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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.
AM broadcasting is radio broadcasting using amplitude modulation (AM) transmissions. It was the first method developed for making audio radio transmissions, and is still used worldwide, primarily for medium wave (also known as "AM band") transmissions, but also on the longwave and shortwave radio bands.
The sound of the program material, usually coming from a radio studio, is used to modulate (vary) a carrier wave of a specific frequency, then broadcast. In AM broadcasting, the amplitude of the carrier wave is modulated to encode the original sound. In FM broadcasting, the frequency of the carrier wave is modulated to encode the sound.
This is used in sound cards that support both audio in and out, for instance. Hardware audio codecs send and receive digital data using buses such as AC-Link , I²S , SPI , I²C , etc. Most commonly the digital data is linear PCM , and this is the only format that most codecs support, but some legacy codecs support other formats such as G.711 ...
The channel steps of 9 and 10 kHz require limiting the audio bandwidth to 9 and 10 kHz (at maximum without causing interference; ±4.5 kHz (9 kHz) and ±5 kHz (10 kHz) on each two sidebands) [3] because the audio spectrum is transmitted twice on each side band. This is adequate for talk and news but not for high-fidelity music.
A sound card (also known as an audio card) is an internal expansion card that provides input and output of audio signals to and from a computer under the control of computer programs. The term sound card is also applied to external audio interfaces used for professional audio applications.
FM is commonly used at VHF radio frequencies for high-fidelity broadcasts of music and speech. In broadcast services, where audio fidelity is important, wideband FM is generally used. Analog TV sound is also broadcast using FM. Narrowband FM is used for voice communications in commercial and amateur radio settings.
Audio signal processing is a subfield of signal processing that is concerned with the electronic manipulation of audio signals.Audio signals are electronic representations of sound waves—longitudinal waves which travel through air, consisting of compressions and rarefactions.