.

[0009] 本发明的目的是通过以下技术方案来实现的:基于卡尔曼滤波的GPS接收机跟踪环路,包括NC0载波发生器、本地C/A码发生器、多个积分累加模块、码环卡尔曼滤波器和载波环卡尔曼滤波器; [0009] The object of the present invention is achieved by the following technical solutions: based on the GPS receiver tracking loop Kalman filter, comprising NC0 carrier generator, a local C / A code generator, a plurality of integral accumulation module, code ring Kalman filter and a Kalman filter carrier ring;

[0010] N⑶载波发生器生成的一路载波信号与输入的中频信号进行相关,得到同相支路数据I;NC0载波发生器生成的另一路载波信号经过90°耦合后与输入的中频信号进行相关, 得到正交支路数据Q; [0010] N⑶ carrier intermediate frequency signal generator generates a carrier signal along with the input of the correlating data obtained in-phase branch I; NC0 carrier generator generating the carrier signals after the other 90 ° with the intermediate frequency signal input coupled to the associated, Q quadrature branch data obtained;

[0011]本地C/A码发生器分别产生三组信号:超前信号E、即时信号P和滞后信号L,超前信号E、即时信号P和滞后信号L分别与同相支路数据I和正交支路数据Q进行相关,然后通过积分累加模块进行积分累加后得到同相支路累加数据Ie、Ip、Il和正交支路累加数据Qe、Qp、Ql; 同相支路累加数据Ie、Ip、Il和正交支路累加信号Qe、Qp、Ql分别与码环卡尔曼滤波器的输入端相连,码环卡尔曼滤波器的输出端连接本地C/A码发生器;同相支路累加数据Ip和正交支路累加信号Qp还分别连接载波环卡尔曼滤波器的输入端,载波环卡尔曼滤波器的输出端与NC0载波发生器相连。 [0011] the local C / A code generator generate three signals: a signal ahead of E, and a prompt signal lag signal P L, advanced signal E, and a prompt signal P L respectively lag signal I and a quadrature phase legs support the same data Q channel data correlation, and by integrating the integral accumulation accumulation module to obtain the accumulated data with the phase leg Ie, Ip, Il and quadrature branches accumulated data Qe, Qp, Ql; phase legs with the accumulated data Ie, Ip, Il and quadrature branch summation signal Qe, Qp, Ql is connected to an input of each code ring Kalman filter, the Kalman filter output terminal is connected to the code ring local C / a code generator; Ip and the data accumulated with the positive phase legs Qp deposit slip accumulated signal input also connected to the carrier ring Kalman filter, connected to the output of the Kalman filter carrier ring NC0 carrier generator.

[0012] 进一步地,所述超前信号E与即时信号P之间相差0.5个C/A码元,即时信号P与和滞后信号L之间相差0.5个C/A码元。 [0012] Further, a difference of 0.5 C / A code element between the immediate early signal E and signal P, a difference of 0.5 Instant C / A code and the P element between the signal and the delay signal L.

[0013] 进一步地,所述码环卡尔曼滤波器采用二阶平方根扩展卡尔曼滤波器,载波环卡尔曼滤波器采用二阶平方根扩展卡尔曼滤波器。 [0013] Further, the second-order Kalman filter loop code root extended Kalman filter, the Kalman filter carrier ring second-order extended Kalman filter is a square root.

[0014] 进一步地,本发明的码环与载波环的卡尔曼滤波器既可以同时使用在跟踪环路中,也可以与传统的跟踪环路配合单独使用其中一个:采用码环鉴相器代替本发明的码环卡尔曼滤波器,即只对载波跟踪环路采用卡尔曼滤波模型;采用环路滤波器代替载波环卡尔曼滤波器,即只对码环跟踪环路采用卡尔曼滤波模型。 [0014] Further, the Kalman filter code carrier ring and the ring of the present invention may be used simultaneously in the tracking loop may be used with a conventional tracking loop used alone wherein one of: a code loop discriminator employed in place of code Kalman filter loop of the present invention, i.e., only the Kalman filter model for a carrier tracking loop; instead of using a loop filter carrier ring Kalman filter, that is, only the code loop tracking loop Kalman filter model.

[0015] 本发明的有益效果是: [0015] Advantageous effects of the present invention are:

[0016] 1、使用卡尔曼滤波算法,在更新阶段,利用转移矩阵和观测方程计算出先验状态向量和观测量的估计值,在校正阶段,利用真实的观测量对状态向量及其协方差矩阵进行校正,得到后验状态向量并输出,新的观测向量又作为输入如此循环迭代更新状态向量。 [0016] 1, using the Kalman filter update stage, using the transfer matrix equation and the observed values ​​of the a priori estimate of the state vector and observables, in calibration phase, with real observations of the state vector and its covariance correction matrix, to obtain and output a posteriori state vector, the new observation vector and an input loop so iteratively updated state vector. 在捕获结果准确且侦测出导航数据的情况下,同时使用两个卡尔曼滤波器的跟踪环路可以跟踪载噪比低至19dB-Hz的信号;而载噪比低至13dB-Hz时使用两个卡尔曼滤波的跟踪环路仍能保持对信号的跟踪并且跟踪误差在l〇m以内,相比于传统的跟踪方法性能大大提高; In the case of capture and detect the accurate navigation data while using two Kalman filter tracking loop carrier to noise ratio of up to 19dB-Hz signal can be tracked; the use of carrier-to-noise ratio of 13dB-Hz low as two Kalman filter can still keep track of the tracking loop and a tracking error signal is within l〇m compared to the conventional method of tracking the performance greatly improved;

[0017] 2、本发明的码环卡尔曼滤波器与载波环卡尔曼滤波器既可以同时使用在跟踪环路中,也可以与传统的跟踪环路配合单独使用其中一个,用户可以根据实际情况自由选择, 提尚了GPS跟踪环路的使用范围。 [0017] 2, the code ring with a Kalman filter of the present invention, the carrier ring Kalman filter may be used simultaneously in the tracking loop may be used with a conventional tracking loop used alone wherein a user according to the actual situation freedom of choice, yet mention the use of GPS tracking loop.

附图说明 BRIEF DESCRIPTION

[0018] 图1为卡尔曼滤波器的工作流程图; [0018] FIG. 1 is a flow chart of the Kalman filter;

[0019] 图2为本发明的GPS接收机跟踪环路结构图; [0019] GPS receiver tracking loop structure of the present invention. FIG. 2;

[0020] 图3为本发明的单独使用码环卡尔曼滤波器的跟踪环路结构图; [0020] FIG. 3 of the present invention used alone code tracking loop configuration diagram of the Kalman filter loop;

[0021] 图4为本发明的单独使用载波环卡尔曼滤波的跟踪环路结构图; Tracking loop structure using separate carrier ring Kalman filter [0021] FIG. 4 of the present invention;

[0022] 图5为本发明的跟踪环路测试结果仿真图。 [0022] FIG 5 FIG tracking loop simulation test results of the present invention.

具体实施方式 Detailed ways

[0023]卡尔曼滤波:卡尔曼滤波器(KalmanFiIter),也被称为线性二次估计,是一种用于离散时间估计的预测算法。 [0023] Kalman filter: Kalman filter (KalmanFiIter), also referred to as linear quadratic estimate is a prediction algorithm for discrete time estimation. 卡尔曼滤波的预测对象被称为状态向量,相邻状态向量的关系用转移矩阵表示。 Relationship Kalman filter prediction target state vector is referred to, the adjacent state vector is represented by the transfer matrix. 通常状态向量是无法直接得到的,可以被测得的量被称为观测向量,每一时刻的状态向量对应着一个观测向量,观测向量与状态向量之间的关系用观测方程表示。 The state vector is usually not directly obtained, the amount can be measured is referred to as an observation vector obtained, each time the state vector corresponds to the relationship between an observation vector, the state vector and the observation vector is represented by an observation equation. 卡尔曼滤波分为更新和校正两部分,其工作流程可以用图1表示。 Kalman filter update and the correction are divided into two parts, which can be represented by the workflow of FIG. 1. 在更新阶段,利用转移矩阵和观测方程计算出先验状态向量和观测量的估计值,在校正阶段,利用真实的观测量对状态向量及其协方差矩阵进行校正,得到后验状态向量并输出。 In the update stage, using the transfer matrix equation and the observed values ​​of the a priori estimate of the state vector and observables, in calibration phase, using real observations of the state vector and covariance matrix correction, obtain and output a posteriori state vector . 新的观测向量又作为输入如此循环迭代更新状态向量。 The new observation vector and input so as to update the state vector loop iteration. 本发明中使用相干积分和非相干积分结果作为观测值,使用本地C/A码码相位和载波频率、多普勒频移、多普勒频移变化率作为状态量,对码环和载波环分别建立了平方根扩展卡尔曼滤波模型。 The present invention using coherent integration and non-coherent integration results as an observation value, using the local C / A code phase and carrier frequency code, Doppler shift, Doppler shift rate of change as the state quantity, and the code ring carrier ring were established root extended Kalman filter model. 码环与载波环的卡尔曼滤波器既可以同时使用在跟踪环路中,也可以与传统的跟踪环路配合单独使用其中一个。 Kalman filter code ring carrier ring may be used simultaneously in both the tracking loop may be used with a conventional tracking loop used alone wherein a.

[0024]下面结合附图进一步说明本发明的技术方案。 [0024] The following further aspect of the present invention is described in conjunction with the accompanying drawings.

[0025]如图2所示,基于卡尔曼滤波的GPS接收机跟踪环路,包括NC0载波发生器、本地C/A 码发生器、多个积分累加模块、码环卡尔曼滤波器和载波环卡尔曼滤波器; [0025] 2, the Kalman filter based GPS receiver tracking loops, including carrier generator NC0, the local C / A code generator, the plurality of accumulation module integrator, a code loop filter, and carrier loop Kalman Kalman filter;

[0026] N⑶载波发生器生成的一路载波信号与输入的中频信号进行相关,得到同相支路数据I;NC0载波发生器生成的另一路载波信号经过90°耦合后与输入的中频信号进行相关, 得到正交支路数据Q; [0026] N⑶ carrier intermediate frequency signal generator generates a carrier signal along with the input of the correlating data obtained in-phase branch I; NC0 carrier generator generating the carrier signals after the other 90 ° with the intermediate frequency signal input coupled to the associated, Q quadrature branch data obtained;

[0027]本地C/A码发生器分别产生三组信号:超前信号E、即时信号P和滞后信号L,超前信号E、即时信号P和滞后信号L分别与同相支路数据I和正交支路数据Q进行相关,然后通过积分累加模块进行积分累加后得到同相支路累加数据Ie、Ip、Il和正交支路累加数据Qe、Qp、Ql; 同相支路累加数据Ie、Ip、Il和正交支路累加信号Qe、Qp、Ql分别与码环卡尔曼滤波器的输入端相连,码环卡尔曼滤波器的输出端连接本地C/A码发生器;同相支路累加数据Ip和正交支路累加信号Qp还分别连接载波环卡尔曼滤波器的输入端,载波环卡尔曼滤波器的输出端与NC0载波发生器相连。 [0027] the local C / A code generator generate three signals: a signal ahead of E, and a prompt signal lag signal P L, advanced signal E, and a prompt signal P L respectively lag signal I and a quadrature phase legs support the same data Q channel data correlation, and by integrating the integral accumulation accumulation module to obtain the accumulated data with the phase leg Ie, Ip, Il and quadrature branches accumulated data Qe, Qp, Ql; phase legs with the accumulated data Ie, Ip, Il and quadrature branch summation signal Qe, Qp, Ql is connected to an input of each code ring Kalman filter, the Kalman filter output terminal is connected to the code ring local C / a code generator; Ip and the data accumulated with the positive phase legs Qp deposit slip accumulated signal input also connected to the carrier ring Kalman filter, connected to the output of the Kalman filter carrier ring NC0 carrier generator.

[0028] 进一步地,所述超前信号E与即时信号P之间相差0.5个C/A码元,即时信号P与和滞后信号L之间相差0.5个C/A码元。 [0028] Further, a difference of 0.5 C / A code element between the immediate early signal E and signal P, a difference of 0.5 Instant C / A code and the P element between the signal and the delay signal L.

[0029] 进一步地,所述码环卡尔曼滤波器采用二阶平方根扩展卡尔曼滤波器,载波环卡尔曼滤波器采用二阶平方根扩展卡尔曼滤波器。 [0029] Further, the second-order Kalman filter loop code root extended Kalman filter, the Kalman filter carrier ring second-order extended Kalman filter is a square root.

[0030] 进一步地,本发明的码环与载波环的卡尔曼滤波器既可以同时使用在跟踪环路中,也可以与传统的跟踪环路配合单独使用其中一个:采用码环鉴相器代替本发明的码环卡尔曼滤波器,即只对载波跟踪环路采用卡尔曼滤波模型;采用环路滤波器代替载波环卡尔曼滤波器,即只对码环跟踪环路采用卡尔曼滤波模型。 [0030] Further, the Kalman filter code carrier ring and the ring of the present invention may be used simultaneously in the tracking loop may be used with a conventional tracking loop used alone wherein one of: a code loop discriminator employed in place of code Kalman filter loop of the present invention, i.e., only the Kalman filter model for a carrier tracking loop; instead of using a loop filter carrier ring Kalman filter, that is, only the code loop tracking loop Kalman filter model.

[0031] 下面通过仿真平台分别对单独使用码环卡尔曼滤波器、单独使用载波环卡尔曼滤波器、同时使用码环卡尔曼滤波器和载波环卡尔曼滤波器进行性能验证。 [0031] Next, by using the simulation platform, respectively Kalman filter code ring alone, a separate carrier ring Kalman filter, the Kalman filter using both the code loop and the carrier loop Kalman filter performance verification.

[0032] 1、单独使用码环卡尔曼滤波器,其跟踪环路如图3所示,仿真中一共产生了两种信号,第一种信号中包含载波、C/A码和噪声,第二种信号只包含载波和噪声。 [0032] 1, a separate code ring Kalman filter, which is shown in FIG tracking loop, two simulation produced a total of 3 signal, a first signal includes a carrier, C / A code and the noise, second species signal containing only the carrier and the noise. 载波的取值范围为[_1,1],使用PRN为21的C/A码,取值范围为{1,-1}。 Carrier is in the range [selected, 1], the use of PRN C / A code 21, in the range of {1, -1}.

[0033] 单独测试码跟踪环使用二阶扩展卡尔曼滤波的仿真中,使用包含C/A码的第一种信号。 [0033] tested separately second order code tracking loop simulation using the extended Kalman filter, comprising the use of C / A code of a first signal. 载波信息由理想的载波环提供,本地复现载波与接收信号一致。 Provided by the carrier over the carrier ring, it is consistent with the local carrier reproduced received signal. 与传统的跟踪方法相比,是将其中的码环鉴相器和环路滤波器由卡尔曼滤波代替了,卡尔曼滤波将码相位误差输出给本地C/A码发生器以调节复现C/A码的相位。 Compared with the traditional tracking method, which is a code loop phase detector and the loop filter instead of the Kalman filter, the Kalman filter outputs the phase error code to a local C / A code generator to adjust the reproduction C / a code phase.

[0034] 状态向量x是单位为秒的本地C/A码的码相位与接收信号C/A码的相位差,初始值x =〇,即假设本地C/A码与接收信号C/A码没有相位误差。 [0034] The state vector x is a unit for the second phase of the local C / A code of the code phase of the received signal C / A code, the initial value x = square, i.e., assuming the local C / A code and the received signal C / A code no phase error. 由于每次校正后,C/A码码相位误差应该是0,且在之后的更新中维持不变,所以状态转移方程A为单位矩阵。 Because after each correction, C / A code phase error code should be 0, and remained unchanged after the updating, the state transition equation for the matrix A.

[0035] 传播噪声v在实际中来源于接收机时钟晶振的噪声。 [0035] v watch crystal propagation from the receiver noise noise in practice. 状态向量协方差矩阵P表示C/ A码码相位误差的方差,根据捕获的原理可知,跟踪开始时码相位五码不超过半个码片,由于状态向量x是以时间为单位的,所以状态向量协方差矩阵初始值为半个码片时长的平方。 The state vector covariance matrix C P represents the code phase error variance / A code, in accordance with principles known captured, tracking code phase at the beginning of no more than five yards half a chip, since the state vector x based on units of time, the state vector covariance matrix initial value of the square of half the code length films.

[0036] 观测向量z使用非相干积分,为 [0036] The measurement vector z used noncoherent integration, as

[0037] [0037]

Figure CN106338748AD00061

[0038] 其中,4^、分别表示超前信号E、即时信号P和滞后信号L与同相支路数据I的第W欠非相干积分; [0038] wherein ^ 4, respectively early signal E, and a prompt signal P and L lag signal I with the data of the W phase arm under non-coherent integration;

Figure CN106338748AD00062

t分别表示超前信号E、即时信号P和滞后信号L与正交支路数据Q的第W欠非相干积分;超前信号E与同相支路数据I的第v次相干积分则以 t represent early signal E, and a prompt signal P and L lag signal Q of the quadrature branch data W under non-coherent integration; advance signal I E and the v-th phase legs with the coherent integration data places

[0039] 所观测向量中超前信号支路的非相干积分结果的期望为 [0039] noncoherent integration result signal ahead branch vector desirably observed

[0040] [0040]

Figure CN106338748AD00063

[0041]类似可以得出即时信号和滞后信号支路的观测结果期望,将不含C/A码相关值衰减的信号成分的幅度记为Av,即 [0041] Similar observations can be drawn prompt signal and the delay signal branch result desired, the amplitude of the signal component containing no C / A code correlation value is referred to as the attenuation Av, i.e.

[0042] [0042]

Figure CN106338748AD00064

[0043] 其中4^表示第W欠相干积分周期内信号幅度,Nvk表示设定的非相干积分次数。 [0043] ^ 4 wherein W represents less coherent integration period signal amplitude, Nvk represents the number of noncoherent integration set.

[0044] 则观测向量Zv的期望值可以由Av表示为 [0044] the desired value Zv observation vector may be represented by Av is

[0045] [0045]

Figure CN106338748AD00065

[0046] 为了得到观测向量< 的估计值,在第W欠滤波中首先根据即时码支路的积分结果和设定的相干积分次数%可以计算出Av的估计值。 [0046] In order to obtain observation vectors <estimated value of W under the first filtering the estimated value Av can be calculated based on an integration result of immediate branch code and coherent integration times set%.

[0047] 进而可以计算出观测向量的估计值毛。 [0047] Further we can calculate the estimated value of the gross observation vector.

[0048] 2、单独使用载波环卡尔曼滤波器,其跟踪环路如图4所示,使用只有噪声和载波的第二种信号。 [0048] 2, using the Kalman filter individual carrier ring, which follow, the use of noise-only signal and a second carrier ring 4 as shown in FIG. 状态向量x的初始值由捕获结果提供,载波相位值初始化为〇,多普勒频移为准确值。 The initial value of the state vector x is provided by the captured result, the carrier phase value is initialized square, the exact value of the Doppler shift. 卡尔曼滤波器不断输出校正后的载波相位、多普勒频移和多普勒频移的变化率以产生本地信号。 Kalman filter continuously outputs the corrected carrier phase, Doppler shift and rate of change of Doppler shift signals to generate local.

[0049] 载波跟踪的扩展卡尔曼滤波中,状态向量为 [0049] The carrier tracking extended Kalman filter, a state vector is

[0050] xu=[9u wu au]T [0050] xu = [9u wu au] T

[0051]状态向量的三项分别表示经过第u次卡尔曼滤波校正后,本地对接收信号在当前相关周期内第一个采样点处的载波相位、多普勒频移和多普勒频移的加速度的估计值,单位分别为rad,rad/s,rad/s2。 Three [0051] denote the state vector after the u-th Kalman filter corrected carrier phase of the received signal at a first sample point in the current local correlation period, Doppler shift and Doppler shift the estimated value of the acceleration unit are rad, rad / s, rad / s2.

[0052]仿真中假设多普勒频移的加速度恒定不变,设第u次参与积分计算的信号采样点总时长为Tu,卡尔曼滤波的状态转移方程为 [0052] The simulation assumed that the Doppler shift of the acceleration constant, provided the u-th integral calculation involved in signal sampling point when the total length of Tu, the Kalman filter state transition equation

[0053] [0053]

Figure CN106338748AD00071

[0054]载波环中的扩展卡尔曼滤波使用即时码的相干积分值作为观测向量,观测向量为 [0054] Extended Kalman filter carrier ring code using the instant coherent integration value as the observation vector, the observation vector is

[0055] [0055]

Figure CN106338748AD00072

[0056] 则观测向量z的期望值为 [0056] the observation vector z is the expected value

[0057] [0057]

Figure CN106338748AD00073

[0058]其中Au表示理想情况下同相支路的积分幅值。 [0058] where Au represents the magnitude of the integral over the same below the phase legs. 观测向量的期望值的估算为 We estimate the expected value of the observation vector is

[0059] [0059]

Figure CN106338748AD00074

[0060] 观测噪声是相干积分中的噪声,协方差R为12X2。 [0060] The observation noise is coherent integration noise covariance R is 12X2.

[0061] 3、同时使用码环卡尔曼滤波器和载波环卡尔曼滤波器,其跟踪环路如图2所示。 [0061] 3, while using the code loop and the carrier loop Kalman filter is a Kalman filter, which tracking loop as shown in FIG. 码环和载波环都使用卡尔曼滤波的仿真中,使用了包含C/A码的第一种信号。 Code and carrier ring ring simulation uses Kalman filter, a first signal comprises the C / A code. 与传统的跟踪方法相比,是将其中的码环鉴相器和环路滤波器由卡尔曼滤波代替了,假设初始化时捕获环节给出了准确的C/A码起始位置采样点的序号和准确的多普勒频移,载波相位初始化为0。 Compared with the traditional tracking method, which is a code loop phase detector and the loop filter is replaced by a Kalman filter, the link is assumed to initialize the capture gives an accurate C / A code to the start position of the sampling point number and accurate Doppler shift, the carrier phase is initialized to zero. [0062]在第u次更新时,本地载波发生器产生同相、正交支路的本地复现载波,本地C/A码发生器载波频偏产生超前、即时、滞后三路本地复现C/A码。 [0062] When the u-th update the in-phase local carrier generator, a local carrier wave reproduction of the quadrature branch, the local C / A code generator generates a carrier frequency offset in advance, instant, three-way local reproducible hysteresis C / A code. 将本地复现信号与接收信号做相关后的相干积分值和非相干积分值作为卡尔曼滤波器的输入,卡尔曼滤波器的输出包括:本地C/A码码相位误差、校正后的载波相位、多普勒频移和多普勒频移的变化率。 The local reproduction signals associated with the received signal to make the values ​​of coherent integration and non-coherent integration Kalman filter as an input value, the output of the Kalman filter comprising: a local carrier phase after the C / A code code phase error correction , Doppler shift and rate of change of Doppler shift. 这些参数被用于下一次积分周期中产生本地复现信号。 These parameters are used for the next integration period to generate a local signal reproduction.

[0063] 仿真平台测试了在以上三种情况下,载噪比从13dB-Hz以1为步长增加到22dB-Hz, 积分时间为400ms,跟踪开始时给出了理想的捕获结果。 [0063] The simulation platform tested in the above three cases, the carrier to noise given the results from the capture of over 13dB-Hz is increased in steps of 1 to 22dB-Hz, the integration time of 400ms, than the start of tracking. 测试结果如图5所示。 Test results are shown in FIG. 图中三条曲线都随载噪比上升呈现下降趋势。 Figure three curves are rising with the carrier to noise ratio downward trend. 也可看出在一个环路提供了理想结果时,整体的跟踪性能得到了提升。 When also be seen in the results over a loop, the overall tracking performance has improved. 仅使用载波卡尔曼滤波的曲线性能优于仅使用码环卡尔曼滤波的结果说明了码跟踪环的性能对跟踪结果的影响比载波跟踪环更大。 Kalman filter using only the carrier profile superior to using only the ring result code illustrates the Kalman filter code tracking loop affects the performance of the tracking result is larger than the carrier tracking loop. 在传统的跟踪环路中,若码环鉴相器使用超前减滞后法,其理论方差在载噪比为22dB-Hz时已达26m。 In a conventional tracking loop, a code loop discriminator when using lead lag subtraction method, the variance has reached its theoretical 26m when the carrier to noise ratio of 22dB-Hz. 而载噪比低至13dB-Hz时使用两个卡尔曼滤波的跟踪环路仍能保持对信号的跟踪并且跟踪误差在l〇m以内,相比于传统的跟踪方法性能大大提尚。 And carrier to noise ratio using two Kalman filter as low as 13dB-Hz tracking loop can keep track of the tracking error signal and l〇m less, compared to the conventional methods are still greatly enhanced tracking performance.

[0064]本领域的普通技术人员将会意识到,这里所述的实施例是为了帮助读者理解本发明的原理,应被理解为本发明的保护范围并不局限于这样的特别陈述和实施例。 [0064] Those of ordinary skill in the art will appreciate that the embodiments described herein are to aid the reader in understanding the principles of the present invention, it should be understood that the scope of the present invention is not limited to such embodiments and specifically stated . 本领域的普通技术人员可以根据本发明公开的这些技术启示做出各种不脱离本发明实质的其它各种具体变形和组合,这些变形和组合仍然在本发明的保护范围内。 Those of ordinary skill in the art can make various modifications and other various concrete compositions of the present invention without departing from the spirit of techniques according to teachings of the present disclosure, it is still within the scope of the present invention such variations and combinations.

Claims (6)

1. 基于卡尔曼滤波的GPS接收机跟踪环路,其特征在于,包括NCO载波发生器、本地C/A 码发生器、多个积分累加模块、码环卡尔曼滤波器和载波环卡尔曼滤波器; NC0载波发生器生成的一路载波信号与输入的中频信号进行相关,得到同相支路数据I;NC0载波发生器生成的另一路载波信号经过90°耦合后与输入的中频信号进行相关,得到正交支路数据Q; 本地C/A码发生器分别产生三组信号:超前信号E、即时信号P和滞后信号L,超前信号E、 即时信号P和滞后信号L分别与同相支路数据I和正交支路数据Q进行相关,然后通过积分累加模块进行积分累加后得到同相支路累加数据Ie、IP、Il和正交支路累加数据Qe、Qp、QL;同相支路累加数据Ie、Ip、Il和正交支路累加信号Qe、Qp、Ql分别与码环卡尔曼滤波器的输入端相连,码环卡尔曼滤波器的输出端连接本地C/A码发生器;同相支路累 1. Kalman filter based GPS receiver tracking loop, wherein the NCO comprises a carrier generator, a local C / A code generator, the plurality of accumulation module integrator, a code loop and the carrier loop Kalman filter Kalman filter device; the NC0 carrier generator generates a carrier signal along the intermediate frequency signal inputted to the correlation data to obtain the in-phase branch I; NC0 carrier generator generating a carrier signal of the other path is coupled after the 90 ° IF signal correlated with the input, to give Q quadrature branch data; local C / A code generator generate three signals: a signal ahead of E, and a prompt signal lag signal P L, advanced signal E, and a prompt signal P L respectively lag signal inphase data I leg and Q quadrature branch related data, and then by integrating the integral accumulation accumulation module obtained after the accumulated data Ie same phase leg, IP, Il and quadrature branches accumulated data Qe, Qp, QL; phase legs with the accumulated data Ie, Ip, Il and quadrature branches summation signal Qe, Qp, Ql is connected to an input of each code ring Kalman filter, the Kalman filter output terminal is connected to the code ring local C / a code generator; tired legs inphase 数据Ip和正交支路累加信号Qp还分别连接载波环卡尔曼滤波器的输入端,载波环卡尔曼滤波器的输出端与NC0 载波发生器相连。 Accumulating data signals Ip and Qp quadrature branches are also connected an input terminal of the Kalman filter carrier ring, the carrier ring is connected to the output of the Kalman filter NC0 carrier generator.
2. 根据权利要求1所述的基于卡尔曼滤波的GPS接收机跟踪环路,其特征在于,所述超前信号E与即时信号P之间相差0.5个C/A码元,即时信号P与和滞后信号L之间相差0.5个C/A 码元。 The GPS receiver tracking loop based on the Kalman filter as claimed in claim 1, wherein a difference of 0.5 C / A code element between the immediate early signal E and signal P, and the prompt signal P a difference of 0.5 C / A code element between the delay signal L.
3. 根据权利要求1所述的基于卡尔曼滤波的GPS接收机跟踪环路,其特征在于,所述码环卡尔曼滤波器采用二阶平方根扩展卡尔曼滤波器。 According to claim Kalman filter based GPS receiver tracking loop of claim 1, wherein said second-order Kalman filter loop code root extended Kalman filter.
4. 根据权利要求1所述的基于卡尔曼滤波的GPS接收机跟踪环路,其特征在于,所述载波环卡尔曼滤波器采用二阶平方根扩展卡尔曼滤波器。 GPS receiver according to claim Kalman filter based tracking loop of claim 1, wherein the carrier loop Kalman filter is an extended Kalman filter uses a square root of second order.
5. 根据权利要求1所述的基于卡尔曼滤波的GPS接收机跟踪环路,其特征在于,采用码环鉴相器代替码环卡尔曼滤波器。 GPS receiver according to claim Kalman filter based tracking loop of claim 1, wherein the loop using code instead of the code phase Kalman filter loop.
6. 根据权利要求1所述的基于卡尔曼滤波的GPS接收机跟踪环路,其特征在于,采用环路滤波器代替载波环卡尔曼滤波器。 GPS receiver according to claim Kalman filter based tracking loop of claim 1, wherein the carrier loop instead of using a loop filter Kalman filter.
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