【作者】 吕伟锋；

【导师】 章专； 王柏祥；

【作者基本信息】 浙江大学 ， 电路与系统， 2004， 硕士

【摘要】 随着我国电信业的迅猛发展，目前我国已有多家电信运营商提供语音接入，其内部和各电信运营商之间对相同时间通话的计费因用户选择的呼叫方式不同便有很大的差异，用户可以选择某个运营商的网络作为自己某次呼叫的语音接口，而各新兴运营商的有线网络未完全覆盖或不能覆盖的情况下，无线接入无疑是一种理想的选择。 课题基于以上事实，将固话功能和无线接入设备有机的集成在一个系统中，内置MCU主控模块。拨号时，在不改变使用习惯的前提下按用户意愿将部分所拨号码从无线系统中旁路出去，在用户端即可完成电信网络的自动路由选择。并可在拨号过程中自动加入网络标识码，既节约费用，还方便用户，提高效率。 论文根据系统功能描述先完成各个部分硬件电路设计。端口电路包括自动路由切换，负载转换，反极跳转，摘挂机检测等部分。固话电路提供产生的双音多频信号及振铃和通话功能，双音多频收号电路将DTMF信号变成二进制码，便于MCU的识别和处理。模拟语音信号的调理处理普通固话中的通话和无线模块的语音的接口。MCU及其外围电路是整个系统的控制核心，显示电路用于指示系统工作状态和设备信息。结合实际应用情况，又简要讨论了数字信号的电平转换等问题及应用。 软件分为主程序和中断程序，前者完成系统本身的设置以及初始化，外设的驱动等功能。中断程序包括串口中断，外部中断和定时器中断服务程序。分别执行与无线通信模块的通信，读取来电信号，定时查询话机的摘挂机状态功能。无线模块的控制通过AT命令，包括其初始化设置和拨号等操作。软件还涉及的内容包括来自PSTN网络的FSK解码信号的正确接收，DTMF信号的收号与路由控制，以及查旁路数据结构等内容。 这种设计方法不但能完成系统功能和目标，还表现为设备结构简单，电路清晰，并能最大范围的减少MCU负担，扩展系统的功能灵活也容易等特点。更多还原

【Abstract】 With the fast development of telecom industry in China, There are several telecom companies can provide telecom access" service now. Also there are big differences in call fees at the same time because of the differences call way between the companies or inside companies. Customer should have the right to select a company’s telecom network as one call access of his or hers. However, the PSTN network hasn’t distributed or can’t distribute all over the China now, obviously, wireless access is an ideal selection in this case.Based on above, we designed a device that a telephone and a wireless access device made together in a system and they are controlled by a MCU. So some numbers dialed will be redialed by the MCU through the GSM modem according to customers’ will, also the IP number can be added automatically, which not only reduce call fees but also make convenience and improve efficiency for customers:We design the hardware circuits first. Interface circuits include auto-routing, load switch, polarity-reverting signal inverting and on-off hook checking. Telephone circuit produce DTMF signal, receive ring signal and perform speech function. DTMF receiver lets it becomes binary code for MCU to read. Analog circuit process speech signals between phone and GSM modem. MCU and its peripherals are central control unit. Display system is used to show work states and device information. In the last section of this party, we discuss voltage level shift and its application in the system.The software is divided two parts, main and interrupt. The former performs initial and setting of itself and drive of peripherals, et al. The later includes serial communication, external and timer/counter interrupt. They fulfill communication with the GSM modem, read ring signal, and check on-off hook timely respectively. The GSM modem is controlled by AT commands and the operation is such as its initial setting and number dialing. Other software program includes the receiving of decoded FSK signal from PSTN network, the receiving of decoded DTMF signal, auto-routing and the query of bypass data frame et al.The design method not only can complete system function but also reduce thecomplexity of device, make the circuits clearly, lighten the burden of MCU and let the system extend easily and simply.更多还原