Abstract: This chapter focuses on the bandwidth requirements and modulation. For analogue signals, the base bandwidth is the range of frequencies contained in the signal; it is not the same as that occupied by a radio frequency carrier modulated by the signal. For radio transmission, the low frequency information signal is carried on a radio frequency wave and it must modulate that carrier. The modulation may change the amplitude, frequency, or phase of the carrier. Modulation aims to achieve: (1) the transfer of information with the minimum distortion or corruption; (2) the modulation of the carrier with the minimum loss of power; and (3) efficient use of the frequency spectrum. There are a number of methods of modulation where the amplitude of the carrier is varied by the information signal but the most commonly used is double sideband amplitude modulation. When the modulation is increased to the point where the minimum amplitude falls to zero, 100% modulation occurs.
Publication Year: 1994
Publication Date: 1994-01-01
Language: en
Type: book-chapter
Indexed In: ['crossref']
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