Fax, sometimes called telecopying or telefax, is the telephonic transmission of scanned printed material, normally to a telephone number connected to a printer or other output device. The original document is scanned with a fax machine, which processes the contents as a single fixed graphic image, converting it into a bitmap, and then transmitting it through the telephone system in the form of audio-frequency tones. The receiving fax machine interprets the tones and reconstructs the image, printing a paper copy. Early systems used direct conversions of image darkness to audio tone in a continuous or analog manner. Since the 1980s, most machines transmit an audio-encoded digital representation of the page, using data compression to more quickly transmit areas that are all-white or all-black.
The early history of radio is the history of technology that produces and uses radio instruments that use radio waves. Within the timeline of radio, many people contributed theory and inventions in what became radio. Radio development began as "wireless telegraphy". Later radio history increasingly involves matters of broadcasting.
A superheterodyne receiver, often shortened to superhet, is a type of radio receiver that uses frequency mixing to convert a received signal to a fixed intermediate frequency (IF) which can be more conveniently processed than the original carrier frequency. It was invented by French radio engineer and radio manufacturer Lucien Lévy. Virtually all modern radio receivers use the superheterodyne principle.
Shortwave radio is radio transmission using radio frequencies in the shortwave bands (SW). There is no official definition of the band range, but it always includes all of the high frequency band (HF), which extends from 3 to 30 MHz ; above the medium frequency band (MF), to the bottom of the VHF band.
In electronics and telecommunications, a radio transmitter or just transmitter is an electronic device which produces radio waves with an antenna with the purpose of signal transmission up to a radio receiver. The transmitter itself generates a radio frequency alternating current, which is applied to the antenna. When excited by this alternating current, the antenna radiates radio waves.
Reginald Aubrey Fessenden was a Canadian-born inventor who received hundreds of patents in various fields, most notably ones related to radio and sonar.
In radio communication, skywave or skip refers to the propagation of radio waves reflected or refracted back toward Earth from the ionosphere, an electrically charged layer of the upper atmosphere. Since it is not limited by the curvature of the Earth, skywave propagation can be used to communicate beyond the horizon, at intercontinental distances. It is mostly used in the shortwave frequency bands.
In radio communications, a radio receiver, also known as a receiver, a wireless, or simply a radio, is an electronic device that receives radio waves and converts the information carried by them to a usable form. It is used with an antenna. The antenna intercepts radio waves and converts them to tiny alternating currents which are applied to the receiver, and the receiver extracts the desired information. The receiver uses electronic filters to separate the desired radio frequency signal from all the other signals picked up by the antenna, an electronic amplifier to increase the power of the signal for further processing, and finally recovers the desired information through demodulation.
Nathan Beverly Stubblefield was an American inventor best known for his wireless telephone work. Self-described as a "practical farmer, fruit grower and electrician", he received widespread attention in early 1902 when he gave a series of public demonstrations of a battery-operated wireless telephone, which could be transported to different locations and used on mobile platforms such as boats. While this initial design employed conduction, in 1908 he received a U.S. patent for a wireless telephone system that used magnetic induction. However, he was ultimately unsuccessful in commercializing his inventions. He later went into seclusion, and died alone in 1928.
Van Eck phreaking, also known as Van Eck radiation, is a form of eavesdropping in which special equipment is used to pick up side-band electromagnetic emissions from electronic devices that correlate to hidden signals or data to recreate these signals or data to spy on the electronic device. Side-band electromagnetic radiation emissions are present in keyboards, computer displays, printers, and other electronic devices.
Radiofacsimile, radiofax or HF fax is an analogue mode for transmitting monochrome images via high frequency (HF) radio waves. It was the predecessor to slow-scan television (SSTV). It was the primary method of sending photographs from remote sites from the 1930s to the early 1970s. It is still in limited use for transmitting weather charts and information to ships at sea.
Beamforming or spatial filtering is a signal processing technique used in sensor arrays for directional signal transmission or reception. This is achieved by combining elements in an antenna array in such a way that signals at particular angles experience constructive interference while others experience destructive interference. Beamforming can be used at both the transmitting and receiving ends in order to achieve spatial selectivity. The improvement compared with omnidirectional reception/transmission is known as the directivity of the array.
Mechanical television or mechanical scan television is an obsolete television system that relies on a mechanical scanning device, such as a rotating disk with holes in it or a rotating mirror drum, to scan the scene and generate the video signal, and a similar mechanical device at the receiver to display the picture. This contrasts with vacuum tube electronic television technology, using electron beam scanning methods, for example in cathode-ray tube (CRT) televisions. Subsequently, modern solid-state liquid-crystal displays (LCD) and LED displays are now used to create and display television pictures.
Passive radar is a class of radar systems that detect and track objects by processing reflections from non-cooperative sources of illumination in the environment, such as commercial broadcast and communications signals. It is a specific case of bistatic radar – passive bistatic radar (PBR) – which is a broad type also including the exploitation of cooperative and non-cooperative radar transmitters.
The concept of television is the work of many individuals in the late 19th and early 20th centuries. The first practical transmissions of moving images over a radio system used mechanical rotating perforated disks to scan a scene into a time-varying signal that could be reconstructed at a receiver back into an approximation of the original image. Development of television was interrupted by the Second World War. After the end of the war, all-electronic methods of scanning and displaying images became standard. Several different standards for addition of color to transmitted images were developed with different regions using technically incompatible signal standards. Television broadcasting expanded rapidly after World War II, becoming an important mass medium for advertising, propaganda, and entertainment.
Giovanni Caselli was an Italian priest, inventor, and physicist. He studied electricity and magnetism as a child which led to his invention of the pantelegraph, the forerunner of the fax machine. The world's first practical operating facsimile machine ("fax") system put into use was by Caselli. He had worldwide patents on his system. His technology idea was further developed into today's analog television.
WRNY was a New York City AM radio station that began operating in 1925. It was started by Hugo Gernsback's Experimenter Publishing Company to promote his radio and science magazines. Starting in August 1928, WRNY was one of the first stations to make regularly scheduled experimental television broadcasts. Experimenter Publishing went bankrupt in early 1929 and the station was purchased by the Curtiss Aeroplane and Motor Company to promote aviation. WRNY was deleted in 1934, as part of a consolidation on its shared frequency by surviving station WHN.
Bistatic sonar is a sonar configuration in which transmitter and receiver are separated by a distance large enough to be comparable to the distance to the target. Most sonar systems are monostatic, in that the transmitter and receiver are located in the same place. A configuration with multiple receivers is called multistatic.
The following timeline tables list the discoveries and inventions in the history of electrical and electronic engineering.
Dr. Otho Fulton (1868–1938) was an American inventor with a number of inventions in facsimile transmissions, including the fultograph. He sent a picture across a radio channel from London to Sydney. He was also a director of the British General Electric Company, and served in the Boer War and World War I as a captain in the British Army. He was also a friend of Robert Baden-Powell and was the third appointed member of The Scout Association.
