【作者】 刘第；

【导师】 刘明亮；

【作者基本信息】 北京工业大学 ， 计算机应用， 2000， 硕士

【摘要】 为解决无线电波污染和覆盖之间的矛盾，各寻呼台服务商纷纷采用卫星链路方式。但由于各设备接口协议不同，故需要通过网关（转码卡）实现连接。本课题就是为解决这一问题而提出的。 本文首先简单的介绍无线寻呼系统及其原理，其次对不同方案进行了论证，最后比较详细的介绍了转码卡的设计、调试和测试。 转码卡设计分为软件和硬件两部分。采用8XC196单片机，外围芯片，如光电隔离4N35、电平转换ICL232、4位二进制可置数计数器74LS161、单稳态触发器74LS123、八位移位寄存器74LS595等，作为POCSAG码字的接收、格式转换和发送的硬件支持。其关键技术采用自同步方式，即从输入数据中提取时钟。软件采用8XC196的汇编语言，用高效率的中断方式完成码字的比较、匹配。该转码卡只用一路就能识别出不同极性、不同波特率的输入数据。 调试和测试的结果表明，本文所介绍的方案是可行的。本转码卡位同步和纠正时钟误差上明显强于前一版本转码卡。但是由于时间等原因，软件未能包括对POCSAG码字进行BCH校验的功能。更多还原

【Abstract】 The service agent of each pager station adopts the satellite channel to solve the conflicting of pollution and covering of radio wave. However due to the difference of the interface devices, the gate which called transform card is need .So the task emerges as the times require.Radio Paging System and it principle are introduced simple in the paper. Then three schemes are demonstrated. Finally the design~ debug and test of transform card are present in detail.The design of transform card is divided into two part, software and hardware. The hardware of transform card is constituted by microchip 8XC 196 and peripheral chip such as 4N35 which is photo-electricity segregating~ 1CL232 which is transforming the levels chip 74LS 161 which is binary system counter~ 74LS 123 which is single stable trigger~ 74LS 595 which is shift register and so on, Which key technology is selfsynchronizing, namely clock is abstracted from input data. The assembly language of 8XC196 which have the high efficiency interruption is used to compare and match with POCSAG codes. This transform card can recognize the POCSAG code of different polarity and different rate.Debug and test indicate the scheme in the paper is feasible. The transform card is stronger than the old transform card on bit synchronizing and error correcting of the clock. However the BCH calibrating of the POCSAG code has not been included in the software due to the urgent times.更多还原