外文翻譯----基于wince的adsl線路參數(shù)的研究-其他專業(yè)(編輯修改稿)
2025-02-24 09:10 本頁面
【文章內(nèi)容簡(jiǎn)介】 navigation and PhonePad input. Devices running SmartPhone do not include a touchscreen interface. SmartPhone devices generally resemble other cellular handset form factors, whereas most Phone Edition devices use a PDA form factor with a larger display. Competitors to consumer CE based PDA platforms like Pocket PC – the main application of Windows CE – are Java, Symbian OS, Palm OS, iPhone OS and Linux based packages like Qtopia Embedded Linux environment from Trolltech, Convergent Linux Platform from a La Mobile, and Access Linux Platform from Orange and Access. The secondary usage of CE is in devices in need of graphical user interfaces, (point of sale terminals, media centers, web tablets, thin clients) as the main selling point CE is the look and feel being similar to desktop Windows. The petition is Windows XP, Linux and graphical packages for simpler embedded operating systems. Being an RTOS, Windows CE is also theoretically a petitor to any realtime operating system in the embedded space, like VxWorks, ITRON or eCos. The dominating method, however, of mixing Windows look and feel with realtime on the same hardware, is to run double operating systems using some virtualization technology, like TRANGO Hypervisor from TRANGO Virtual Processors or Intime from TenAsys in the case of Windows, and OS Ware from VirtualLogix, Padded Cell from Green Hills Software, OKL4 from Open Kernel Labs, TRANGO Hypervisor from TRANGO Virtual Processors, RTS Hypervisor from RealTime Systems or PikeOS from Sysgo, in case of the petition. Asymmetric Digital Subscriber Line (ADSL) is a form of DSL, a data munications technology that enables faster data transmission over copper telephone lines than a conventional voiceband modem can provide. It does this by utilizing frequencies that are not used by a voice telephone call. A splitter or microfilter allows a single telephone connection to be used for both ADSL service and voice calls at the same time. Because phone lines vary in quality and were not originally engineered with DSL in mind, it can generally only be used over short distances, typically less than 3mi ( km) [William Stallings39。 book]. The distinguishing characteristic of ADSL over other forms of DSL is that the volume of data flow is greater in one direction than the other, . it is asymmetric. Providers usually market ADSL as a service for consumers to connect to the Inter in a relatively passive mode: able to use the higher speed direction for the download from the Inter but not needing to run servers that would require high speed in the other direction. ADSL works vand installation issues： Currently, most ADSL munication is full duplex. Full duplex ADSL munication is usually achieved on a wire pair by either frequency division duplex (FDD), echo canceling duplex (ECD), or time division duplexing (TDD). FDM uses two separate frequency bands, referred to as the upstream and downstream bands. The upstream band is used for munication from the end user to the telephone central office. The downstream band is used for municating from the central office to the end user. With standard ADSL (an
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