外文翻譯---香農(nóng)和“香農(nóng)公式”-其他專業(yè)-資料下載頁
2025-01-19 09:48本頁面
【導(dǎo)讀】在科學(xué)技術(shù)史上，十九世紀(jì)中葉和二十世紀(jì)中葉是一個非常突出的時期。這個時期，一些發(fā)明和創(chuàng)作的實現(xiàn)消除了許多對個人和社會的有影響的限制。別是在通信領(lǐng)域，迅速的發(fā)展就好像高架鐵路，蒸汽輪船，航空和電信一樣。得人注意的是一些有趣的事情。由于一些限制被拆除，一些基本的或主要的隨即。建立了新的限制。例如，卡羅表明，從熱機(jī)提煉出來的熱能量是有一個極限值的。后來，這一定律被推廣到了第二定律熱力學(xué)。機(jī)制的速度被發(fā)現(xiàn)。其他例子包括Kelvin的絕對零度，Heissenberg的測不準(zhǔn)原。理和哥德爾不完備性定理的數(shù)學(xué)。在1948年出版的香農(nóng)信道編碼定理似乎是最后。些事態(tài)的發(fā)展對香農(nóng)公式的影響。更常見的是有幾個獨立的小組在一個特定的成熟的時機(jī)逐步研究出來。許多數(shù)學(xué)表達(dá)式都用有關(guān)香農(nóng)的名字來命名。對香農(nóng)工作的介紹，這個問題在N.Knudtzon的論文上看到了。而帶寬和信號的力量因此出名，并且出現(xiàn)在第一期的―香農(nóng)‖報上。
【正文】 rest led hi m to founding the science of cyberics. This field, which is perhaps best defined by the subtitle of [2]: ―Control and Communication in the Animal and the Machine‖ included, among other things, a theory for information content in a signal and the transmission of this information through a channel. Wiener was, however, not a master of municating his ideas to the technical munity, and even though the relation to Shannon’s formula is pointed out in [2], the notation is cumbersome, and 7 the relevance to practical munication systems is far from obvious. Reference to Wiener’s work was done explicitly by Shannon in [1]. He also acknowledged the work by Tuller3. William G. Tuller was an employee at MIT’s Research Laboratory for Electronics in the second half of the 1940s. In 1948 he defended a thesis at MIT on ―Theoretical Limitations on the Rate of Transmission of Information4‖. In his thesis Tuller starts by referring to Nyquist’s and Hartley’s works (see below). Leaning on the use of sampling and quantization of a bandlimited signal, and arguing that intersymbol interference introduced by a bandlimited channel can in principle be eliminated, he states quite correctly that under noisefree conditions an unlimited amount of information can be transmitted over such a channel. Taking noise into account, he delivers an argument partly based on intuitive reasoning, partly on formal mathematics, arriving at his main result that the information H transmitted over a transmission link of bandwidth B during a time interval T with carriertonoiseratio C/N is limited by H ≤ 2BT log(1 + C/N). (2) This expression has a striking resemblance to Shannon’s formula, and would by most readers be considered equivalent. It is interesting to note that for the derivation of (2) Tuller assumes the use of PCM encoding. A work not referenced by Shannon is the paper by Clavier [16]5. In a similar fashion to Tuller, starting out with Hartley’s work, and assuming the use of PCM coding, Clavier finds a formula essentially equivalent to (1) and (2). A fourth independent discovery is the one by Laplume published in 1948 以上內(nèi)容出自 ：
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