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多载波频率分集扩展频谱通信的同步原理分析 总被引:6,自引:1,他引:5
多载波频率分集扩展频谱通信系统(FD/SSMA)是基于多载波传输技术上的一种新的扩展频谱多址系统。本文分析研究该系统的同步原理,其中包括接收机参考信号与所接收信号的定时同步的识别、定时同步的跟踪、载波频率跟踪及载波相位跟踪。分析表明,通过三个误差信号,即定时同步误差信号、载波频率误差信号及载波相位误差信号的获取及它们对系统的控制,从原理上解决了FD/SSMA系统的同步问题 相似文献
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介绍了靶场测量雷达新一代引导接收机。它是一种模拟/数字混合型锁相接收机,可对USB(UnifyS-Band)信号进行谱线识别和谱线跟踪,其捕捉范围和跟踪范围可达±180kHz。它能提供目标角误差信号、目标强度信息和目标速度信息。 相似文献
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电磁环境日益恶劣且到达接收机的导航信号非常微弱,导航接收机的输出性能受干扰影响非常明显,因此在干扰背景下提高导航接收机的输出性能是十分重要的。阵列信号处理中的传统抗干扰方法包括采样协方差矩阵求逆 SMI(Sample Matrix Inverse)方法、最小均方误差 LMS(Least Mean Square)迭代方法、功率倒置 PI(Power Inverse)算法等,这些方法具有较高的抗干扰性能,但抗干扰后对信号增强没有效果。本文在子空间投影抗干扰方法的基础上,结合导航信号相关性特点,对子空间投影后信号进行运算,构造最优相关峰矢量,利用该矢量进行波束合成,实现导航信号增强的目的。对实测数据处理可知,该方法可以有效提高抗干扰后导航信号强度。 相似文献
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GPS接收机中晶振误差的模拟方法 总被引:8,自引:0,他引:8
GPS(Global Positioning System)接收机中参考频率源的性能对接收机整体性能有着诸多影响。该文对在GPS接收机中使用最多的晶振的误差特性和性能影响进行了分析,在此基础上提出了一种模拟晶振频率误差的方法,即首先确定晶振在给定取样时间间隔上各主要随机误差成分的Allan(阿仑)方差参数,由此反演产生相应的各项晶振频率误差模拟序列并进行叠加。文中给出了计算机数值模拟的方法,并对仿真实验结果进行了分析,从而为GPS接收机设计、性能评估和测试平台如GPS信号模拟器的研制提供有关的理论支持和设计方法。 相似文献
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本文分析了多径衰落信道的相关特性,计算了利用RAKE接收机实时测量信号功卓的误差。结果表明,采用RAKE接收机进行测量可以显著提高测量的准确性.同时,研究了各种因素对测量滤波器性能的影响。 相似文献
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全数字接收机的结构及关键技术 总被引:7,自引:1,他引:6
全数字接收机是近几年提出的新的接收机结构,它采用高稳定度晶体振荡器产生本地时钟用于解调及采样,载波相差和时钟寒时误差的消除,信号的判定等全部由数字信号处理器来完成,本文介绍了全数字接收机的体系结构,并对其实现的关键技术进行详细的讨论。 相似文献
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单比特数字接收机 总被引:5,自引:0,他引:5
介绍了单比特电子战数字接收机的基本原理,该接收机在简化DFT算法的同时采用低比特A/D变换,降低了宽带电子战接收机的实现难度,克服了由于超宽带高速采样带来的一系列问题。分析了加窗对单比特接收机的性能影响,并给出了一种基于DSP的实现方法,在此基础上建立了一个单比特电子战系统测试系统。利用该系统通过仿真试验,详细研究了单比特接收机的虚警概率、检测概率及双信号动态范围,并与DFT接收机进行了比较,并指出除了双信号动态范围较小外,单比特电子战接收机的性能基本相同。增加输入信号的比特数是提高单比特电子战接收机双信号动态范围的有效方法,当采用2比特量化时该动态范围可以增加5dB。最后分析了该接收机的应用前景。 相似文献
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基于欠抽样技术的软件单边带接收机 总被引:1,自引:0,他引:1
理想的软件单边带接收机应该是对射频信号直接进行抽样,在通用数字信号处理器中用软件完成单边带接收机的所有功能。但是,由于DSP速度的限制,目前对无线电接收机的软件化还只局限于中频。本文在讨论了欠抽样技术在软件单边带接收机中的应用的基础是,提出了一种对中频信号直接采样的软件单边逼带接收机的软硬件实现方案。 相似文献
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由模拟器件构成的宽带正交解调接收机会由于正交通道的幅相不一致性造成整个系统的失真,进而影响整个接收系统的性能。本文仔细分析了幅相误差对接收机性能的影响,提出了基于FIR滤波的一种数字域校正的方法。通过计算机彷真,证实了该方法的可行性。 相似文献
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In this paper, a new spatial quadrature modulation ( NSQM ) scheme is proposed to improve the error
performance of indoor visible light communication ( VLC) systems. NSQM is different from generalized spatial
quadrature modulation ( SQM) in two aspects. First, the transmitted optical signal is directly detected at the
receiver, which does not need to estimate the indices of the transmitted antenna. Second, an optimization approach
is used with NSQM to minimize the upper error bound of the transmitted signals. In addition, several NSQM
schemes are described in detail. Numerical results show that the proposed NSQM scheme achieves superior error
performance compared with the SQM scheme. 相似文献
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In this paper, we present a new partially coherent receiver architecture motivated by optimum detection of quadrature amplitude modulation (QAM) signals in the presence of time-varying Tikhonov-distributed residual phase estimation error due to phase-locked loop (PLL)-aided phase tracking scheme. Performance is established in terms of bit error rate (BER). In this paper, an approximate performance measure motivated by union bound is presented for the proposed receiver architecture for 8- and 16-QAM constellations. The performance measures are assessed via simulation and analytical means for additive white Gaussian noise (AWGN) as well as for Rayleigh and Rician fading channels. The performance measures are shown to follow those of the optimum receiver over a wide range of signal-to-noise ratio (SNR), while outperforming a standard coherent receiver operating in the presence of residual phase error by as much as 2 dB. 相似文献
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超宽带正交解调接收机的误差分析与数字补偿方法 总被引:5,自引:0,他引:5
本文提出了超宽带正交解调接收机的误差分析方法,并且针对超宽带线性调频信号,分析了超宽带正交解调误差对脉冲压缩的影响,然后提出了超宽带正交解调误差的数字补偿方法,在实际系统中获得了比较理想的脉冲压缩输出响应。 相似文献
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The receiver processing that is often employed for direct-sequence spread spectrum with quaternary data modulation operates separately on in-phase and quadrature components of the spread-spectrum signal. Previous results on complex quaternary sequences, which are also referred to as four-phase sequences, provide a strong motivation to employ alternative processing methods that permit the receiver to benefit from the correlation properties of these sequences. With this goal in mind we present receiver architectures that use complex processing and are capable of demodulating the signals proposed for the third-generation mobile cellular code-division multiple-access systems. The performance of the proposed receiver architecture with complex processing is shown to be determined by the complex aperiodic correlation functions for the spreading sequences. Comparisons are made with systems in which the quaternary sequences are derived from pairs of common binary spreading sequences and the receiver employs separate in-phase and quadrature processing. We find that in spite of their superior periodic crosscorrelation properties, the previously developed quaternary sequences do not provide significantly smaller error probabilities in multiple-access systems 相似文献
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A maximum-likelihood sequence estimation (MLSE) receiver structure for constant-envelope quadrature pulse-overlapping modulated (QPOM) signals in fading channels is presented. QPOM is first decomposed into a liner encoder followed by a memoryless modulator. The trellis diagram representing this inherent nonredundant coding structure is then used to construct its MLSE receiver. The upper bounds on the average bit error probability in both AWGN and Rayleigh fading channels are derived. Computer simulations are also used to verify the analytical results. In fast-fading shadowed mobile satellite channels the scheme is shown to outperform conventional QPSK techniques. It maintains the low complexity of 4PSK, but its performance is comparable to that of four-state 8PSK TCM schemes. The constant envelope, compact spectrum, superior performance, and low complexity enable QPOM to meet the requirements of low cost, small size, and high power and bandwidth efficiencies for portable/mobile satellite systems 相似文献
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Chirp (linear FM) signals provide an attractive wideband digital modulation scheme in applications where interference rejection is important. This paper evaluates the error rate (performance) of coherent binary continuous phase chirp (CPC) receivers operating on the additive white Gaussian noise (AWGN) channel and determines the improvement in performance made possible by multiple bit observation. In particular, it is shown that a receiver with two bit observation, giving up to 1.75 dB signal-to-noise ratio (SNR) improvement over the optimum single bit chirp receiver, provides a good compromise between SNR gain and system complexity. Furthermore, a simple, suboptimum, average matched filter (AMF) receiver is analyzed, and it is shown that a two-bit observation is optimum, giving a performance equivalent to that of antipodal phaseshift keying (PSK). An implementation of this receiver in the form of in-phase and quadrature demodulators is also derived. 相似文献
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Xinping Huang 《Communications Letters, IEEE》2000,4(11):363-365
This letter explores the benefits of compensating for transmitter gain and phase imbalances in a receiver for quadrature communication systems. It is assumed that the gain and phase imbalances are introduced at the transmitter only. The Gram-Schmidt orthogonalization procedure is used at the receiver to compensate for the imbalances. Computer simulation has been performed to study a coherent differential QPSK communication system. It has been found that the bit error rate performance is improved significantly if the transmitter phase imbalance is compensated for. However, no improvement can be obtained if the transmitter gain imbalance is compensated for 相似文献