Amplitude modulation (AM) is a form of modulation in which the amplitude of a carrier wave is varied in direct proportion to that of a modulating signal. (Contrast this with frequency modulation, in which the frequency of the carrier is varied; and phase modulation, in which the phase is varied.) AM is commonly used at radio frequencies and was the first method used to broadcast commercial radio. The term "AM" is sometimes used generically to refer to the AM broadcast (mediumwave) band (see AM radio). Ampli ...

Including:

• Amplitude modulation - Applications in radio
• Amplitude modulation - AM vs. FM
• Amplitude modulation - Forms of AM
• Amplitude modulation - Example
• Amplitude modulation - A more general example
• Amplitude modulation - Modulation index
• Amplitude modulation - Amplitude modulator designs
• Amplitude modulation - Circuits
• Amplitude modulation - Low level
• Amplitude modulation - High level

Read more here: » Amplitude modulation: Encyclopedia - Amplitude modulation

See also:

Amplitude modulation, Amplitude modulation - Applications in radio, Amplitude modulation - AM vs. FM, Amplitude modulation - Forms of AM, Amplitude modulation - Example, Amplitude modulation - A more general example, Amplitude modulation - Modulation index, Amplitude modulation - Amplitude modulator designs, Amplitude modulation - Circuits, Amplitude modulation - Low level, Amplitude modulation - High level

Read more here: » Amplitude modulation: Encyclopedia II - Amplitude modulation - Example

Amplitude modulation - Circuits. A wide range of different circuits have been used for AM, but one of the simplest circuits uses anode or collector modulation applied via a transformer. While it is perfectly possible to create good designs using solid-state electronics, valved (tube) circuits are shown here. In general, valves are able to easily yield RF powers far in excess of what can be achieved using solid state. Most high-power broadcast stations still use valves. Modulation circuit designs can be broadly divided into low and high l ...

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Amplitude modulation, Amplitude modulation - Applications in radio, Amplitude modulation - AM vs. FM, Amplitude modulation - Forms of AM, Amplitude modulation - Example, Amplitude modulation - A more general example, Amplitude modulation - Modulation index, Amplitude modulation - Amplitude modulator designs, Amplitude modulation - Circuits, Amplitude modulation - Low level, Amplitude modulation - High level

Read more here: » Amplitude modulation: Encyclopedia II - Amplitude modulation - Amplitude modulator designs

AM may refer to: Aeroméxico, IATA airline designator Amazonas State, Brazil (ISO 3166-2:BR) AM broadcasting, radio transmission using Amplitude modulation Amran Governorate, Yemen (ISO 3166-2:YE) Anno Mundi, year since Earth's creation Arkansas and Missouri Railroad, reporting mark Armenia, country code Arthur-Merlin protocol in computational complexity theory Master's degree in Arts, Artium Magister Minesweeper (ship), U.S. Navy 1921 warship classification code Order ...

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Amplitude-shift keying (ASK) is a form of modulation which represents digital data as variations in the amplitude of a carrier wave. Amplitude-shift keying - Encoding. The simplest and most common form of ASK operates as a switch, using the presence of a carrier wave to indicate a binary one and its absence to indicate a binary zero. This type of modulation is called on-off keying, and is used at radio frequencies to transmit Morse code (referred to as continuous wave operation). More s ...

Including:

• Amplitude-shift keying - Encoding
• Amplitude-shift keying - Probability of error
• Amplitude-shift keying - Considerations

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Carrier frequency is the fundamental frequency used in both amplitude modulation and frequency modulation i.e. it is the frequency which is modulated and is the frequency to which a receiver should be tuned in order to demodulate the information signal. It is, simply, the fixed frequency upon which the variable modulator frequency will be imposed, and the beat frequency of the two is what the listener will hear. In a ...

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A carrier wave is a waveform (usually sinusoidal) that is modulated (modified) to represent the information to be transmitted. This carrier wave is usually of much higher frequency than the modulating signal (the signal which contains the information). Carrier waves are used when transmitting radio signals to a radio receiver. Frequency modulation (FM) and amplitude modulation (AM) signals are both transmitted with the help of carrier frequencies. The frequency for a given radio stati ...

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Amplitude is a nonnegative scalar measure of a wave's magnitude of oscillation, that is, magnitude of the maximum disturbance in the medium during one wave cycle. In the following diagram, the distance y is the amplitude of the wave. Sometimes this distance is called the "peak amplitude", distinguishing it from another concept of amplitude, used especially in electrical engineering: the root mean square (RMS) amplitude, defined as the square root of the temporal mean of the square of the vertical distance o ...

Including:

• Amplitude - Related topics

Read more here: » Amplitude: Encyclopedia - Amplitude

AM radio is radio broadcasting using Amplitude Modulation. AM broadcasting - History. AM was the dominant method of broadcasting during the first two thirds of the 20th century and remains widely used into the 21st. The Central Intelligence Agency World Factbook list approximately 16,265 AM stations worldwide. AM radio began with the first, experimental broadcast in 1906 by Reginald Fessenden, and was used for small-scale voice and music broadcasts up until World War I. The great increa ...

Including:

• AM broadcasting - History
• AM broadcasting - Operation
• AM broadcasting - Frequencies
• AM broadcasting - Limitations of AM radio
• AM broadcasting - Other distribution methods
• AM broadcasting - External link

Read more here: » AM broadcasting: Encyclopedia - AM broadcasting

Orthogonal frequency-division multiplexing (OFDM), also sometimes called discrete multitone modulation (DMT), is a transmission technique based upon the idea of frequency-division multiplexing (FDM). Orthogonal frequency-division multiplexing - Characteristics. An OFDM carrier signal is the sum of a number of orthogonal sub-carriers, with baseband data on each sub-carrier being independently modulated commonly using some type of quadrature amplitude modulation (QAM) or phase-shift keyin ...

Including:

• Orthogonal frequency-division multiplexing - Characteristics
• Orthogonal frequency-division multiplexing - Benefits
• Orthogonal frequency-division multiplexing - Disadvantages of OFDM
• Orthogonal frequency-division multiplexing - OFDM feature abstract
• Orthogonal frequency-division multiplexing - Usage
• Orthogonal frequency-division multiplexing - ADSL
• Orthogonal frequency-division multiplexing - Wireless LAN
• Orthogonal frequency-division multiplexing - Digital radio and television
• Orthogonal frequency-division multiplexing - DVB-T's implementation of COFDM
• Orthogonal frequency-division multiplexing - DRM and Eureka-147's DAB implementation of COFDM
• Orthogonal frequency-division multiplexing - Ultra wideband
• Orthogonal frequency-division multiplexing - Flash-OFDM
• Orthogonal frequency-division multiplexing - BST-OFDM
• Orthogonal frequency-division multiplexing - Ideal encoder
• Orthogonal frequency-division multiplexing - Mathematical Description
• Orthogonal frequency-division multiplexing - OFDM history

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Analogue Electronics refers to electronics systems with analogue signals with any continuously variable signal. It differs from digital electronics in that small fluctuations in the signal are meaningful in that they are continuously variable rather than digitally quantised. Analogue is usually thought of in an electrical context, however mechanical, pneumatic, hydraulic, and other systems may also use analogue signals. Analogue Electronics is frequently confused with other sub-divisions of the general field of Electroni ...

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An analog or analogue signal is any variable signal continuous in both time and amplitude. It differs from a digital signal in that small fluctuations in the signal are meaningful. Analog is usually thought of in an electrical context, however mechanical, pneumatic, hydraulic, and other systems may also use analog signals. The word "analog" implies an analogy between cause and effect, voltage in and voltage out, cur ...

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In telecommunications and electronics, baud (pronounced /bɔːd/) is a measure of the "signaling rate" which is the number of changes to the transmission media per second in a modulated signal. It is named after Émile Baudot, the inventor of the Baudot code for telegraphy. For Example: 250 baud means that 250 signals are transmitted in one second. If each sign ...

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The crystal radio receiver (also known as a crystal set) was first built circa 1900 by Greenleaf Whittier Pickard, who used crystalline minerals to detect radio signals. Crystal radio receiver - History. Crystal radio receiver - Early years. People first built and used simple and inexpensive crystal radio sets without batteries or electrical power. Even though vacuum tube radios were common following World War I, crystal radios remained popular, especially among be ...

Including:

• Crystal radio receiver - History
• Crystal radio receiver - Early years
• Crystal radio receiver - 1920s and 1930s
• Crystal radio receiver - 1940s
• Crystal radio receiver - Later years
• Crystal radio receiver - Composition
• Crystal radio receiver - Espionage

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As with all modulation schemes, QAM conveys data by changing some aspect of a base signal, the carrier wave, (usually a sinusoid) in response to a data signal. In the case of QAM, the amplitude of two quadrature waves is changed (modulated or keyed) to represent the data signal. Phase modulation (analogue PM) and phase-shift keying (digital PSK) can be regarded as a special case of QAM, where the amplitude of the modulating signal is constant, with only the phase varying. This can also be extended to frequency modulation (FM) and frequency-shift keying (FSK), as ...

See also:

Quadrature amplitude modulation, Quadrature amplitude modulation - Overview, Quadrature amplitude modulation - Ideal structure, Quadrature amplitude modulation - Transmitter, Quadrature amplitude modulation - Receiver, Quadrature amplitude modulation - Performance, Quadrature amplitude modulation - Definitions, Quadrature amplitude modulation - Rectangular QAM, Quadrature amplitude modulation - Odd-k QAM, Quadrature amplitude modulation - Non-rectangular QAM

Read more here: » Quadrature amplitude modulation: Encyclopedia II - Quadrature amplitude modulation - Overview

The first rectangular QAM constellation usually encountered is 16-QAM, the constellation diagram for which is shown here. A Gray coded bit-assignment is also given. The reason that 16-QAM is usually the first is that a brief consideration reveals that 2-QAM and 4-QAM are in fact binary phase-shift keying (BPSK) and quadrature phase-shift keying (QPSK), respectively. 8-QAM presents problems in dividing an odd number of bits between the tw ...

See also:

Quadrature amplitude modulation, Quadrature amplitude modulation - Overview, Quadrature amplitude modulation - Ideal structure, Quadrature amplitude modulation - Transmitter, Quadrature amplitude modulation - Receiver, Quadrature amplitude modulation - Performance, Quadrature amplitude modulation - Definitions, Quadrature amplitude modulation - Rectangular QAM, Quadrature amplitude modulation - Odd-k QAM, Quadrature amplitude modulation - Non-rectangular QAM

Read more here: » Quadrature amplitude modulation: Encyclopedia II - Quadrature amplitude modulation - Rectangular QAM

Two diagrams of circular QAM constellation are shown, for 8-QAM and 16-QAM. The circular 8-QAM constellation is known to be the optimal 8-QAM constellation in the sense of requiring the least mean power for a given minimum Euclidean distance. The 16-QAM constellation is suboptimal although the optimal one may be constructed along the same lines as the 8-QAM constellation. The circular constellation highlights the relationship between QAM and PSK. Other orders of constellation may be constructed along similar (or very different!) lines. It is ...

See also:

Quadrature amplitude modulation, Quadrature amplitude modulation - Overview, Quadrature amplitude modulation - Ideal structure, Quadrature amplitude modulation - Transmitter, Quadrature amplitude modulation - Receiver, Quadrature amplitude modulation - Performance, Quadrature amplitude modulation - Definitions, Quadrature amplitude modulation - Rectangular QAM, Quadrature amplitude modulation - Odd-k QAM, Quadrature amplitude modulation - Non-rectangular QAM

Read more here: » Quadrature amplitude modulation: Encyclopedia II - Quadrature amplitude modulation - Non-rectangular QAM

Very early radio transmitters used a spark gap to produce radio-frequency oscillations in the transmitting antenna; these signals had a characteristic rapidly damped amplitude during each pulse of radiated energy. When alternators and later electronic oscillators became available, the signal strength remained constant during each code element, leading to the description of this technique as "continuous" waves. An unmodulated carrier has no bandwidth and conveys no information; the act of keying the carrier on and off produces a finite ...

See also:

Continuous wave, Continuous wave - Radio, Continuous wave - Key clicks, Continuous wave - Laser physics

Read more here: » Continuous wave: Encyclopedia II - Continuous wave - Radio

Any form of digital modulation necessarily uses a finite number of distinct signals to represent digital data. In the case of PSK, a finite number of phases are used. In the case of FSK, a finite number of frequencies are used. In the case of ASK, a finite number of amplitudes are used. This is very similar to pulse code modulation Each of these phases, frequencies or amplitudes are assigned a unique pattern of binary bits. Usually, each phase, frequency or amplitude encodes an equal number of bits. This number of bits comprises th ...

See also:

Modulation, Modulation - Analog modulation techniques, Modulation - Digital modulation techniques, Modulation - Pulse modulation, Modulation - Miscellaneous techniques

Read more here: » Modulation: Encyclopedia II - Modulation - Digital modulation techniques

Definition and meaning of pulse amplitude modulation, PAM fluorometer:

pulse amplitude modulation (PAM) fluorometer - a portable submersible fluorometer. Fluorometers that use the PAM technique work by rapidly sending brief pulses of light to a plant or other organism  A healthy organism responds to this light very quickly (within microseconds) by re-emitting some of the

(Source: US National Oceanic and Atmospheric Administration (NOAA) )

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