Fax

FFax (short for facsimile, from Latin fac simile, "make similar", i.e. "make a copy") is a telecommunications technology used to transfer copies (facsimiles) of documents, especially using affordable devices operating over the telephone network. The word telefax, short for telefacsimile, for "make a copy at a distance", is also used as a synonym. Although fax is not an acronym, it is often written as “FAX”. The device is also known as a telecopier in certain industries. When sending documents to people at large distances, faxes have a distinct advantage over postal mail in that the delivery is nearly instantaneous, yet its disadvantages in quality have relegated it to a position beneath email as the prevailing form of electronic document transfer.

What is a FAX?

The transmission of photographs, drawings, maps, and written or printed words by electric signals. Light waves reflected from an image are converted into electric signals, transmitted by wire or radio to a distant receiver, and reconstituted on paper or film into a copy of the original.
Facsimile is used by news services to send news and photos to newspapers and television stations, by banks, airlines, and railroads to transmit the content of documents, and by many other businesses as an aid in data handling and record keeping.
Facsimile systems involve optical scanning, signal encoding, modulation, signal transmission, demodulation, decoding, and copy making.
Scanning
Scanning is done in a manner similar to that used in television. An original, a photo for example, is illuminated and systematically examined in small adjacent areas called pixels (picture elements). Light reflected from each pixel is converted into electric current by an electronic device, a photocell, photodiode, or charge-coupled device (CCD).
A single such device may be used to cover one pixel after another in a row, row after row from top to bottom until the entire image has been translated into electric impulses. This is rectilinear scanning. Scanning may also be done a row at a time by a battery of devices; this is array scanning.
In multispot scanning, a vertical array of photodevices moves across the image, examining the pixels column by column. As the array passes down the copy, it produces a set of current pulses from each photodevice. The separate currents, however produced, are then transmitted successively over a single circuit to the distant receiver.
To secure fine detail in the reproduced image it is necessary to use very small pixels. In one standard, Group 3 of the International Telegraph and Telephone Consultative Committee ( CCITT ), each pixel is a rectangle 0.12 by 0.13 mm ( 1 inch=25.4 mm ). On this standard, subject copy measuring 8 by 11 inches ( 20 x 28 cm ) is divided into 3.6 million pixels.
This compares with about 200,000 pixels for televised images. The pixels used in high-resolution facsimile systems have dimensions one-fifth those of the CCITT standard mentioned above, whereas in low-definition systems the dimensions may be twice as great.
The image may be illuminated as in rectilinear scanning, or a relatively large area of the image may be illuminated, the photodevice viewing the image through a lens aperture that restricts its field to a single pixel at a time.
In a commonly used facsimile scanning system ( invented by Frederick Bakewell in 1848 and based on Alexander Bain's work of 1842 ) the subject copy is wrapped around a drum. A finely focused spot of light falls on the copy and the light reflected from that pixel is picked up by the photodevice. The drum is rotated so that the light spot traces a line across the copy, examining each pixel in turn.
As the drum rotates, the light source is moved slowly on a carriage parallel to the drum axis, tracing out a spiral of adjacent lines until the entire area of the copy has been scanned. At least once in each rotation of the drum a signal transmitted to the recorder keeps the scanner and the recorder in step.
In drum scanning, the copy may also be illuminated broadly and examined by a photodevice fitted with a lens aperture.
Copy cannot always be conveniently wrapped around a drum. In such cases, flat copy may be scanned by a spot of light directed across its surface by a moving mirror. Mirror scanning may also be used when the copy is wrapped on a drum, or while it is being pulled from a roller. Laser light produces a very fine beam that travels across the copy, row by row, as the copy moves vertically.
In one arrangement the mirror is rocked back and forth, moving the beam across the copy. In another, a rotating polygonal mirror is used. This mirror typically has 18 flat mirror surfaces on its periphery, each capable of scanning a row of pixels.
Very fast scanning can be achieved by rapid rotation of the mirror and corresponding vertical motion of the copy. The beam is reflected from each pixel into a photodevice that converts successive light values into corresponding currents. Electronic scanning of flat copy may also be done by arrays of photodiodes or charge-coupled devices.
For scanning rates higher than about 6 rows per second laser beams with polygonal mirrors and arrays of photodevices are favored.

Breakthrough at last

The Japanese state telecom was the pioneer in opening its lines to public fax machines - not surprisingly, considering the advantages that the fax machine offers for transmitting text in a language with as many letters as Japanese, a nightmare to write on a teleprinter. The Japanese were drawing the practical conclusions of what the Chinese emperor had realized almost a century earlier. This was the start of the brief but intense heyday of the fax, which has radically changed our ways of communicating, only to be progressively replaced by direct communication between computers.It is intriguing to speculate about the enormous consequences for business and news services, not to mention homes, that an early breakthrough for Caselli's pantelegraph might have had. With telephone lines already spanning the world, the technology for the fax revolution was in place one hundred years ago. So it is not too far-fetched, after all, to imagine Queen Victoria faxing off her order for Scottish salmon!

Modest progress

The fax made progress nevertheless. Dr Arthur Korn, a German scientist, invented the principle of photoelectric reading in 1902. By 1910 newspapers were regularly sending and receiving pictures between major cities in Europe. In 1922, Dr Korn managed to transmit images between Europe and the U.S. by radio. In the U.S. of the Roaring Twenties, the fax was expected to become a common household appliance and millions of dollars were spent on developing it. However, the anticipated breakthrough did not occur, and it was not until the 1960s that the fax machine spread from the offices of the leading newspapers to become a familiar item of equipment in other business sectors.Electronics companies, meanwhile, were preoccupied with other, seemingly more glamorous, inventions, such as television, and it was some time before fax machines became mutually compatible and reasonably priced. In 1970, there were no more than 50,000 facsimile machines in the entire USA. But by 1948, the AT&T fax system could be incorporated in a desktop fax and transmit a 15 x 20 cm photograph in seven minutes.

Fax machine commercialized

However, it is a far cry from merely demonstrating a device at an exhibition to making it into a commercial success. The honor of designing the first fax service in actual use goes to Giovanni Caselli, an Italian abbot, born in Siena in 1815, who turned his hand to science and was, by 1849, editing a scientific magazine. In 1856 he claimed that he had developed a device, which he called a "pantelegraph," that could send facsimiles of images and text.Caselli received enthusiastic support from the French emperor, Napoleon III, who personally visited Caselli's workshop in 1860. He ensured that Caselli had access to the telegraph lines he needed, and a commercial fax service was inaugurated in Paris in 1865. It transmitted pictures and text between major French cities for some five years. A Pantelegraph Society was also founded in order to promote the new invention, which attracted extensive and enthusiastic press coverage at the time. When Caselli succeeded in opening a regularly working fax connection between Paris and Lyons, he was awarded the Cross of the Legion of Honor by Napoleon III. There still exist fully legible copies of letters sent by facsimile during this period, and a few contemporary facsimile machines are displayed in French museums.After Caselli's fax service achieved worldwide renown in the 1860s, he was invited by King Victor Emmanuel of Italy to demonstrate the fax machine at a world exhibition in Turin. He also made successful experimental fax transmissions between London and Manchester, and a company was founded to start regular services. However, it was swept away by the bank crisis of 1864

Space Meteorology History

Meterology is the focus of many scientists all over the world, meteorology forecasts were not available on mass to the general public until H.C. Russell, New South Wales Government Astronomer and Meteorologist from 1870 to 1905, produced Australia's first newspaper weather map in 1877.Space meteorology on the other hand had its origins in the early 1950s. It was not until the 1st of April 1960, that the TIROS-I (Television Infrared Operational Satellite) the world's first meteorological satellite was launched. The first direct picture transmission took place on 21st December 1963 by TIROS-VIII. The World Weather Watch (WWW) and Global Atmospheric Research Program (GARP) were established worldwide.The WWW developed as an international collaborative system for global weather observation by satellite and by conventional means.The Global Research Program initiated a series of innovative developments in meteorological satellite technology during the 1960s and 1970s.The First GARP Global Experiment (FGGE) of 1979 provided the first global view of the earth's atmosphere, essential to the provision of medium-range forecasts, and essential to the understanding of the meteorological processes, which govern the evolution of climate.The spin-scan camera on board the Applications Technology Satellite ATS-1 provided near-continuous photo coverage of the earth and its cloud cover. This was the first weather satellite in a geostationary orbit, launched 6 December 1966.Three years later the first detailed quantitative measurements by satellite of the temperature and moisture of the atmosphere at various levels were obtained.

1898 Hummel's Telediagraph

The Telediagraph was one of several early fax-like devices sending pictures via telegraph lines. It was invented circa 1895 by Ernest A. Hummel, a watchmaker of St. Paul, Minnesota. The first machines were installed in the office of the New York Herald in 1898. By 1899, Hummel had improved the machine and the newspaper had machines in the offices ofthe Chicago Times Herald, the St. Louis Republic, the Boston Herald, and the Philadelphia Inquirer.The system used synchronised rotating 8-inch drums, with a platinum stylus used as an electrode in the transmitter. The original image was drawn on 8x6" tin-foil using a non-conducting ink made from shellac mixed with alcohol. The image was received on carbon paper wrapped between two sheets of blank paper. When the electrode touched the tin-foil in the transmitter the circuit was closed; when it touched the shellac the circuit was open.The signal controlled a moving stylus in the receiver, making it touch or move back from the paper. At the end of each rotation a synchronising signal was sent, and the styluses in both machines moved 1/56" to the left before scanning the next line.The first picture sent was "an accurate picture of the first gun fired at Manila." The machine took 20-30 minutes to send the picture