数字化可视对讲系统设计与实现

发布时间：2018-06-03 01:42

本文选题：可视对讲 + i.MX27　；参考：《南京理工大学》2014年硕士论文

【摘要】：随着国民经济的增长和科技水平的提高,人们对家居环境的要求也日益升高,可视对讲系统已经成为住宅小区必不可少的基础设施。传统的对讲系统采用模拟音视频信号传输,存在施工布线复杂、成本高、容易占线、传输距离有限、抗干扰能力差、稳定性差、无法兼容等局限性。而数字化技术的导入弥补了以上缺陷。本文对模拟可视对讲系统进行数字化改造,设计完成了数字可视对讲系统的核心部分——数字联网切换器。首先研究了目前可视对讲系统发展趋势以及网络音视频传输的相关技术,对比了多种音视频编解码标准以及系统架构,结合本系统的设计需求,提出了以多媒体SoC处理器i.MX27为核心的总体设计方案。其次,本文详细介绍了联网切换器各功能模块的工作原理与实现方法,包括H.264视频编解码、音频处理、DDR内存、RTC实时时钟、RS-232/485通讯、以太网通讯等,并根据各模块外设芯片的功能特性完成原理图设计。然后本文基于高速电路信号完整性理论,考虑信号反射、串扰、电源完整性等因素,结合高速PCB设计经验,对PCB层叠、器件布局、传输线宽、线间距等进行规则设定,最终完成了PCB设计。另外,本文根据应用需求,在Linux系统开发环境下对Bootloader以及GPIO、RS485等设备驱动程序进行设计与修改,为应用程序提供API。最后对联网切换器进行模块化调试以及系统联调,验证设计的正确性。经过调试,数字化改造后的可视对讲系统实现了门口机与室内机之间的双向视频通话、视频监控、拍照、录音、开锁、报警等功能。系统运行稳定,视频通话效果良好。
[Abstract]:With the growth of the national economy and the improvement of science and technology, people's requirements for the home environment are also increasing day by day. Visual intercom system has become an essential infrastructure in residential areas. The traditional intercom system uses analog audio and video signal transmission, which has the limitations of complex construction wiring, high cost, easy busy, limited transmission distance, poor anti-interference ability, poor stability and incompatibility. The introduction of digital technology makes up for the above defects. In this paper, the analog visual intercom system is digitized and the core part of the digital visual intercom system is designed and completed. Firstly, this paper studies the development trend of visual intercom system and the related technology of network audio and video transmission, compares various audio and video coding and decoding standards and system architecture, and combines the design requirements of the system. An overall design scheme based on multimedia SoC processor i.MX27 is presented. Secondly, this paper introduces the working principle and implementation method of each function module of the network switch in detail, including H.264 video coding and decoding, audio processing DDR memory RTC real-time clock RS-232 / 485 communication, Ethernet communication, etc. According to the functional characteristics of each module peripheral chip, the schematic design is completed. Then, based on the theory of signal integrity of high-speed circuit, considering the factors of signal reflection, crosstalk, power integrity and so on, combined with the design experience of high-speed PCB, this paper sets the rules of PCB stack, device layout, transmission line width, line spacing and so on. Finally, the PCB design is completed. In addition, according to the application requirements, this paper designs and modifies the Bootloader and GPIO RS485 device drivers in the Linux system development environment, so as to provide the application program with API. Finally, modularization debugging and system tuning are carried out to verify the correctness of the design. After debugging, the digital video intercom system realizes the functions of two-way video communication, video surveillance, photography, recording, unlock, alarm and so on between the door machine and the indoor machine. The system runs stably and the effect of video communication is good.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN929.54

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