| 单词 | facsimile (fax) |
| 释义 | facsimile (fax) From the Latin facere simile, which translates to make similar. Technology that enables the transmission of images between paired transmitters and receivers.The transmitting fax scans the image document from top to bottom and from left to right, looking for dots of color — most machines support only black and white, some systems will also support 256 levels of grayscale, and some will support a large color palette — at various levels of resolution, as measured in lines per inch (lpi) and dots per inch (dpi). The fax machine translates the dots into data bits, which it compresses in order to reduce transmission time, and transmits through a network to the receiving machine. If the local loop is analog in nature, as is usually the case, an embedded modem transmits the digital data by modulating the analog waveforms. Just in case you were wondering about the origin and evolution of facsimile technology, Edward Davy invented the first practical facsimile machine in 1837, but abandoned the invention soon thereafter. Alexander Bain (1811–1877), a Scottish clockmaker and inventor, revived the concept and patented the recording telegraph in 1843. The first commercial facsimile service was established in 1865 by Giovanni Casselli over a circuit between Paris and Lyon, France. Circuits were added to other cities, and Casselli sent 5,000 faxes in the first year using his patented Pantelegraph machine, which was based on the Bain recording telegraph. A number of other inventors developed various wireline facsimile devices over the next 50 years or so, but all soon failed in the face of competition from the much more functional and practical electric telegraph (1844), invented by Samuel F.B. Morse (1791–1872) and Alfred Vail (1807–1859). Fax development began anew in the 1920s, but it was not until the 1970s that the ITU-T set international interoperability standards and the technology found some level of market acceptance. The ITU-T developed standards for fax machines in stages, designated as Group I, Group II, Group III, and Group IV.The Group III specification (1980) succeeded in making facsimile truly affordable for mass business markets. The Group IV specification (1984) addressed digital technology, which led to the development of high-capacity, networked fax servers and made fax broadcasting and fax-on-demand (FOD) possible. It is possible for a personal computer (PC) to emulate a fax machine through the use of a fax board and fax software, 74570c06.qxd 9/11/07 12:21 PM Page 178 |
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