单词 | passband |
释义 | passbandenUKpass·bandP0096700 (păs′bănd′)PassbandenUKpassband[′pas‚band]Passbandthe frequency range within which the amplitude-frequency characteristic of an acoustic, radio-engineering, or optical device is sufficiently uniform to assure the transmission of a signal without substantial distortion of the signal’s shape. The basic parameters of a passband are the width of the band and the nonuniformity of the amplitude-frequency characteristic within the band. The bandwidth is usually defined as the difference between the upper and the lower limiting frequencies of the section of the amplitude-frequency curve where the minimum amplitude of the oscillations is not less than 0.707, or The passband required for a particular device depends on the device’s purpose. For example, telephone systems require band-widths of 300 to 3400 Hz, high-quality reproduction of musical performances requires 30 to 16,000 Hz, and television broadcasting uses bandwidths of up to 8 MHz. The widening of a passband permits the transmission of a greater amount of information; by reducing the nonuniformity of the amplitude-frequency characteristic within the passband, the reproduction of the shape of the transmitted signal can be improved. Passbands are sometimes defined also in terms of the device’s phase-frequency characteristic. REFERENCEGonorovskii, I. S. Radiotekhnicheskie tsepi i signaly. 2nd ed. Moscow, 1971.A. S. Grinchik |
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