一种用于卫星便携站的数字复接器的设计

数字复接器是卫星通信中重要的组成部分。介绍了在便携式数字卫星通信系统中,利用硬件描述语言(VHDL)和硬件可编程器件,给出了一种采用时分复用技术,对视频、语音、同步数据、异步数据和局域网(LAN)数据等多路数字信号进行复分接的设计方案及仿真结果,并进行了同步性能分析,最后对设计与实现过程中的要点和需要注意的问题进行了详细的论述。     

非线性卫星信道均衡

在数字卫星通信系统中,大功率放大器工作于饱和点附近会引起非线性失真,制约其传输功率和传输效率。 针时这一特点,对信道非线性进行分析和建模,给出了一种模型:Volterra级数信道模型。然后利用非线性自适应滤波器- Volterra滤波器进行了信道非线性均衡的仿真,仿真结果表明,均衡后接收机的性能获得了明显的改善。     

Satellite Sound Broadcasting Around 1 GHz

This paper presents the technical factors affecting the design of a geostationary satellite sound broadcasting system operating around 1 GHz to serve low-cost consumer-quality portable and automobile receivers. The technical characteristics for such a system are under study in a number of countries in preparation for the 1985/1988 ITU Space Services Planning Conference.The first session will make appropriate recommendations to the second session on the future regulatory provisions for the service. A medium-quality monophonic or stereophonic service would be provided using frequency modulation. Signals would be received using a simple circularly polarized omnidirectional antenna. Link margins to serve indoor portable receivers and automobile receivers in rural and urban areas are discussed. Building penetration loss for single family dwellings is expected to be about 11.8 dB in 90 percent of the houses not using foil-backed insulation or shadowed by trees, increasing to over 17 dB with foil-backed insulation. Shadowing by trees increases the loss by 12-15 dB. Apartment and commercial building penetration loss is expected to approach 20 dB. Automobile reception in rural areas will be primarily affected by foliage attenuation due to trees. At a 30° elevation angle, an attenuation of about 15 dB with probability of 0.90 is expected. In situations where the line-of-sight path is unobstructed, multipath fading of 2.8 dB at 0.90 probability is the predominant source of degradation. Automobile reception in urban areas requires operating margins of 24-30 dB because of shadowing and multipath by large buildings. Based on the foregoing considerations, an e.i.r.p. from 66 to 79 dBW is required from a geostationary satellite to serve low-cost portable and automobile receivers in rural and urban environments.     

Characterization of the Indoor/Outdoor to Indoor MIMO Radio Channel at 2.140 GHz

In this paper the radio channel characteristics of the 8 × 4 MIMO system consisting of a base station and a small terminal equipped with multiple antennas for indoor-indoor and outdoor-indoor scenarios are presented. We study the large-scale variation and small-scale characteristics of the measured channel coefficients. Although the mean received power is very much dependent on the measured location, the channel capacity seems to be unchanged when the receiver's location is altered. The data collected from different scenarios (e.g. measurement locations, antenna setting) were used to investigate the advantage of having the knowledge of the channel at both ends of the transmission link. It is shown that using the water filling algorithm there is indeed an increase in the channel capacity. At low SNR, the benefit of knowing the channel at both link ends observed in the measurement data is much higher than which can be obtained in the channel matrix with usual assumption on identical independently distributed components. Using the small-scale and large-scale information in the formulation of the channel capacity we show that in our measurement, the variation of the mean received power has a greater influence on the change of the overall system performance than the change in the environmental multipath scattering property.     

数字多路选择器网络最小化设计的一种简便方法

多路选择是一种重要的多功能通用逻辑器件,已经证明利用多路选择器网络可以实现任何逻辑函数。本文给出数字多路选择器网络最小化设计的一种简便方法。这种方法的关键是求出待实现函数的简化的不相交积之和(SCIP)形式;选择合适的各级控制(地址)变量;利用展开定理分别求出原函数(或其子函数)的关于各积项的函数限制。从本文给出的设计实例说明这种方法是有效而易行的。     

A Digital Echo Suppressor for Satellite Circuits

An echo suppressor that is composed solely of digital logic circuits and based on a digital voice detector [1] has been designed. The unit is simple and requires no adjustment. Its basic application is to the SPADE [2] PCM channel, although it can be adapted to work with other systems. Results of initial subjective tests are included.     

一种适用于非城市区域的卫星移动信道统计模型

本文提出了一种适用于非城市区域的卫星移动信道统计模型—莱斯 K模型 ,采用K 分布来描述由于遮蔽引起的接收信号包络的缓慢变化 ,用莱斯分布来描述包含直视信号分量 (主径 )在内的多径快衰落 ,得到了接收信号包络的概率分布和误比特率 .在此基础上 ,本文利用样本矩对莱斯 K模型参数进行了估计并对参数估计性能进行了评价 .最后 ,本文利用实测数据对模型进行了验证 .     

A Model of 60 GHz Indoor Radio Channel

A novel model of millimeter-wave (MMW) indoor radio channel is presented in this paper. The model is related the random properties of the MMW radio channel to the underlying geometry of the environment. The geometric simplicity of the MMW channel is allowed examining fundamental deterministic properties of the wave propagation behavior in environments of predefined randomness. The dimensions and properties of environments are described by various probability distributions. Stochastic influence on the radio channel is studied for the down-link of a wireless local area network at 60 GHz. Other related factors, such as amplitudes of path lengths, angles of departure, and amplitudes, as well as spatial power densities, average power of the direct paths are investigated.     

A BER-Based Partitioned Model for a 2.4GHz Vehicle-to-Vehicle Expressway Channel

Statistical channel models based on BER performance are presented for a frequency- and time-selective vehicle-to-vehicle wireless communications link in an expressway environment in Atlanta, Georgia, where both vehicles traveled in the same direction. The models are developed from measurements taken using the direct sequence spread spectrum (DSSS) technique at 2.45GHz. A collection of tapped delay line models, referred to as a “partitioned” model in the paper, is developed to attempt to capture the extremes of BER performance of the recorded channel. Overall and partition models are compared to the recorded channel in terms of the BER statistics obtained when the channels are inserted in a dedicated short range radio (DSRC) standard simulation system. The quality of the match between synthesized and recorded channel BER statistics is analyzed with respect to type of modulation (fixed or adaptive), the frame length, and the length of the interval over which the BER was calculated. Guillermo Acosta was born in Mexico City, Mexico, in 1962. He is a Ph.D. Candidate and a graduate research assistant in the School of Electrical and Computer Engineering at the Georgia Institute of Technology, in Atlanta, Georgia. He obtained his Bachelor of Engineering with Honors and Master of Engineering, both in Electrical Engineering, from Stevens Institute of Technology, Hoboken, New Jersey, in 1985 and 1987, respectively. He also obtained a Master of Business Administration with Honors from the Instituto Tecnologico Autonomo de Mexico (ITAM), Mexico City, Mexico, in 1996. Mr. Acosta has held technical and managerial positions in the recording, radio, and TV industries and in the Communications Ministry of Mexico. He has been an adjunct instructor in Electrical Engineering in the Instituto Tecnologico y Estudios Superiores de Monterrey Campus Estado de Mexico (ITESM-CEM) and the Universidad Iberoamericana. He is member of the IEEE, INCE, Tau Beta Pi, and Eta Kappa Nu. Mary Ann Ingram received the B.E.E. and Ph.D. degrees from the Georgia Institute of Technology, in Atlanta, Georgia, in 1983 and 1989, respectively. From 1983 to 1986, she was a Research Engineer with the Georgia Tech Research Institute in Atlanta, performing studies on radar electronic countermeasure (ECM) systems. In 1986, she became a graduate research assistant with the School of Electrical and Computer Engineering at the Georgia Institute of Technology, where in 1989, she became a Faculty Member and is currently Professor. Her early research areas were optical communications and radar systems. In 1997, she established the Smart Antenna Research Laboratory (SARL), which emphasizes the application of multiple antennas to wireless communication systems. The SARL performs system analysis and design, channel measurement, and prototyping, relating to a wide range of wireless applications, including wireless local area network (WLAN) and satellite communications, with focus on the lower layers of communication networks. Dr. Ingram is a Senior Member of the IEEE.     

A Digital Satellite Communications System for Corporate Telecommunications

A satellite communications system has been implemented by Citicorp to meet its present and future internal domestic telecommunications requirements. This system is currently being used for voice and data transmission and video teleconferencing between corporate facilities in New York, Los Angeles, San Francisco, and Sioux Falls, SD. Six additional cities will be served by the end of 1984. This system utilizes an 11-m earth station in each city to transmit and receive 60 Mbit/s TDMA signals from a satellite transponder on the Western Union WESTAR V satellite. Various terrestrial microwave, fiber optic, and copper cable facilities interconnect the earth stations to the users of the system. The basic trunk is digital at a T1, or 1.544 Mbit/s rate or multiple thereof, except some local distribution. A network control center provides centralized monitoring and control for all facilities in the system.     

A 20 GHz Band 0.5 W GaAs FET Amplifier for Satellite Communications

GaAs FET amplifier modules for 20 GHz band satellite communications have been developed using newly developed power FETs. The deep recess gate structure was adopted in the power FET, which improved both power output capability and power gain. Power added efficiency of 22 percent with more than 1 W power output has been achieved with 3 mm gate width FETs. The amplifier modules containing two-stage internally matched FET's can be hermetically sealed in metal packages. The modules had 8.4-8.9 dB linear gain in the 17.7-18.8 GHz band and 7.9-8.4 dB linear gain in the 18.5-19.6 GHz band. The power output at 1 dB gain compression point was more than 0.5 W. The third-order intermodulation distortion ratio was 81-83 dB at 18.2 GHz and 77-80 dB at 18.9 GHz, when individual output signal power was -4 dBm.     

An Area-Effective Cell-Based Channel Decoder LSI For a Digital Satellite TV Broadcasting

A new channel decoder LSI, which will be used in digital satellite TV broadcasting Set-Top Boxes, has been designed. This LSI's functions include AD/DA conversion, QPSK demodulating, Viterbi decoding, frame synchronization, convolutional deinterleaving, Reed-Solomon (RS) decoding, and descrambling. We use a new method for Viterbi Decoding called the Tracking Survivor State Information (TSSI) method, which not only reduces power consumption, but also solves the problem of increasing memory size. To reduce the size of RS decoder circuit, we used a three-stage-pipeline structure as well as designed a new architecture to realize Euclid's algorithm. This device has been fabricated in a 0.35 µm 3-metal CMOS standard cell-based process and is composed of 670 K transistors. In this paper, we describe the TSSI method of the Viterbi Decoder and the Reed-Solomon Decoder's new 3-stage pipeline architecture.     

气密封性测量装置

借助外壳防护的通信设备大都按照IP65防护等级的标准设计,IP65要求设备外壳的防护性能力可达到尘密和防喷水等级,是国标(GB4208-2008/IEC60529:2001)外壳防护等级中的一个分级.外壳的防护性能测量在生产领域中十分重要.然而由于各种原因,防喷水等级试验,即防水试验,难以在规模性生产领域推广应用.气密...     

一种新型的高性能50GHz光纤光栅滤波器

提出了一种新型的能同时实现光学滤波和色散补偿的50GHz光纤光栅滤波器。采用基于LP算法的IS光栅设计方法,按照50GHz信道间隔的DWDM系统要求设计了具有不同色散补偿距离的光纤光栅滤波器。结果表明,所设计的光纤光栅性能优良,完全满足系统要求。     

12千兆赫卫星直播电视接收站

已研制了一种简单、低成本的12千兆赫卫星直播电视接收站.给出了该站与主要微波部件如混频器、参放等的性能.该站在南京长期试收了日本直播卫星播出的节日,达到了预期的良好效果.     

A 65 mW, 0.4–2.3 GHz Bandpass Filter for Satellite Receivers

A monolithic tunable bandpass filter for satellite receiver front-ends is presented. The center frequency of the bandpass filter can be tuned from 0.4 GHz to 2.3 GHz. The filter is constructed using four transconductor-C poly-phase filter sections and has a 50 dB variable gain range. At 20 dB attenuation and at 30 dB gain the measured 1 dB compression point is –21 dBm and –56 dBm, respectively. Measured input IP3 is –12 dBm. The noise figure is 15 dB at maximum gain. An on-chip I/Q oscillator tracks the center frequency and enables automatic tuning. The bandpass filter dissipates 65 mW with 5 Volt supply voltage and occupies 0.16 mm² chip area. The filter is realized in a standard 11 GHz f _t bipolar technology.     

卫星移动通信的信道模拟技术

信道的计算机模拟是数字卫星通信在探索，研究和发展过程中的重要手段和必比阶段，本文基作者经验的总结，圣卫星通信计算机模拟的方法论给出一个简要而系统的介绍，重点放在移动卫星信道上。其内容包括：等效复基带表示法，一种信道分析和模拟研究所采用的非常方便珠数学形式。     

卫星数字视频广播系统中信道编译码性能的分析

本文分析了卫星数字视频广播系统（DVB－S）中信道编码的方式,并采用Viterbi译码器字节错误概率代替比特错误概率的方法来对DVB－S信道编码系统进行分析,所得到的字节错误概率上限界更适于分析DVB－S系统中级联卷积码内码和R－S外码的编码方案。     

Channel Modeling for Multiple Satellite Broadcasting Systems

In this contribution we present the results of a study on land mobile satellite channel models for satellite systems with multiple satellites. The slow fading of our channel model for several satellites is based on a Markov channel state model for joint processes while the Probability Density Function (PDF) of the signal amplitude within each state is fitted to the Loo distribution. The correlation between two satellite channels and the channel spatial autocorrelation have also been studied. We show that a channel state model that uses a Markov state model of order one or of a fixed higher order is not appropriate if the state duration is of very high importance, which can be the case in the process of system planning. Therefore, we propose a dynamic higher order Markov state model for joint processes that depends on the current state duration. This approach models precisely any PDF of the channel state duration for both single and multiple satellite broadcasting systems while having a significantly lower computational complexity than a fixed higher order Markov model. It models the channel states of the whole system correctly, as well as the channel states of each satellite observed independently. It is able to capture the state correlation between multiple satellites. We also study possible approximations of the proposed models in order to reduce their computational complexity while having a good PDF match. Our channel state models are validated by measurements.      

A Practical Optimization Approach for QPSK/TDMA Satellite Channel Filtering

This paper reports the results of computer and laboratory hardware simulation studies concerning optimum pulseshaping filter characteristics and configurations to be employed with conventional QPSK signaling in a nonlinear channel. An understanding of the factors and issues contributing to transmission impairments was obtained through an initial hardware simulation which was confirmed and extended with computer simulation. Based on this understanding, the critical characteristics of the channel pulseshaping transmit and receive filters were determined, promising filter candidates were implemented, and a complete system laboratory hardware simulation study was configured to evaluate the candidate filters using an INTELSAT IV satellite. This study emphasizes the performance tradeoff between the nonlinear channel-induced bit-error-rate impairment and the adjacent channel interference levels caused by HPA spectrum regeneration of filtered QPSK as a function of filter configuration. The results show that a more gentle rolloff Nyquist or wider bandwidth non-Nyquist transmit filter produces similar significantly improved performance compared to a conventional sharp rolloff Nyquist transmit filter in nonlinear satellite channels. For the wider non-Nyquist filter case, employing a Nyquist filter at the demodulation also benefits performance.