什麼叫藍牙

藍牙是一種近距離的無線傳輸應用技術，在10—100米範圍內，把專用的半導體裝入機器中，無須藉助電纜就可連接計算機、打印機、數字相機、電視機、手機、微波爐等，並能同時進行數據和語音傳輸。是英語blue tooth的直譯。下面是小編爲您收集整理的什麼叫藍牙，供大家參考!

What is Bluetooth?

Bluetooth is a universal radio interface in the 2.45GHz frequency band that enables portable electronic devices to connect and communicate wirelessly via short-range, ad hoc networks. Each unit can simultaneously communicate with up to sever other units per piconet. Moreover, each unit can simultaneously belong to several piconets.

What is Bluetooth Technology?

Bluetooth technology which apart from Ericsson, has gained the support of Nokia, IBM, Toshiba, Intel and many other manufacturers.

Eliminates the need for wires, cables and connectors for and between cordless or mobile phones, modems, headsets, PDAs, Computers, printers, projectors, local area networks, and so on, and paves the way for new and completely different devices and nology Characteristics—1Ms/s symbol rate exploits maximum available channel bandwidth.

Fast frequency hopping avoids interference

Adaptive output power minimizes interference

Short data packets maximize capacity during interference

Fast acknowledge allows low coding overhead for links

CVSD(Continuous Variable Slope Delta Modulation)voice coding enables operation at high bit- error rates

Flexible packet types supports wide application range

Air interface tailored to minimize current consumption

Basic Technical Information—Based upon a small, high performance integrated radio transceiver, each of which is allocated a unique 48-bit address derived from the IEEE dard.

Operate in the unrestricted 2.45GHz ISM free band, Which is available globally although slight variation of location and width of band apply.

Range set at 10m to optimize for target market of mobile and business user

Gross data rate 1Mbit/s with second generation plans to increase to 1Mbit/s

One-to-one connections allow maximum data transfer rate of 721kbit/s (3 voice channels)

Uses packet switching protocol based on frequency hop scheme with 1600 hops/s to enable high performance in noisy radio environments. The entire available frequency spectrum is used with 79 hops of 1Mhz bandwidth, analogous to the IEEE 802.11 standard.

Low power consumption longevity for battery powered devices. During data transfer the maximum current drain is 30mA. However during pauses or at lower data rates will be lower.

藍牙是一個頻率爲2.45GHz的通用無線電通信接口，它通過一個特殊的網絡可以在各種便攜設備之間建立起無線連接並進行短程通信。在一個微微網中，每個單元都能同時與其它各單元進行通信。而且，每一個單元可以同時屬於幾個微微網。

什麼是“藍牙”技術?

“藍牙”技術最先是由愛立信開始研製的，現在已經得到了諾基亞、IBM、東芝、因特爾及許多其它相關製造廠家的支持。其目的是爲了免除在無繩電話或移動電話、調制解調器、頭套式送/受話器、PDAs、計算機、打印機、幻燈機、局域網等之間加裝電線、電纜和連接器。而且，這種技術可以延伸到那些完全不同的新設備和新應用中去。“藍牙”的技術特性—以每秒1M個碼元的字符速率傳輸，充分利用信道的最大有效帶寬。

快速跳頻避免干擾

可變的電源輸出使干擾減小到最小

採用短數據包傳輸增強抗干擾能力

快速確認允許有附加低速率的編碼被髮送到鏈路上

連續可變斜率增量調製的語音編碼可以在高誤碼率的情況下正常工作

靈活的分組類型支持多種應用

無線電空中接口使電耗達到最小"藍牙"基本技術概要

每一個小型、高性能、集成的無線電收發機都有IEEE 802標準所規定的一個唯一的48比特位地址

開放的2.45GHz ISM自由頻段，全球都可以自由使用。

10公里是最適於移動通信市場和商業用戶的通信範圍

總速率爲1Mbit/s，計劃下一代產品將達到2Mbit/s

點到點連接允許的最大數據傳輸速率爲721kbit/s

在無線電噪聲環境裏，利用基於每秒1600跳跳頻表的分組交換協議可以提高系統性能。以1Mhz帶寬79跳來利用這個完整的可用頻譜。這類似於IEEE 802.11標準。

低電能的消耗。在備用模式下僅需0.3mA，這能延長那些使用電池供電設備的壽命。數據傳送時電流的最大消耗爲30mA.當暫停工作或低速傳送數據時電流消耗更低。

　　數字錢包

Digital Wallets

A digital wallet is software that enables users to pay for goods on the Web. It holds credit-card numbers and other personal information such as a shipping address. Once entered, the data automatically populates order fields at merchant sites.

When using a digital wallet, consumers don't need to fill out order forms on each site when they purchase an item because the information has already been stored and is automatically updated and entered into the order fields across merchant sites. Consumers also benefit when using digital wallets because their information is encrypted or protected by a private software code. And merchants benefit by receiving protection against fraud.

Digital wallets are available to consumers free of charge, and they're fairly easy to obtain. For example, when a consumer makes a purchase at a merchant site that's set up to handle server-side digital wallets, he types his name and payment and shipping information into the merchant's own form. At the end of the purchase, one consumer is asked to sign up for a wallet of his choice by entering a user name and password for future purchases. Users can also acquire wallets at a wallet vendor's site.

Although a wallet is free for consumers, vendors charge merchants for wallets.

Digital wallets come in two main types: client-side and server- side. Within those divisions are wallets that work only on specific merchant sites and those that are merchant agnostic.

Client-based digital wallets, the older of the two types, are falling by the wayside, according to analysts, because they require users to download and install software. A user downloads the wallet application and inputs payment and mailing information. At that point, the information is secured and encrypted on the user's hard drive. The user retains control of his credit card and personal information locally.

With a server-based wallet, a user fills out his personal information, and a cookie is automatically downloaded. (A cookie is a text file that contains information about the user.)In this scenario, the consumer information resides on the server of a financial institution or a digital wallet vendor rather than on the user's PC.

Server-side wallets provide assurance against merchant fraud because they use certificates to verify the identity of all parties. When a party makes a transaction, it presents its certificate to the other parties involved. A certificate is an attachment to an electronic message used to verify the identity of the party and to provide the receiver with the means to encode a reply.

Furthermore, the cardholder's sensitive data is typically housed at a financial institution, so there's an extra sense of security because financial environments generally provide the highest degree of security.

But even though wallets provide easy shopping online, adoption hasn't been widespread.

Standards are pivotal to the success of digital wallets.

數字錢包是一種能使用戶在Web網上支付貨款的軟件。它保存信用卡號碼和其它個人信息，如送貨地址。數據一旦被輸入，就自動轉移到商家網站的訂貨域。

使用數字錢包時，當消費者購買物品時，不需要填寫每個站點上的訂單，因爲信息已經存儲了，並自動更新和進入到廠商站點的訂貨域。消費者使用數字錢包時也能得到好處，因爲他們的信息被加密了，即由私人軟件代碼加以保護。商家也避免了受騙而得到保護，也從中獲益。

對消費者來說，數字錢包是免費的，可以相當容易得到。例如，當消費者在建立了處理服務器端數字錢包的商家網站上購買東西時，他把其名字、付款額和送貨信息輸入到商家自己的表格中。在購買結束時，他被要求爲他選擇的錢包簽上用戶名和今後購買時的口令。用戶也能從錢包供應商的站點上得到錢包。

雖然錢包對消費者是免費的，但(錢包)供應商對商家使用錢包要收費。

數字錢包分兩大類型：客戶端和服務器端(數字錢包)。在這些分類中是那些只在某些商家網站上工作的錢包和那些商家不可知的錢包。

基於客戶的數字錢包是兩種錢包中較陳舊的一種，據分析人士稱，這類錢包已開始沒人理睬了，因爲它們要求用戶下載和安裝軟件。用戶下載錢包的應用程序和輸入付款額和郵寄信息。在這個意義上，信息是安全的，並在用戶的硬盤上進行了加密。用戶在本地獲得對其信用卡和個人信息的控制。

使用基於服務器的錢包時，用戶填寫其個人信息，並自動下載點心文件(點心文件是一個包括了有關用戶信息的文本文件)。在這種情況下，消費者的信息駐留在金融機構或者數字錢包供應商的服務器上，而不是用戶的PC機上。

服務器端錢包提供了針對商家欺騙的安全措施，因爲它們使用證書，來驗明各方的身份。當一方進行交易時，它向涉及的另一方提交證書。證書附着在電子報文上，用於驗明另一方身份，並向接收方提供對回答進行編碼的手段。

另外，信用卡持有人的敏感信息一般保存在金融機構內，由於金融環境通常提供最高等級的安全性，因而這又是一種額外的安全措施。

但是即使錢包提供了方便的網上購物，尚未被廣泛採用。

標準化是數字錢包能否成功的關鍵。