Statistical Characteristics of the cosGBOC Signals of Promising Satellite Radio Navigation Systems

Journal of Communications Technology and Electronics - Properties and statistical (time and frequency) characteristics of the cosGBOC signals for new generations of satellite radio navigation...     

Correlation Functions of Navigational cosGBOC Signals as the Inverse Fourier Transform of the Energy Spectra

Journal of Communications Technology and Electronics - Abstract—The modulating functions (MFs) of cosGBOC signals (cosine generalized BOC signals) for new-generation satellite radio...     

Spurious Signals in Satellite Command Systems

The Project RELAY command system is described with emphasis given to the spacecraft equipment. Errors in the RELAY command system are discussed, and the probability of error in a single command word and the probability of a spurious command are given as a function of the signal-to-noise ratio (SNR) at the output of the command receiver in the satellite. The performance of the actual RELAY command system is discussed and shown to differ considerably from the performance predicted by theory. The results of an analysis of the orbiting command system are presented. The probable cause for the anomalous performance of the command system is shown to be Radio Frequency Interference from ground based transmitters. The techniques which are available to the system designer to avoid the problems experienced by the RELAY system are discussed in detail.     

Correlation Functions of Navigational GBOC Signals

The structure of generalized binary offset carrier (GBOC) signals of satellite radio navigation systems, such as global positioning system (GPS) (USA), global navigation satellite system (GLONASS) (Russia), Galileo (European Union), and BeiDou/Compass (China), is examined. Analytical expressions for the correlation functions (CFs) characterizing the single components of the GBOC-signal modulation function (MF) are derived at the typical pulse multiplicity coefficients N_R (N_R = 2 and 4) and different duty cycles. The CFs properties of the components of GBOC-signal MFs are discussed and their graphs are constructed at ρ = 0 (or ρ = 1) corresponding to binary phase-shift keying signals, ρ = 0.1 (or ρ = 0.9), ρ = 0.25 (or ρ = 0.75), ρ = 0.3 (or ρ = 0.7), ρ = 0.45 (or ρ = 0.55), and ρ = 0.5 corresponding to binary offset carrier signals. The energy spectra (power spectral densities) of the single components of GBOC-signal MFs are calculated via the Fourier transform of CFs at the pulse multiplicity coefficients N_R= 2 and 4.     

卫星数字调制混合信号的自动识别

针对卫星数字混合信号的特征,提出了在载波速率和符号速率初判基础上的自动识别方案.该方案利用数字混合信号与常用数字调制信号在信号频谱以及星座点的差异提取特征参数进行自动识别.仿真结果表明,该方案具备实用性和可行性.     

Suboptimal Algorithms for Receiving and Processing BOC Signals in Advanced Global Navigation Satellite Systems

Journal of Communications Technology and Electronics - Suboptimal algorithms for receiving and processing BOC signals have been developed for use in modern and advanced Global Navigation Satellite...     

卫星电视信号的接收

近年来,随着数字压缩技术的突破,这项技术在节目制作和传输领域等方面得到了广泛的应用,其中应用最多的还是卫星电视广播领域。全国各省、直辖市电视台纷纷上星,这给各地有线电视台提供了丰富多彩的节目源,卫星电视信号的接收与维护也成为有线电视台日常的工作之一。 下面是笔者从事卫星电视信号的接收这项工作所做的一点资料收集和工作总结,希望与有线电视同仁和爱好者们共同探讨。     

卫星多路信号收发端机的设计

概述了卫星通信的特点，论述了卫星特种多路信号收发系统的设计。此收发端机是一个将光纤通信技术应用于卫星地测信号传输的设备，其作用是将卫星地测设备中的多路检测信号通过光纤系统传输到远处的控制中心进行检测，以改善卫星姿控系统监测信号质量。此方案与现今已采用的一些方案相比，在系统易用性、可靠性、安全性和降低软硬件投资等方面具有相当大的优势。同时由于采用时分复用及解复用技术，该收发端机传输信号量大、体积小，因此具有极强的需求背景。     

Suboptimal Algorithms with Parameter Reassignment for Receiving and Processing BOC Signals in Global Navigation Satellite Systems

Journal of Communications Technology and Electronics - In this paper, we develop suboptimal algorithms for receiving and processing binary offset carrier (BOC) signals for use in global navigation...     

卫星通信信号调制识别技术研究

通信信号的调制方式识别是非协作通信领域的一个研究热点,它需要在没有任何先验条件,且环境复杂有噪声的条件下,不依赖于其它的先验知识,确定目标信号的调制方式。然后就可提取载频、码速率、滚降系数等参数,为信号的进一步深入研究提供依据。分析了几种经常用于卫星通信的MPSK调制信号和高阶调制信号16APSK,提出了一种基于高阶累积量与频谱特征的识别算法。在特定的数据长度和信噪比条件下,理论分析与仿真验证均验证了该算法易于实现、识别率高（≥95％）。     

VSAT卫星信号中的邮件数据分析与提取

随着VSAT网络的不断发展,卫星信道越来越多地被用来传送基于IP协议的多种数据.为获取这类信息,本文对承载IP数据的卫星DVB信号传送数据的MPEG-2协议及多协议封装格式进行了深入研究,并结合实际数据对这些协议在实际数据中的应用进行了深入分析.对数据的分析采用了软件编程的方法,在协议逐层提取的基础上,对数据进行了逐层剥离,在剥离同时对数据按特定关键字段进行分类,得到了所需的邮件数据.最后给出了在VSAT网络卫星DVB信号中提取邮件的流程.     

Advanced Communications Satellite Systems

Demand for in-orbit capacity through the use of satellite systems will continue throughout the next two decades. The potential of the 30/20 GHz frequency band for fixed satellite services will be exploited. However, many technology questions must be answered if the band is to be used commercially because of the high rain fades that can occur at these high frequencies. NASA has conducted a technology development program in high gain antenna and on-board switching and processing systems which can be combined such that cost competitive services are possible at acceptable rain outage percentages. Other supporting technologies have also been pursued including transmitters, both tube type and solid state, and low noise receivers. The critical technologies have been combined into an experimental satellite payload; an experimental flight is planned to verify these technologies and enable development of operational systems. Implementation of such systems would be by commercial carriers and could occur in the early 1990's, depending on the demand for additional or bit capacity. The high capacity systems that can be made possible through the use of the 30/20 GHz band and the employment of frequency reuse technology will contribute to the continued downward trend in circuit costs and may allow new and innovative satellite services.     

雷达干扰卫星电视信号的对策

卫星电视信号遭雷达干扰是个棘手的问题,本文就台州枫山电视发射台在2015年中央广播电视节目无线数字化覆盖工程建设过程中,有效解决雷达严重干扰中星6A卫星电视信号所采取的技术手段和方法作了介绍,供广电同行参考.     

Promising Performance of PA-Coded SIMO FM-DCSK Communication Systems

Frequency-modulated differential chaos shift keying (FM-DCSK) is an attractive scheme which combines chaotic modulation with the spread-spectrum property. It is simple to implement and robust in multipath fading channels. A single-input multiple-output (SIMO) FM-DCSK architecture has recently been developed to increase data rate and achieve diversity gain. In this paper, several main channel coding schemes, i.e., error-correcting coding schemes, are introduced into the SIMO FM-DCSK communication system, with different code rates and different frame lengths, over multipath fading channels. It is found that, in contrast to low density parity check codes and convolutional codes, product accumulate (PA) codes can provide outstanding bit error rate performance improvement to the existing SIMO FM-DCSK system. In this paper, moreover, the optimum code rate for the PA-coded SIMO FM-DCSK system is investigated through simulations at a medium frame length. Because of its merits in several aspects, such as prominent advantages in better performance, simple encoding and decoding structures, and a flexibly adjustable code rate, this paper demonstrates that PA code is a strong candidate as the error-correcting scheme for the SIMO FM-DCSK system in transmitting medium and long frame lengths over multipath fading channels. This research was partially supported by the City University of Hong Kong under the SRG Grant 7002274, the Dept. of Education Administration of China (NCET-04-0601), NSFC (No. 60272005), as well as the Key Project of Science and Technology in Fujian Province of China (No. 2006H0039).     

卫视频道高清信号上星传输系统建设实践

根据《广播电视安全播出管理规定》"卫星广播电视地球站实施细则"要求,以"具备两路或两路以上不同路由或传输方式的信号源"并"应配置能独立承担上行播出任务的备份上行系统"为建设原则,系统建设一套主、备上行链路系统和第三条独立上行链路系统,共计三路高清上行链路系统.系统功能健全,具备全流程信号监控、全系统设备管控,全方位运维...     

接收32路数字声卫星广播节目信号应考虑的几个问题

本文阐述了ACS1200型数字声卫星广播接收机的工作原理，并结合安徽人民广播电台使用该设备收转中央人民广播电台三套广播节目信号的实际，总结了使用该设备时应注意的几个问题，提出了自己的看法。     

卫星信道下混合信号频偏的估计方法

针对非协作卫星通信场合中同调制参数的MSK单通道混合信号的载波频偏估计问题进行研究,推导了卫星信道条件下MSK混合信号的循环谱表达式。通过搜索零频率处循环频率轴上的大强度谱线进行混合信号频偏估计,并针对谱线选择时存在的模糊问题,利用循环谱快速算法中的泄漏谱线包络辅助进行模糊消除。仿真结果表明在信噪比大于-20 dB时,对混合信号载波频偏估计较为准确。该方法对混合信号载波初相和时延等未知参数影响不敏感,并且不需要任何先验信息,其估计精度能够满足后续信号处理的需要。     

"信号与系统"课程教学改革初探

本文分析了"信号与系统"课程的特点和当前发展趋势,介绍了对"信号与系统"课程进行全方位教学改革,包括了教学内容、教学方法和手段、课程体系、考试方式等方面.经过多年的教学改革实践,其成果包括立体化的教材、Matlab在课堂教学和实验教学中的应用、实验单独设课以及试题库等.     

一种基于信标的移动卫通相控阵波束跟踪算法

提出并实现了一种利用卫星信标信号来实施基于相控阵天线的波束跟踪算法。该方法适用于采用相控阵天线技术的各种卫星"动中通"天线,克服了卫星信标信号强度弱,检测困难的弱点,提高了跟踪信噪比,同时采用了软件无线电方式解调可以提供最大的灵活性。跟踪算法的最大优点是没有任何陀螺仪的辅助,极大地提高了天线在各种极端运动环境下的适应能力。算法最终在自行研制的Ku波段相控阵移动卫星天线系统上获得验证。     

星上MF-TDMA系统信道管理方法

MF-TDMA被广泛应用于现代宽带通信卫星系统的上行链路设计中,而时隙分配算法是系统资源利用率的重要保证。针对MF-TDMA时隙分配复杂,时隙资源浪费严重等难题,该文给出一种可动态调整载波信道的MF-TDMA系统时隙分配算法,算法将天基移动通信系统用户接入时隙分配问题分解为载波确定和载波内时隙分配两个部分,并针对用户终端载波确定问题,给出一种带载波调整的RCP算法(RCP-A)算法,解决现有方法在多业务多用户条件下资源浪费大、使用率低的问题;针对载波内时隙分配问题,采用基于倒序时隙编号时隙资源树管理方式,解决业务因时隙分配而带来的时延抖动问题;并给出了适合星上处理能力的时隙资源管理其实现方法。仿真测试显示,该实现方法适合于星上MF-TDMA无线资源管理器。