Study of the required crosspolar protection ratio in G-PAL TV FMsatellite transmissions planning

A study including simulation and a measurement campaign using live TV broadcast satellite signals and receiving commercial equipment has been carried out to investigate the required cross-polar protection ratio at the terrestrial receiving antenna for satellite transmission planning. This experiment provides useful and realistic results for efficient channel allocation in the spectrum band of broadcast satellite systems. Among them is the frequency offset required between cross-polar channels, depending on the cross-polar rejection at the receiving antenna, for a certain degree of video signal impairment due to the cross-polar channel interference effect, and taking into account the noise contribution to the signal. A worst case in frequency offset value, i.e., larger subjective impairment of the picture at equal carrier to noise ratio (CNR), has been detected around 5 MHz (near the chroma carrier in G-PAL system 4.43 MHz) only for high values of CNR. Different subjective degradation of the image due to cross-polar channel interference and noise has been observed, and their particular contributions to impairment have been evaluated     

基于VB的卫星电视接收天线定位系统的研究与开发

卫星电视信号接收天线定位的主要参数是方位角、仰角和极化角。以VisualBasic语言为工具开发了卫星电视信号接收天线定位系统,系统界面友好、功能强大,用户在选择接收地和卫星的基础上,系统输出天线定位参数并以图示方式显示,还可显示被选择卫星的主要参数及转发的电视节目,供接收卫星电视信号时参考。     

利用安捷伦ADS产生DVB-S数字卫星电视信号--ADS仪表连接应用

在数字卫星电视接收系统的开发过程中,为了验证接收系统的正确性,(即接收系统是否可以正常工作,是否可以正常地播放出图像)需要一个卫星信号源,要求它应该能够产生具有卫星编码的活动图像信息,从而使接收系统工作于符合DVB标准的数字卫星系统中.本文将阐述如何利用安捷伦ADS仿真软件和ESG E4438C矢量信号发生器,产生出带有图像信息的DVB-S数字卫星电视信号.     

数字卫星电视信号的接收调试及天线维护

通过实例的计算，阐述了作为有线电视系统信号源的数字电视信号余量与接收天线口径的关系，另外介绍了在卫星接收调试及天线维护方面的一些经验体会。     

关于乡镇模数转换的几点思考

目前全国的城市社区都已经普及了数字电视,但在一些偏远的乡镇,还在使用一些天线、卫星电视接收器等接收模拟电视节目。利用天线等接收设备,只能收看到为数不多的电视频道,在一些特别偏远的地区,甚至接收不到电视信号,更谈不上数字电视,为此就乡镇的模数转换进行讨论,并提出一些建议和想法。     

LNB本振随环境的变化及应变措施

卫星电视接收天线LNB的本振频率对于一定的接收系统在理论上是一个固定值,但实际上其值受到工作环境变化的影响会出现漂移;其次,由于所选用的LNB不同,本振频率与理论值的频偏不同。在实际的保障工作中,接收同一卫星信号,用不同的接收天线得到的中频不同,严重时会出现二者的频偏相差超过2 MHz,这样在更换备用天线时必须调整卫星电视解码器的参数设置。     

用于卫星DBS调谐器的数字滤波器设计与仿真

为防止陆地UHF频道的信号到达卫星DBS调谐器并降低其灵敏度,在机顶盒的输入端需要使用高通滤波器。在分析卫星电视信号和陆地信号的基础上,给出了适合卫星DBS调制器的滤波器的性能指标;应用Matlab中的FDATool,设计出了符合指标要求的的IIR高通滤波器,给出了幅频和相频响应曲线。仿真结果表明,设计结果的各项性能指标达到要求,且设计过程简便易行。     

进一步规范卫星电视广播地面接收设施管理的探讨

卫星广播电视接收是当前我国实现广播电视无线覆盖“村村通”工程的有效途径,针对目前卫星电视广播地面接收设施管理混乱的现状,就如何进一步规范卫星电视广播地面接收设施的管理进行探讨。     

基于S3C4510B的卫星接收复用器的设计

针对数字卫星电视的应用,提出了一套卫星接收复用器的设计方案。该方案实现了将卫星接收功能和TS流再复用功能集成在一个系统中,大大降低了数字卫星电视前端的应用成本,为数字卫星电视平台的搭建提供了一个新方法．     

A satellite system for CATV

The increasing capacity of CATV systems has generated a demand for more program material than can be economically generated with local facilities. A possible solution is a nationwide satellite distribution system dedicated to CATV which would provide the additional material directly to the CATV head-end. This paper presents a satellite system design that would distribute six TV channels to 10 ft antenna terminals located at the head-end. Since such a system requires thousands of receiving terminals, their cost must be minimized to produce an economically viable system. The system addressed in this paper requires a ground terminal that is comparable to a standard microwave relay terminal in both cost and complexity. The system consists of three satellites, covering the Eastern, Central, and Western portions of the United States. Based on tradeoffs of spectrum availability and low-noise amplifiers, the 12 GHz frequency band has been selected for the satellite to terminal link. The proposed terminal uses a fixed high-efficiency 10 ft antenna with extremely simple but rigid construction. A low-cost tunnel diode amplifier is used for the receiver front end. After the necessary down-conversion, detection of each channel is performed at the standard 70 MHz IF frequency. The required satellites could be launched on an Atlas Centaur launch vehicle using present technology. The satellites would weigh an approximate 1500 Ib and generate 5 kW of dc power.     

CATV中卫星电视接收匹配问题的理论分析与计算

在ＣＡＴＶ中卫星电视接收匹配是实际工作中的技术问题，特别是在接收ＳＣＰＣ方式下行的数字压缩节目时，由于其下行信号比模型拟信号低１０ｄＢ左右，直接影响接收信号的质量，所以有必要在对此理论上进行详细尽的分析与匹配计算。     

Cross-polarization measurements at Martlesham Heath (UK) using OTS

Slant-path propagation measurements using transmissions to and from the Ots satellite are being carried out at Martlesham Heath (Uk)at an elevation angle of 29.9°. The measurements allow the determination of the attenuation and cross-polarization for circularly-polarized signals at 14.5 and 11.8 GHz and attenuation and cross-polarization for a linearly-polarized signal at 11.6 GHz. This paper reports the results of cross-polar measurements made during the summer of 1978 together with examples of particularly severe cross-polar effects from 1979. The measurements are compared with both a Ccir curve relating cross-polar discrimination to fade depth for rain and theoretical curves supplied by Essex University. The results clearly demonstrate the superior cross-polar performance of linear polarization compared to circular polarization.     

Method for the computation of interference and distortion levels insatellite FM-TV systems

A method for the prediction of interference and distortion levels in satellite FM-TV systems is proposed. The procedure, which is based on a statistical model of live video signals, makes it possible to predict the levels of both intersystem interference and intrasystem signal distortion. Statistical properties of video baseband spectra are investigated by evaluating the results of long-term measurements of live satellite TV channels. In particular the joint probability distribution for the random variables describing luminance and chrominance components of the video signal is derived from the measurements. The spectrum of the frequency-modulated signal is then analyzed, and the cumulative distribution of signal distortion due to bandlimiting is computed. Similarly, the distributions of adjacent and cochannel interference levels are calculated with examples illustrating the effects of subcarrier loading and energy dispersion. The procedure is particularly useful for the investigation of relative effects of system parameters on interference and distortion levels     

A statistical model of FM-TV spectra for satellite interference and distortion prediction

The requirement for a model of FM-TV spectra in the planning procedure of satellite communication systems is introduced. Based on long-term measurements of live TV channels, statistical properties of video spectra are examined and probability distributions for the luminance and chrominance components are proposed. The spectrum of the frequency-modulated signal is then derived, and signal distortion due to bandlimiting is calculated. Adjacent and cochannel interference effects are also investigated, with example cases illustrating influences of subcarrier loading and energy dispersion. The proposed model, which describes FM-TV spectra in terms of random variables, makes it possible to examine relative effects of system parameters, and will, therefore, be of benefit in the planning of new satellite services.     

一种Ku双本振多输出高频头的设计

高频头是一种数字卫星电视信号接收装置,它能对卫星接收信号进行变频和放大.介绍一种Ku双本振多输出高频头的工作原理、性能指标、仿真结果、技术难点、实测结果,并在工程实践中实现批量化生产.     

STV0299B在卫星数字电视接收机中的应用

QPSK基带信号处理芯片STV0299B是集解调与解码功能于一体的高度集成芯片，是数字卫星接收机前端信号处理部分的重要设备，被广泛应用于各种高频头电路中。描述了STV0299B在数字卫星电视接收机中的应用，介绍了其内部结构及内部主要功能部分的结构特点及其工作原理。     

数字阵列天线接收通道宽带信号校准与波束形成技术研究

 本文提出了一种简洁、实用的天线接收通道宽带信号校准方法.该方法采用零中频信号处理技术,通过理论分析将数字阵列天线接收通道宽带线性调频信号校准分为通道间的时间和相位校准,证明了接收通道间宽带线性调频信号相位校准可以转化为单频信号进行,给出了接收通道间宽带信号的幅度校准方法和时间校准允许的误差范围.在通道校准基础上,采用脉冲压缩技术合成了宽带天线方向图.实验结果表明,本文方法是有效、可行的.     

一种针对转发式欺骗干扰信号的负延时补偿方法

针对卫星导航转发式欺骗干扰中转发信号存在负延时需求而工程上又无法实现的问题,提出了一种负延时补偿方法。该方法根据预设欺骗位置,通过转发式欺骗干扰延时算法,获得各卫星信号通道所需转发延时量;然后基于接收机钟差最小化原则选取最优的延时修正量添加到所有通道的转发信号中。理论分析和仿真结果表明,该方法不影响接收机的定位结果,消除了负延时无法实现的问题对转发式欺骗干扰的限制。     

库车市融媒体中心节目IP录制系统

节目录制是电视台每天要做的一项工作,库车市融媒体中心基于IP信号录制进行了摸索和测试,成功实现了IP信号的自动录制,提高了节目质量,解放了录制人员。IP录制系统由卫星接收系统、VLC软件、录制计算机、调用计算机、录制系统网络5部分组成。