| 摘要 |
466,071. High-frequency transmission. STANDARD TELEPHONES & CABLES, Ltd. June 12, 1936, No. 16507. Convention date, Sept. 18, 1935. Drawings to Specification. [Class 40 (iv)] [Also in Group XL] In the transmission of signals covering a wide frequency band such as 0 .. 2000 Kc., the. lower part of the band (say) 0 .. 300 Kc. is shifted to a position above the highest frequency in the original band. Where, as in television, the energy of the signals is concentrated in regions centred on harmonics of a base frequency, the intervening regions being void of useful signals, the point of division between the shifted and unshifted ports of the band is put in one of the void regions. At the receiving end the shifted band may be passed through a phase corrector before being restored to its original position. Alternatively an anticipatory correction is applied at the sending end. The invention is useful in the distribution of television signals over a network of co-axial distribution cables including amplifying sub-distributing stations in which a single amplifier feeds several branch lines. The feeders connected to the terminal apparatus may be associated with the main cable by transformers or by direct con. nection. |
