共查询到18条相似文献,搜索用时 187 毫秒
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石栋元刘正平钱锐夏威何子述 《电视技术》2012,(9):37-40
在采用LMS算法实现回波抵消功能的同频数字直放站中,针对节省资源来降低成本的问题,结合Pipeline和Systolic技术,提出了复数DLMS算法的2倍复用结构。由测试结果可知,所提的结构在节省了一半乘法器资源的基础上实现了回波抵消功能。 相似文献
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在采用LMS算法实现回波抵消功能的同频数字直放站中,针对节省资源来降低成本的问题,结合Pipeline和Systolic技术,提出了复数DLMS算法的2倍复用结构。由测试结果可知,所提的结构在节省了一半乘法器资源的基础上实现了回波抵消功能。 相似文献
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基于WCDMA标准提出了FPGA+DPS平台下实现在数字中频技术中抵消WCDMA直放站回波干扰信号的方案.首先发射与WCDMA信号不相关的伪随机序列CAZAC码作为训练序列进行信道初估计,然后将初估计得到的时延和幅度信息作为赋给LMS自适应滤波器的初值,生成逼近干扰信号的抵消信号,实现回波对消.使用MATLAB和SIMULINK联合仿真,证明该方法拥有良好的性能. 相似文献
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WCDMA数字无线直放站由于架设方便,外形美观等优点受到市场的追捧。它采用自适应干扰抵消技术,可以消除由于自身收发天线隔离度小而产生的自激问题。文章针对WCDMA系统中的自适应干扰抵消技术展开了研究。重点对时域的三种干扰抵消算法:LMS、NLMS和RLS算法,进行了研究和性能分析,并在原有的NLMS算法的基础上,为降低复杂度和节省资源,提出一种新的H-NLMS算法。最后在MATLAB仿真环境中建立WCDMA干扰抵消直放站系统链路级仿真模型,验证改进的算法和干扰抵消单元的性能。 相似文献
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以数字电视地面广播国家标准DVB-T为基础,提出了一种基于FPGA和DSP实现回波对消的方案.其原理是:首先该系统不发送数字电视信号,通过发射CAZAC序列进行信道初估计.由于信道在实际中会发生一定的变化,所以还需要用自适应算法进行信道特性的跟踪,其中DSP运用自适应算法保证对消信号接近回波信号.其次FPGA系统获得了回波信道的参数并生成逼近回波信号的对消信号.最后,将接收信号与对消信号相减完成对消.提出了对回波信道的初估计并利用变换域LMS算法进行信道跟踪的一种方案.最后仿真结果表明,该方法具有良好的回波对消性能. 相似文献
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The radio frequency feedback (RFF) occurs when the insulation is insufficient between the antennas of an on‐frequency repeater, increasing digital transmission errors. In addition, a strong RFF could compromise system stability of the on‐frequency repeater because of the growing power in the closed‐loop. Automatic gain control is widely used by the on‐frequency repeater to regulate the power, this solution being generally used with echo cancellation processes. Most of echo cancellation techniques are based on digital processing such as adaptive filters whose the effectiveness and the algorithm speed are depending on the signal frequency, the bandwidth and the closed‐loop parameters. This paper describes a solution of RFF estimation and detection regardless of the receiving signal modulation. By using the frequency scanning and the analysis of the power spectral density peaks in the system, this solution is reliable whatever are the values of the gain‐margin and the loop‐delay. Simulations and experimental implementation using field‐programmable gate array validate the solution. In addition, an example of applications is given in the context of the interference cancellation. 相似文献
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This paper investigates the design and performance of a digital on‐channel repeater (DOCR) for use in Advanced Television Systems Committee (ATSC) digital television (DTV) broadcasting. The main drawback of a DOCR is the echo interference caused by coupling between transmitter and receiver antennas, which induces system instability and performance degradation. In order to overcome this problem, an echo canceller based on the adaptive echo channel estimation (ECE) technique has been researched and applied for a DOCR. However, in the case of ATSC, the pilot signal, which is used for carrier synchronization, may cause a DC offset error and reduce the isolation performance of the echo canceller for a DOCR in an ATSC network. Moreover, since the multipath fading effect of a radio channel usually occurs in a real environment, it should be minimized to improve the overall performance of a DOCR. Therefore, due to the limited isolation performance of echo canceller and the multipath fading effect, an interference cancellation system (ICS) is proposed for a DOCR in an ATSC network. The performance of the proposed DOCR with an ICS is evaluated by software simulation and hardware test results. 相似文献
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从介绍传统模拟直放站在工程应用中遇到的问题入手,通过ICS数字直放站与传统模拟直放站和基站RRU的比较阐述了ICS数字直放站的技术优势,最后给出了适合采用ICS数字直放站的几个典型的覆盖场景。 相似文献
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Kitami T. Yamaguchi H. Hoshino T. Murata T. 《Communications, IEEE Transactions on》1980,28(5):764-771
The design and performance of an experimental 800 Mbit/s repeater for four-level digital transmission over a coaxial cable is described in this paper. The 800 Mbit/s digital system exceeds the 60 MHz analog system, both in capacity and in economy. The repeater is designed to operate in repeater housings located at 1.6 km maximum spacing to be compatible with the 60 MHz analog sytsem. A nonredundant four-level line code has been employed, using a newly developed quantized feedback dc restoration technique. The most important item in realizing the high-speed multilevel repeater is the reduction of intersymbol interference. A simple quantized feedback scheme and an adjustable three-tap transversal equalizer have been used to compensate for intersymbol interference. The experimental repeater has been tested for 1.1-1.7 km repeater spacings using 2.6/9.5 mm coaxial cable. The results show that an 800 Mbit/s repeater with 1.6 km maximum repeater spacing is feasible. 相似文献