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Amplitude-shift Keying
Amplitude-shift keying (ASK) is a form of amplitude modulation that represents digital data as variations in the amplitude of a carrier wave. In an ASK system, a symbol, representing one or more bits, is sent by transmitting a fixed-amplitude carrier wave at a fixed frequency for a specific time duration. For example, if each symbol represents a single bit, then the carrier signal could be transmitted at nominal amplitude when the input value is 1, but transmitted at reduced amplitude or not at all when the input value is 0. Any digital modulation scheme uses a finite number of distinct signals to represent digital data. ASK uses a finite number of amplitudes, each assigned a unique pattern of binary digits. Usually, each amplitude encodes an equal number of bits. Each pattern of bits forms the symbol that is represented by the particular amplitude. The demodulator, which is designed specifically for the symbol-set used by the modulator, determines the amplitude of the received si ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amplitude Modulation
Amplitude modulation (AM) is a modulation technique used in electronic communication, most commonly for transmitting messages with a radio wave. In amplitude modulation, the amplitude (signal strength) of the wave is varied in proportion to that of the message signal, such as an audio signal. This technique contrasts with angle modulation, in which either the frequency of the carrier wave is varied, as in frequency modulation, or its phase, as in phase modulation. AM was the earliest modulation method used for transmitting audio in radio broadcasting. It was developed during the first quarter of the 20th century beginning with Roberto Landell de Moura and Reginald Fessenden's radiotelephone experiments in 1900. This original form of AM is sometimes called double-sideband amplitude modulation (DSBAM), because the standard method produces sidebands on either side of the carrier frequency. Single-sideband modulation uses bandpass filters to eliminate one of the sidebands and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PSTN
The public switched telephone network (PSTN) provides infrastructure and services for public telecommunication. The PSTN is the aggregate of the world's circuit-switched telephone networks that are operated by national, regional, or local telephony operators. These consist of telephone lines, fiber optic cables, microwave transmission links, cellular networks, communications satellites, and undersea telephone cables, all interconnected by switching centers which allow most telephones to communicate with each other. Originally a network of fixed-line analog telephone systems, the PSTN is now almost entirely digital in its core network and includes mobile and other networks, as well as fixed telephones. The technical operation of the PSTN adheres to the standards created by the ITU-T. These standards allow different networks in different countries to interconnect seamlessly. The E.163 and E.164 standards provide a single global address space for telephone numbers. The combinat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantized Radio Modulation Modes
Quantization is the process of constraining an input from a continuous or otherwise large set of values (such as the real numbers) to a discrete set (such as the integers). The term ''quantization'' may refer to: Signal processing * Quantization (signal processing) ** Quantization (image processing) *** Color quantization ** Quantization (music) Physics * Quantization (physics) ** Canonical quantization ** Geometric quantization * Discrete spectrum, or otherwise discrete quantity ** Spatial quantization ** Charge quantization Computing * The process of making the signal discrete in amplitude by approximating the sampled signal to the nearest pre-defined level is called as quantization Linguistics * Quantization (linguistics) Similar terms * Quantification (science) In mathematics and empirical science, quantification (or quantitation) is the act of counting and measuring that maps human sense observations and experiences into quantity, quantities. Quantification i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frequency-shift Keying
Frequency-shift keying (FSK) is a frequency modulation scheme in which digital information is transmitted through discrete frequency changes of a carrier signal. The technology is used for communication systems such as telemetry, weather balloon radiosondes, caller ID, garage door openers, and low frequency radio transmission in the VLF and ELF bands. The simplest FSK is binary FSK (BFSK). BFSK uses a pair of discrete frequencies to transmit binary (0s and 1s) information. With this scheme, the 1 is called the mark frequency and the 0 is called the space frequency. Modulating and demodulating Reference implementations of FSK modems exist and are documented in detail. The demodulation of a binary FSK signal can be done using the Goertzel algorithm very efficiently, even on low-power microcontrollers. Variations Multiple frequency-shift keying Continuous-phase frequency-shift keying In principle FSK can be implemented by using completely independent free-running oscillat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nyquist ISI Criterion
In communications, the Nyquist ISI criterion describes the conditions which, when satisfied by a communication channel (including responses of transmit and receive filters), result in no intersymbol interference or ISI. It provides a method for constructing band-limited functions to overcome the effects of intersymbol interference. When consecutive symbols are transmitted over a channel by a linear modulation (such as Amplitude-shift keying, ASK, Quadrature amplitude modulation, QAM, etc.), the impulse response (or equivalently the frequency response) of the channel causes a transmitted symbol to be spread in the time domain. This causes intersymbol interference because the previously transmitted symbols affect the currently received symbol, thus reducing tolerance for noise. The Nyquist theorem relates this time-domain condition to an equivalent frequency-domain condition. The Nyquist criterion is closely related to the Nyquist–Shannon sampling theorem, with only a differing poi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ask Dia Calc Prob 2
Ask is the active verb for a direct question. Ask may also refer to: Places * Ask, Akershus, a village in Gjerdrum municipality, Viken county, Norway * Ask, Buskerud, a village in Ringerike municipality, Viken county, Norway * Ask, Vestland, a village in Askøy municipality, Vestland county, Norway * Ask, Iran, a village in Mazandaran Province People * Ask la Cour, Danish ballet dancer * Beatrice Ask (born 1956), Swedish politician * Morten Ask (born 1980), Norwegian ice hockey player Other * Ask (horse), a British Thoroughbred race horse * "Ask" (song), a 1986 song by The Smiths * Ask and Embla, in Norse mythology * Ask price, in economics * Ask.com, a web search engine, formerly Ask Jeeves * Ask.fm, a social Q&A web site * "Ask", a song by Avail from ''Over the James'' See also *ASK (other) Ask is the active verb for a direct question. Ask may also refer to: Places * Ask, Akershus, a village in Gjerdrum municipality, Viken county, Norway * Ask, Buskerud, a vil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ask Dia Calc Prob
Ask is the active verb for a direct question. Ask may also refer to: Places * Ask, Akershus, a village in Gjerdrum municipality, Viken county, Norway * Ask, Buskerud, a village in Ringerike municipality, Viken county, Norway * Ask, Vestland, a village in Askøy municipality, Vestland county, Norway * Ask, Iran, a village in Mazandaran Province People * Ask la Cour, Danish ballet dancer * Beatrice Ask (born 1956), Swedish politician * Morten Ask (born 1980), Norwegian ice hockey player Other * Ask (horse), a British Thoroughbred race horse * "Ask" (song), a 1986 song by The Smiths * Ask and Embla, in Norse mythology * Ask price, in economics * Ask.com, a web search engine, formerly Ask Jeeves * Ask.fm, a social Q&A web site * "Ask", a song by Avail from ''Over the James'' See also *ASK (other) Ask is the active verb for a direct question. Ask may also refer to: Places * Ask, Akershus, a village in Gjerdrum municipality, Viken county, Norway * Ask, Buskerud, a vil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ask Ideal Diagram
Ask is the active verb for a direct question. Ask may also refer to: Places * Ask, Akershus, a village in Gjerdrum municipality, Viken county, Norway * Ask, Buskerud, a village in Ringerike municipality, Viken county, Norway * Ask, Vestland, a village in Askøy municipality, Vestland county, Norway * Ask, Iran, a village in Mazandaran Province People * Ask la Cour, Danish ballet dancer * Beatrice Ask (born 1956), Swedish politician * Morten Ask (born 1980), Norwegian ice hockey player Other * Ask (horse), a British Thoroughbred race horse * "Ask" (song), a 1986 song by The Smiths * Ask and Embla, in Norse mythology * Ask price, in economics * Ask.com, a web search engine, formerly Ask Jeeves * Ask.fm, a social Q&A web site * "Ask", a song by Avail from ''Over the James'' See also *ASK (other) Ask is the active verb for a direct question. Ask may also refer to: Places * Ask, Akershus, a village in Gjerdrum municipality, Viken county, Norway * Ask, Buskerud, a vil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amplitude Modulation
Amplitude modulation (AM) is a modulation technique used in electronic communication, most commonly for transmitting messages with a radio wave. In amplitude modulation, the amplitude (signal strength) of the wave is varied in proportion to that of the message signal, such as an audio signal. This technique contrasts with angle modulation, in which either the frequency of the carrier wave is varied, as in frequency modulation, or its phase, as in phase modulation. AM was the earliest modulation method used for transmitting audio in radio broadcasting. It was developed during the first quarter of the 20th century beginning with Roberto Landell de Moura and Reginald Fessenden's radiotelephone experiments in 1900. This original form of AM is sometimes called double-sideband amplitude modulation (DSBAM), because the standard method produces sidebands on either side of the carrier frequency. Single-sideband modulation uses bandpass filters to eliminate one of the sidebands and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital Data
Digital data, in information theory and information systems, is information represented as a string of discrete symbols each of which can take on one of only a finite number of values from some alphabet, such as letters or digits. An example is a text document, which consists of a string of alphanumeric characters . The most common form of digital data in modern information systems is ''binary data'', which is represented by a string of binary digits (bits) each of which can have one of two values, either 0 or 1. Digital data can be contrasted with ''analog data'', which is represented by a value from a continuous range of real numbers. Analog data is transmitted by an analog signal, which not only takes on continuous values, but can vary continuously with time, a continuous real-valued function of time. An example is the air pressure variation in a sound wave. The word ''digital'' comes from the same source as the words digit and ''digitus'' (the Latin word for ''finger'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phase (waves)
In physics and mathematics, the phase of a periodic function F of some real variable t (such as time) is an angle-like quantity representing the fraction of the cycle covered up to t. It is denoted \phi(t) and expressed in such a scale that it varies by one full turn as the variable t goes through each period (and F(t) goes through each complete cycle). It may be measured in any angular unit such as degrees or radians, thus increasing by 360° or 2\pi as the variable t completes a full period. This convention is especially appropriate for a sinusoidal function, since its value at any argument t then can be expressed as \phi(t), the sine of the phase, multiplied by some factor (the amplitude of the sinusoid). (The cosine may be used instead of sine, depending on where one considers each period to start.) Usually, whole turns are ignored when expressing the phase; so that \phi(t) is also a periodic function, with the same period as F, that repeatedly scans the same range of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
