车载式无线双模音视频传输监控系统设计与实现

基于CDMA2000和WCDMA的无线网络,设计并实现了车载式音视频监控系统,包括运行于后台的监控中心子系统和运行于终端的调用子系统.重点阐述了该监控系统中监控终端以及监控中心的软件设计和关键技术.系统在工程环境下进行了调用测试,测试结果表明,基于该设计的车载终端充分利用了CDMA2000和WCDMA网络的传输带宽,相对于单模的音视频传输,在传输效果上有较大的提高.     

Fiber optic microcellular radio

A distributed antenna system consisting of optical fiber connected canisters is proposed to replace or supplement the base station antennas required for cell splitting of growing cellular mobile radio systems. The end-to-end linear transmission of RF signal voltage can be maintained over the wide dynamic range of mobile radio. The technical feasibility of multiplexed subcarrier transmission using available lightwave components has been verified by signal-to-noise ratio and intermodulation distortion measurements. Measurements of a two-way audio link over both simulated and real radio paths have demonstrated the compatibility of a prototype lightwave transceiver, designed for the canister, with the existing base station and mobile equipment     

A mobile satellite news gathering system using a flat antenna

We propose a mobile SNG (satellite news gathering) RF terminal that transmits TV programs from a ship or a vehicle to a broadcasting center in real time via a communications satellite. The terminal consists of a transmitter using beam steering flat antenna with 16 subarrays and of a turntable and pitch-roll stabilizer for mechanical tracking. The antenna beam is steered according to a received beacon signal, and rapid tracking with an accuracy of 0.05° cart be achieved even if slant angles in the pitch and roll of the ship in which the terminal is set, are ±10° and ±15°. We demonstrated the good performance of the terminal by transmitting a TV program from a ship in Tokyo Bay     

重庆轻轨实时移动视频监控系统研究

文章给出了一种设计实时移动视频监控系统的方案。实时移动视频监控系统包括：控制中心监视子系统、车站监视子系统、车载子系统和传输子系统。文章首先从结构和功能两个方面阐述了各个子系统，然后从技术层面说明了实时移动视频监控系统的优越性。该系统在重庆轻轨中得到应用，并取得了较好的实际效果。     

Simulation,implementation and performance evaluation of a diversity enabled WCDMA mobile terminal

Smart antenna array technology has been shown to greatly improve the performance of wireless communication systems. In this article, we describe the impact of smart antenna array processing at the mobile terminal for Wideband Code Division Multiple Access (WCDMA) cellular networks. Using system simulations we demonstrate the quality of service, network coverage, and network capacity improvement provided by a WCDMA dual antenna receiver and we establish a relationship between this improvement and the link level performance. We then describe a receiver architecture for a dual antenna WCDMA mobile receiver. The proposed receiver was implemented, as part of a complete mobile terminal solution, in an ASIC using a 0.18 μm, 1.8 V CMOS technology. The ASIC was integrated with RF, analog and digital components in a PCMCIA card form factor. The PCMCIA is a 3GPP compliant user equipment and has been submitted to standardized performance and conformance tests. Experimental measurements gathered with the PCMCIA card illustrate the impact of a diversity enabled mobile data terminal on the link level performance. For various propagation environments and transmission data rates, improvements in the range of 2.7 – 10 dB in the required DPCH I _c/I _or for a 1% Block Error Rate (BLER) were observed. These measurements are within 1.4 dB of the ideal link level simulations which indicates that the predicted improvement at the network level should also materialize. The results presented in this paper show the tremendous potential of smart antenna arrays in 3G WCDMA cellular networks and establish diversity as a viable solution for high-speed cellular communications.     

米波雷达射频数字化接收系统实验研究

在雷达系统中，将数字化处理（A／D变换和D／A变换）尽量靠近天线即实现射频数字化接收系统是发展方向，也是实现全数字化雷达的关键技术。射频数字化接收技术简化了系统设计，降低了设备量，减小了系统的非线性失真。文中讨论了射频数字化接收系统研制中的关键技术，给出了实验结果。     

Design of a tunnel relay system with a leaky coaxial cable in an 800-MHz band land mobile telephone system

System design of a tunnel relay system in an 800-MHz band land mobile telephone system is described. Several dozen RF signals from a base station or many different mobile units in the tunnel are directly amplified in the RF stage, without frequency conversion, by a common amplifier in the relay equipment installed near the tunnel entrance, then radiated into the tunnel through a leaky coaxial cable (LCX) or to the base station by a unidirectional antenna. Repeaters are inserted along the LCX to compensate for transmission loss in RF signal power inside the cable. Amplifying a number of RF signals simultaneously, a common amplifier generates intermodulation products and radiates spurious signals. The required amplifier linearity to suppress the spurious signals is discussed in detail. The combination of LCX and service area in the tunnel is determined according to the amplifier performance, the number of radio channels assigned to the base station, and the radio wave propagation characteristics in the tunnel.     

基于RTP协议的移动视频监控系统的设计

无线移动网络环境稳定性较差,需要研究如何自适应有效带宽的动态变化,以获得最佳的视频监控效果。H．264是高压缩比的视频编解码标准,相同条件下需要的传输带宽更少。RTP/RTCP协议专为实时数据的传输而设计。本系统中,视频采集终端用RTP协议封装和发送H．264数据,用RTCP协议接收网络传输质量信息,自适应调整发送速率;监控平台对收到的数据进行整理和过滤,确保视频图像的正确播放。实验表明该设计在无线移动网络环境下,视频监控效果良好。     

Integration of Voice and Data in the Wideband Packet Satellite Network

The Wideband (packet satellite) network is an experimental 3 Mbit/s communications system developed under sponsorship of the Defense Advanced Research Projects Agency and the Defense Communications Agency. This system is being used to evaluate the use of packet transmission for efficient voice communication, voice conferencing, and integration of voice and data over a satellite channel. Each station in the Wideband network consists of an earth terminal (dedicated 5 m antenna plus associated IF/RF equipment), a burst-modem and codec unit, and a station controller. Station controllers provide interfaces to host computers (including packet speech sources) and manage the allocation of the satellite channel on a TDMA demand-assigned basis. TDMA demand-assignment is implemented using a reservation-based packet-oriented protocol capableof handling traffic at multiple priority levels. The channel protocol provides a reservation-per-message mode of service (datagrams) to support transmission from bursty traffic sources and a reservation-per-call mode of service (streams) to support traffic with more regular arrival statisticS (e.g., vioce). A distributed scheduler running in every station controller eliminates the need for a central control station and minimizes network transit delay for datagram transmission as well as stream creation, modification, and deletion. In this paper we describe the protocols and mechanisms upon which the Wideband packet satellite network is based.     

二网融合的可视电话与多媒体增值业务系统

提出一种分别利用PSTN传送话音,利用Internet传送视频和提供实时广告、视频点播或直播的可视电话与多媒体增值业务系统及其实现方法,给出了通话者音、视频传送并在终端同步还原的设计要点,以及实现其他多媒体业务的设计框架。介绍了系统的运营模式及其特点。     

Circuit multiplication equipment

This paper discusses the main issues relating to the configuration and equipment which are to be provided in earth-stations for implementing satellite links with digital circuit multiplication (DCM). Such an implementation is possible using either FDMA/TDM/PSK (continuous) or TDMA/PSK (burst mode) carriers. The main accent will be put in the paper on earth-stations operating with FMDA/TDM/PSK carriers (called IDR carriers by INTELSAT). As regards the RF/IF subsystem, it is shown that IDR and TDMA are very effective in terms of earth-station equipment as compared with conventional FDM/FM operation. As regards the communication subsystem—independently of the DCM equipment proper—a compact terminal, integrating all the signal processing and baseband functions is described.     

Adaptive equalisation of multipath interference for mobile videosignal reception

By using multiantenna diversity system to combat fading for mobile reception of video signals a nearly omnidirectional antenna pattern diagram can be achieved. However ghosts, especially fluttering ghosts, mainly caused by the fast rotating echo phases and RF signal level fluctuation, still affect the picture quality. It is shown that a single ghost cancelling reference (GCR)-signal is not sufficient for fluttering ghost suppression. A blind TV signal equalisation algorithm, which is based on image processing techniques, is developed to remove the interference of echoes with rapidly changing phases. A simplified version of this algorithm is included to reduce the computational load and allow suitable IC integration     

Television Transmission Performance of an Experimental Small Aperture Earth Station

The background for the characterization of small aperture earth stations suitable for use in a proposed U.S. Domestic System is described and system considerations for transmission performance given. Three experimental stations were constructed and extensively tested to demonstrate the key features required. Test results are given for antenna gain, noise, station G/T, and television transmission performance. The system used an FM subcarrier for audio transmission, and crosstalk between the video and audio signals was determined. Interference from terrestrial radio relay systems was encountered at the test location, and the RF spectrum plotted. Sun outage was measured during the autumnal equinox.     

一种无线遥控报警与手动报警相集成方法的实现

为使安防子系统更具可靠性、针对性、实用性,基于手动报警按钮,无线遥控报警器,海康视频服务器,声光报警器,终端传输等设备,设计了一种无线遥控报警与手动报警相集成的电路,并给出了设计效果图,在突发事件情况下能快速反应,及时发出信号,有效实现了阵地安防子系统报警方式的多样化、可用化、便捷化.     

A new protocol for the integration of voice and data over PRMA

In packet reservation multiple access (PRMA) the receiver in the mobile terminal is required to listen continuously to monitor the acknowledgment messages broadcasted at the end of every time slot. A new scheme for the integration of voice and data based on PRMA is proposed. The voice and the data subsystems are logically separated. The total available bandwidth is divided into three regions-voice information, voice contention, and data regions. The available bandwidth is dynamically partitioned between the above three regions subject to the fulfillment of the quality of service (QoS) requirements of the voice users. The voice subsystem has been modeled as a Markov chain and an exact analytical method used to compute the voice packet dropping probability is described. A nonlinear programming problem is formulated to optimize the bandwidth allocated for the data users. Solutions to this nonlinear programming problem that are very close to optimum have been obtained heuristically. Numerical results indicate that a significant amount of data traffic can be supported without sacrificing the voice capacity of the system     

Measurement tools for digital video transmission

An overview of test equipment and applications targeted specifically for digital broadcast signal distribution is given. The vector generator and analyzer evaluate the constellation accuracy, give direct conclusions with regard to the source of impairments, and allow SER (symbol error rate) estimates. Peak power and peak-to-average power ratio, key parameters in digital broadcasting, are monitored with the digital video power analyzer. The power distribution functions of the power analyzer may prove useful as an economic tool for linearity and group delay adjustments. The effects of potential impairments in the transmission path, like reflections, multipath signals, or Doppler effects from antenna sway, can be evaluated with a channel simulator. The bottom line assessment of a total system's transmission quality is delivered by BER (bit error rate) measurements from modulator input to receiver demodulator output     

4G蜂窝网中移动互联网IP电视服务的优化研究

4G蜂窝网的频谱分配效率难以负担日益增长的移动IPTV服务与大视频流数据,为此提出了蜂窝网支持移动IPTV服务的优化方案,在保持传统语音电话质量的前提下,提高了移动IPTV服务的性能.首先,为语音电话分配较高的频率分配优先级以维护语音电话的QoS(Quality of Service);然后,采用软频谱复用技术来增强频谱的效率,并降低相邻蜂窝之间的频谱干扰;最终,设计了动态频谱分配算法,对相邻蜂窝间边缘频带的频谱分配进行协调与优化,进一步地提高了频谱利用率.仿真结果显示,本频谱分配算法在不降低语音电话服务质量的前提下,明显地提高了移动IPTV服务的性能.     

A novel portable bipolar near-field measurement system for millimeter-wave antennas: construction, development, and verification

As new antenna designs require higher frequencies and smaller sizes, traditional large-scale antenna measurement systems become ill-suited for such measurements. External mixing, room-sized chambers, and expensive test equipment add large costs and burdens to antenna measurement systems. A smaller and more cost-effective system is presented in this paper. Using the bipolar planar scanning technique developed at UCLA, a portable millimeter-wave antenna measurement system has recently been constructed. The system was designed to fit on the end of a standard optical table, and enjoys the spacesaving and accuracy inherent to the bipolar planar configuration. Simple construction of the chamber allows for relatively easy assembly and disassembly, and allows movement of the system from one table to another, if needed. Antennas of diameters up to 24 in can be accommodated, and scan planes of up to a diameter of 60 in can be measured. Millimeter-wave frequencies from around 30 GHz to 67 GHz can be measured, with potential extension to higher frequencies. Planar nearfield- to-far-field techniques are used to construct the antenna's far-field patterns from the measured near field. In particular, the post processing follows the OSI/EFT method for pattern reconstruction and diagnostics. The design of the scanner configuration allows the incorporation of the phase-retrieval techniques developed for the bipolar configuration. These phaseless measurements allow the use of scalar millimeter-wave test equipment, with much lower cost than comparable vector test equipment.     

未来中国4G开放移动通信终端和网络接入架构

This paper relates to an advanced open mobile communication system and method of integrating the mobile communications, wireless access systems and wired communications into one common platform architecture for China＇s 4th generation mobile communications, supporting costeffective broadband voice, data and video services in wireless, mobile and wired environment with one single integrated mobile terminal device. The paper includes new architecture in the integrated mobile device and converged network access, and minimum modification in the existing mobile telecommunication infrastructures. This paper introduces the long-term evolution strategy for China＇s TDD system platform towards China＇s future 4G mobile communications.     

实时多模式无线视频传输原型系统的实现

给出了一种新颖的无线视频传输原型系统。其设计特点是,无线终端以高性能多媒体DSP作为实时视频压缩编码和系统控制的核心,接口板集成了多种现有的无线网络接口,通过软件控制,系统不仅可以工作在单个网络模式,也可在多种网络模式下自动选择合适的传输方式,提供最佳的视频传输质量。详细描述了系统的组成结构,无线终端的软硬件设计和控制策略。实际测试结果表明,该系统在GPRS/WLAN和CDMA/WLAN的网络组合测试环境下,均能在各种网络模式之间正确切换,图像质量令人满意。