端到端支持简化了MPC5500汽车动力系统开发

Zarlink公司的ZL10038 IC拟应用于先进的卫星机顶盒和高清晰度电视,符合"数字视频广播卫星2"国际标准,该公司说它是第一种符合该标准的产品(见照片).与以前的卫星标准相比,该广播标准增加了30%的带宽,以便通过一个3 3MHz转发器传送25个标准清晰度频道或6个高清晰度频道.该标准适应多种调制方式,如8PSK(相移键控)、16QAM(正交调幅)和16/32APSK(非对称PSK).     

Link22数据链调制方式性能分析

Link22工作频段的频率资源是有限的,为了提高信息速率,Link22使用了环形星座的QAM（正交调幅）及8PSK的调制方式。在加性高斯白噪声环境下,8PSK调制方式的误符号率计算方法已相当成熟,而环形星座的QAM调制方式的误符号率只有边界较为松疏的计算公式。文中采取将QAM环形星座上的星座点分解成两个相互正交的非均匀的PAM（脉冲振幅调制）信号的方法,计算出Link22在加性高斯白噪声环境下的16QAM环形星座误符号率。计算结果与相关资料相比具有很好的一致性,表明此分析方法是正确可行的。此方法也适于Link22的32QAM及64QAM的调制方式。     

浅析数字信号的载波调制

由于数字电视系统采用数字传输 ,而在传输系统中都使用到了数字调制技术 ,本文就对ASK (振幅键控 )、FSK (移频键控 )、PSK (相移键控 )、QAM (正交调幅 )等数字调制方法进行详细的介绍。     

TD-SCDMA标准的CDMA/TDMA改革方案

文章证明了TD-SCDMA标准所定义的智能天线在TD-SCDMA标准中的不可用性,因此必须对该标准进行大规模改造。文章给出一种在上/下行信道分别使用码分多址/时分多址(CDMA/TDMA)的TD-SCDMA标准的改革方案。该方案在下行信道中可以继续使用TD-SCDMA标准所定义的智能天线,使中国唯一具有自主知识产权的移动通信标准获得新生。在下行信道中还可以使用八相相移键控(8PSK)、16进制正交调幅(16QAM)等高频谱利用率的调制方法,能将富裕的下行功率变换为频谱利用率。改革后的TD-SCDMA标准将能满足移动因特网的应用要求。     

微波中继通信发展近况

70年代以来,由于数字交换设备的大量应用,作为传输用的数字微波中继通信也得到很大的发展,总的趋势是提高信道容量和频带利用率,因而调制制度是一个关键。第一代数字微波通信系统大多采用2PSK和4PSK,在单极化传输时频谱效率低于2bps/Hz。其后有人采用8PSK或9电平正交部分响应信号(QPRS),目前16QAM、64QAM     

CO-OFDM系统不同调制方式的性能分析(本期优秀论文)

在没有色散补偿的情况下,对不同调制方式的相干光正交频分复用(CO-OFDM)系统的性能进行研究.结果表明:2PSK抗误码性能较好,频带利用率较低;4QAM频带利用率是2PSK的两倍,当系统误码率在10<'-3>以内时,所需OSNR约为9dB;8QAM频带利用率比前两者高,但抗误码性能较前两者差.因此,设计通信系统时,要...     

一种矩形16QAM网格编码的构造

本文将网格编码(Trellis Code)和矩形正交幅度调制16QAM相结合,运用线性分组码和子集旋转法分割星座。构造了两种8状态3/4TC-16QAM高效网格编码,其中之一具有180°相位旋转不变性,这一特性有利于克服相干接收机载波恢复时的180°相位模糊。3/4TC-Q16AM在不增加带宽的前提下与8PSK和8AMPM相比分别获得了5.33和3.98dB的渐近编码增益。本文还给出了以平方欧氏距离为度量准则下3/4TC-16QAM的最大似然译码,最后我们对三种不同调制下的比特误码率进行了近似计算,结果与理论分析相符。     

8×40 Gbit/s全光OFDM系统的传输性能研究

通过对基于傅里叶变换过程的全光OFDM(正交频分复用)进行理论模型分析,采用马赫-曾德干涉仪级联的方式构造出复用/解复用模块,在光域上直接进行IDFT/DFT(离散型傅里叶逆变换/离散型傅里叶变换)过程。在DPSK(差分相移键控)调制、DQPSK(差分四相相移键控)调制、4QAM(2阶正交幅度调制)和16QAM(4阶正交幅度调制)下,利用全光复用/解复用模块模拟了8×40Gbit/s无保护间隔的OFDM系统传输,对误码率等性能作出分析。     

一种多波段矢量毫米波信号概率整形性能分析

光子辅助方法易于产生和调制宽带矢量毫米波或太赫兹信号.基于强度调制器与同相/正交(I/Q)调制器级联的相干光路结构,结合概率整形技术,在VPI和MATLAB环境下对其多波段矢量毫米波信号的产生和传输性能进行了联合仿真分析.在载波频率分别为70 GHz和130 GHz的两个波段上,针对净比特速率为32 Gbit/s的均匀16阶正交幅度调制(16QAM)格式与概率整形16QAM格式的单边带矢量毫米波信号,分析对比了两者的产生与传输性能.研究结果表明:概率整形16QAM毫米波信号的光纤传输性能均优于均匀16QAM毫米波信号,且发现在考虑光纤非线性效应时其概率整形的矢量信号具有更大的传输优势.     

数字电视设备原理及应用第五讲 QAM调制器原理及应用

复用器输出的TS传输流在送入信道传输前必须将数字码流调制到适合信道传输的载波上或变换为适合信道传输的形式。为了提高频谱利用率，必须采用多进制的调制方法，这样在一个码元上可以传输多个比特，可以降低码率和信道带宽，QAM调制就是常用的多进制调制方法，它采用幅度、相位联合调制的技术，利用载波的幅度和相位来传递信息比特。正交幅度调制也称为正交幅移键控，这种键控由两路数字基带信号对正交的两个载波调制合成而得到。为了避免符号上的混淆，一般用m—QAM代表m电平正交调幅，用MQAM代表m状态正交调幅，通常有4电平正交幅移键控（4一QAM或16QAM）、8电平正交幅移键控（8-QAM或64QAM）等，在日常应用中QAM调制器的命名一般用后者即64QAM、128QAM等。商用化的QAM调制器并不只是QAM调制单元，还包括信道编码单元。信道编码是指纠错，是为提高数字通信传输的可靠性而采取的技术措施。为了能在接收端检测和纠正传输中出现的错误，在发送的信号中增加了一部分冗余码，这些冗余比特与信息比特之间存在着特定的相关性。个别信息比特在传输过程中出现错误，     

数字通信中增强型六维64PSK调制设计与性能分析

为了进一步提高数字通信的可靠性,在两个三维8PSK星座图的基础上设计了一种增强型六维64PSK调制格式.相比传统的二维64PSK、64QAM调制格式,在功率归一化的条件下,增强型六维64PSK调制格式的最小欧氏距离(Minimum Euclidean Distance,MED)变得更大,而且能够分别获得21.6 dB和11.8 dB的解调增益.在最大化最小欧氏距离的过程中没有使用重复的算法,因此新方法的计算复杂度较低,这种增强型六维64PSK调制格式非常适合完成一个高可靠性的数字通信系统.     

Optical Systems With High-Order DPSK and Star QAM Modulation Based on Interferometric Direct Detection

Increased interest in novel modulation formats for optical transmission has come up in recent years. Receivers with interferometric direct detection can be used to detect arbitrary modulation formats with differentially encoded phases as differential phase-shift keying (DPSK) and differentially phase-encoded star-shaped quadrature amplitude modulation (Star QAM). In this paper, two novel 16-ary modulation formats, which are the 16 DPSK and the Star 16 QAM (ASK-8 DPSK), are characterized for optical transmission for the first time. To be able to identify clear performance tendencies for high-order optical modulation, the novel formats are compared to a wide range of already investigated formats by conducting comprehensive calculations in a uniform simulation environment. The influence of different transmitter structures and decision schemes is considered, and all the systems are characterized with respect to the optical signal-to-noise ratio requirements, dispersion tolerance, and self-phase-modulation (SPM) performance for nonreturn-to-zero (NRZ) and RZ pulse shapes. Moreover, an inherent problem of Star QAM transmission concerning SPM is illustrated, and compensation techniques are examined. The results give a substantial insight into the properties of high-order optical modulation formats.     

Flexible high-order QAM transmitters for elastic optical networks

In order to adapt to the dynamics in the future optical networks, we propose and experimentally demonstrate two flexible high-order quadrature amplitude modulation (QAM) transmitter schemes: (a) a flexible transmitter using a tandem in-phase/quadrature modulators for generating 16QAM, 32QAM, 64QAM signals; and (b) a scheme based on monolithically integrated quad-Mach–Zehnder in-phase/quadrature with binary driving electronics for synthesizing minimum phase-shift keying (MSK), quadrature phase-shift-keying (QPSK), 8-ary phase-shift keying (8PSK), and 16QAM. These schemes provide different approaches to configure a flexible high-order QAM transmitter, either using cascaded off-the-shelf modulators or via highly integrated monolithic modulator. These flexible and reconfigurable transmitter schemes exhibit different characteristics in terms of system performance, which provides the network operators different flexible transmitter solutions suitable for different application scenarios in elastic optical networks.     

Trellis coding of quadrature frequency/phase modulated signals

The authors explore the trellis coding of continuous-phase quadrature frequency/phase modulated (CPQFPM) signal sets and continuous-phase FPM (CPFPM) signal sets, which are embodiments of the quadrature biorthogonal modulation (QBOM) technique. Conventional TCM and multiple TCM schemes with these modulation formats are examined using both the AWGN channel and the Rician fading channel design. Asymptotic coding gains in d²(free) are tabulated for trellis-coded rate 3/4, 5/6, and 6/7 QFPM schemes, in comparison with uncoded modulations (8AMPM, 32AMPM) and other trellis-coded modulations [TCM (2FSK/4PSK 16QAM, 64QAM), MTCM (2FSK/8PSK)] of equivalent throughput rate. Performance gains on the Rician fading channel are demonstrated by increased values of the design parameters for this channel, namely symbol diversity L_min and branch distance product P     

一种基于D8PSK／ASK正交调制的新型光标记方案研究

深入研究了差分八相移键控（I）8PSK）j幅移键控（AsK）正交调制格式的机理,提出了一种基于D8PsKjASK正交调制的新型光标记方案,利用D8PSK作为载荷的调制方式,ASK作为标记的调制方式,仿真实现了载荷120Gb／s、标记10Gb／s的传输速率。分析了信号的消光比（ER）对误码率（BER）的影响,仿真结果表明...     

Peak power and bandwidth efficient linear modulation

In portable wireless communication systems, power consumption is of major concern. Traditional modulation and coding schemes have been designed from the standpoint of minimizing average power. However, for linear power amplifiers needed for spectrally efficient modulation formats, amplifier efficiency and hence power consumption are determined by the peak power of the transmitted signal. This paper looks into modulation formats which minimize peak power and retain high spectral efficiency. Peak power is broken into a sum (in terms of decibels) of average power and a peak-to-average power ratio, and a variety of modulation formats are evaluated in terms of peak power efficiency in both a Gaussian noise and Rayleigh fading channel. A generalized phase shift keying (PSK) modulation format is developed and shown to offer superior peak power efficiency relative to that of commonly used linear modulation formats. Two schemes are presented for reducing the peak-to-average power ratio of various modulation formats. First, data translation codes are used to avoid data sequences which cause large peaks in the transmitted signal. This approach was found to be most productive in quadrature amplitude modulation (QAM) formats. Finally, an adaptive peak suppression algorithm is presented which further reduces the peak-to-average power ratios of the PSK and generalized PSK formats. The peak suppression algorithm is also applicable to π/4-QPSK and was found to improve peak power efficiency of that format by about 1.25 dB over a Rayleigh fading channel     

New phase and frequency detectors for carrier recovery in PSK andQAM systems

Phase and frequency detectors (PFDs) are presented that considerably extend the acquisition range of carrier-recovery loops in digital communication systems. Based on a simple modification of conventional phase detectors (PDs), the proposed detectors are applicable to a large variety of modulation schemes, including the popular PSK and QAM signal formats. Their application to QPSK and 16- and 64-QAM is extensively discussed, and simulated frequency-detector (FD) characteristics, as well as acquisition behavior of several PFDs, are reported for QPSK and 16 QAM. The results of an experimental evaluation using a 16-QAM laboratory modem are also reported which show that the detectors increase the acquisition range achievable by conventional PDs by more than one order of magnitude. In PSK, the improved acquisition performance is obtained with no penalty in steady-state phase jitter. In combined amplitude- and phase-shift keying, it generally leads to increased jitter, but this is easily avoided by incorporating a lock indicator and switching back to the original PD after lock is acquired     

16 QAM Modulation for High Capacity Digital Radio System

A computational method allowing the calculation of bit error rate in the presence of filtering and some other impairments is described for 16 QAM modulation; a breadboard working at a bit rate of 140 Mbits/s has been implemented and experimental results are compared with calculated values. The possible use of this modulation type for a high capacity digital radio-relay system is considered. Some parameters are introduced for this purpose, especially the net fade margin parameter. In the case of the 140 Mbit/s system in the 10.7-11.7 GHz frequency band, 4 PSK and 8 PSK modulation types are compared with 16 QAM. System gain, frequency arrangement, nodal capacity and outage performances are evaluated.     

卫星通信中不同调制信号的预失真研究

卫星通信技术近年来发展较快,承载的通信业务也较多,导致频谱资源紧张,功率资源受限,迫切需要采用高阶调制、多载波传输等方式来缓解通信资源的紧张,QPSK、8PSK、16QAM等更高阶调制方式在卫星通信中将会获得越来越广泛的应用。这类信号直接通过功放后,信号产生失真,影响接收端信号的正确解调,预失真技术是近年来补偿功放非线性的最有效手段之一。在研究这几种高阶调制信号特点的基础上,对几种调制方式的信号分别进行预失真处理,并分析各信号的抗噪声性能,总结出16QAM信号在卫星通信中的应用会缓解目前通信资源紧缺问题。