wideband

ds3超宽频是什么？

超宽频（‎Ultra-wideband，简称UWB）是一种具备低耗电与高速传输的无线个人局域网络通讯技术，适合需要高质量服务的无线通信应用，可以用在无线个人局域网络（WPAN）、家庭网络连接和短距离雷达等领域。它不采用连续的正弦波（sine waves），而是利用脉冲讯号来传送。

利用纳秒（ns）至皮秒（ps）级的非正弦波窄脉冲传输数据,而时间调变技术令其传送速度可以大大提高，而且耗电量相对地低，并有较精确的定位能力。与常见的通信使用的连续载波方式不同，UWB采用极短的脉冲信号来传送数据。这些脉冲所占用的带宽甚至达到几GHz，因此最大数据传输速率可以达到几百Mbps。因为使用的是极短脉冲，在高速通信的同时，UWB设备的发射功率却很小，仅仅只有目前的连续载波系统的几百分之一。
超宽带的传输距离都是在十公尺之内，它的传输速率高达480Mbps，是蓝牙的159倍，是Wi-Fi标准的18.5倍，非常适合多媒体信息的大量传输。[

电子类英语论文

A Low-Cost and Low-Power CMOS Receiver Front-End for MB-OFDM Ultra-Wideband Systems要该文全文，更换别的论文，或要中英文对照都可以找我Mahim Ranjan, Member, IEEE, and Lawrence E. Larson, Fellow, IEEE0Abstract—This paper presents an RF receiver front-end for MB-OFDM-based ultra-wideband (UWB) systems. The receiver occupies only 0.35 in a 0.18 CMOS process and consists of a low-noise amplifier, downconverter and a bandpass filter. There are no on-chip inductors and the receiver requires no off-chip matching components. The measured receiver gain is 21 dB, noise figure is less than 6.6 dB, input IIP3 is 5.6 dBm, and the receiver consumes 19.5 mA from a 2.3 V supply. The receivercovers all the MB-OFDM bands from 3.1 to 8 GHz.Index Terms—CMOS, distortion, OFDM, receiver, ultra wideband, UWB.I. INTRODUCTIONULTRA-WIDEBAND (UWB)multi-band orthogonal frequency-division multiplexing (MB-OFDM) systems have been proposed as an emerging solution to wireless communicationapplications requiring high data rates (up to 480 Mb/s) over short distances. In one proposed version [1], the carrier, with a bandwidth of 528 MHz, can hop to one of 14 channels（2904+528n,n=123…14）, divided into four groups of three channels and one group of two channels. This representative time-frequency interleaving for a Group 1-only systemis depicted in Fig. 1. Design of a receiver for such a systempresents many challenges due to the wide bandwidth of the RF front-end. However, to assure the widest possible adoption, RF portions of these systems should consume little DC power and die area, and be implemented in a standard CMOS process. These last requirements argue against the use of on-chip inductors wherever possible.Since theUWBfront-end intrinsically possesses a wide bandwidth, it is open to reception of undesired narrowband signals such as 802.11 a/b/g and the recently proposedWiMAX [2] systems, as shown in Fig. 2. Although OFDM systems are less susceptible to relatively narrowband jammers, nonlinearities in the receiver can result in jammer cross-modulation with wideband input signals, resulting in reduced signal-to-noise ratio (SNR) and a degradation in system performance [3]. In addition, received wideband signals (from other UWB transmitters) can intermodulate and the resulting products can land in a desired channel. Since the system is inherently wideband, harmonic distortion of a single unwanted UWB transmitter can also produce in-band distortion products and reduce the SNR. For the system to successfully operate in such a hostile environment, the linearity specifications of the receiver need to include these distortion effects. Fig. 1. Representative time-frequency interleaving pattern of a Group 1MB-OFDM signal [1]. Fig. 2. Representative spectrum at an MB-OFDM receiver antenna.This paper describes a UWB heterodyne receiver front-end that is designed to minimize the effects of wideband jammers from a variety of undesired sources [4]. In addition, the receiver is designed to minimize silicon area, so on-chip inductors are not employed. The receiver architecture is presented in Section II. Specifications for the receiver are derived in Section III. Detailed block design is presented in Sections IV–VI. Layout and packaging of the chip is discussed in Section VII. Measured results are presented in Section VIII, followed by a conclusion in Section IX.II. RECEIVER ARCHITECTUREWhen it comes to designing a low-power and low-cost receiver, the traditional choice is a direct conversion architecture. However, a direct conversion UWBreceiver, while attractive for power consumption and simplicity of its local oscillator (LO) scheme [5], [6], has a well-known problem of time-varying DC offset and sensitivity to narrowband jammers. A DC offset at the output of the receiver can degrade the SNR of the digitized baseband signal. In addition, it can introduce second-order distortion in the baseband signal, which further degrades the SNR. A Low-Cost and Low-Power CMOS Receiver Front-End for MB-OFDM Ultra-Wideband SystemsMahim Ranjan, Member, IEEE, and Lawrence E. Larson, Fellow, IEEE0Abstract—This paper presents an RF receiver front-end for MB-OFDM-based ultra-wideband (UWB) systems. The receiver occupies only 0.35 in a 0.18 CMOS process and consists of a low-noise amplifier, downconverter and a bandpass filter. There are no on-chip inductors and the receiver requires no off-chip matching components. The measured receiver gain is 21 dB, noise figure is less than 6.6 dB, input IIP3 is 5.6 dBm, and the receiver consumes 19.5 mA from a 2.3 V supply. The receivercovers all the MB-OFDM bands from 3.1 to 8 GHz.Index Terms—CMOS, distortion, OFDM, receiver, ultra wideband, UWB.I. INTRODUCTIONULTRA-WIDEBAND (UWB)multi-band orthogonal frequency-division multiplexing (MB-OFDM) systems have been proposed as an emerging solution to wireless communicationapplications requiring high data rates (up to 480 Mb/s) over short distances. In one proposed version [1], the carrier, with a bandwidth of 528 MHz, can hop to one of 14 channels（2904+528n,n=123…14）, divided into four groups of three channels and one group of two channels. This representative time-frequency interleaving for a Group 1-only systemis depicted in Fig. 1. Design of a receiver for such a systempresents many challenges due to the wide bandwidth of the RF front-end. However, to assure the widest possible adoption, RF portions of these systems should consume little DC power and die area, and be implemented in a standard CMOS process. These last requirements argue against the use of on-chip inductors wherever possible.Since theUWBfront-end intrinsically possesses a wide bandwidth, it is open to reception of undesired narrowband signals such as 802.11 a/b/g and the recently proposedWiMAX [2] systems, as shown in Fig. 2. Although OFDM systems are less susceptible to relatively narrowband jammers, nonlinearities in the receiver can result in jammer cross-modulation with wideband input signals, resulting in reduced signal-to-noise ratio (SNR) and a degradation in system performance [3]. In addition, received wideband signals (from other UWB transmitters) can intermodulate and the resulting products can land in a desired channel. Since the system is inherently wideband, harmonic distortion of a single unwanted UWB transmitter can also produce in-band distortion products and reduce the SNR. For the system to successfully operate in such a hostile environment, the linearity specifications of the receiver need to include these distortion effects. .........................

网络的缩写是什么？

网络的缩写是：ISP。全称：Internet Service Provider。提供互联网服务的公司。通常大型的电讯公司都会兼任互联网供应者。互联网供应者所提供的服务可以很广泛。除了为一般企业及私人互联网浏览所提供的拨号连线、综合业务数字网（ISDN）、DSL、缆线调制解调器、专线（LeasedLine）等上网服务外，还可以包括主机托管（Colocation）、电子邮件（E-Mail）、网页寄存（webhosting）等服务。中国五大基础运营商：中国电信：拨号上网、ADSL中国网通：拨号上网、ADSL中国铁通：拨号上网、ADSL中国移动：GPRS及EDGE无线上网中国联通：GPRS及CDMA无线上网其他：珠江宽频：有线电视线路（中国电信广州分公司出口）长城宽带：宽频中海宽带：宽频广东有线视讯宽带网：有线电视线路（中国网通广州分公司出口）

宽带网英文缩写

宽带网英文缩写介绍如下：宽带网英文缩写是BN。宽带网络（Broadband network）一般指的是带宽超过155kbps以上的网络。和宽带网对应的是窄带网络。宽带网络可分为宽带骨干网和宽带接入网两个部分。宽带网络可分为宽带骨干网和宽带接入网两个部分。1、骨干网又称为核心交换网，它是基于光纤通信系统的，能实现大范围的数据流传送。电信业一般认为传输速率达到了2Gbps的骨干网称做宽带网。2、接入网技术可根据所使用的传输介质的不同分为光纤接入、铜线接入、光纤同轴电缆混合接入和无线接入等多种类型。现有有线宽带品牌：“联通”、“电信”、“铁通”、“教育网”。 采用内置无线网卡或者外接无线网卡访问Internet，多应用于笔记本电脑，操作简单方便，其可移动性和高速性，使其在进入3G时代后具有无限潜力和竞争力，但各大无线宽带运营上所推出的套餐资费较高。现有无线宽带品牌有：“G3”、“沃”、“天翼”。 中国联合网络通信集团有限公司（简称“中国联通”），于2008年10月15日由原中国联通红筹公司、中国网通红筹公司合并成立。是经国务院批准，于1994年7月19日成立的我国唯一一家能提供全面电信基本业务的综合性电信运营企业。中国联通旗下有两家上市公司，港交所，（联通红筹）和上交所（中国联通）。

wcnm是什么意思？

wcnm的意思是我吃柠檬的意思；你忙吧，我吃柠檬：取这句话的首字母:“nmb wcnm”。形容感觉对方在敷衍自己，然后自我安慰的一种情绪语言。也是一句网络语言。需知：网络语言包括拼音或者英文字母的缩写。含有某种特定意义的数字以及形象生动的网络动画和图片，起初主要是网虫们为了提高网上聊天的效率或某种特定的需要而采取的方式，久而久之就形成特定语言了。网络上冒出的新词汇主要取决于它自身的生命力，如果那些充满活力的网络语言能够经得起时间的考验，约定俗成后我们就可以接受。而如果它无法经得起时间的考验，将很快的被网友抛弃。由网络人群新创或约定俗成。这类语言的出现与传播主要寄生于网络人群，还有为数不少的手机用户。Chat里经常能出现“恐龙、美眉、霉女、青蛙、菌男、东东”等网络语言，BBS里也常从他们的帖子里冒出些“隔壁、楼上、楼下、楼主、潜水、灌水”等“专业”词汇。