wheatstone bridge. able to count the voltage once resistor changed.
标签： wheatstone resistor changed voltage
上传时间： 2014-01-27
上传用户：zhuimenghuadie
Playfair Cipher 1.not even the large number of keys in a monoalphabetic cipher provides security 2.one approach to improving security was to encrypt multiple letters 3.the Playfair Cipher is an example 4.invented by Charles wheatstone in 1854,but named after his friend Baron Playfair Playfair Key Matrix 1.a 5X5 matrix of letters based on a keyword 2.fill in letters of keyword (sans duplicates) 3.fill rest of matrix with other letters Encrypting and Decrypting -plaintext is encrypted two letters at a time 1. if a pair is a repeated letter, insert filler like X’ 2. if both letters fall in the same row, replace each with letter to right (wrapping back to start from end) 3. if both letters fall in the same column, replace each with the letter below it (again wrapping to top from bottom) 4. otherwise each letter is replaced by the letter in the same row and in the column of the other letter of the pair
标签： monoalphabetic Playfair provides security
上传时间： 2017-05-24
上传用户：变形金刚
Telecommunications is today widely understood to mean the electrical means of communicating over a distance. The first form of telecommunications was that of the Telegraph, which was invented quite independently in 1837 by two scientists, wheatstone and Morse. Telegraphy was on a point-to-point unidirectional basis and relied on trained operators to interpret between the spoken or written word and the special signals sent over the telegraph wire. However, the use of telegraphy did greatly enhance the operations of railways and, of course, the dissemination of news and personal messages between towns.
标签： Telecommunications Understanding Networks
上传时间： 2020-06-01
上传用户：shancjb
