- 行业: Printing & publishing
- Number of terms: 178089
- Number of blossaries: 0
- Company Profile:
McGraw Hill Financial, Inc. is an American publicly traded corporation headquartered in Rockefeller Center in New York City. Its primary areas of business are financial, publishing, and business services.
An electronic circuit that produces an output frequency which is an integral multiple of the input frequency. There are three basic types of frequency multipliers. The first type is a nonlinear amplifier that generates harmonics in its output current and a tuned load that resonates at one of these harmonics. The second type uses the nonlinear capacitance of a junction (semiconductor) diode to couple energy from the input circuit, which is tuned to the fundamental frequency, to the output circuit, which is tuned to the desired harmonic. The third type of multiplier uses a frequency divider in a locked-oscillator circuit.
Industry:Science
An electronic circuit that produces an output signal at a frequency that is an integral submultiple of the frequency of the input signal.
Industry:Science
An electronic circuit that produces an output voltage or current whenever two input levels simultaneously satisfy predetermined amplitude requirements. A comparator circuit may be designed to respond to continuously varying (analog) or discrete (digital) signals, and its output may be in the form of signaling pulses which occur at the comparison point or in the form of discrete direct-current (dc) levels.
Industry:Science
An electronic circuit whose function is to accept an input voltage and produce a magnified, accurate replica of this voltage as an output voltage. The voltage gain of the amplifier is the amplitude ratio of the output voltage to the input voltage. Often, electronic amplifiers designed to operate in different environments are categorized by criteria other than their voltage gain, even though they are voltage amplifiers in fact. Many specialized circuits are designed to provide voltage amplification.
Industry:Science
An electronic component used to convert electrical signals into visual imagery in real time suitable for direct interpretation by a human operator. It serves as the visual interface between human and machine. The visual imagery is processed, composed, and optimized for easy interpretation and minimum reading error. The electronic display is dynamic in that it presents information within a fraction of a second from the time received and continuously holds that information, using refresh or memory techniques, until new information is received. The image is created by electronically making a pattern from a visual contrast in luminance between (1) individual electrically alterable picture elements (pixels) in a matrix array of pixels in flat-panel displays (FPDs) or (2) electrically excited and nonexcited areas in a phosphor film in cathode-ray tubes (CRTs). High-information-content (HIC) displays are those displays that have a sufficient number of pixels (75,000 to 2,000,000) to show standard or high-definition television images, or comparable computer images.
Industry:Science
An electronic device in which one or more input signals can be routed to one or more outputs by the application of the appropriate electrical control signals. The term is most often applied when analog signals are involved, but the terminology is occasionally used when digital signals are involved.
Industry:Science
An electronic device that converts audio and video signals into modulated radio-frequency (rf) energy which can be radiated from an antenna and received by a television receiver. The term can also refer to the entire television transmitting plant, consisting of the transmitter proper, associated visual and aural input and monitoring equipment, transmission line, the antenna with its tower or other support structure, and the building in which the equipment is housed. In the United States, both analog NTSC (National Television Systems Committee) and digital 8-VSB transmitters are in service. The digital transmitters are used for what is termed high-definition television (HDTV).
Industry:Science
An electronic display in which a large orthogonal array of display elements, such as liquid-crystal or electroluminescent elements, form a flat screen. Since the days of the first television tube, display engineers have dreamed of producing flat-panel displays (FPDs) with the visual attributes of a cathode-ray tube (CRT). The term “flat-panel display” is actually a misnomer, since thinness is the distinguishing characteristic. Most television sets and computer monitors currently employ cathode-ray tubes. Cathode-ray tubes cannot be thin because the light is generated by the process of cathodoluminescence whereby a high-energy electron beam is scanned across a screen covered with an inorganic phosphor, one point, or pixel, at a time, activating light-emitting centers in the material. The cathode-ray tube must have moderate depth to allow the electron beam to be magnetically or electrostatically scanned across the entire screen.
Industry:Science
An electronic filter implemented as an integrated circuit, as contrasted with filters made by inter-connecting discrete electrical components. The design of an integrated-circuit filter (also called simply an integrated filter) is constrained by the unavailability of certain types of components, such as piezoelectric resonators, that are often valuable in filtering. However, integrated filters can benefit from small size, close integration with other parts of a system, and the low cost of manufacturing very complex integrated circuits.
Industry:Science
An electronic filter that modifies the frequency response (amplitude and phase versus frequency) of a system for a specific purpose. While filters in some applications perform the conceptually simple operations of rejecting specific bands of frequencies and passing other bands of frequencies, equalizers typically realize a more complicated frequency response in which the amplitude response varies continuously with frequency, amplifying some frequencies and attenuating others. An equalizer may have a response fixed in time or may be automatically and continuously adjusted. However, its frequency response is usually matched to some external physical medium, such as an acoustic path or communication channel, and thus inherently needs to be adjustable.
Industry:Science
