数字传输

Digital Data Network is a data transmission network by using digital channel. By contrast with analog channel, it has some strongpoint, such as higher transmission quality, greater speed, better utilization factor of bandwidth and so on.

数字数据网是利用数字信道传输数据信号的数据传输网，利用数字信道传输数据信号与传统的模拟信道相比，具有传输质量高、速度快、带宽利用率高等一系列优点。

It with wired compares mainly has the cost to be low, carries conveniently, omits the wired wiring the worry; Specially is suitable to grasping the equipment the correspondence, the battery power supply equipment, the vehicles monitoring, the remote control, the telemetering, the small wireless network, wireless copies the table, the system, the plot messenger call, the industry data acquisition system, the wireless label, the status recognition, must contacts the RF smart card, the small wireless data terminal, the safe fire protection is systematic, wireless domain and so on in external guidance system, biological signal gathering, hydrometeorology monitoring, robot control, digital audio frequency, numeral image transmission the low power loss, the microminiaturization is the current wireless correspondence product then takes along the product in particular the urgent need and the key question.

它与有线相比主要有成本低，携带方便，省去有线布线的烦恼；特别适用于手持设备的通信、电池供电设备、车辆监控、遥控、遥测、小型无线网络、无线抄表、门禁系统、小区传呼、工业数据采集系统、无线标签、身份识别、非接触RF智能卡、小型无线数据终端、安全防火系统、无线遥控系统、生物信号采集、水文气象监控、机器人控制、数字音频、数字图像传输等领域中。低功耗、微型化是当前无线通信产品尤其是便携产品的迫切要求和关键问题。无线通信的另一个关键问题是数据传输的可靠性，这取决于诸多因素，如频率选择、同频干扰、传输距离、天线选择等，这些在设计无线通信系统时都要认真考虑和比较。

This paper mainly introduces the baseband transmission and the waveband transmission of digital communication system.

介绍了数字通信系统中信号的基带传输和频带传输；分别论述了基带传输系统和频带传输系统模型，说明了基带信号无码间干扰传输条件及频带数字调制的工作原理。

My company have a foothold local actual condition, gather the international list price equipments to produce the factory to lead the technique and products,detrusion to quility price compares have advantage of the product line: Digital transfer product: MPG-2 ,DVB,DAB encoder,MUX,modulator,conversion and so on.

立足国内实际状况，集合国际定价设备生产厂商的领先技术和产品，推出了极具性价比优势的产品线：数字传输产品：MPEG-2 DVB、DAB编码器、复用器、调制器、转换器；有线宽带产品：双向放大器、光通信设备、CMTS、机顶盒、交换机、路由器；流媒体产品：VOD服务器、CA系统

The second phase of networking ,which occurred in the 1960s ,included three major milestones:software switching, digital transmission ,and satellite deployment,in 1965 ,american telephone and telegraph introduced the first stored program control local switch ,the 1 ees switching system ,with the ues of software control, a family of custom calling services (speed calling,call waiting ,call forwarding and three way calling ,etc ,) was mande possible, the first software program for the 1ees switching system had approximately 100,000 lines of codes, today switches may contain ten million lines of code.

第二阶段是网络化，其发生在20世纪60年代，包括三大里程碑：软件交换，数字传输，卫星的运用，在1965年，美国电话电报介绍第一个存储程序控制区域交换机，第1 ees交换系统中，软控制运用在家庭式的呼叫服务中（快速呼叫，呼叫等待，呼叫转接和三方呼叫等，成为可能，第一个软件程序，为1ees切换系统大约有 10万行代码今日交换系统可能含有1千万行的代码。

The system is made up of two separate parts: collection and reception. The collection part digitalizes the signal from the sensor and sends it out using wireless digital transmission technology.

该系统由采集和接收两部分组成：采集端将传感器的输出信号进行模数转换，利用无线数字传输技术将数据发送到接收端，在接收端对数据进行存储和显示。

The nRF903 single chip RF transceiver was employed to modulate and demodulate for data transfer. The system is made up of two separate parts: collection and reception. The collection part digitalizes the signal from the sensor and sends it out using wireless digital transmission technology.

该系统由采集和接收两部分组成：采集端将传感器的输出信号进行模数转换，利用无线数字传输技术将数据发送到接收端，在接收端对数据进行存储和显示。

The invention discloses a digital good transaction system and the method. It mainly carries on coding process to at least one digital good in a content downloading center into a coded digital good, and the coded digital good will be transmitted to at least one content downloading station with real memory transmission path, when the consumer selects a digital good, the user can uses a content downloading card into a content downloading station, uses a reality transmission path to store the digital good to be purchased, and uses a network transmission wire to connect the content downloading center, the center incriminates the card number in order to generate a card number decoding data, and download the decoding data into a content downloading card, when the consumer want toe buy a digital good, the content can be downloaded into a content card reader, and the reader incriminate the card number to reduces the decoded data and the digital good, in order to generate the digital good which can be read and used.

本发明公开了一种数字商品交易系统及其交易方法，其主要是将至少一数字商品在一内容下载中心进行加密处理以成为一加密数字商品，而加密数字商品将以实际的储存器传递线路以直接送到至少一内容下载点中，当消费者选定一欲购买数字商品时，可持一内容下载卡至其中一内容下载点，利用一实体传输线路直接储存所欲购买的加密数字商品，并藉由一网络传输线路以连接内容下载中心，内容下载中心将根据卡号识别码以产生一卡号解密资料，并将卡号解密资料下载至内容下载卡，当消费者欲使用欲购买数字商品时，即可将内容下载卡置入一内容卡片阅读机中，而内容卡片阅读机将根据卡号识别码以还原卡号解密资料及加密数字商品，以产生可供读取使用的数字商品。

The speech signal is a analog one, and we can perform its digital transmission by sampling, quantizing and coding.

话音信号是一个模拟信号，通过采样、量化和编码，我们可以实现话音信号的数字传输。

The speech signal is a analog one, and we can perform its digital transmission by sampling, quantizing and coding.

话音信号是一个模拟信号，通过采样，量化和编码，话音信号是一个模拟信号，通过采样，量化和编码，我们可以实现话音信号的数字传输。

Neither the killing of Mr Zarqawi nor any breakthrough on the political front will stop the insurgency and the fratricidal murders in their tracks.

在对危险的南部地区访问时，他斥责什叶派民兵领导人对中央集权的挑衅行为。

In fact,I've got him on the satellite mobile right now.

实际上 我们已接通卫星可视电话了