共查询到20条相似文献,搜索用时 15 毫秒
1.
Alix L. Paultre 《今日电子》2005,(12):27-27
电子制造商Panasonic已经研制出80nm AlGaAs/GaAs(砷化铝镓/砷化镓)垂直共振腔面射型激光器(VCSEL),为光纤和空间光线传输等低成本光通信提供了解决方案。 相似文献
2.
A variable rate data transmission scheme with blind rate detection is described for pilot-symbol-assisted coherent DS-CDMA mobile radio. Cyclic redundancy check (CRC) coding and decoding is used for blind rate detection. Computer simulations of eight-rate variable rate data transmission demonstrate that when 16 bit CRC is used, the loss in required total Eb/N0 at a frame error rate of 10 -2 under two-path Rayleigh fading, is only ~0.1 dB from the known rate case 相似文献
3.
文章首先概述了产生超宽通道的行业背景,接着介绍了产生超宽通道的两种主要方式;分别阐述了OFDM(正交频分复用)调制方式和Nyquist(奈奎斯特)滤波方式的基本原理和产生途径,分析了这两种方式的优劣特点并进行了比较;最后综述了两种方式的研究现状及今后展望。 相似文献
4.
A single edge detector for coded mark inversion, data transmission is proposed. Its detection performance depends mainly on the false transition probability if the bandwidth of the receiver low-pass filter is reasonably large, say equal to twice the data rate. An approximate expression for the bit error rate (BER) performance of this detector operating in white Gaussian noise is derived by considering the level crossing probability of the noise process. Measurements show that this approximation is closer to the actual BER performance than results obtained from a previously established theoretical approach in some cases 相似文献
5.
6.
7.
具有波特率自适应功能的无线数据传输模块设计 总被引:1,自引:0,他引:1
介绍了基于nRF401无线数据传输器件的数传模块的设计与实现,给出了微控制器与nRF401的接口原理图,针对微控制器串行口不足的问题,用软件模拟实现了一个串行口,并得出了51系列单片机波特率自适应功能的定时器初值设定方法,给出了计算公式. 相似文献
8.
Some preliminary results are presented for the transmission of data using two phase DPSK modulation at burst rates of 10 kbit/s over a short distance in shallow water. Average data rates of 1.6 kbit/s were achieved.<> 相似文献
9.
10.
Coefficients for interpolation and extrapolation, including average sampling rates below the Nyquist rate, have been derived. The method is applicable for nonuniform patterns obtained through omission of samples in a uniform pattern with a sampling rate slightly higher than the Nyquist rate. The interpolations and extrapolations are valid for band-limited signals, except those theoretical signals that are zero valued at all sampling points. 相似文献
11.
12.
The author discusses the concept that data sampled beyond the Nyquist frequency is meaningless. A simple signal processing scheme to extend resolution to nearly twice the Nyquist without the problem of alias emerged. It starts by placing one-dimensional signals into a simulated sample-and-hold process in a Mathcad application 相似文献
13.
We propose a carrier phase estimation method using unequaled digital pilot tone in a faster than Nyquist WDM transmission system, in which the digital pilot tone is employed to estimate laser phase noise induced by the lasers located at the transmitter and the receiver ends. The method can effectively overcome the scale of the inter-symbol interference introduced by FTN signaling, with the good features of high phase noise tolerance and simple hardware complexity. 相似文献
14.
利用空时分组编码技术提高数据传输速率的研究 总被引:2,自引:0,他引:2
未来的通信对移动通信业务的要求越来越高,随着从单纯语音业务到多媒体业务的转变,通信中数据传输速率成为抑制日后发展的因素之一。因此人们努力研究各种高效的编码、调制以及传输的技术,用以提高数据的传输速率。空时编码是近年提出的重要技术之一,这种技术已经在第三代移动通信(3G)方案中广泛应用。本文在介绍简单的空时分组编码原理的基础上,着重研究了对共道信号产生的干扰进行抵消抑制的技术。采用具有干扰抵消技术的空时分组编码系统进行并行数据传输可以充分利用干扰信号之间的相关性进行有效的抵消处理,在原有的信道上能够极大的提高数据的传输速率。文中提出了一种利用多种调制方式抗干扰性能的不同,对共道信号进行分步解码来削弱共道干扰的影响的空时分组编码并行传输策略。这种方法能够进一步提高信号传输的性能,为提高通信系统的数据传输速率做出了保证。 相似文献
15.
在基于第二代数字卫星视频广播协议(DVB-S2)标准的遥感卫星可变编码调制(VCM)高码速数传信道中,宽带信号的大失真、大频偏和低信噪比会导致解调器载波环路不锁定。传统的DVB-S2解调器并不能解决这个问题。在载波环路前增加一个均衡器补偿失真,可以让载波环路稳定锁定。为了克服载波环路前信号的频偏和相偏对均衡器的影响,提出了一种均衡技术,利用起始序列(SOF)和导频的先验信息进行双重自相关变换,设计了一种新的误差函数和迭代过程。仿真结果表明,该均衡技术可在该应用条件下支持解调稳定工作。 相似文献
16.
Bandlimited direct‐sequence code division multiple access (DS‐CDMA) attracts much attention for its compact spectrum and the ability to suppress inter‐symbol interference. Among the various bandlimited DS‐CDMA systems available, minimum‐bandwidth DS‐CDMA (MB‐DS‐CDMA) is the only realizable Nyquist rate transmission system. But, MB‐DS‐CDMA only applies to certain kinds of spreading codes. Accordingly, this study proposes a modified DS‐CDMA structure which extends the application of MB‐DS‐CDMA to all common spreading codes at the expense of a negligible reduction in the transmission rate. Additionally, the bit error rate of the proposed schemes adopting either single‐user or multi‐user detection receiver is analyzed and compared with that of the commonly‐used raised‐cosine‐pulsed DS‐CDMA over multipath fading channels. The numerical results show that given a sufficiently large number of users, the bit error rate performance of modified MB‐DS‐CDMA is comparable to that of the raised‐cosine‐pulsed DS‐CDMA scheme; meanwhile, the realizable modified MB‐DS‐CDMA approaches the ultimate transmission rate. 相似文献
17.
M. A. M. El-Bendary A. E. Abou-El-Azm N. A. El-Fishawy F. Shawki M. El-Tokhy F. E. Abd El-Samie H. B. Kazemian 《Wireless Networks》2013,19(4):517-532
Bluetooth is a wireless personal area network. This type of networks is widely used for image communication. This paper presents a study for the transmission of images over mobile Bluetooth networks. It presents a novel chaotic interleaving scheme for this purpose. In this scheme, the chaotic Baker map is used for bit interleaving and enhanced data rate packets are used for data transmission. In the proposed scheme, the chaotic interleaver can be applied on the whole bit stream or on a packet-by-packet basis. The proposed scheme is applied with 2DH1, 2DM1, 3DH5, and 3DM5 packets. A comparison study between the proposed scheme and the traditional interleaving schemes for image transmission over correlated and uncorrelated fading channels is presented. The simulation results show the superiority of the proposed scheme over the traditional schemes. The proposed scheme also adds a degree of security to data transmission. 相似文献
18.
In this paper, we investigate the problem of maximizing the data transmission rate of a cooperative relay system in an underwater acoustic communication channel. With amplify‐and‐forward relaying and adaptive source transmission, we present optimal transmit signal power adaptation policies that maximize the data transmission rate, considering both frequency and time domains. The analysis takes into account a physical model of acoustic path loss and ambient noise power spectral density. Typical characteristics of underwater channel such as frequency‐dependent fading and time variations are also considered. Capacity bounds for channel state information (CSI) only at the receiver and CSI at both transmitter and receiver are presented. To maximize the data rate, we use the notion of an optimal bandwidth which corresponds to efficient allocation of signal power across the transmission bandwidth. Under the constraint of an average transmit power, the optimal transmit power adaptation policy is found to be ‘water‐pouring’ in frequency‐time domain, while the transmit power adaptation policy with a total power constraint is ‘water‐pouring’ in frequency domain. Results show that both frequency domain and frequency‐time domain power adaptation schemes provide much greater improvement in average data rate over that of the constant power case. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
19.
Michael J. Robusto 《International Journal of Satellite Communications and Networking》1988,6(4):369-389
The evolution of IDR digital carrier performance requirements, a summary of their characteristics, and some of the trade-offs made in the selection of various IDR parameters are described in this paper. 相似文献
20.
提出了一种适用于强度调制直接检测(IM/DD) 光系统的信号调制格式。这种基于Nyquist脉冲half cycle副载波调制(SCM)信号能有效提高频谱效率,为了减少传递函数引起的系统的性能 恶化,采 用了数字预均衡和后均衡实现对光纤损伤的补偿;建立了偏振复用(PDM)IM/DD系统 平台, 分析了Nyquist脉冲SCM信号在系统中的PAPR性能,实现了72Gbit/s 64-QAM N yquist脉冲SCM信号经过20km标准单模光纤(SMF)传输后其误码性能 小于前向纠错(FEC)阀值3.8×10-3。 相似文献