GEOSTAR卫星无线电定位系统扩频接收机的实现

GEOSTAR卫星无线电定位系统是为美国本土和世界各地妁地面移动用户以及航海、航空用户提供准确的位置信息和辅助双向信息。用户至Geostar中心线路由移动站的发射机、中继卫星和中心接收站组成并已经建成。来自用户终端的扩频和卷积编码的突发射频信号通过卫星被中继到GEOSTAR中心,由该中心进行信息包的捕获、解调和处理。在突发工作方式的扩频系统中,传输和数据误差率取决予线路特性、捕获概率、虚警概率和使用的解调器数量。本文比较了用户至GEOSTAR中心线路理论和实测传输特性和数据误差特性。     

Optimizing receiver performance using harm claim thresholds

More and more systems need to be squeezed together in frequency, space and time in order to satisfy the growth in demand for radio services. However, greater proximity increases the risk of service breakdowns caused both by poor interference tolerance in receivers and by inappropriate signals radiated by transmitters.     

Transmitters and receivers' investment to avoid interference: Is there an optimal regime?

The management of interference has been, and still is, the main concern in spectrum policy. Historically, interference has been dealt with by heavy regulation under an administrative control regime. Over the last decades, a new approach has been put forward based on users' property rights, better able to cope with a rapidly changing technological environment. The issue of dealing with interference across bands, however, remains crucial: What obligations should be put on users so as to keep interference at a socially acceptable level? Also, given that some unwanted emissions are bound to occur, how can private parties be provided with the right incentives to invest in high-quality reception technology? This paper assesses how well different regulatory regimes can lead to efficient outcomes. It develops an economic model of spectrum interference and identifies the efficient solution. A regime where spectrum users have the power to enjoin intruding emissions beyond a predefined level (property rights protection) is compared with a regime where users are forced to bear with intruding emissions, but are entitled to economic compensation for the harm suffered (liability rules protection). The analysis suggests that different regimes may perform differently under different circumstances depending on the cause of interference and, critically, on whether the services are organised as an open- or a close-architecture system. This suggests that regulators should pay more attention to the specific features of the different bands, and that the appropriate spectrum management regime should be designed to recognise these differences.     

发展中的我国卫星电视接收技术

本文综述了我国卫星电视接收的发展情况，论述了当前卫星电视接收中的关键技术－超低噪声高频头和一体化高频头，低噪声天线和天线的小型化，多制式微处理器控制的低门限接收机，多星广播的接收和多波束天线，卫星电视信道的综合利用。