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为了在第一代移动通信卫星的基础上进一步开发移动卫星业务,美航宇局喷气推进实验室(JPL)已经完成了拟于90年代中期发射的第二代移动通信卫星的论证。JPL提出的这代移动卫星使用大功率的通信卫星公用舱,采用UHF频段,星上装有20米直径的大型可展开天线,可提供24个波束,有9000条信道,可为几十万用户服务。一、公用舱移动通信卫星的设计目标是要实现最大的卫星信道数量和最低的用户费用,然而它们要受到卫星公用舱容量的限制。所提出的
In order to further develop the mobile satellite service based on the first-generation mobile communications satellite, the NASA Jet Propulsion Laboratory (JPL) has completed the demonstration of the second-generation mobile communications satellite to be launched in the mid-1990s. This generation of mobile satellites proposed by JPL uses high-power communications satellites common to UHF bands. The satellite is equipped with a large 20-meter diameter deployable antenna that provides 24 beams and 9000 channels for hundreds of thousands of users . I. Public Class Mobile communication satellites are designed to achieve the maximum number of satellite channels and the lowest user fees, yet they are subject to the capacity of satellite public cabins. Proposed