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Pagers
A pager, also known as a beeper or bleeper, is a wireless telecommunications device that receives and displays alphanumeric or voice messages. One-way pagers can only receive messages, while response pagers and two-way pagers can also acknowledge, reply to, and originate messages using an internal transmitter. Pagers operate as part of a paging system which includes one or more fixed transmitters (or in the case of response pagers and two-way pagers, one or more base stations), as well as a number of pagers carried by mobile users. These systems can range from a restaurant system with a single low power transmitter, to a nationwide system with thousands of high-power base stations. Pagers were developed in the 1950s and 1960s, and became widely used by the 1980s through the late 1990s and early 2000s. Later in the 21st century, the widespread availability of cellphones and smartphones with text messaging capability has greatly diminished the pager industry. Nevertheless ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Al Gross (engineer)
Irving "Al" Gross (; February 22, 1918 – December 21, 2000) was a pioneer in mobile wireless communication. He created and patented many communications devices, specifically in relation to an early version of the walkie-talkie, Citizens' Band radio, the telephone pager and the cordless telephone. Biography Gross was born in Toronto, Ontario, Canada in 1918, the son of Romanian-Jewish immigrants, he grew up in Cleveland, Ohio, in the United States. His lifelong enthusiasm for radio was sparked at age nine, when traveling on Lake Erie by a steamboat. While sneaking around the boat he ended up in the radio transmissions room. The ship's operator let him listen in on transmissions. Later, Gross turned the basement of his house into a radio station, built from scavenged junkyard parts. At sixteen he earned his amateur radio license, and he used his call sign (W8PAL) his whole life. The walkie-talkie His interest and knowledge in radio technology had grown considerab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Man-made Disasters
A disaster is an event that causes serious harm to people, buildings, economies, or the environment, and the affected community cannot handle it alone. ''Natural disasters'' like avalanches, floods, earthquakes, and wildfires are caused by natural hazards. ''Human-made disasters'' like oil spills, terrorist attacks and power outages are caused by people. Nowadays, it is hard to separate natural and human-made disasters because human actions can make natural disasters worse. Climate change also affects how often disasters due to extreme weather hazards happen. Disasters usually hit people in developing countries harder than people in wealthy countries. Over 95% of deaths from disasters happen in low-income countries, and those countries lose a lot more money compared to richer countries. For example, the damage from natural disasters is 20 times greater in developing countries than in industrialized countries. This is because low-income countries often do not have well-built bui ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mobile Phone
A mobile phone or cell phone is a portable telephone that allows users to make and receive calls over a radio frequency link while moving within a designated telephone service area, unlike fixed-location phones ( landline phones). This radio frequency link connects to the switching systems of a mobile phone operator, providing access to the public switched telephone network (PSTN). Modern mobile telephony relies on a cellular network architecture, which is why mobile phones are often referred to as 'cell phones' in North America. Beyond traditional voice communication, digital mobile phones have evolved to support a wide range of additional services. These include text messaging, multimedia messaging, email, and internet access (via LTE, 5G NR or Wi-Fi), as well as short-range wireless technologies like Bluetooth, infrared, and ultra-wideband (UWB). Mobile phones also support a variety of multimedia capabilities, such as digital photography, video recordin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DTMF
Dual-tone multi-frequency (DTMF) signaling is a telecommunication signaling system using the voice-frequency band over telephone lines between telephone equipment and other communications devices and switching centers. DTMF was first developed in the Bell System in the United States, and became known under the trademark Touch-Tone for use in push-button telephones, starting in 1963. The DTMF frequencies are standardized in ITU-T Recommendation Q.23. The signaling system is also known as ''MF4'' in the United Kingdom, as ''MFV'' in Germany, and ''Digitone'' in Canada. Touch-tone dialing with a telephone keypad gradually replaced the use of rotary dials and has become the industry standard in telephony to control equipment and signal user intent. The signaling on trunks in the telephone network uses a different type of multi-frequency signaling. Multifrequency signaling Before the development of DTMF, telephone numbers were dialed with rotary dials for loop-disconnect (LD) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reed Receiver
A reed receiver or tuned reed receiver (US) was a form of multi-channel signal decoder used for early radio control systems. It uses a simple electromechanical device or '' 'resonant reed' '' to demodulate the signal, in effect a receive-only modem. The encoding used is a simple form of frequency-shift keying. These decoders appeared in the 1950s and were used into the early 1970s. Early transistor systems were in use in parallel to them, but they were finally displaced by the appearance of affordable digital proportional systems, based on early integrated circuits. These had the advantage of proportional control. Operation The decoder of the reed receiver is based on the 'resonant reed' unit. This comprises a number of vibrating metal reeds, each one having a tuned vibration frequency like a tuning fork. These reeds are manufactured from a single tapered sheet of iron or steel, giving a comb of reeds of varying length. This resembles the comb used to sound musical notes in a m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bell Labs
Nokia Bell Labs, commonly referred to as ''Bell Labs'', is an American industrial research and development company owned by Finnish technology company Nokia. With headquarters located in Murray Hill, New Jersey, Murray Hill, New Jersey, the company operates several laboratories in the United States and around the world. As a former subsidiary of the American Telephone and Telegraph Company (AT&T), Bell Labs and its researchers have been credited with the development of radio astronomy, the transistor, the laser, the photovoltaic cell, the charge-coupled device (CCD), information theory, the Unix operating system, and the programming languages B (programming language), B, C (programming language), C, C++, S (programming language), S, SNOBOL, AWK, AMPL, and others, throughout the 20th century. Eleven Nobel Prizes and five Turing Awards have been awarded for work completed at Bell Laboratories. Bell Labs had its origin in the complex corporate organization of the Bell System telepho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transistor
A transistor is a semiconductor device used to Electronic amplifier, amplify or electronic switch, switch electrical signals and electric power, power. It is one of the basic building blocks of modern electronics. It is composed of semiconductor material, usually with at least three terminal (electronics), terminals for connection to an electronic circuit. A voltage or Electric current, current applied to one pair of the transistor's terminals controls the current through another pair of terminals. Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal. Some transistors are packaged individually, but many more in miniature form are found embedded in integrated circuits. Because transistors are the key active components in practically all modern electronics, many people consider them one of the 20th century's greatest inventions. Physicist Julius Edgar Lilienfeld proposed the concept of a field-effect transisto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bell System
The Bell System was a system of telecommunication companies, led by the Bell Telephone Company and later by the AT&T Corporation, American Telephone and Telegraph Company (AT&T), that dominated the telephone services industry in North America for over 100 years from its creation in 1877 until United States v. AT&T (1982), its antitrust breakup in 1983. The system of companies was often colloquially called Ma Bell (as in "Mother Bell"), as it held a vertical monopoly over telecommunication products and services in most areas of the United States and Canada. At the time of the breakup of the Bell System in the early 1980s, it had assets of $150 billion (equivalent to $ billion in ) and employed over one million people. Beginning in the 1910s, American antitrust regulators had been observing and accusing the Bell System of abusing its monopoly power, and had brought legal action multiple times over the decades. In 1974 the United States Department of Justice Antitrust Division, Anti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Motorola
Motorola, Inc. () was an American multinational telecommunications company based in Schaumburg, Illinois. It was founded by brothers Paul and Joseph Galvin in 1928 and had been named Motorola since 1947. Many of Motorola's products had been radio-related communication equipment such as two-way radios, consumer walkie-talkies, cellular infrastructure, mobile phones, satellite communicators, pagers, as well as cable modems and semiconductors. After having lost $4.3 billion from 2007 to 2009, Motorola was split into two independent public companies: Motorola Solutions (its legal successor) and Motorola Mobility (spun off), on January 4, 2011. Motorola designed and sold wireless network equipment such as cellular transmission base stations and signal amplifiers. Its business and government customers consisted mainly of wireless voice and broadband systems (used to build private networks), and public safety communications systems like Astro and Dimetra. Motorola's h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Francis Mitchell
Patents U.S. Patent 2,833,994 July 2, 1954, for High Frequency Long-Line Variably End-Loaded with Clarence P. Pipes.U.S.Patent 2,912,573 November 10, 1959, for Receiver having frequency and amplitude modulation detecting.U.S. Patent 3,087,117 April 23, 1963, for Portable Transmitter Apparatus with Selective.U.S. Patent 2,975,274 March 14, 1961, for Frequency Modulation Radio Receiver.U.S. Patent 3,126,514 October 13, 1961, for Noise Reducing system with Jack Germain. (Germain retired as director of quality assurance.)U.S. Patent 3,906,166 September 16, 1975, for a Radio Telephone System, the cell phone.U.S. Patent 5,650,776 July 22, 1997, for a Communications Receiver with Thomas F. Holmes Family and early years He was born in Chicago, Illinois, the son of Catholic Irish immigrants,Stephen Miller"John Francis Mitchell Retirement" ''The Wall Street Journal'', June 20–21, 2009 William Mitchell of Sligo and Bridget Keane, of Listowel. He was married to Margaret and had three childr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Associated Press
The Associated Press (AP) is an American not-for-profit organization, not-for-profit news agency headquartered in New York City. Founded in 1846, it operates as a cooperative, unincorporated association, and produces news reports that are distributed to its members, major U.S. daily newspapers and radio and television broadcasters. Since the award was established in 1917, the AP has earned 59 Pulitzer Prizes, including 36 for photography. The AP is also known for its widely used ''AP Stylebook'', its AP polls tracking National Collegiate Athletic Association, NCAA sports, sponsoring the National Football League's annual awards, and its election polls and results during Elections in the United States, US elections. By 2016, news collected by the AP was published and republished by more than 1,300 newspapers and broadcasters. The AP operates 235 news bureaus in 94 countries, and publishes in English, Spanish, and Arabic. It also operates the AP Radio Network, which provides twice ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
