有线电视数字机顶盒维修教程

有线电视数字机顶盒维修教程 第1节 数字机顶盒的故障诊断和检修单元 单元, 数字机顶盒工作原理和电路分析 一(有线电视系统 1有线电视系统的组成 有线电视系统是由前端、干线传输和用户分配三大部分组成. (1) 前端部分 前端部分是有线电视系统传输节目的总源头,为有线电视提供信号源。前端部分应用的设备主要有高频放大器、解调器、调制器、混合器等。电视信号数字化后，前端部分还包括信号源编码和数字调制系统。有线电视信号源通常有多种类型，如其他有线电视台的有线电视节目、卫星电视地节目、自办节目、录像机播放的电视连续剧节目等。 (2) 干线传输部分 干线传输部分是一个传输网，主要是把前端接收、处理、混合后的电视信号传到用户分配部分的一系列传输设备。干线传输部分应用的设备主要有光发射机、光接收机、分配放大器、干线放大器、同轴电缆、光放大器、光纤维、还包括多路微波分配系统等。根据有线电视用户总数的不同，需要干线提供的信号大小也不一样。干线放大器用来补偿干线上的传输损耗，把输入的有线电视信号调整到合适的大小输出。 (3) 用户分配部分 用户分配部分是有线电视系统的最后部分，直接将来自干线传输系统的信号分配、传送到各户的电视机中。用户分配部分应用的设备主要有分支器、分配放大器、同轴电缆、用户终端等。有线电视系统的前端部分位于有线电视中心，它是节目源的产生和处理部分。它将声音、图像等节目信息源进行收集，然后采用 MPEG-2编码器将信息转换成音频、视频数据信号，最后经QAM调制器，再分别对各种节目的数据信号进行调制，并送到服用器进行合成处理，最后由混合器输出。有线电视中心往往通过多个卫星天线接收来自国内外电视台通过数字卫星播出的电视节目，用卫星接收机可以将这些节目下来还原成音频、视频信号。这些and special tools for emergency response equipment and facilities. Emergency preparedness and response plan 1) emergency response (1) If a major accident occurs, the project should set up emergency response teams, chaired by the project manager, head of production and safety coordinators, professional foreman for the crew, primarily responsible for the orderly rescue when an emergency occurs or processing, outsourcing, team manager and support staff, assisting the Deputy Project Manager for related auxiliary work. (2) after the accident, the project manager is responsible for field commander, advance the establishment of emergency response team personnel, accountability, seriously injured officers sent out rescue, have procedures to deal with accidents, incidents, maximum reduction in casualties and property loss. (3) If an accident occurs, press Division in advance for emergency personnel cleared, concentrate manpower and material and financial resources to rescue the injured, decrease of the maximum loss. (4) after the accident processing work (5) identified the cause of the accident and the person responsible. (6) the written report to the supervisor in writing, including the time and place of the accident, injury (death) person's name, sex, age, trades, injuries, injuries. (7) the development of effective preventive measures to prevent such accidents from happening again. (8) education of all personnel of the organization. (9) informed criticism of those responsible. (10) all personnel read out the results, and responsible disposal. (11) maintenance of emergency supplies, maintenance and testing ? strengthening the day-to-day management of the various fire fighting equipment fire-fighting equipment, authorities should be staffed, equipped with fire extinguishers. Fire hydrants identified person responsible for regularly inspecting, testing, at any time in good condition. ? Guard monthly check-fire extinguishers and fire-fighting equipment. ? once every quarter, inspections and tests of a fire hydrant in good condition. 2), plans to develop (1) casualties occurred in construction, such as accidents or accidents of the direct economic 音频、视频信号经过压缩编码和QAM调制后，通过有线系统传送到用户终端。此外，有线电视中心还可以将自办节目和录像机播放的电视节目分别经调制器调制到射频信号上，也送入混合器。混合器输出的射频信号是多频道节目混合在一起的宽带射频信号。多频道电视信号要通过有线传输系统送到千家万户。传输系统常采用管线和同轴电缆混合的方式，先经光发射机将电信号变成光信号，由光纤进行较远距离的传送，送到居民社区。光接收机再将光信号变成电信号，并由同轴电缆、干线放大器、分配放大器、分支器分成多路信号送到用户终端。在用户终端系统中实际上也包含分支器、分配放大器和机顶盒等。传输系统和终端使用普通模拟电视机可以直接收看模拟电视节目，而收不到数字节目。如果使用数字有线机顶盒或带数字解调器的电视机，就可以收看数字电视节目。 2. 有线电视的信号传输 有线电视中心将多路电视节目信号混合后，经同轴电缆或光线传输系统送到用户终端。有限电视传输系统的信号编码处理过程包括信源编码和信道编码两大部分。信源编码部分主要是对音频和视频信号进行A/D变换和数据压缩编码的电路.信道编码则是为便于频道传输而设置的电路,它主要包括数据扰乱、RS纠错编码、数据交织、字节到符号的转换、差分编码、基带整形、QAM调制等部分。QAM调制后的信号作为中频信号再经变频器变成射频信号，然后进行有线传输。 在模拟有线传输系统中，每个频道占用1个载频，信号采用幅度调制的方法(AM)。信号的传输有两个方向:向用户终端传输电视节目(下行)，称为向前路径:用户向有线中心(上行)传送信息，称为反向路径。目前有线电视系统中心数字电视的频道还较少，主要的还是模拟电视节目，因此是数字电视的频道安排仍沿用模拟电视的频道划分方式，每个频道带宽为8MHz。上、下信道频谱有4个频段:下行信道，87,550MHz传送模拟电视信道，550,750MHz传输数字电视信道，750,1000MHz传输通信数据;上行信道，6,65MHz传送用户向有线电视中心发送的信息。 3. 有线电视系统传输设备的功能特点 传输系统是有线电视系统的重要子系统，它位于前端和用户分配部分之间，其作用是将前端部分输出的各种信号不失真地、稳定地传输给用户分配部分。传输部分由多种传输设备构成，目前创建的主要传输设备有光发射机、干线放大器、and special tools for emergency response equipment and facilities. Emergency preparedness and response plan 1) emergency response (1) If a major accident occurs, the project should set up emergency response teams, chaired by the project manager, head of production and safety coordinators, professional foreman for the crew, primarily responsible for the orderly rescue when an emergency occurs or processing, outsourcing, team manager and support staff, assisting the Deputy Project Manager for related auxiliary work. (2) after the accident, the project manager is responsible for field commander, advance the establishment of emergency response team personnel, accountability, seriously injured officers sent out rescue, have procedures to deal with accidents, incidents, maximum reduction in casualties and property loss. (3) If an accident occurs, press Division in advance for emergency personnel cleared, concentrate manpower and material and financial resources to rescue the injured, decrease of the maximum loss. (4) after the accident processing work (5) identified the cause of the accident and the person responsible. (6) the written report to the supervisor in writing, including the time and place of the accident, injury (death) person's name, sex, age, trades, injuries, injuries. (7) the development of effective preventive measures to prevent such accidents from happening again. (8) education of all personnel of the organization. (9) informed criticism of those responsible. (10) all personnel read out the results, and responsible disposal. (11) maintenance of emergency supplies, maintenance and testing ? strengthening the day-to-day management of the various fire fighting equipment fire-fighting equipment, authorities should be staffed, equipped with fire extinguishers. Fire hydrants identified person responsible for regularly inspecting, testing, at any time in good condition. ? Guard monthly check-fire extinguishers and fire-fighting equipment. ? once every quarter, inspections and tests of a fire hydrant in good condition. 2), plans to develop (1) casualties occurred in construction, such as accidents or accidents of the direct economic 光接收机、同轴电缆及光纤等。 4. 有线电视系统的工作过程 有线电视系统中有线电视中心对接收到的由卫星传送的电视信号、无线广播的电视信号、微波传送的电视信号以及自办和录像机播放的电视信号进行编码、调制、合成等处理，由混合器输出到传输系统，在传输系统中再经放大分支等处理后送入用户终端。 有线电视中心对各种电视节目进行整合并统一规划，进行频段和频道的安排，其中一部分电视节目进行模拟调试，仍以模拟调制的方式传输，用户可以用模拟电视机直接收看。另一部分则分别进行数字编码和数字调制，然后分别调制到各自的频道上传输出去，由数字机顶盒进行数字解调和数字处理，最后输出音频、视频信号，再传送到电视机供用户收看。有线电视中心对电视信号的是自调制方式与卫星传播的数字调制方式不同，因而有线电视机顶盒的数字解调方式也不同。有些机顶盒中设有可兼容的解码芯片，可接收和处理两种信号。 二、数字机顶盒整机电路构成 数字有线电视机顶盒的基本功能是接收有线电视系统传输的数字电视广播信号，通过解调、解复用、解码和音、视频编码，可供用户在模拟电视机上观看数字电视节目和浏览各种数据信息。 1 典型数字有线电视接收机顶盒的整机构成 以北京TC2132C2型数字有线机顶盒的整机结构为例: 它主要由主电路板、操作显示面板和电源电路板等构成。如图1.1.1，1.1.2，1.1.3，1.1.4所示。 and special tools for emergency response equipment and facilities. Emergency preparedness and response plan 1) emergency response (1) If a major accident occurs, the project should set up emergency response teams, chaired by the project manager, head of production and safety coordinators, professional foreman for the crew, primarily responsible for the orderly rescue when an emergency occurs or processing, outsourcing, team manager and support staff, assisting the Deputy Project Manager for related auxiliary work. (2) after the accident, the project manager is responsible for field commander, advance the establishment of emergency response team personnel, accountability, seriously injured officers sent out rescue, have procedures to deal with accidents, incidents, maximum reduction in casualties and property loss. (3) If an accident occurs, press Division in advance for emergency personnel cleared, concentrate manpower and material and financial resources to rescue the injured, decrease of the maximum loss. (4) after the accident processing work (5) identified the cause of the accident and the person responsible. (6) the written report to the supervisor in writing, including the time and place of the accident, injury (death) person's name, sex, age, trades, injuries, injuries. (7) the development of effective preventive measures to prevent such accidents from happening again. (8) education of all personnel of the organization. (9) informed criticism of those responsible. (10) all personnel read out the results, and responsible disposal. (11) maintenance of emergency supplies, maintenance and testing ? strengthening the day-to-day management of the various fire fighting equipment fire-fighting equipment, authorities should be staffed, equipped with fire extinguishers. Fire hydrants identified person responsible for regularly inspecting, testing, at any time in good condition. ? Guard monthly check-fire extinguishers and fire-fighting equipment. ? once every quarter, inspections and tests of a fire hydrant in good condition. 2), plans to develop (1) casualties occurred in construction, such as accidents or accidents of the direct economic 图1.1.1数字有线机顶盒的整机结构 图1.1.2 主电路板图 主电路板是数字有线电视接收机顶盒的核心部件，数据存储器、一体化调谐器、A/V解码芯片、IC卡座以及视频输出接口等核心器件都集成在主电路板上。 图1.1.3 操作显示面板 操作显示面板，它主要是由数码显示器、操作显示接口电路、按键以及遥控接收电路等组成，主要功能是为机顶盒输入人工操作指令、显示机顶盒的工作状态以及接收遥控器的指令。 and special tools for emergency response equipment and facilities. Emergency preparedness and response plan 1) emergency response (1) If a major accident occurs, the project should set up emergency response teams, chaired by the project manager, head of production and safety coordinators, professional foreman for the crew, primarily responsible for the orderly rescue when an emergency occurs or processing, outsourcing, team manager and support staff, assisting the Deputy Project Manager for related auxiliary work. (2) after the accident, the project manager is responsible for field commander, advance the establishment of emergency response team personnel, accountability, seriously injured officers sent out rescue, have procedures to deal with accidents, incidents, maximum reduction in casualties and property loss. (3) If an accident occurs, press Division in advance for emergency personnel cleared, concentrate manpower and material and financial resources to rescue the injured, decrease of the maximum loss. (4) after the accident processing work (5) identified the cause of the accident and the person responsible. (6) the written report to the supervisor in writing, including the time and place of the accident, injury (death) person's name, sex, age, trades, injuries, injuries. (7) the development of effective preventive measures to prevent such accidents from happening again. (8) education of all personnel of the organization. (9) informed criticism of those responsible. (10) all personnel read out the results, and responsible disposal. (11) maintenance of emergency supplies, maintenance and testing ? strengthening the day-to-day management of the various fire fighting equipment fire-fighting equipment, authorities should be staffed, equipped with fire extinguishers. Fire hydrants identified person responsible for regularly inspecting, testing, at any time in good condition. ? Guard monthly check-fire extinguishers and fire-fighting equipment. ? once every quarter, inspections and tests of a fire hydrant in good condition. 2), plans to develop (1) casualties occurred in construction, such as accidents or accidents of the direct economic 图1.1.4 电源电路板 电源电路的主要作用是为整机提供工作电压和电流，它主要由交流输入电路(滤波电容、互感线圈)、整流滤波电路(桥式整流电路，+300V滤波电容)、开关振荡电路(开关振荡集成电路、开关变压器)、次级输出电路和稳压控制(光电耦合器等)等部分构成。 三、数字机顶盒各部分功能 1(调谐解调器 有线电视调谐器接收信号的频率较低(48,860MHZ)，频带较宽(812M)，中频频率为(36M)，解调器采用QAM解调方式。一体化调谐解调器的作用是将传输过来的调制数字信号解调还原成传输流。调谐解调器的不同就构成了不同的数字机顶盒，例如用于QPSK解调的卫星机顶盒(DVB-S)，用于QAM解调的有线数字机顶盒(DVB-C)以及用于OFDM解调的地面传输数字机顶盒(DVB-T)。 2(解复用器和MPEG解码器 解复用器由信道接口信道FIFO、PID处理器、PID后处理器、内部音/视频接口和节目时钟提取电路等组成。其中信道接口提供自动传输包同步字节检测及实现同步锁定/未锁定的具有可编程时延的滞后机构，一旦建立同步，信道接口就通过信道FIFO将完整的传输包传输到PID处理器。信道接口还用于检查传输包的完整性，指示传输错误等。 3(视频编码器和视频解码器 SC2005芯片内集成了一个视频编码器，可将8位或16位YCrCb数字视频流编码残生复合视频、S视频或RGB视频信号，支持PAL、NTSC和SECAM制式。它and special tools for emergency response equipment and facilities. Emergency preparedness and response plan 1) emergency response (1) If a major accident occurs, the project should set up emergency response teams, chaired by the project manager, head of production and safety coordinators, professional foreman for the crew, primarily responsible for the orderly rescue when an emergency occurs or processing, outsourcing, team manager and support staff, assisting the Deputy Project Manager for related auxiliary work. (2) after the accident, the project manager is responsible for field commander, advance the establishment of emergency response team personnel, accountability, seriously injured officers sent out rescue, have procedures to deal with accidents, incidents, maximum reduction in casualties and property loss. (3) If an accident occurs, press Division in advance for emergency personnel cleared, concentrate manpower and material and financial resources to rescue the injured, decrease of the maximum loss. (4) after the accident processing work (5) identified the cause of the accident and the person responsible. (6) the written report to the supervisor in writing, including the time and place of the accident, injury (death) person's name, sex, age, trades, injuries, injuries. (7) the development of effective preventive measures to prevent such accidents from happening again. (8) education of all personnel of the organization. (9) informed criticism of those responsible. (10) all personnel read out the results, and responsible disposal. (11) maintenance of emergency supplies, maintenance and testing ? strengthening the day-to-day management of the various fire fighting equipment fire-fighting equipment, authorities should be staffed, equipped with fire extinguishers. Fire hydrants identified person responsible for regularly inspecting, testing, at any time in good condition. ? Guard monthly check-fire extinguishers and fire-fighting equipment. ? once every quarter, inspections and tests of a fire hydrant in good condition. 2), plans to develop (1) casualties occurred in construction, such as accidents or accidents of the direct economic 由数据控制单元、解码器、输出接口、RGB处理器和D/A变换器等部分构成。 MPEG视频解码器是一个支持MPEG-1和MPEG-2标准的视频压缩处理器，显示图像的格式转换由垂直和水平滤波器完成，用户定义的位图可以通过使用屏上显示功能叠加在显示图像上。MPEG视频解码器包括内容随图像改变的寄存器、可变长度解码器(VLD)、视频解码控制器、PES分析器、位缓冲器和启动码检测器等部分。 4(音频D/A转换器 音频D/A变换器是一种具有可编程锁相环(PLL)的立体声D/A变换器，其作用是将由音频解码器输出的PCM音频数据转换成左右声道的模拟立体声信号。 以PCM1723E为例说明音频D/A转换器的组成，它包括串行输入音频数据接口，具有功能控制的8倍过采样数字滤波器、多电平调制器、D/A变换器、模拟低通滤波器、模式控制单元、可编程锁相环PLL系统等。 5(智能卡读卡器 通过读卡器读取CA智能卡中的数据用于数字电视节目的解扰，特别是在付费电视发展的今天，这是大多数STB必不可少的部件。除了标准的读卡器外，在有些STB中也采用通用接口CI(Common Interface)来完成对CA智能卡的读取。CI是一个由DVB组织为机顶盒和分离的硬件模块之间定义的标准接口。这种起源于PCMCIA的技术应用，使机顶盒可以批量生产，也为机顶盒带来了变化，有着广泛的应用前景。 6(系统控制与存储器 机顶盒的系统控制电路有CPU、程序存储器、数据存储器、地址译码器和总线接口电路组成，完成系统控制和数据存储。 7(操作显示面板 操作显示面板通常由键盘矩阵及扫描电路、显示电路、红外遥控接收器等组成。用户通过操作面板按键或遥控器为CPU输入人工指令，完成设置功能。 8(开关稳压电源 开关电源部分是机顶盒中非常重要的一个环节。它主要由交流输入电路、整流滤波电路、开关振荡电路、开关变压器T602、次级整流滤波和稳压电路等部分构成。如图1.1.5所示 and special tools for emergency response equipment and facilities. Emergency preparedness and response plan 1) emergency response (1) If a major accident occurs, the project should set up emergency response teams, chaired by the project manager, head of production and safety coordinators, professional foreman for the crew, primarily responsible for the orderly rescue when an emergency occurs or processing, outsourcing, team manager and support staff, assisting the Deputy Project Manager for related auxiliary work. (2) after the accident, the project manager is responsible for field commander, advance the establishment of emergency response team personnel, accountability, seriously injured officers sent out rescue, have procedures to deal with accidents, incidents, maximum reduction in casualties and property loss. (3) If an accident occurs, press Division in advance for emergency personnel cleared, concentrate manpower and material and financial resources to rescue the injured, decrease of the maximum loss. (4) after the accident processing work (5) identified the cause of the accident and the person responsible. (6) the written report to the supervisor in writing, including the time and place of the accident, injury (death) person's name, sex, age, trades, injuries, injuries. (7) the development of effective preventive measures to prevent such accidents from happening again. (8) education of all personnel of the organization. (9) informed criticism of those responsible. (10) all personnel read out the results, and responsible disposal. (11) maintenance of emergency supplies, maintenance and testing ? strengthening the day-to-day management of the various fire fighting equipment fire-fighting equipment, authorities should be staffed, equipped with fire extinguishers. Fire hydrants identified person responsible for regularly inspecting, testing, at any time in good condition. ? Guard monthly check-fire extinguishers and fire-fighting equipment. ? once every quarter, inspections and tests of a fire hydrant in good condition. 2), plans to develop (1) casualties occurred in construction, such as accidents or accidents of the direct economic 图1.1.5 机顶盒的开关电源电路 (1) 交流输入电路 交流输入电路是由保险丝F601、互感滤波器T601以及滤波电容C601/C603/C604等部分构成，主要功能是滤除交流输入信号中的脉冲干扰。 (2) 整流滤波电路 交流220V电压经滤波后由桥式整流堆D601、整流和滤波电容C605进行处理，桥式整流堆输出的约300V直流电压送到开关变压器T602的4脚 (3) 开关振荡电路。 开关振荡电路主要是由IC601和外围电路等部分构成的。振荡电路、稳压控制电路和开关场效应晶体管等部分都集成在IC601之中。开机后，交流220V电压经整流输出的300V直流电压经开关变压器T601的初级绕组4~3加到IC601的4、5脚。IC601的4、5脚内接开关场效应管的漏极。在开机的同时，直流300V电压经过R603形成启动电压加到IC601的7脚，为IC601内的电路供电，使IC601内的振荡电路起振，开关变压器T601的初级绕组4~3中开始有开关电流。 T602的次级绕组抽头的输出端都有整流滤波电路，分别输出3.3V 5V 12V电压。 以同洲CDVB2200型数字有线电视接收机顶盒为例说明机顶盒的组成: 同洲CDVB2200 机顶盒由一体化调谐解调器CD1316、传输流解复用器和and special tools for emergency response equipment and facilities. Emergency preparedness and response plan 1) emergency response (1) If a major accident occurs, the project should set up emergency response teams, chaired by the project manager, head of production and safety coordinators, professional foreman for the crew, primarily responsible for the orderly rescue when an emergency occurs or processing, outsourcing, team manager and support staff, assisting the Deputy Project Manager for related auxiliary work. (2) after the accident, the project manager is responsible for field commander, advance the establishment of emergency response team personnel, accountability, seriously injured officers sent out rescue, have procedures to deal with accidents, incidents, maximum reduction in casualties and property loss. (3) If an accident occurs, press Division in advance for emergency personnel cleared, concentrate manpower and material and financial resources to rescue the injured, decrease of the maximum loss. (4) after the accident processing work (5) identified the cause of the accident and the person responsible. (6) the written report to the supervisor in writing, including the time and place of the accident, injury (death) person's name, sex, age, trades, injuries, injuries. (7) the development of effective preventive measures to prevent such accidents from happening again. (8) education of all personnel of the organization. (9) informed criticism of those responsible. (10) all personnel read out the results, and responsible disposal. (11) maintenance of emergency supplies, maintenance and testing ? strengthening the day-to-day management of the various fire fighting equipment fire-fighting equipment, authorities should be staffed, equipped with fire extinguishers. Fire hydrants identified person responsible for regularly inspecting, testing, at any time in good condition. ? Guard monthly check-fire extinguishers and fire-fighting equipment. ? once every quarter, inspections and tests of a fire hydrant in good condition. 2), plans to develop (1) casualties occurred in construction, such as accidents or accidents of the direct economic MPEG-2解码器MB87L2250、智能卡读卡器、操作显示面板和开关稳压电源电路等组成。 (1) 一体化调谐器 调谐器由高频段、中频段、低频段3路带通滤波器，前置放大器，变频器以及锁相环PLL频率合成器，中频放大器等组成，其结构类似于彩电的高频头。CD1316的接收频率范围为51~858MHz，其调谐电压由内部的DC/DC变换器提供，频率选择与频道转换由I2C总线控制内部带有数字可编程锁相环的调谐系统完成。调谐接收有线电视数字前端的RF信号后，再经滤波、低噪声前置放大、变频后转换成两路相位相差90度的I、Q信号，送入QAM解调器解调。 (2) 解码器 解码器采用了单片芯片MB87L2250(图1.1.6)，该芯片内还包含嵌入式CPU、DVB解扰器、视频控制器及各种接口电路等。 图1.1.6 MB87L2250解码器的内部组成方框图 调制器输出的并行或串行码流先送到DVB解扰器进行解扰。DVB解扰器能必行处理8个不同的码流，能对TS流和PES流进行解扰。接收加密节目时，通过解扰后才能收看。加密节目的码流中包含了前端发送来的ECM EMM信息，这些信息是前端系统通过使用密钥及通过加密算法对码流数据包进行变换处理形成的。ECM信息加密所用的初始密码来自前端的智能卡加密系统。加密密钥事先存在智能卡的数据区内，解扰时接收机通过读取放置在机内的智能卡中的用户信息，与从TS码流中提取的ECM的节目授权信息进行比较，凡符合条件的ECM信息即可解出其中的控制符，然后用此控制符对传输码进行解扰，解扰后得传输码and special tools for emergency response equipment and facilities. Emergency preparedness and response plan 1) emergency response (1) If a major accident occurs, the project should set up emergency response teams, chaired by the project manager, head of production and safety coordinators, professional foreman for the crew, primarily responsible for the orderly rescue when an emergency occurs or processing, outsourcing, team manager and support staff, assisting the Deputy Project Manager for related auxiliary work. (2) after the accident, the project manager is responsible for field commander, advance the establishment of emergency response team personnel, accountability, seriously injured officers sent out rescue, have procedures to deal with accidents, incidents, maximum reduction in casualties and property loss. (3) If an accident occurs, press Division in advance for emergency personnel cleared, concentrate manpower and material and financial resources to rescue the injured, decrease of the maximum loss. (4) after the accident processing work (5) identified the cause of the accident and the person responsible. (6) the written report to the supervisor in writing, including the time and place of the accident, injury (death) person's name, sex, age, trades, injuries, injuries. (7) the development of effective preventive measures to prevent such accidents from happening again. (8) education of all personnel of the organization. (9) informed criticism of those responsible. (10) all personnel read out the results, and responsible disposal. (11) maintenance of emergency supplies, maintenance and testing ? strengthening the day-to-day management of the various fire fighting equipment fire-fighting equipment, authorities should be staffed, equipped with fire extinguishers. Fire hydrants identified person responsible for regularly inspecting, testing, at any time in good condition. ? Guard monthly check-fire extinguishers and fire-fighting equipment. ? once every quarter, inspections and tests of a fire hydrant in good condition. 2), plans to develop (1) casualties occurred in construction, such as accidents or accidents of the direct economic 流送入解复用器进一步处理。解复用器包括传输流解复用器和节目流解复用器。传输流解复用器对DVB解扰器送来的传输码流进行数字化滤波，从中分解出节目PID。接着再由节目流解复用器作进一步处理，即将节目流分解成只含有音、视频和传输数据的基本码流。其过程是将与之在PID表中的PID值与TS包中的PID值进行比较，如这两个PID值相匹配，将相匹配的PID值送到存储器中缓存起来，给MPEG解码器作进一步处理。由上述可知，解复用器实际上是一个PID 分析器，用来识别传输包中可编程PID中的一个。除此之外，解复用器还处理基本流同步和进行错误校正。它通过分析PES包头，从中提出满足控制和同步需要的节目基准始终(PCR). (3) MPEG-2解码器 MPEG是国际移动图像专家组的英文缩写，这里指按照该组织指定的信号处理标准对信号进行处理的方法及电路。MPEG-1是VCD影碟机对音、视频信号压缩解压缩的技术标准，图像分辨率较低。MPEG-2是DVD影碟机、卫星接收机、数字电视机所采用的技术标准，图像分辨率较高。 MPEG-2解码器是解压缩处理的核心电路。在进行数字电视信号的传输时对音频和视频数字信号进行压缩处理，在接收机中则进行解压缩处理。在解码芯片内对信号处理的过程中，将传输流解复用器分离出的数据信号送入MPEG解压缩处理的电路中，先进行数据分离，然后分别对音频数据和视频数据进行解压缩处理，还原出压缩前的数字信号。数字视频信号再进行视频编码和D/A转换，变成复合视频信息信号以及亮度、色度信号。音频数字信号再经多声道环绕立体声解码和音频D/A变换后输出立体或多声道音频信号。 (4)系统控制微处理器(CPU) 机顶盒的系统控制电路有CPU、程序存储器、数据存储器、地址译码器和总线接口电路组成。CPU为MB87L2250芯片中的嵌入式CPU，在芯片中集成了32位高性能CPU。其中SRAM和SDRAM中的两个主要电路可与不同速度的存储器连接，在读写时序中插入等待状态信息。 程序存储器29LV160BE是一种16MB FLASH ROM，整机的控制程序固化在片内。它有16条数据线与CPU的16bit外部数据总线D0~D15相连。还有19条地址线与CPU外部的地址总线A0~A18来连接，为CPU提供了2MB的存储空间。CPUand special tools for emergency response equipment and facilities. Emergency preparedness and response plan 1) emergency response (1) If a major accident occurs, the project should set up emergency response teams, chaired by the project manager, head of production and safety coordinators, professional foreman for the crew, primarily responsible for the orderly rescue when an emergency occurs or processing, outsourcing, team manager and support staff, assisting the Deputy Project Manager for related auxiliary work. (2) after the accident, the project manager is responsible for field commander, advance the establishment of emergency response team personnel, accountability, seriously injured officers sent out rescue, have procedures to deal with accidents, incidents, maximum reduction in casualties and property loss. (3) If an accident occurs, press Division in advance for emergency personnel cleared, concentrate manpower and material and financial resources to rescue the injured, decrease of the maximum loss. (4) after the accident processing work (5) identified the cause of the accident and the person responsible. (6) the written report to the supervisor in writing, including the time and place of the accident, injury (death) person's name, sex, age, trades, injuries, injuries. (7) the development of effective preventive measures to prevent such accidents from happening again. (8) education of all personnel of the organization. (9) informed criticism of those responsible. (10) all personnel read out the results, and responsible disposal. (11) maintenance of emergency supplies, maintenance and testing ? strengthening the day-to-day management of the various fire fighting equipment fire-fighting equipment, authorities should be staffed, equipped with fire extinguishers. Fire hydrants identified person responsible for regularly inspecting, testing, at any time in good condition. ? Guard monthly check-fire extinguishers and fire-fighting equipment. ? once every quarter, inspections and tests of a fire hydrant in good condition. 2), plans to develop (1) casualties occurred in construction, such as accidents or accidents of the direct economic 通过外部控制I2C总线直接对其进行读、写操作。 数据存储器是HY57V161610D,它是一种16MB同步动态SDRAM。本例共用两片HY57V161610D，一片用于系统控制电路的数据存储器，另一片用作解码器的数据缓冲存储器和帧存储器。它们分别用来存储执行程序需要的各种数据、传输码流中的专用数据和OSD数据等。 (5) 操作显示面板 本例的键盘扫描电路由74HC245与CPU的键盘接口电路组成。显示电路由4位七段数码管和驱动电路74HC595组成。 (6) 智能卡读卡器 该电路用专用于IC卡的接口电路和IC 卡座等组成，它的作用是用来处理属于某个CA系统的CA信息，利用得到的ECM启动解扰电路，解密并接通授权的用户。 (7)开关稳压电路 该机采用脉宽调制式开关稳压电源，它由输入整流滤波电路、DC/DC变换器、输出稳压电路和保护电路等组成，为整机提供-12V、3.3V、5V、12V、23V、30V的直流电压。 四 数字机顶盒故障分析 1、常见数字机顶盒的故障 常见数字机顶盒的故障主要有:开关稳压电源板故障、主板硬件故障、主板软件故障和音、视频输出电路故障。 (1) 开关稳压电源板故障 开关电源电路板鼓掌是机顶盒中较为常见的故障之一，其故障现象多为开机后电源指示灯不亮，而面板无任何显示等 (2) 主板硬件故障 (3) 主板软件故障 机顶盒主板软件故障主要表现为将机器重启后故障消失。引起此故障的原因多是认为操作不当。 (4) 音频输出电路故障 音频输出电路故障多表现为有图像无伴音等。 and special tools for emergency response equipment and facilities. Emergency preparedness and response plan 1) emergency response (1) If a major accident occurs, the project should set up emergency response teams, chaired by the project manager, head of production and safety coordinators, professional foreman for the crew, primarily responsible for the orderly rescue when an emergency occurs or processing, outsourcing, team manager and support staff, assisting the Deputy Project Manager for related auxiliary work. (2) after the accident, the project manager is responsible for field commander, advance the establishment of emergency response team personnel, accountability, seriously injured officers sent out rescue, have procedures to deal with accidents, incidents, maximum reduction in casualties and property loss. (3) If an accident occurs, press Division in advance for emergency personnel cleared, concentrate manpower and material and financial resources to rescue the injured, decrease of the maximum loss. (4) after the accident processing work (5) identified the cause of the accident and the person responsible. (6) the written report to the supervisor in writing, including the time and place of the accident, injury (death) person's name, sex, age, trades, injuries, injuries. (7) the development of effective preventive measures to prevent such accidents from happening again. (8) education of all personnel of the organization. (9) informed criticism of those responsible. (10) all personnel read out the results, and responsible disposal. (11) maintenance of emergency supplies, maintenance and testing ? strengthening the day-to-day management of the various fire fighting equipment fire-fighting equipment, authorities should be staffed, equipped with fire extinguishers. Fire hydrants identified person responsible for regularly inspecting, testing, at any time in good condition. ? Guard monthly check-fire extinguishers and fire-fighting equipment. ? once every quarter, inspections and tests of a fire hydrant in good condition. 2), plans to develop (1) casualties occurred in construction, such as accidents or accidents of the direct economic (5) 视频输出电路故障 视频输出电路故障多表现为伴音正常但无图像等。 2.对数字机顶盒的故障进行分析和定位 (1) 开关稳压电源板故障分析和定位 开机后电源指示灯不亮，面板无任何显示为开关稳压电源板故障。出现此故障现象后应先检查保险管是否烧断，如保险丝已烧断，说明电路中有元件短路、过载的故障，应重点查滤波电容、整流堆、开关稳压模块等。如保险丝未烧断，应查直流电压输出电路、稳压控制电路以及开关稳压模块。 (2)主板硬件故障分析和定位 主板主要是由解码芯片、存储器电路、信号处理集成电路、电源供电电路以及各种接口和派驻电路等部分构成的。对于这部分，主要是通过对数据信号、地址信号、时钟信号、同步信号以及控制信号的检索来寻找故障线索。 (3)主板软件故障分析和定位 重启后故障消失，为软件故障。 (4)音频输出电路故障分析和定位 无伴音的故障多为音频D/A变换器或输出放大电路出现问题，可重点检查这些电路及外围的相关元件。若声音很小或失真，通常为运算放大器或周围的电阻、电容损坏，更换即可。 (5)视频输出电路故障分析和定位 无图像一般是视频或后续编码器或后续滤波等电路故障，可用示波器检查视频编码器的时钟信号、输入信号和输出信号。如这些信号异常，先查其外围元件是否损。如外围元件正常，可判明视频编码器损坏，更换即可。 定位可通过直接观察法、测量法、替换法、对比推理法、加温法、干扰法、短路法和断路法来实现。 (1) 直接观察法 观察法是定位维修过程的第一步，也是最基本、最直接、最重要的一种方法。当机顶盒出现故障后，先不要接通电源，打开机壳，对机内可视部位进行全面检查，看元件有无烧断、烧焦、熏黑、开裂等明显损坏现象，插接件有无脱落、松动、脱焊现象，导线是否短路、开路，印制板是否完整，走线有无断裂、开路、and special tools for emergency response equipment and facilities. Emergency preparedness and response plan 1) emergency response (1) If a major accident occurs, the project should set up emergency response teams, chaired by the project manager, head of production and safety coordinators, professional foreman for the crew, primarily responsible for the orderly rescue when an emergency occurs or processing, outsourcing, team manager and support staff, assisting the Deputy Project Manager for related auxiliary work. (2) after the accident, the project manager is responsible for field commander, advance the establishment of emergency response team personnel, accountability, seriously injured officers sent out rescue, have procedures to deal with accidents, incidents, maximum reduction in casualties and property loss. (3) If an accident occurs, press Division in advance for emergency personnel cleared, concentrate manpower and material and financial resources to rescue the injured, decrease of the maximum loss. (4) after the accident processing work (5) identified the cause of the accident and the person responsible. (6) the written report to the supervisor in writing, including the time and place of the accident, injury (death) person's name, sex, age, trades, injuries, injuries. (7) the development of effective preventive measures to prevent such accidents from happening again. (8) education of all personnel of the organization. (9) informed criticism of those responsible. (10) all personnel read out the results, and responsible disposal. (11) maintenance of emergency supplies, maintenance and testing ? strengthening the day-to-day management of the various fire fighting equipment fire-fighting equipment, authorities should be staffed, equipped with fire extinguishers. Fire hydrants identified person responsible for regularly inspecting, testing, at any time in good condition. ? Guard monthly check-fire extinguishers and fire-fighting equipment. ? once every quarter, inspections and tests of a fire hydrant in good condition. 2), plans to develop (1) casualties occurred in construction, such as accidents or accidents of the direct economic 短路等想象。如存在上述问题，应先更换修复。若经检查表面无其他问题，可接通电源，观察机内是否有打火，冒烟现象，闻一闻是否有焦味，听一听是否有异常声音，摸一摸变压器、散热片等有无异常升温、发烫等现象。 (2) 测量法 测量法主要有电阻测量法、电压测量发、电流测量法和电平测量法几种，通常要根据图纸资料确定检测部位。 电阻测量法是指用测量阻值大小的方法大致判断芯片或元件的好坏，以及判断电路的严重短路和断路情况。 电压测量法是指用万用表电压挡检查供电电压和各有关元件的电压，特别是关键点的电压。直流电压的测量有静态和动态之分。通过静态直流电压的测量可以判断直流供电回路是否正常，各晶体管是否导通;通过动态直流电压的测量，一般可以判断交流信号回路的工作是否正常。 电流测量法是指用万用表的电流挡测量设备总电流或晶体管的工作电流，以迅速判断故障部位。对无信号、信号弱、交调干扰等故障，均可采用电平测量法，通过用场强仪测量信号的电平高低可以判断故障的部位。 (3) 替换法 替换法是指用好的相应元件去替换怀疑故障的元件。若故障因此消失，说明怀疑正确;若故障依旧，说明判断错误，应进一步检查、判断。有时为可证实一些疑难故障，可反复采用替换法判断故障产生的真正原因。 (4) 对比推理法 对比推断法是一种简单易行的检查方法，通过对相同型号的正常机顶盒和故障机顶盒的直流电压、在路电阻等参数进行逐一对比找不同之处，推断故障的部位。此法主要适用于检修一些没有电原理图的机顶盒。 (5) 加温法 对一些可疑元件或电路进行加温，可使故障及早出现或使电路恢复正常工作。如有的机顶盒开机正常，随着工作时间延长，某些元件开始发热，发热到一定程度就不能正常工作，关机冷却后，再开机又正常。检修时将电烙铁靠近发热元件对其加温，若故障出现或故障出现的速度快于加温前，或故障程度加剧，即可断定被加温元件有问题。 and special tools for emergency response equipment and facilities. Emergency preparedness and response plan 1) emergency response (1) If a major accident occurs, the project should set up emergency response teams, chaired by the project manager, head of production and safety coordinators, professional foreman for the crew, primarily responsible for the orderly rescue when an emergency occurs or processing, outsourcing, team manager and support staff, assisting the Deputy Project Manager for related auxiliary work. (2) after the accident, the project manager is responsible for field commander, advance the establishment of emergency response team personnel, accountability, seriously injured officers sent out rescue, have procedures to deal with accidents, incidents, maximum reduction in casualties and property loss. (3) If an accident occurs, press Division in advance for emergency personnel cleared, concentrate manpower and material and financial resources to rescue the injured, decrease of the maximum loss. (4) after the accident processing work (5) identified the cause of the accident and the person responsible. (6) the written report to the supervisor in writing, including the time and place of the accident, injury (death) person's name, sex, age, trades, injuries, injuries. (7) the development of effective preventive measures to prevent such accidents from happening again. (8) education of all personnel of the organization. (9) informed criticism of those responsible. (10) all personnel read out the results, and responsible disposal. (11) maintenance of emergency supplies, maintenance and testing ? strengthening the day-to-day management of the various fire fighting equipment fire-fighting equipment, authorities should be staffed, equipped with fire extinguishers. Fire hydrants identified person responsible for regularly inspecting, testing, at any time in good condition. ? Guard monthly check-fire extinguishers and fire-fighting equipment. ? once every quarter, inspections and tests of a fire hydrant in good condition. 2), plans to develop (1) casualties occurred in construction, such as accidents or accidents of the direct economic (6) 干扰法 用螺丝刀或镊子的金属部分碰触有关电路的输入点，看屏幕上有无杂波反应，有无不正常的声音，以便判断故障的部位。此法常用来检查无图像、无伴音故障。 (7) 短路法 当出现交流声干扰时，可用0.1uF的电容足迹将电路的输入端对地断路，若短路到某一级时交流声消失，则可断定故障在前一级。用断路法还可以判断振荡线圈或振荡电容，观察电压变化情况，如果有变化，表明振荡电路正常，否则表示停振。 (8) 断路法 割断某一电路或焊开某一元件或连线来缩小故障范围。如电流过大，可断开一些供电负载来观察电流电压的变化。 注意事项: 机顶盒的技术含量比较高，当使用过程中出现一些故障时，要先确定故障是否是由机顶盒引起的，因为有时候电视机方面的问题也会引起伴音不良、无图像、无显示等故障。 单元2 数字机顶盒的信号流程 PART1 数字有线机顶盒: 一、数字有线机顶盒信号流程 数字机顶盒是一种专门用来接收数字有线电视信号的解调器。数字有线电视接收机顶盒接收的频率范围为48~860MHz，中频频率为36MHz，带宽为1200MHZ，中频频率为479.5MHz,采用QPSK方式解调。图1.2.1为九洲DVC-2008CT型数字有线电视接收机顶盒的组成方框图。由图可见，本机的工作流程是: and special tools for emergency response equipment and facilities. Emergency preparedness and response plan 1) emergency response (1) If a major accident occurs, the project should set up emergency response teams, chaired by the project manager, head of production and safety coordinators, professional foreman for the crew, primarily responsible for the orderly rescue when an emergency occurs or processing, outsourcing, team manager and support staff, assisting the Deputy Project Manager for related auxiliary work. (2) after the accident, the project manager is responsible for field commander, advance the establishment of emergency response team personnel, accountability, seriously injured officers sent out rescue, have procedures to deal with accidents, incidents, maximum reduction in casualties and property loss. (3) If an accident occurs, press Division in advance for emergency personnel cleared, concentrate manpower and material and financial resources to rescue the injured, decrease of the maximum loss. (4) after the accident processing work (5) identified the cause of the accident and the person responsible. (6) the written report to the supervisor in writing, including the time and place of the accident, injury (death) person's name, sex, age, trades, injuries, injuries. (7) the development of effective preventive measures to prevent such accidents from happening again. (8) education of all personnel of the organization. (9) informed criticism of those responsible. (10) all personnel read out the results, and responsible disposal. (11) maintenance of emergency supplies, maintenance and testing ? strengthening the day-to-day management of the various fire fighting equipment fire-fighting equipment, authorities should be staffed, equipped with fire extinguishers. Fire hydrants identified person responsible for regularly inspecting, testing, at any time in good condition. ? Guard monthly check-fire extinguishers and fire-fighting equipment. ? once every quarter, inspections and tests of a fire hydrant in good condition. 2), plans to develop (1) casualties occurred in construction, such as accidents or accidents of the direct economic 图1.2.1 九洲DVC-2008CT型数字有线电视接收机顶盒的组成方框图 射频信号输入后，先由一体化调谐器进行低噪声放大，滤波和变频，再由QAM解调器进行解调，去交织，RS解码等一系列处理，成为符合MPEG-2标准的传输码流，接收加密节目时，由于该码流为用Irdeto加密加扰的码流，只有解扰后才能供用户收看。加密节目的码流中包含前端CA系列发送来的ECM EMM的信息，这些信息是前端系统通过密钥及通过加密算法对码流数据包进行变换处理后生成的。ECM信息加密所用的初始密钥取自前端的智能卡加密系统，加密密钥事先存在于智能卡的数据区内，加密时通过获取函数得到密钥，密钥的安全性有智能卡的安全性来保证。解扰时，本机通过读取放置在本机中的智能卡中的用户授权信息，与从TS码流中提取的ECM的节目授权信息比较，对于符合条件的ECM信息皆可解出其中的控制字，然后再用此控制字对传输流进行解扰。 解扰后的传输码流经解复用器分解为音、视频和专用数据基本码流。这些码流分别送到音、视频解码器，经解码后还原成原始的音、视频带数据。其中的音频数据送到音频D/A转换器，在那里转换成两路立体声音频信号，再由音频放大器放大后输出;视频数据送到视频解码器，在那里转换成符合ITU-R 601标准的复合视频(CVBS)信号和S视频信号，经过滤波网络滤波后输出。 二 数字有线机顶盒解码板工作原理 1 解码电路的结构 数字电视机顶盒的主要功能就是将接收的数字信号转换为模拟电视信号，使用户不用更换模拟电视机就能收看数字电视节目。经过一体化调谐解调器解调后输出的TS码流是一种包含视频、音频和数据信息的多路节目数据流，按MPEG-2标准复合而成，因此，在解码前要先对TS码流进行解复用，根据所要收看节目and special tools for emergency response equipment and facilities. Emergency preparedness and response plan 1) emergency response (1) If a major accident occurs, the project should set up emergency response teams, chaired by the project manager, head of production and safety coordinators, professional foreman for the crew, primarily responsible for the orderly rescue when an emergency occurs or processing, outsourcing, team manager and support staff, assisting the Deputy Project Manager for related auxiliary work. (2) after the accident, the project manager is responsible for field commander, advance the establishment of emergency response team personnel, accountability, seriously injured officers sent out rescue, have procedures to deal with accidents, incidents, maximum reduction in casualties and property loss. (3) If an accident occurs, press Division in advance for emergency personnel cleared, concentrate manpower and material and financial resources to rescue the injured, decrease of the maximum loss. (4) after the accident processing work (5) identified the cause of the accident and the person responsible. (6) the written report to the supervisor in writing, including the time and place of the accident, injury (death) person's name, sex, age, trades, injuries, injuries. (7) the development of effective preventive measures to prevent such accidents from happening again. (8) education of all personnel of the organization. (9) informed criticism of those responsible. (10) all personnel read out the results, and responsible disposal. (11) maintenance of emergency supplies, maintenance and testing ? strengthening the day-to-day management of the various fire fighting equipment fire-fighting equipment, authorities should be staffed, equipped with fire extinguishers. Fire hydrants identified person responsible for regularly inspecting, testing, at any time in good condition. ? Guard monthly check-fire extinguishers and fire-fighting equipment. ? once every quarter, inspections and tests of a fire hydrant in good condition. 2), plans to develop (1) casualties occurred in construction, such as accidents or accidents of the direct economic 的数据包识别符(PID)提取出相应的视频音频和数据信息，恢复符合MPEG-2标准打包的节目基本数据流(PES)，然后进行MPEG-2解码。节目基本流数据包送到MPEG-2解码器芯片中进行解压缩，生成CCIR601格式的视频数据流和PCM格式的音频数据流，分别送到视频解码器和音频D/A转换器。视频解码器在按一定电视制式解码，最后经D/A变换变成模拟图像信号和模拟音频信号，供电视机接收。 2 解码电路的工作原理 以SC2005解码芯片为例，如图1.2.2 (1)嵌入式CPU 嵌入式微处理器内部包括通用寄存器，系统控制处理器，算术逻辑单元和移位寄存器，系统控制处理器包括各种信息的处理，算术逻辑单元与逻辑运算以及计算地址等操作，移位器主要完成移位操作。 CPU总线接口用于CPU与其外围单元交换数据，它通过内部总线分别于系统控制处理器，存储器管理单元和总线接口单元实现紧耦合连接，从而增强了CPU的通用计算功能。 图1.2.2 SC2005芯片内部结构方框图 (2) 解复用器 and special tools for emergency response equipment and facilities. Emergency preparedness and response plan 1) emergency response (1) If a major accident occurs, the project should set up emergency response teams, chaired by the project manager, head of production and safety coordinators, professional foreman for the crew, primarily responsible for the orderly rescue when an emergency occurs or processing, outsourcing, team manager and support staff, assisting the Deputy Project Manager for related auxiliary work. (2) after the accident, the project manager is responsible for field commander, advance the establishment of emergency response team personnel, accountability, seriously injured officers sent out rescue, have procedures to deal with accidents, incidents, maximum reduction in casualties and property loss. (3) If an accident occurs, press Division in advance for emergency personnel cleared, concentrate manpower and material and financial resources to rescue the injured, decrease of the maximum loss. (4) after the accident processing work (5) identified the cause of the accident and the person responsible. (6) the written report to the supervisor in writing, including the time and place of the accident, injury (death) person's name, sex, age, trades, injuries, injuries. (7) the development of effective preventive measures to prevent such accidents from happening again. (8) education of all personnel of the organization. (9) informed criticism of those responsible. (10) all personnel read out the results, and responsible disposal. (11) maintenance of emergency supplies, maintenance and testing ? strengthening the day-to-day management of the various fire fighting equipment fire-fighting equipment, authorities should be staffed, equipped with fire extinguishers. Fire hydrants identified person responsible for regularly inspecting, testing, at any time in good condition. ? Guard monthly check-fire extinguishers and fire-fighting equipment. ? once every quarter, inspections and tests of a fire hydrant in good condition. 2), plans to develop (1) casualties occurred in construction, such as accidents or accidents of the direct economic SC2005芯片内的解复用器包括传输流解复用器和节目流解复用器。解复用器有信道接口，信道FIFO，PID处理器，PID后处理器，内部音/视频接口和节目时钟提取电路等组成。其中信号接口提供自动传输包同步字节检测及实现同步锁定或未锁定的具有可编程时延的滞后机构，一旦建立同步，信道接口就通过信道FIFO将完整的传输包传输到PID处理器。信道接口还用于检查传输包的完整性，指示传输错误等。 (3) MPEG-2解码器 解码器包括I2C总线接口、DMA控制器、MPEG-2音、视频解码器接口、音频解码器、视频解码器和音频D/A转换器等电路。视频解码器和音频解码器使用外部存储器作为缓冲器。 (4) 字符显示电路 芯片内集成了一个在屏图像子(OSG)系统。该子系统能产生的图文与解码视频相叠加，还能产生光标，OSD和静止图像。 (5) 视频解码器 芯片内集成了一个视频解码器，可将8位或16位数字视频流编码产生复用视频，S视频或RGB 视频信号，支持PAL、NTSC、SECAM制式。它由数据控制单 输出接口RGB处理器和DA转换器部分组成。 元，解码器 (6) 音频DA转换器 芯片内还集成了一个音频DA转换器。与其他音频DA转换器一样，它也是一种具有可编程锁相环PLL的立体声D/A转换器，其作用是将由音频解码器输出的PCM音频数据转换成左、右声道的模拟立体声信号 (7) 10Base-T以太网接口 芯片内包含了一个10Base-T以太网控制器，为系玩统提供了一个以太网接口，使系统能以高速方式与PC进行通信。 PART2 数字卫星机顶盒 一、数字卫星机顶盒信号流程 数字卫星接收机顶盒的信号处理电路主要由天线和变频器部分(高频头又称变频器或第一变频器)、调谐器(第二变频器)、卫星信号解调器(QPSK 解调、and special tools for emergency response equipment and facilities. Emergency preparedness and response plan 1) emergency response (1) If a major accident occurs, the project should set up emergency response teams, chaired by the project manager, head of production and safety coordinators, professional foreman for the crew, primarily responsible for the orderly rescue when an emergency occurs or processing, outsourcing, team manager and support staff, assisting the Deputy Project Manager for related auxiliary work. (2) after the accident, the project manager is responsible for field commander, advance the establishment of emergency response team personnel, accountability, seriously injured officers sent out rescue, have procedures to deal with accidents, incidents, maximum reduction in casualties and property loss. (3) If an accident occurs, press Division in advance for emergency personnel cleared, concentrate manpower and material and financial resources to rescue the injured, decrease of the maximum loss. (4) after the accident processing work (5) identified the cause of the accident and the person responsible. (6) the written report to the supervisor in writing, including the time and place of the accident, injury (death) person's name, sex, age, trades, injuries, injuries. (7) the development of effective preventive measures to prevent such accidents from happening again. (8) education of all personnel of the organization. (9) informed criticism of those responsible. (10) all personnel read out the results, and responsible disposal. (11) maintenance of emergency supplies, maintenance and testing ? strengthening the day-to-day management of the various fire fighting equipment fire-fighting equipment, authorities should be staffed, equipped with fire extinguishers. Fire hydrants identified person responsible for regularly inspecting, testing, at any time in good condition. ? Guard monthly check-fire extinguishers and fire-fighting equipment. ? once every quarter, inspections and tests of a fire hydrant in good condition. 2), plans to develop (1) casualties occurred in construction, such as accidents or accidents of the direct economic 数据流解码解复用)、MPEG-2 A/V解码器及视频编码器、视频D/A变换器、音频D/A变换器、射频调制器等部分构成。如图1.2.3: 图1.2.3 数字卫星电视接收机顶盒的信号处理过程 (1) C波段及Ku波段的卫星信号经过天线接收后送到安装在天线上的高频头，在高频头中经过放大、变频后输出标准的950~2150MHz的信号，输入至机顶盒的IF输入端。调谐器进行信号放大、混频(选台)，经变频后将信号送到QPSK解调器。在解调器中先完成模拟I、Q信号的A/D变换，得到数字式I、Q信号，再经数字式QPSK解调、FEC滤波后，还原出MPEG-2数据流信号。 (2) 数据流解码解复用电路完成MPEG-2数据流解码和分离，分解出视频、音频、同步控制及其他数字信号。MPEG-2 A/V解码器完成视音频信号的解压缩、解码，还原出完整的图像及伴音数字信号。 (3) 视频编码器将数字图像信号编码，然后经D/A变换后输出模拟电视机所能接收的全电视信号或Y、C信号。音频D/A变换器将音频数字信号变成左、右两路模拟信号输出。 接收和处理数字卫星电视信号最主要的设备是电视接收机顶盒，因为它的功能是通过解码器处理数字信号，所以又成为接收解码器。 二(A/V解码电路工作原理: and special tools for emergency response equipment and facilities. Emergency preparedness and response plan 1) emergency response (1) If a major accident occurs, the project should set up emergency response teams, chaired by the project manager, head of production and safety coordinators, professional foreman for the crew, primarily responsible for the orderly rescue when an emergency occurs or processing, outsourcing, team manager and support staff, assisting the Deputy Project Manager for related auxiliary work. (2) after the accident, the project manager is responsible for field commander, advance the establishment of emergency response team personnel, accountability, seriously injured officers sent out rescue, have procedures to deal with accidents, incidents, maximum reduction in casualties and property loss. (3) If an accident occurs, press Division in advance for emergency personnel cleared, concentrate manpower and material and financial resources to rescue the injured, decrease of the maximum loss. (4) after the accident processing work (5) identified the cause of the accident and the person responsible. (6) the written report to the supervisor in writing, including the time and place of the accident, injury (death) person's name, sex, age, trades, injuries, injuries. (7) the development of effective preventive measures to prevent such accidents from happening again. (8) education of all personnel of the organization. (9) informed criticism of those responsible. (10) all personnel read out the results, and responsible disposal. (11) maintenance of emergency supplies, maintenance and testing ? strengthening the day-to-day management of the various fire fighting equipment fire-fighting equipment, authorities should be staffed, equipped with fire extinguishers. Fire hydrants identified person responsible for regularly inspecting, testing, at any time in good condition. ? Guard monthly check-fire extinguishers and fire-fighting equipment. ? once every quarter, inspections and tests of a fire hydrant in good condition. 2), plans to develop (1) casualties occurred in construction, such as accidents or accidents of the direct economic 图1.2.4 采用CX24142系列解码芯片的数字卫星机顶盒的电路 以CX24142系列为例来说明原理(如图 1.2.4)。来自卫星高频头的第一中频信号送到调谐器中进行调谐和变频处理，然后将调谐器解调后的信号送到解码芯片CX24142中。在芯片中进行QPSK解调、纠错解码、MPEG-2解压缩处理，解码后的视频数字信号再进行视频编码和D/A变换，变成模拟视频信号输出。它可以输出S视频和复合视频两种信号、数字音频信号在芯片中进行解码和D/A变换变成模拟音频信号输出。视频和音频信号再送到射频调制器调制成射频电视信号输出。: 三、电源板工作原理 1.电源电路的结构 以同洲CDVB3188C接收机顶盒开关电源电路为例，其电路如下图1.2.5 同洲CDVB3188C一个典型的开关式稳压电源。交流输入电流路是由保险丝，300V滤波器，桥式整流二极管电路等部分构成的，其功能是将交流220V电压变成直流300电压，并滤除来自市电的噪声和干扰。 开关振荡电路是由开关晶体管，正反馈电路和开关变压器组成的。其功能是将300V直流电压变成高频脉冲信号(其频率1~50KHz)。脉冲信号经过开关变压and special tools for emergency response equipment and facilities. Emergency preparedness and response plan 1) emergency response (1) If a major accident occurs, the project should set up emergency response teams, chaired by the project manager, head of production and safety coordinators, professional foreman for the crew, primarily responsible for the orderly rescue when an emergency occurs or processing, outsourcing, team manager and support staff, assisting the Deputy Project Manager for related auxiliary work. (2) after the accident, the project manager is responsible for field commander, advance the establishment of emergency response team personnel, accountability, seriously injured officers sent out rescue, have procedures to deal with accidents, incidents, maximum reduction in casualties and property loss. (3) If an accident occurs, press Division in advance for emergency personnel cleared, concentrate manpower and material and financial resources to rescue the injured, decrease of the maximum loss. (4) after the accident processing work (5) identified the cause of the accident and the person responsible. (6) the written report to the supervisor in writing, including the time and place of the accident, injury (death) person's name, sex, age, trades, injuries, injuries. (7) the development of effective preventive measures to prevent such accidents from happening again. (8) education of all personnel of the organization. (9) informed criticism of those responsible. (10) all personnel read out the results, and responsible disposal. (11) maintenance of emergency supplies, maintenance and testing ? strengthening the day-to-day management of the various fire fighting equipment fire-fighting equipment, authorities should be staffed, equipped with fire extinguishers. Fire hydrants identified person responsible for regularly inspecting, testing, at any time in good condition. ? Guard monthly check-fire extinguishers and fire-fighting equipment. ? once every quarter, inspections and tests of a fire hydrant in good condition. 2), plans to develop (1) casualties occurred in construction, such as accidents or accidents of the direct economic 器输出多组脉冲电压，再经过多组整流滤波电路变成多个直流电压输出，为信号处理电路和控制电路供电。稳压电路是由误差检测电路和光电耦合器等部分构成。它的功能是通过负反馈电路自动检测输出误差电压，自动控制开关振荡电路，从而实现输出电压的稳定。 2.电源电路的工作原理 (1)交流输入电路 交流输入电路是由电源开关K，交流输入接口CN801，热敏电阻THR801，保险丝F801和压敏电阻RV801等部分构成的。如接收机出现过在故障，保险丝将熔断，起保护作用。如果外部输入电压过高(高于260V)，压敏电阻将短路，并使保险丝熔断，同样起到保护作用。 (2)抗干扰滤波电路 抗干扰滤波电路主要是由滤波电容CX101 CX102 CY801 CY802和互感滤波器LEM801等元件构成的，它主要用于滤除来自交流电网的干扰脉冲，同时也可以防止开关电源产生的振荡脉冲反送到电网中对其他设备造成干扰。 (3)整流滤波电路 整流滤波电路是由桥式整流电路VD801~VD804和滤波电容C801构成的，它的主要功能是将交流220V电压整流成直流电压(约300V),再由电容C801平滑、滤波后消除脉动分量，为开关振荡电路供电。 (4)开关振荡电路 开关振荡电路主要是由开关振荡集成电路U801，开关变压器T801，变压器次级输出电路和稳压电路等部分构成的。 and special tools for emergency response equipment and facilities. Emergency preparedness and response plan 1) emergency response (1) If a major accident occurs, the project should set up emergency response teams, chaired by the project manager, head of production and safety coordinators, professional foreman for the crew, primarily responsible for the orderly rescue when an emergency occurs or processing, outsourcing, team manager and support staff, assisting the Deputy Project Manager for related auxiliary work. (2) after the accident, the project manager is responsible for field commander, advance the establishment of emergency response team personnel, accountability, seriously injured officers sent out rescue, have procedures to deal with accidents, incidents, maximum reduction in casualties and property loss. (3) If an accident occurs, press Division in advance for emergency personnel cleared, concentrate manpower and material and financial resources to rescue the injured, decrease of the maximum loss. (4) after the accident processing work (5) identified the cause of the accident and the person responsible. (6) the written report to the supervisor in writing, including the time and place of the accident, injury (death) person's name, sex, age, trades, injuries, injuries. (7) the development of effective preventive measures to prevent such accidents from happening again. (8) education of all personnel of the organization. (9) informed criticism of those responsible. (10) all personnel read out the results, and responsible disposal. (11) maintenance of emergency supplies, maintenance and testing ? strengthening the day-to-day management of the various fire fighting equipment fire-fighting equipment, authorities should be staffed, equipped with fire extinguishers. Fire hydrants identified person responsible for regularly inspecting, testing, at any time in good condition. ? Guard monthly check-fire extinguishers and fire-fighting equipment. ? once every quarter, inspections and tests of a fire hydrant in good condition. 2), plans to develop (1) casualties occurred in construction, such as accidents or accidents of the direct economic 图1.2.5 CDVB3188C同洲CDVB3188C接收机开关电源电路图 开机后300V直流电压加到开关变压器T801初级绕组的1脚，经初级绕组后 由2脚输入开关振荡集成电路U801的D端，该端接U801内的开关场效应晶体管 and special tools for emergency response equipment and facilities. Emergency preparedness and response plan 1) emergency response (1) If a major accident occurs, the project should set up emergency response teams, chaired by the project manager, head of production and safety coordinators, professional foreman for the crew, primarily responsible for the orderly rescue when an emergency occurs or processing, outsourcing, team manager and support staff, assisting the Deputy Project Manager for related auxiliary work. (2) after the accident, the project manager is responsible for field commander, advance the establishment of emergency response team personnel, accountability, seriously injured officers sent out rescue, have procedures to deal with accidents, incidents, maximum reduction in casualties and property loss. (3) If an accident occurs, press Division in advance for emergency personnel cleared, concentrate manpower and material and financial resources to rescue the injured, decrease of the maximum loss. (4) after the accident processing work (5) identified the cause of the accident and the person responsible. (6) the written report to the supervisor in writing, including the time and place of the accident, injury (death) person's name, sex, age, trades, injuries, injuries. (7) the development of effective preventive measures to prevent such accidents from happening again. (8) education of all personnel of the organization. (9) informed criticism of those responsible. (10) all personnel read out the results, and responsible disposal. (11) maintenance of emergency supplies, maintenance and testing ? strengthening the day-to-day management of the various fire fighting equipment fire-fighting equipment, authorities should be staffed, equipped with fire extinguishers. Fire hydrants identified person responsible for regularly inspecting, testing, at any time in good condition. ? Guard monthly check-fire extinguishers and fire-fighting equipment. ? once every quarter, inspections and tests of a fire hydrant in good condition. 2), plans to develop (1) casualties occurred in construction, such as accidents or accidents of the direct economic 的漏极D。与此同时，300V直流电压经启动电阻R805，R804为U801的M端加上启动电压，使U801内的振荡电路起振，于是U801内的开关场效应晶体管受到振荡信号的驱动而进入振荡状态。开关变压器次级绕组的4脚在起振时输出的信号经整流滤波后，由光耦U802反馈到U801的F、C端。开关电源起振后，开关变压器次级各绕组的输出经整流滤波后输出多种直流电压，为接收机供电。 (5)稳压电路 稳压电路接在+5V输出电路中，+5V输出电压经R812、R811构成分压电路，分压点的正常电压为2.5V。该电压作为误差取样信号送到误差放大器U803的输入端R，如果输出的+5V电压有波动，会引起取样点电压的变化。该误差电压加到U803的R端，会引起U803 的K、A端间的阻抗变化，改阻抗的变化会引起光耦U802中发光二极管发光强度的变化，于是引起光耦U802中光敏晶体管阻抗的变化，并使U802的3脚电压发生变化。该电压作为负反馈信号加到开关振荡集成电路的F端，是U801中的振荡脉冲宽度变化，从而使开关电源的输出保持稳定。 (6)直流输出电路 T801次级绕组5~10脚经各自的整流、滤波电路产生直流电压供给主电路板，其中+3.3V电压是由+5 V电压经低压差(LDO)稳压块U804产生的。为主芯片MB87L2250和QPSK解调芯片等供电;，5V电压向音频D/A变换器，调谐器等供电; 正负12V电压向音频放大电路供电。 +22V电压经过主板的可调试三端稳压集成电路LM317二次稳压后，;在CPU的控制下，向LNB提供13/18V极化切换电压;+30V电压由VD810/VT812整流滤波后，再经过R817、C813、VT801和30V稳压管ZD801构成的简单串联式稳压电路产生，为调谐器中的AGC电路供电。在-12V +12V +30V和+22V电源输出电路中，分别接有R814、 R815 、R818、 R819负载电阻，以降低该支路的空载及轻载电压。 由于TOP234Y芯片的开关频率较高，因此在输出整流管关断后的反向恢复过程中会产生开关噪声，容易损坏整流管。一般常用阻容元件组成的RC滤波电路虽然能对保护二极管和降噪起到一定作用，会在电阻上产生功率损耗，因此在需要提供较大功率输出的+5V +22V 电源中选用LC滤波电路，用电路L801 L802and special tools for emergency response equipment and facilities. Emergency preparedness and response plan 1) emergency response (1) If a major accident occurs, the project should set up emergency response teams, chaired by the project manager, head of production and safety coordinators, professional foreman for the crew, primarily responsible for the orderly rescue when an emergency occurs or processing, outsourcing, team manager and support staff, assisting the Deputy Project Manager for related auxiliary work. (2) after the accident, the project manager is responsible for field commander, advance the establishment of emergency response team personnel, accountability, seriously injured officers sent out rescue, have procedures to deal with accidents, incidents, maximum reduction in casualties and property loss. (3) If an accident occurs, press Division in advance for emergency personnel cleared, concentrate manpower and material and financial resources to rescue the injured, decrease of the maximum loss. (4) after the accident processing work (5) identified the cause of the accident and the person responsible. (6) the written report to the supervisor in writing, including the time and place of the accident, injury (death) person's name, sex, age, trades, injuries, injuries. (7) the development of effective preventive measures to prevent such accidents from happening again. (8) education of all personnel of the organization. (9) informed criticism of those responsible. (10) all personnel read out the results, and responsible disposal. (11) maintenance of emergency supplies, maintenance and testing ? strengthening the day-to-day management of the various fire fighting equipment fire-fighting equipment, authorities should be staffed, equipped with fire extinguishers. Fire hydrants identified person responsible for regularly inspecting, testing, at any time in good condition. ? Guard monthly check-fire extinguishers and fire-fighting equipment. ? once every quarter, inspections and tests of a fire hydrant in good condition. 2), plans to develop (1) casualties occurred in construction, such as accidents or accidents of the direct economic 来代替电阻，可以滤除VD807、VD811在反向恢复过程中产生的开关噪声，以减小输出波纹电压。 PART3 机顶盒解码电路的故障及检修操作步骤: 步骤1:故障分析 步骤2:根据故障可能出现点进行电气检测 步骤3:如果发现元件损坏，更换 步骤4:开机试播 附 故障实例 实例一: 故障情况说明:开机后指示灯和数码显示管不亮，无图无声。 故障分析: 这种故障表明机顶盒的供电电路或合租电路板有故障，应先查电源与主电路板的连接接口以及主电路板与操作显示板的接口电路，寻找故障线索。 故障检修: 打开机盖试机，发现解码板上的电解电容顶部有突起现象，可能为电压升高或温度升高引起的爆裂。拔下电源板送往解码板的两支插头，测电源板的各组输出电压，5V电压正常，其余各组电压均不同程度地偏高，由此说明稳压失控。更换TL431后，故障排除。(TL431各引脚的电压R:2.4V，A 0V ，K 2V) 第2节 数字机顶盒的调试 单元1 数字机顶盒功能菜单 以北京TC2132C2型数字有线机顶盒为例，说明机顶盒功能菜单的调试: 功能菜单介绍: 在菜单播放的状态下，按前面板上或遥控器上的【菜单】键，电视机将显示主菜单界面。如下图2.1.1,2.1.2所示: 主菜单包括以下几项: 1 节目管理 2 导视视频 3 影视点播 4 XX资讯 5 财富空间 6 电视信箱 7 系统设置 and special tools for emergency response equipment and facilities. Emergency preparedness and response plan 1) emergency response (1) If a major accident occurs, the project should set up emergency response teams, chaired by the project manager, head of production and safety coordinators, professional foreman for the crew, primarily responsible for the orderly rescue when an emergency occurs or processing, outsourcing, team manager and support staff, assisting the Deputy Project Manager for related auxiliary work. (2) after the accident, the project manager is responsible for field commander, advance the establishment of emergency response team personnel, accountability, seriously injured officers sent out rescue, have procedures to deal with accidents, incidents, maximum reduction in casualties and property loss. (3) If an accident occurs, press Division in advance for emergency personnel cleared, concentrate manpower and material and financial resources to rescue the injured, decrease of the maximum loss. (4) after the accident processing work (5) identified the cause of the accident and the person responsible. (6) the written report to the supervisor in writing, including the time and place of the accident, injury (death) person's name, sex, age, trades, injuries, injuries. (7) the development of effective preventive measures to prevent such accidents from happening again. (8) education of all personnel of the organization. (9) informed criticism of those responsible. (10) all personnel read out the results, and responsible disposal. (11) maintenance of emergency supplies, maintenance and testing ? strengthening the day-to-day management of the various fire fighting equipment fire-fighting equipment, authorities should be staffed, equipped with fire extinguishers. Fire hydrants identified person responsible for regularly inspecting, testing, at any time in good condition. ? Guard monthly check-fire extinguishers and fire-fighting equipment. ? once every quarter, inspections and tests of a fire hydrant in good condition. 2), plans to develop (1) casualties occurred in construction, such as accidents or accidents of the direct economic 图2.1.1电视机开机画面 图2.1.2主菜单选项 功能菜单使用与调整: 1 节目管理调试方法 进入主菜单后，按遥控器上的【CH+】键和【CH-】键选择“节目管理”，并按【V+】键或【V-】键进入节目管理菜单，在这里可以选择电视节目管理:广播节目管理、视讯节目管理和预定节目管理4个节目管理项目选项，如下图2.1.3: 图2.1.3电视节目管理下级菜单中的全部电视频道列表 (1)电视节目管理 进入电视节目管理菜单后，可以按【CH+】键或【CH-】键选择全部电视频道列表、家庭电视频道列表、电视喜爱频道列表、电视喜爱频道编辑、电视节目预告。 <1>全部电视频道 按【CH+】键或【CH-】键实现上翻页下翻页选择要收看的节目，点确认 播放。 and special tools for emergency response equipment and facilities. Emergency preparedness and response plan 1) emergency response (1) If a major accident occurs, the project should set up emergency response teams, chaired by the project manager, head of production and safety coordinators, professional foreman for the crew, primarily responsible for the orderly rescue when an emergency occurs or processing, outsourcing, team manager and support staff, assisting the Deputy Project Manager for related auxiliary work. (2) after the accident, the project manager is responsible for field commander, advance the establishment of emergency response team personnel, accountability, seriously injured officers sent out rescue, have procedures to deal with accidents, incidents, maximum reduction in casualties and property loss. (3) If an accident occurs, press Division in advance for emergency personnel cleared, concentrate manpower and material and financial resources to rescue the injured, decrease of the maximum loss. (4) after the accident processing work (5) identified the cause of the accident and the person responsible. (6) the written report to the supervisor in writing, including the time and place of the accident, injury (death) person's name, sex, age, trades, injuries, injuries. (7) the development of effective preventive measures to prevent such accidents from happening again. (8) education of all personnel of the organization. (9) informed criticism of those responsible. (10) all personnel read out the results, and responsible disposal. (11) maintenance of emergency supplies, maintenance and testing ? strengthening the day-to-day management of the various fire fighting equipment fire-fighting equipment, authorities should be staffed, equipped with fire extinguishers. Fire hydrants identified person responsible for regularly inspecting, testing, at any time in good condition. ? Guard monthly check-fire extinguishers and fire-fighting equipment. ? once every quarter, inspections and tests of a fire hydrant in good condition. 2), plans to develop (1) casualties occurred in construction, such as accidents or accidents of the direct economic 按【电视/广播】建，菜单在全部电视频道列表和全部广播频道列表切换。 按【视讯】建，进入全部视讯频道列表菜单 【确认】播放所选节目，【返回】返回上级菜单【推出】退出菜单 <2>家庭电视频道列表:在电视节目管理菜单中，选择“家庭电视频道列 表”,再按【确认】进入家庭电视频道列表菜单，选择想看的节目 <3>电视喜爱频道列表:在电视节目管理菜单中，选择“电视喜爱频道列 表”,再按【确认】进入电视喜爱频道列表菜单，选择喜爱的节目 <4>电视喜爱频道编辑:在电视节目管理菜单中，选择“电视喜爱频道编 辑”,再按【确认】进入电视喜爱频道编辑菜单，对喜爱的频道进行设置，如 图2.1.4。 <5>电视节目预告:在电视节目管理菜单中，选择“电视节目预告”，再 按【确认】键进入电视节目预告菜单。电视节目预告菜单如图2.1.5。 图2.1.4 电视喜爱频道编辑 图2.1.5电视节目预告菜单界面 (2) 广播节目管理 在广播节目管理的各级菜单下，可以看到如下项目:全部广播频道列表，家庭广播频道列表，广播喜爱频道列表，广播喜爱频道编辑和广播节目预告。如图2.1.6。 (3) 视讯节目列表 在视讯节目管理的各级菜单下，可以看到如下项目:全部视讯频道列表和家庭视讯频道列表，如图2.1.7。 and special tools for emergency response equipment and facilities. Emergency preparedness and response plan 1) emergency response (1) If a major accident occurs, the project should set up emergency response teams, chaired by the project manager, head of production and safety coordinators, professional foreman for the crew, primarily responsible for the orderly rescue when an emergency occurs or processing, outsourcing, team manager and support staff, assisting the Deputy Project Manager for related auxiliary work. (2) after the accident, the project manager is responsible for field commander, advance the establishment of emergency response team personnel, accountability, seriously injured officers sent out rescue, have procedures to deal with accidents, incidents, maximum reduction in casualties and property loss. (3) If an accident occurs, press Division in advance for emergency personnel cleared, concentrate manpower and material and financial resources to rescue the injured, decrease of the maximum loss. (4) after the accident processing work (5) identified the cause of the accident and the person responsible. (6) the written report to the supervisor in writing, including the time and place of the accident, injury (death) person's name, sex, age, trades, injuries, injuries. (7) the development of effective preventive measures to prevent such accidents from happening again. (8) education of all personnel of the organization. (9) informed criticism of those responsible. (10) all personnel read out the results, and responsible disposal. (11) maintenance of emergency supplies, maintenance and testing ? strengthening the day-to-day management of the various fire fighting equipment fire-fighting equipment, authorities should be staffed, equipped with fire extinguishers. Fire hydrants identified person responsible for regularly inspecting, testing, at any time in good condition. ? Guard monthly check-fire extinguishers and fire-fighting equipment. ? once every quarter, inspections and tests of a fire hydrant in good condition. 2), plans to develop (1) casualties occurred in construction, such as accidents or accidents of the direct economic 图2.1.6广播节目管理列表 图2.1.7视讯节目管理列表 2 导视频道 在主菜单中选择“导视频道”，再按【确认】键，、可进入电视台播出的导视频道。 3 影视点播 主菜单中选择影视点播后，再按【确认】键进入影视点播菜单 】或【CH-】选择节目，按【V+】和【V-】切换栏目，按【确认】 可按【CH+ 进行点播。选择节目后按【确认】键，会出现时间列表菜单。可以使用【CH+】或【CH-】键选择节目播放时间，按【确认】键进行点播。 4 天津视讯 从主菜单中选择“天津视讯”，按【确认】键后进入天津视讯菜单中。节目导视会提示“数据信息正在导入，请稍后...”。进入后，可使用【CH+】或【CH-】 ，【V+】和【V-】选择相关视讯，然后按【确认】键即可。 5 系统设置 进入主菜单之后，选择“系统设置”并按【确认】键，可进入系统设置菜单，再按【CH+】或【CH-】键可以选择以下项目:频道搜索、参数设置、系统管理、CA信息。 (1)频道搜索 在频道搜索菜单下，按【CH+】或【CH-】可以选择自动搜索，手动搜索、全频段搜索。 <1>自动搜索:在频道搜索菜单中，选择“自动搜索”，确认后进入自动 搜索菜单，搜索完成后显示最新搜索的电视节目和节目信息。 <2>手动搜索:在频道搜索惨淡中，选择“手动搜索”，确认后进入手动and special tools for emergency response equipment and facilities. Emergency preparedness and response plan 1) emergency response (1) If a major accident occurs, the project should set up emergency response teams, chaired by the project manager, head of production and safety coordinators, professional foreman for the crew, primarily responsible for the orderly rescue when an emergency occurs or processing, outsourcing, team manager and support staff, assisting the Deputy Project Manager for related auxiliary work. (2) after the accident, the project manager is responsible for field commander, advance the establishment of emergency response team personnel, accountability, seriously injured officers sent out rescue, have procedures to deal with accidents, incidents, maximum reduction in casualties and property loss. (3) If an accident occurs, press Division in advance for emergency personnel cleared, concentrate manpower and material and financial resources to rescue the injured, decrease of the maximum loss. (4) after the accident processing work (5) identified the cause of the accident and the person responsible. (6) the written report to the supervisor in writing, including the time and place of the accident, injury (death) person's name, sex, age, trades, injuries, injuries. (7) the development of effective preventive measures to prevent such accidents from happening again. (8) education of all personnel of the organization. (9) informed criticism of those responsible. (10) all personnel read out the results, and responsible disposal. (11) maintenance of emergency supplies, maintenance and testing ? strengthening the day-to-day management of the various fire fighting equipment fire-fighting equipment, authorities should be staffed, equipped with fire extinguishers. Fire hydrants identified person responsible for regularly inspecting, testing, at any time in good condition. ? Guard monthly check-fire extinguishers and fire-fighting equipment. ? once every quarter, inspections and tests of a fire hydrant in good condition. 2), plans to develop (1) casualties occurred in construction, such as accidents or accidents of the direct economic 搜索菜单。这时按【CH+】或【CH-】可以将光标移动到需要设置的参数项，并 【确认】键按选择;按0~9数字键或【CH+】【CH-】或【V+】和【V-】配合输入正确的频率值，按【确认】键确认，采用同样的方法设置符号率;在QAM选项中，按【V+】和【V-】选择相应的调试方式，如QAM64，QAM128，QAM256。 各个参数设置完毕后，按【CH+】或【CH-】键将光标移动到“开始搜索”，按【确认】键后，数字有线机顶盒开始搜索节目。 <3>全频段搜索:在进入频道搜索菜单，选择“全频段搜索“，按【确认】键后进入全频段搜索菜单，数字有线机顶盒将按照中国频道规划标准顺序一次搜索全部频点。 (2)参数配置 进入主菜单之后，选择“系统设置”，确认后进入系统设置菜单。选择“参数配置”， 按【确认】键后进入参数配置菜单，此时可以选择设置屏幕格式，菜单语言和菜单背景透明度等。 (3)系统管理 在主菜单中选择“系统设置“可以进入系统设置菜单。然后选择“系统管理”， CH-】键可以选择童锁设置、恢复出厂设置、系统工作状态系统版按【CH+】或【 本。 <1> 童锁设置 在系统管理菜单中，选择“童锁设置”。 按【确认】键后进入童锁设置 菜单，按其包含4个选项:节目锁、机顶盒锁、菜单锁、输入新旧密码。用 户可以根据实际需要进行不同的设置。 <2> 恢复出厂设置 在系统管理菜单中，选择“恢复出厂设置”， 按【确认】键后进入恢复出厂设置菜单，系统会给出提示。确认恢复出厂设置后，所有节目列表将被清空，系统会弹出搜台提示。用户选择“确认”后系统自动搜索节目，选择“退出”后保存空机。若不进行任何操作，10s后自动开始搜索。 <3> 系统工作状态 在系统管理菜单中，选择“系统工作状态”， 按【确认】键后进入系统工作状态菜单，菜单中显示当前节目的各项参数和指标。 and special tools for emergency response equipment and facilities. Emergency preparedness and response plan 1) emergency response (1) If a major accident occurs, the project should set up emergency response teams, chaired by the project manager, head of production and safety coordinators, professional foreman for the crew, primarily responsible for the orderly rescue when an emergency occurs or processing, outsourcing, team manager and support staff, assisting the Deputy Project Manager for related auxiliary work. (2) after the accident, the project manager is responsible for field commander, advance the establishment of emergency response team personnel, accountability, seriously injured officers sent out rescue, have procedures to deal with accidents, incidents, maximum reduction in casualties and property loss. (3) If an accident occurs, press Division in advance for emergency personnel cleared, concentrate manpower and material and financial resources to rescue the injured, decrease of the maximum loss. (4) after the accident processing work (5) identified the cause of the accident and the person responsible. (6) the written report to the supervisor in writing, including the time and place of the accident, injury (death) person's name, sex, age, trades, injuries, injuries. (7) the development of effective preventive measures to prevent such accidents from happening again. (8) education of all personnel of the organization. (9) informed criticism of those responsible. (10) all personnel read out the results, and responsible disposal. (11) maintenance of emergency supplies, maintenance and testing ? strengthening the day-to-day management of the various fire fighting equipment fire-fighting equipment, authorities should be staffed, equipped with fire extinguishers. Fire hydrants identified person responsible for regularly inspecting, testing, at any time in good condition. ? Guard monthly check-fire extinguishers and fire-fighting equipment. ? once every quarter, inspections and tests of a fire hydrant in good condition. 2), plans to develop (1) casualties occurred in construction, such as accidents or accidents of the direct economic <4> 系统版本 此屏幕窗口显示本机顶盒的基本信息:机顶盒号、智能卡号、软件版本、硬件版本、LOADER版本、背景版本、软件发布日期等。 (4)CA信息 在系统设置菜单中，选择“CA信息”，按【确认】键后进入CA信息菜单。按【CH+】或【CH-】键来选择授权信息、事件信息、钱包信息、PIN码设置、成人级设置、CA系统信息等。 单元2 数字机顶盒软件调试 一 智能卡及接口电路: 每个有线数字电视用户都配有一张数字电视卡(又称智能卡)，这个卡有一个内置的处理器和一个与数字机顶盒通信的接口。智能卡如同手机卡一样，当用户观看节目时，只需将智能卡插入机顶盒卡槽中，机顶盒就会根据用户收看的节目内容和时间在智能卡上做相应的记录。当智能卡上的余额用完后，可到指定的地点进行充值。智能卡具有高度的安全性，一确保未经授权的用户不能接收有线数字电视服务。目前一个机顶盒配置一张专用的智能卡。 数字电视的MPEG-2传输流是经过加密的，加密方法是使正常传输流与一个伪随记序列进行异或运算。在接收端再与一个相同的伪随机序列进行一次异或运算即可得到解密的MPEG-2传输流。这里所说的伪随机序列相同，是指他它们的起始点相同，这个起始点值成为控制字Ks。这个控制字在授权密钥Kw的控制下快速变化，即控制码加密，控制码加密后成为权益控制信息ECM。付了费的用户智能卡中都有一个分配密钥Kd。在发送端用分配密钥对授权密钥加密，得到权益管理信息EMM.ECM和EMM经过复用方式和加扰的MPEG-2视音频传输流一起传送。 二 机顶盒的连接 1 数字有线电视接收机顶盒的连接 数字有线电视接收机顶盒与电视机和预设有线电视插口的连接都是通过后面板上的各个端口进行的，一般的连接步骤如下(如图2.2.1): and special tools for emergency response equipment and facilities. Emergency preparedness and response plan 1) emergency response (1) If a major accident occurs, the project should set up emergency response teams, chaired by the project manager, head of production and safety coordinators, professional foreman for the crew, primarily responsible for the orderly rescue when an emergency occurs or processing, outsourcing, team manager and support staff, assisting the Deputy Project Manager for related auxiliary work. (2) after the accident, the project manager is responsible for field commander, advance the establishment of emergency response team personnel, accountability, seriously injured officers sent out rescue, have procedures to deal with accidents, incidents, maximum reduction in casualties and property loss. (3) If an accident occurs, press Division in advance for emergency personnel cleared, concentrate manpower and material and financial resources to rescue the injured, decrease of the maximum loss. (4) after the accident processing work (5) identified the cause of the accident and the person responsible. (6) the written report to the supervisor in writing, including the time and place of the accident, injury (death) person's name, sex, age, trades, injuries, injuries. (7) the development of effective preventive measures to prevent such accidents from happening again. (8) education of all personnel of the organization. (9) informed criticism of those responsible. (10) all personnel read out the results, and responsible disposal. (11) maintenance of emergency supplies, maintenance and testing ? strengthening the day-to-day management of the various fire fighting equipment fire-fighting equipment, authorities should be staffed, equipped with fire extinguishers. Fire hydrants identified person responsible for regularly inspecting, testing, at any time in good condition. ? Guard monthly check-fire extinguishers and fire-fighting equipment. ? once every quarter, inspections and tests of a fire hydrant in good condition. 2), plans to develop (1) casualties occurred in construction, such as accidents or accidents of the direct economic 图2.2.1 数字有线电视接收机顶盒的连接方法 (1)根据有线电视信号的接头类型选择正确的用户电缆线，将有线电视信号接头同有线电视机顶盒的“信号输入”端连接好。 (2)用音、视频连接线中的黄线连接有线电视机顶盒的视频端口( 黄色)和电视机的视频输入端口，用音、视频连接线中的红线和白线分别连接该机顶盒的左、右声道和电视机的左、右声道。 如果连接使用的电视机只有一个音频输入端口，将机顶盒的左声道或者右声道连接到该输入端口均可。若连接使用的电视机有S端子接口，则用S-VIDEO线将其与本机的S视频输出接口相连，可得到更高的图像质量。 (3)可以通过光纤数字音频端口连接数字功放或将左、右声道连接到音响设and special tools for emergency response equipment and facilities. Emergency preparedness and response plan 1) emergency response (1) If a major accident occurs, the project should set up emergency response teams, chaired by the project manager, head of production and safety coordinators, professional foreman for the crew, primarily responsible for the orderly rescue when an emergency occurs or processing, outsourcing, team manager and support staff, assisting the Deputy Project Manager for related auxiliary work. (2) after the accident, the project manager is responsible for field commander, advance the establishment of emergency response team personnel, accountability, seriously injured officers sent out rescue, have procedures to deal with accidents, incidents, maximum reduction in casualties and property loss. (3) If an accident occurs, press Division in advance for emergency personnel cleared, concentrate manpower and material and financial resources to rescue the injured, decrease of the maximum loss. (4) after the accident processing work (5) identified the cause of the accident and the person responsible. (6) the written report to the supervisor in writing, including the time and place of the accident, injury (death) person's name, sex, age, trades, injuries, injuries. (7) the development of effective preventive measures to prevent such accidents from happening again. (8) education of all personnel of the organization. (9) informed criticism of those responsible. (10) all personnel read out the results, and responsible disposal. (11) maintenance of emergency supplies, maintenance and testing ? strengthening the day-to-day management of the various fire fighting equipment fire-fighting equipment, authorities should be staffed, equipped with fire extinguishers. Fire hydrants identified person responsible for regularly inspecting, testing, at any time in good condition. ? Guard monthly check-fire extinguishers and fire-fighting equipment. ? once every quarter, inspections and tests of a fire hydrant in good condition. 2), plans to develop (1) casualties occurred in construction, such as accidents or accidents of the direct economic 备上。 (4)将电源线与220V /50Hz交流电插座相连。 2 数字卫星机顶盒的连接 (1) 数字卫星机顶盒与高频头的连接 数字卫星电视接收机顶盒与高频头之间通过同轴电缆进行连接。将加工好的电缆的一头与高频头连接好并拧紧，另一头与机顶盒上的电缆输入端连接好并拧紧。由于卫星接收系统中的天线一般安装于室外，同轴电缆与高频头的连接点也长期处于室外环境中，因此，为了防止雨水等深入，可在高频头的来你接触处包裹塑料膜。 (2) 数字卫星机顶盒与电视机的连接 数字卫星电视接收机顶盒也是通过同轴电缆与电视机进行连接的。通常情况下只需要将机顶盒的音频和视频接口与电视机的音、视频接口相连接就可以。连接时注意连接线接头的颜色与接口颜色相对应，如果颜色无法对应上，机顶盒与电视机的接口也要对应上。也就是说，机顶盒上的黄色视频输出接口与电视机上的视频输入接口相连，红色的左声道输出接口与电视机的音频(左声道)接口相连，右声道通常使用白色的插头连接。 三 机顶盒的软件升级 机顶盒具有软件在线升级功能。数据广播服务器按DVB数据广播标准将升级软件广播下来，数字机顶盒能够识别该机顶盒软件的版本号，在版本号不同时就会接收该版本号的软件，并对保存在机顶盒存储器中的旧软件进行更改。IPTV和支持双向传输的有线电视系统可以向机顶盒透明地传送软件。由于该系统无需额外的电话连接，客户无需其它操作即可自动接收更新。此外，供应商还可将STB更新设备与整个视频内容分布和工作流系统集成在一起。 一般来说，这些系统使用FTP作为文件传输。但是，使用FTP会影响推更新系统的效率及可升级性: FTP是一个点到点协议，因此需要和每个STB建立单独传输，这样既耗时，又占用带宽，而且难于管理。 由于文件容量的提高，传输时间相应延长了，整个用户群的更新时间也随之延长。这样整个更新过程可能会延长到凌晨才能结束。对此，供应商可以通过在数据中心增加应用程序服务器的方式缩短时间，但这是一种不经济的手段，增加了管理成本。 FTP通过重启传输来管理故障。and special tools for emergency response equipment and facilities. Emergency preparedness and response plan 1) emergency response (1) If a major accident occurs, the project should set up emergency response teams, chaired by the project manager, head of production and safety coordinators, professional foreman for the crew, primarily responsible for the orderly rescue when an emergency occurs or processing, outsourcing, team manager and support staff, assisting the Deputy Project Manager for related auxiliary work. (2) after the accident, the project manager is responsible for field commander, advance the establishment of emergency response team personnel, accountability, seriously injured officers sent out rescue, have procedures to deal with accidents, incidents, maximum reduction in casualties and property loss. (3) If an accident occurs, press Division in advance for emergency personnel cleared, concentrate manpower and material and financial resources to rescue the injured, decrease of the maximum loss. (4) after the accident processing work (5) identified the cause of the accident and the person responsible. (6) the written report to the supervisor in writing, including the time and place of the accident, injury (death) person's name, sex, age, trades, injuries, injuries. (7) the development of effective preventive measures to prevent such accidents from happening again. (8) education of all personnel of the organization. (9) informed criticism of those responsible. (10) all personnel read out the results, and responsible disposal. (11) maintenance of emergency supplies, maintenance and testing ? strengthening the day-to-day management of the various fire fighting equipment fire-fighting equipment, authorities should be staffed, equipped with fire extinguishers. Fire hydrants identified person responsible for regularly inspecting, testing, at any time in good condition. ? Guard monthly check-fire extinguishers and fire-fighting equipment. ? once every quarter, inspections and tests of a fire hydrant in good condition. 2), plans to develop (1) casualties occurred in construction, such as accidents or accidents of the direct economic 在一个容纳上万个STB的系统中，这样的重传输可能会发生成百上千次，从而会造成网络拥塞，延长更新过程。 每个STB供应商都有自己的更新系统，如果供应商使用各个品牌的STB，必须使用各个供应商提供的特定更新系统。 对执行STB更新的视频供应商而言，只要系统符合所有要求，推技术更利于管理，成本更经济。很多供应商现在推出使用IP多点传送(multicast)技术的新系统，解决了系统的升级和效率管理问题。基于多点传送的STB更新系统有诸多好处: IP多点传送是一种点到多点协议。它并不是一次更新一个STB，而是将所有更新按照发送到特定组的上万个STB中。这样，供应商仅需有限的传输即可完成更新，而无需发送上万次。这样避免了更新增长带来的超时问题，降低了网络拥塞。 基于多点传送的系统可以在单个会话里使用高级纠错方案广播所有丢失的位。例如，如果10,000个STB中有100个STB出现包丢失的问题，分布软件会在每次STB更新时记录哪些包丢失了，然后将将有错误的STB所丢失的包打包，并一次发送出去。这样可以将带宽和发送时间降至最低。 基于多点传送的系统是非常经济的，它使用标准Windows/Linux服务器，每个STB上运用瘦客户程序。(现有STB可通过已有的更新方法更新。) 因为这种系统可以更新任意数量的STB，因此系统的可升级性好。 它们可以和整个视频管理系统集成在一起，因此所有STB状态记录和更新控制都从中央通过单个系统进行管理。IT工程师们无需受限于多个供应商的特定更新系统和数据库，只需一个数据库，即可访问所有信息。这样可以高效地实现STB选择、文件选择、发送规划及生成。 and special tools for emergency response equipment and facilities. Emergency preparedness and response plan 1) emergency response (1) If a major accident occurs, the project should set up emergency response teams, chaired by the project manager, head of production and safety coordinators, professional foreman for the crew, primarily responsible for the orderly rescue when an emergency occurs or processing, outsourcing, team manager and support staff, assisting the Deputy Project Manager for related auxiliary work. (2) after the accident, the project manager is responsible for field commander, advance the establishment of emergency response team personnel, accountability, seriously injured officers sent out rescue, have procedures to deal with accidents, incidents, maximum reduction in casualties and property loss. (3) If an accident occurs, press Division in advance for emergency personnel cleared, concentrate manpower and material and financial resources to rescue the injured, decrease of the maximum loss. (4) after the accident processing work (5) identified the cause of the accident and the person responsible. (6) the written report to the supervisor in writing, including the time and place of the accident, injury (death) person's name, sex, age, trades, injuries, injuries. (7) the development of effective preventive measures to prevent such accidents from happening again. (8) education of all personnel of the organization. (9) informed criticism of those responsible. (10) all personnel read out the results, and responsible disposal. (11) maintenance of emergency supplies, maintenance and testing ? strengthening the day-to-day management of the various fire fighting equipment fire-fighting equipment, authorities should be staffed, equipped with fire extinguishers. Fire hydrants identified person responsible for regularly inspecting, testing, at any time in good condition. ? Guard monthly check-fire extinguishers and fire-fighting equipment. ? once every quarter, inspections and tests of a fire hydrant in good condition. 2), plans to develop (1) casualties occurred in construction, such as accidents or accidents of the direct economic 图2.2.2. 通过IP多点传送发送更新软件 随着基于IP视频系统的不断增长，STB供应商扩大了产品的多样性和功能。与此同时，IPTV和VOD供应商迫切地希望采纳STB最新功能，这样可以在确保内容和访问安全性的同时，提供更新、更具有竞争性的服务。标准化、中央化和高效的STB更新系统可以在所有STB上实现新的软件架构，这对视频网络的管理和发展是非常关键的。IP多点传送技术对新更新系统是至关重要的。 三、DVB-C5800B数字有线机顶盒故障检修实例 故障实例:无图像，无伴音 故障分析:机顶盒无图像、无伴音的故障原因通常有如下几种: (1) 开关电源故障 (2) 调谐器故障 (3) 解码芯片故障 (4) 音、视频输出电路故障 故障检修: 机顶盒出项无图像、无伴音的故障时，应先查一下机顶盒前面板开机后是否有显示。如果无显示，有可能是电源、保险丝等方面有故障;如果显示正常，则应对音频和视频输出端口进行检测。如果有信号，则属连接不良或监视用电视机故障。正常时的信号检测部位和波形如图。如果波形不正常或无信号，应查端口与电路板的连接处、音、视频输出电路以及相关器件。 应注意主板的印制线，入印制线有短路或短路情况，也会引起无信号输出的故障。实测结果为印制板有裂缝，导致印制线断路，分别焊接后，故障排除。 第三章 测试习题 一、简答题 and special tools for emergency response equipment and facilities. Emergency preparedness and response plan 1) emergency response (1) If a major accident occurs, the project should set up emergency response teams, chaired by the project manager, head of production and safety coordinators, professional foreman for the crew, primarily responsible for the orderly rescue when an emergency occurs or processing, outsourcing, team manager and support staff, assisting the Deputy Project Manager for related auxiliary work. (2) after the accident, the project manager is responsible for field commander, advance the establishment of emergency response team personnel, accountability, seriously injured officers sent out rescue, have procedures to deal with accidents, incidents, maximum reduction in casualties and property loss. (3) If an accident occurs, press Division in advance for emergency personnel cleared, concentrate manpower and material and financial resources to rescue the injured, decrease of the maximum loss. (4) after the accident processing work (5) identified the cause of the accident and the person responsible. (6) the written report to the supervisor in writing, including the time and place of the accident, injury (death) person's name, sex, age, trades, injuries, injuries. (7) the development of effective preventive measures to prevent such accidents from happening again. (8) education of all personnel of the organization. (9) informed criticism of those responsible. (10) all personnel read out the results, and responsible disposal. (11) maintenance of emergency supplies, maintenance and testing ? strengthening the day-to-day management of the various fire fighting equipment fire-fighting equipment, authorities should be staffed, equipped with fire extinguishers. Fire hydrants identified person responsible for regularly inspecting, testing, at any time in good condition. ? Guard monthly check-fire extinguishers and fire-fighting equipment. ? once every quarter, inspections and tests of a fire hydrant in good condition. 2), plans to develop (1) casualties occurred in construction, such as accidents or accidents of the direct economic ,(数字有线电视机顶盒与数字卫星电视机顶盒的不同之处是什么, 答: 数字有线电视机顶盒与数字卫星电视机顶盒的不同之处是输入射频信号的频段不同，数字解码的方式也不同 (1) 输入信号的不同 两者的输入射频信号的频段有所不同。数字有线电视接收机顶盒接收的频率范围为48~860MHz，中频频率为36MHz，带宽为1200MHZ，中频频率为479.5MHz,采用QPSK方式解调。数字卫星电视接收机顶盒接收的频率是卫星信号的C波段后Ku波段。 (2) 工作原理的不同 数字有线电视机顶盒的基本功能是接收有线电视系统传输的数字电视广播信号，通过解调、解复用、解码和音、视频编码，可供用户在模拟电视机上观看数字电视节目和浏览各种数据信息。 数字卫星电视接收机顶盒主要是有前端电路、数字信号解码电路、AV信号处理电路、系统控制电路、外部设备接口电路等部分组成。高频头将卫星天线接收到的射频信号变成第一中频信号，然后送到前端电路对QPSK调制的信号进行解调和纠错。数字信号经过解码后送到AV信号的MPEG解码器中解压缩，然后进 行视频、音频编码D/A变换，还原出视频音频信号送到监视器中。 (3) 信道解调方式的不同: 数字卫星接收机顶盒的核心电路是解码芯片，它决定着卫星接收机的性能。数字卫星接收机顶盒与数字有线电视机顶盒对信号处理的主要区别是信道解码方式不同，卫星信号采用QPSK解调方式，而数字有线机顶盒则采用QAM解调。 (4) 解码过程的不同 数字电视机顶盒的主要功能就是将接收的数字信号转换为模拟电视信号，使用户不用更换模拟电视机就能收看数字电视节目。经过一体化调谐解调器解调后输出的TS码流是一种包含视、音频和数据信息的多路节目数据流，按MPEG-2标准符合而成，因此，在解码前要先对TS码流进行解复用，根据所要收看节目的数据包识别符(PID)提取出相应的视频音频和数据信息，恢复符合MPEG-2标准打包的节目基本数据流(PES)，然后进行MPEG-2解码。节目基本流数据包and special tools for emergency response equipment and facilities. Emergency preparedness and response plan 1) emergency response (1) If a major accident occurs, the project should set up emergency response teams, chaired by the project manager, head of production and safety coordinators, professional foreman for the crew, primarily responsible for the orderly rescue when an emergency occurs or processing, outsourcing, team manager and support staff, assisting the Deputy Project Manager for related auxiliary work. (2) after the accident, the project manager is responsible for field commander, advance the establishment of emergency response team personnel, accountability, seriously injured officers sent out rescue, have procedures to deal with accidents, incidents, maximum reduction in casualties and property loss. (3) If an accident occurs, press Division in advance for emergency personnel cleared, concentrate manpower and material and financial resources to rescue the injured, decrease of the maximum loss. (4) after the accident processing work (5) identified the cause of the accident and the person responsible. (6) the written report to the supervisor in writing, including the time and place of the accident, injury (death) person's name, sex, age, trades, injuries, injuries. (7) the development of effective preventive measures to prevent such accidents from happening again. (8) education of all personnel of the organization. (9) informed criticism of those responsible. (10) all personnel read out the results, and responsible disposal. (11) maintenance of emergency supplies, maintenance and testing ? strengthening the day-to-day management of the various fire fighting equipment fire-fighting equipment, authorities should be staffed, equipped with fire extinguishers. Fire hydrants identified person responsible for regularly inspecting, testing, at any time in good condition. ? Guard monthly check-fire extinguishers and fire-fighting equipment. ? once every quarter, inspections and tests of a fire hydrant in good condition. 2), plans to develop (1) casualties occurred in construction, such as accidents or accidents of the direct economic 送到MPEG-2解码器芯片中进行解压缩，生成CCIR601格式的视频数据流和PCM格式的音频数据流，分别送到视频解码器和音频D/A转换器。视频解码器在按一定电视制式解码，最后经D/A变换变成模拟图像信号和模拟音频信号，供电视机接收。 数字卫星接收机顶盒的接收前端是两套电路，分别处理来自卫星高频头输出的第一中频信号和来自地面波接收天线的地面电视广播数字信号。数字卫星接收机顶盒A/V解码电路是一个信源解码芯片，信号在其中主要是进行解密和音频视频数据的分离。分离后的音频数据和视频数据再分别进行解码处理。视频数据解码器对视频信号进行解压缩处理，还原出数字视频信号，再对数字视频信号进行视频编码(PAL、NTSC制)，然后经D/A变换器变成模拟视频信号输出，经显示处理后输出模拟视频信号。音频数据信号经解压缩处理后有由芯片输出数字音频信号，再经音频D/A变换器变成模拟伴音信号输出。 and special tools for emergency response equipment and facilities. Emergency preparedness and response plan 1) emergency response (1) If a major accident occurs, the project should set up emergency response teams, chaired by the project manager, head of production and safety coordinators, professional foreman for the crew, primarily responsible for the orderly rescue when an emergency occurs or processing, outsourcing, team manager and support staff, assisting the Deputy Project Manager for related auxiliary work. (2) after the accident, the project manager is responsible for field commander, advance the establishment of emergency response team personnel, accountability, seriously injured officers sent out rescue, have procedures to deal with accidents, incidents, maximum reduction in casualties and property loss. (3) If an accident occurs, press Division in advance for emergency personnel cleared, concentrate manpower and material and financial resources to rescue the injured, decrease of the maximum loss. (4) after the accident processing work (5) identified the cause of the accident and the person responsible. (6) the written report to the supervisor in writing, including the time and place of the accident, injury (death) person's name, sex, age, trades, injuries, injuries. (7) the development of effective preventive measures to prevent such accidents from happening again. (8) education of all personnel of the organization. (9) informed criticism of those responsible. (10) all personnel read out the results, and responsible disposal. (11) maintenance of emergency supplies, maintenance and testing ? strengthening the day-to-day management of the various fire fighting equipment fire-fighting equipment, authorities should be staffed, equipped with fire extinguishers. Fire hydrants identified person responsible for regularly inspecting, testing, at any time in good condition. ? Guard monthly check-fire extinguishers and fire-fighting equipment. ? once every quarter, inspections and tests of a fire hydrant in good condition. 2), plans to develop (1) casualties occurred in construction, such as accidents or accidents of the direct economic