共查询到20条相似文献,搜索用时 20 毫秒
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Yiwei Wang Wengang Li 《International Journal of Satellite Communications and Networking》2019,37(3):183-199
The discrimination function shaping method has been proposed to improve the anti‐multipath performance for a global navigation satellite system receiver. However, the existing methods fail to fully exploit the potential anti‐multipath performance of multiplexed binary offset carrier (MBOC)–modulated signals. In this paper, a code phase discrimination function shaping method is proposed for a Compass B1C quadrature MBOC‐modulated signal. The in‐phase binary offset carrier (BOC) (1,1) signal and quadrature‐phase BOC (6,1) signal replicas are designed according to the least squares estimation. Then a shifted cross‐correlation function (CCF) between the in‐phase BOC (1,1) signal and its pseudorandom noise code is multiplied with the obtained CCFs to ensure an unambiguous tracking. Finally, a discrimination function with a small pull‐in range can be obtained by a weighed combination of the in‐phase and quadrature‐phase CCFs. A computer simulation is conducted to assess the performances under multipath and thermal noise conditions. 相似文献
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第3代北斗卫星导航系统中B1C频点信号将使用正交复用二进制偏移载波调制方式。为了增强北斗卫星导航接收机码跟踪环路的抗多径性能并且解决码跟踪中的模糊跟踪问题,该文针对正交复用二进制偏移载波调制信号QMBOC(6, 1, 4/33)提出一种双闸波码跟踪环路结构。根据理想的目标鉴相函数和二进制偏移载波调制信号自相关函数的特点分别设计出针对BOC(1, 1)和BOC(6, 1)信号的闸波,并在本地码跟踪环路中使用这两种不同的闸波分别与输入信号相关,最后将所得的两个相关函数进行加权合并以用于鉴相过程。计算机仿真结果表明所提方法不仅能够有效消除QMBOC(6, 1, 4/33)信号的模糊跟踪可能性,且能够大幅增强接收机的抗多径性能,其对应多径误差包络面积相比于现有的方法能够减少约33%。 相似文献
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The binary offset carrier (BOC) modulated signal can improve the positioning accuracy and increase the multipath resistance in global navigation satellite system (GNSS), and it may cause potential ambiguity in the process of signal acquisition and code tracking. In this paper, a simple but efficient unambiguous receiver is firstly proposed for multiple side‐peaks mitigation by implementing correlation of the received BOC signal with local sine wave instead of square wave used at the transmitter. Moreover, the potential degradation of sharpness of the nonlinear correlation induced by the sine wave is well compensated by optimizing the early‐to‐late spacing. The other reason leading to ambiguity is the multipath propagation, so we further propose a maximum likelihood (ML) estimator with Newton iteration method, where the received GNSS signal is modeled via the line‐of‐sight (LOS) component and the first‐arrived non‐line‐of‐sight (NLOS) component. Finally, the analytical expression of multipath propagation Cramer‐Rao bound is derived for the designed ML estimator. Simulation results indicate that compared with the conventional BOC modulation, the proposed sine wave receiver can achieve unambiguous and more precise code tracking performance and thus turns out to be more robust to multipath propagation. 相似文献
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叉积鉴频器的输出频率范围比较窄,捕获信号以后的多普勒频偏可能不在其跟踪范围内。针对此问题,提出了使用四相鉴频器( FQFD )算法辅助已经成型的二阶锁频环加三阶锁相环模型。首先,利用四相鉴频器的非线性特性将接收信号频偏大步长牵引到较低范围,然后使用锁频环消除其大部分动态性,最后利用锁相环跟踪精度高的特点实现高动态二进制偏移载波( Binary Offset Car-rier,BOC)信号载波的快速准确跟踪。在分析各跟踪模块算法的基础上,讨论了其本身的热噪声误差、动态适应力以及最优带宽等相关问题,理论分析和仿真结果验证了该方法比原有跟踪算法提高了300 Hz左右的鉴频范围,并且跟踪效果良好。 相似文献
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Hui Hua Chen Wei Min Jia Min Li Yao 《Wireless Communications and Mobile Computing》2014,14(15):1500-1508
Global Navigation Satellite Systems positioning accuracy indoor and urban canyons environments are greatly affected by multipath because of distortions in its autocorrelation function. In this paper, we propose a new multipath mitigation technique based on the concept of S‐curve shaping for the new alternative binary offset carrier (AltBOC)‐modulated signals, which will most likely be used in both European Galileo system and Chinese Compass system. The definition of an optimum S‐curve is employed to reduce the false lock points and to improve the multipath mitigation capability via determining the shape of the local code tracking reference function. The structure of the proposed code tracking loop for AltBOC signals is quite simple and only requires one complex correlator. Results demonstrate that the proposed technique provides superior multipath mitigation performance compared with the conventional receiver correlation techniques and removes the ambiguity completely. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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针对同阶二元偏移载波调制卫星导航信号,提出一种高效新算法解决信号跟踪中的模糊性。分析了同阶二元偏移载波调制原理、信号跟踪模糊性及解决方法,利用本地扩频码与接收信号的相关函数特点,构建了码跟踪环路鉴相曲线,选择了合适的相关间距作为符号判决,联合构成鉴相器,推导了算法设计的正确性,给出了实现架构。仿真结果表明,码相位捕获误差±0.9个码片内均可正确跟踪。该方法可进一步应用于全球卫星导航系统新体制信号的接收处理。 相似文献
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针对传统GPS接收机跟踪环路结构复杂,以及在低信噪比(SNR)、高动态条件下跟踪性能较差的问题,该文提出一种基于相位条纹斜率检测的跟踪新方法。通过采用到达时差(TDOA)的频域相位测量伪码时延,到达频差(FDOA)的时域相位测量载波多普勒频偏。该方法降低了环路实现的复杂度,同时提高了跟踪精度。仿真结果验证了该方法的有效性和稳定性,在载噪比为32 dB-Hz时,相比传统方法,基于TDOA/FDOA相位条纹法的码相位测量精度提高了60%,载波多普勒测量精度提高了31%,且在高动态环境中也能实现精确跟踪,对改善GPS接收机跟踪性能具有研究意义。 相似文献
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A new method for carrier recovery in an MPSK DS/CDMA receiver is presented. The proposed scheme employs two balanced X-correlators to form a frequency discriminator which has a tracking range of double the symbol rate, and the tracking range is independent of the keying phase number and the spreading code length 相似文献
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短时突发相移键控(PSK)通信具有隐蔽性好、信道利用率高的特点,得到广泛应用。将已调信号非线性放大、限幅处理,使其幅度稳定在一定范围,基于锁相原理得到与已调信号同步的本地载波,是PSK信号解调相干载波恢复的常用方法。然而接收信号的非线性处理,会使PSK信号信噪比急剧下降,影响载波相位跟踪精度,给帧同步信号生成和码元抽取带来不确定性,导致误码率升高。针对常规方法存在的问题,提出了基于Hilbert变换的短时PSK信号自适应解调算法,通过信号归一化,在不降低解调信号信噪比情况下,确保载波恢复运算不受数据信号幅度的影响,具有恢复速度快、跟踪精度高、帧同步信号解调可靠、码元采样时间准确的特点。 相似文献
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Wafa Feneniche Khaled Rouabah Mustapha Flissi Salim Atia Salah Eddine Mezaache Sabrina Meguellati 《International Journal of Communication Systems》2020,33(9)
In this paper, we propose an efficient method for eliminating ambiguity in the acquisition and tracking processes of binary offset carrier (BOC)‐modulated signals. Our contribution is realized in two stages. The first one is based on the use, at the receiver end, of optimized locally generated subcarrier sequences to get a completely unambiguous composite correlation function (CF). This first stage is used to initialize and control the second stage of the proposed method designed on the basis of a maximum likelihood algorithm (MLA) to mitigate, specifically, multipath (MP) effect. In fact, the idea is to combine, in this second stage, the received signal (affected by noise and MP) with a set of locally generated ideal BOC(m,n)‐modulated signals, which are delayed and weighted by the MLA‐estimated parameters of delays, amplitudes, and phases of all the MP signals, to obtain an unambiguous CF with better performance. The simulation results, based on MATLAB tool, have demonstrated that the proposed method effectively eliminates the ambiguity problem. Besides, a comparative study with several methods has shown that the proposed method grants better performance than the most popular techniques. 相似文献
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A novel navigation signal design method based on spread code time shift position modulation was proposed,which inherits the idea of separating the pilot signal component and the data signal component,and applies time shift position of the spread code to carry data information.The old pattern of using carrier phase to carry information was changed,the power efficiency of data signal components and the performances of the satellite navigation system were improved.Theoretical analysis and simulation results show that the proposed method can significantly improve the transmission rate of data signal component or power ratio of the pilot signal component to data signal component without increasing the total transmission power.Then,the transmission rate,acquisition and tracking performance,positioning accuracy and other technical indicators of the satellite navigation system can be further improved. 相似文献
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Global Satellite Navigation System (GNSS) is applied widely in many fields nowadays, but is still quite limited under complex signal environments, especially weak signal situation. And the major limitation comes from the signal tracking algorithm in GNSS receiver. To solve this problem, this paper mainly deals with performance enhancement for traditional tracking framework. By inviting definition of digital equivalent bandwidth and analyzing sensitivity and stability, this framework is deeply discussed, and the relationship between correlation time and loop bandwidth setting becomes clearer. Based on this foundation, an adaptive tracking algorithm is proposed with longer correlation time under vibrated signal attenuation situation, via statistical learning of carrier phase discriminator outputs. Experiments demonstrate that our proposed algorithm outweighs the traditional one with more gain of sensitivity and stable adaptation under attenuated data situation. 相似文献
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The delay-lock discriminator is a nonlinear feedback system which employs a form of cross correlation to estimate the relative delay between a reference signal and a delayed version of that signal which is perturbed with additive noise. Previous treatments of delaylock tracking have assumed that the binary maximal-length code sequences used as the signal are detected in a coherent manner. The present paper is concerned with delay-lock discriminator tracking behavior when noncoherent detection of the received signal is required and when two-bit quantization is employed to reduce the cost of implementation of the cross-correlation network. It is found that the error signal generated by the cross-correlation network is characterized by "clustering" in the absence of noise, however, this mode of error signal behavior gradually vanishes as the noise level is increased and is replaced by an error signal generation characteristic that more closely resembles the behavior that obtains without quantization. The selection of an appropriate threshold value to achieve minimum steady-state errors for the delay-lock discriminator is reduced to the problem of determining the probability density function of the error signal under the condition of exact alignment. 相似文献
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卫星双向时间频率传递是目前被广泛应用的远距离高精度时间频率量值传递方法,其核心组成设备是双向时间比对调制解调器.文章介绍了由北京无线电计量测试研究所研制的卫星双向时间比对调制解调器,该设备采用直接序列扩频(DSSS)和二进制相移键控(BPSK)方式完成时间信号的调制,采用快速傅里叶变换(FFT)算法实现对信号的快速搜索和捕获;利用二阶锁频辅助三阶锁相环路达到动态性能和跟踪精度的平衡;采用二阶延迟锁定环(DLL)来实现对码相位的精密跟踪和测量.采用两个1.2m口径天线的双向比对地球站进行短基线卫星双向时间比对试验,试验结果表明当系统工作在2.5MChip/s码速率时,该调制解调器的时间比对精度(标准偏差(1σ))能够达到0.13ns. 相似文献
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M. R. Mosavi M. Soltani Azad I. EmamGholipour 《Wireless Personal Communications》2013,72(4):2563-2576
Today Global Positioning System (GPS) is the most important system of positioning in the world and is used in different industries. Basic positioning methods in GPS receivers are based on pseudo-range and carrier phase measurements types whilst each of which has its own advantages and disadvantages. Pseudo-range method is not very much accurate. Carrier phase has a substantial accuracy, but its main problem is that it is an indirect measurement which only computes the displacement. Carrier phase measurement can include some whole cycles plus a fraction of carrier phase. The number of whole cycles may change through time however this change is unknown for us. Code measurements (based on pseudo-range) and carrier phase are corrupted with the same error sources, but with main differences. Basically, code tracking with low accuracy makes unambiguous pseudo-ranges. Carrier phase measurements are highly accurate, but get limited with integer ambiguity. Integer is fixed until the time that carrier tracking loop is saved. Every kind of gap in tracking, no matter how short it is, changes the amount of integer which is the biggest problem in carrier phase utilization. In this paper, the corporation of pseudo-range capability and carrier phase in single-frequency GPS receivers will be discussed which makes a substitute for the pure pseudo-range observations and provides a high level of positioning accuracy. To achieve this aim, Kalman filter will be used. 相似文献