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A telephone keypad using the ITU E.161 standard. A telephone keypad is a keypad installed on a push-button telephone or similar telecommunication device for dialing a telephone number. It was standardized when the dual-tone multi-frequency signaling (DTMF) system was developed in the Bell System in the United States in the 1960s that replaced ...
The acoustic tin can telephone, or "lovers' phone", has been known for centuries. It connects two diaphragms with a taut string or wire, which transmits sound by mechanical vibrations from one to the other along the wire (and not by a modulated electric current). The classic example is the children's toy made by connecting the bottoms of two ...
Pullback, a name given to two different mathematical processes. Pullback (cohomology), a term in topology. Pullback (differential geometry), a term in differential geometry. Pullback (category theory), a term in category theory. Pullback attractor, an aspect of a random dynamical system. Pullback bundle, the fiber bundle induced by a map of its ...
The pullback bundle is an example that bridges the notion of a pullback as precomposition, and the notion of a pullback as a Cartesian square. In that example, the base space of a fiber bundle is pulled back, in the sense of precomposition, above. The fibers then travel along with the points in the base space at which they are anchored: the ...
Private conversation, 1910. Historian John Brooks argues that the telephone created "a new habit of mind--a habit of tenseness and alertness, of demanding and expecting immediate results, whether in business, love or other forms of social intercourse." [70] The telephone was instrumental to modernization.
A push-button telephone is a telephone that has buttons or keys for dialing a telephone number, in contrast to a rotary dial used in earlier telephones. Western Electric experimented as early as 1941 with methods of using mechanically activated reeds to produce two tones for each of the ten digits and by the late 1940s such technology was field ...
1667 to 1875. 1667: Robert Hooke creates an acoustic string telephone that conveys sounds over a taut extended wire by mechanical vibrations. [1] [2] 1844: Innocenzo Manzetti first suggests the idea of an electric "speaking telegraph", or telephone. 1849: Antonio Meucci demonstrates a communicating device to individuals in Havana.
That first cell phone began a fundamental technology and communications market shift to making phone calls to a person instead of to a place. [6] [21] Bell Labs had introduced the idea of cellular communications in 1947, but their first systems were limited to car phones which required roughly 30 pounds (12 kg) of equipment in the trunk. [23]