Amplitude modulation

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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 o Amplitude modulation - AM vs. FM Amplitude modulation - Forms of AM Amplitude modulation - Example o Amplitude modulation - A more general example Amplitude modulation - Modulation index Amplitude modulation - Amplitude modulator designs o Amplitude modulation - Circuits

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Amplitude modulation - Low level Amplitude modulation - High level

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amplitude modulation - applications in radio: Encyclopedia II - Amplitude modulation - Applications in radio A basic AM radio transmitter works by first DC-shifting the modulating signal, then multiplying it with the carrier wave using a frequency mixer. The output of this process is a signal with the same frequency as the carrier but with peaks and troughs that vary in proportion to the strength of the modulating signal. This is amplified and fed to an antenna. Amplitude modulation - AM vs. FM. AM radio's main limitation is its susceptibility to atmospheric interference, which is heard as static from the receive ...

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 Applications in radio

amplitude modulation - applications in radio: Encyclopedia - Automatic gain control Automatic gain control (AGC) is an electronic system found in many types of devices. Its purpose is to control the gain of a system in order to maintain some measure of performance over a changing range of real world conditions. A very common and typical example is the AGC used in AM radio. Such a receiver is essentially linear - that is, the output is proportional to the input. This is a necessary requirement because the information content of the signal is carried by the changes of amplitude of the carrier frequency. If the c ... Read more here: Automatic gain control: Encyclopedia - Automatic gain control

amplitude modulation - applications in radio: Encyclopedia - Very low frequency Very low frequency or VLF refers to radio frequencies (RF) in the range of 3 to 30 kHz. Since there is not much bandwidth in this band of the radio spectrum, only the very simplest signals are used, such as for radionavigation. Because VLF waves can penetrate water only to a depth of roughly 10 to 40 metres (30 to 130 feet), depending on the frequency and the salinity of the water, they are used to communicate with submarines nea ...

Including: Very low frequency - Details of VLF submarine communication methods Very low frequency - PC-based VLF reception Very low frequency - List of VLF transmitters

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amplitude modulation - applications in radio: Encyclopedia - Orthogonal frequencydivision multiplexing 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 o Orthogonal frequency-division multiplexing - Benefits

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Orthogonal frequency-division multiplexing - Disadvantages of OFDM

Orthogonal frequency-division multiplexing - OFDM feature abstract Orthogonal frequency-division multiplexing - Usage o Orthogonal frequency-division multiplexing - ADSL

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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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amplitude modulation - applications in radio: Encyclopedia - Audio level compression Audio level compression, also called compression or limiting, is a process that manipulates the dynamic range of an audio signal. Compression is used in sound recording and live sound reinforcement fields to improve the perceived quality of audio. (This should not be confused

with audio data compression, which reduces the data size of digital audio signals.) A compressor is the device used to create compression. Audio level compression - Controls. A compressor reduces the dynamic range ...

Including: Audio level compression - Controls Audio level compression - Limiting Audio level compression - Side-chaining Audio level compression - Multiband compression Audio level compression - Common uses Audio level compression - Underlying electronics Audio level compression - Other uses

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amplitude modulation - applications in radio: Encyclopedia - Alternator An alternator is an electromechanical device that converts mechanical energy to alternating current electrical energy. Most alternators use a rotating magnetic field. Different geometries such as a linear alternator for use with stirling engines - are also occasionally used. In principle any AC generator can be called an alternator, but usually the word refers to small rotating machines driven by automotive and other internal combustion engines. Alternator - History. Alternating current generating ...

Including: Alternator - History Alternator - Theory of operation Alternator - Automotive alternators Alternator - Radio alternators Alternator - External articles and futher reading

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amplitude modulation - applications in radio: Encyclopedia - Amateur Radio Direction Finding Amateur Radio Direction Finding is an amateur map and compass sport that combines the skills of orienteering and radio direction finding. It is a timed race in which individual competitors use a topographic map and a magnetic compass to navigate through diverse, wooded terrain while searching for radio transmitters. The rules of the sport and international competititions are organized by the International Amateur Radio Union. World wide, the sport is most often refered to by its English language acronym, ARDF, but ...

Including: Amateur Radio Direction Finding - History Amateur Radio Direction Finding - Description of competition and rules o Amateur Radio Direction Finding - Entry categories

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Amateur Radio Direction Finding - Youth competitions Amateur Radio Direction Finding - Local variations

Amateur Radio Direction Finding - Map and course details Amateur Radio Direction Finding - Equipment and clothing o Amateur Radio Direction Finding - Transmitter equipment

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Amateur Radio Direction Finding - Receiver equipment Amateur Radio Direction Finding - Clothing Amateur Radio Direction Finding - Other equipment

Amateur Radio Direction Finding - Variations

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amplitude modulation - applications in radio: Encyclopedia - Amateur radio Amateur radio, often called ham radio, is a hobby enjoyed by many people throughout the world. An amateur radio operator, ham, or radio amateur uses two-way radio to communicate with other radio amateurs, for recreation or self-edification. As of 2004 there were about 3

million hams worldwide with about 700,000 in the USA, 600,000 in Japan, 140,000 each in South Korea and Thailand, 57,000 in Canada, 70,000 in Germany, 60,000 in UK, 11,000 in Sweden, and 5,000 in Norway. Amateur radio - ...

Including: Amateur radio - History Amateur radio - Amateur Radio Activities and Practices o Amateur radio - Emergency and public service communications

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Amateur radio - DXing QSL cards and awards Amateur radio - Contesting Amateur radio - Vintage Radio Amateur radio - VHF UHF and microwave weak-signal operation Amateur radio - Portable operations Amateur radio - Low power operations

Amateur radio - Amateur radio licensing o Amateur radio - US Licensing

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Amateur radio - International operation Amateur radio - Privileges of the Amateu