| 摘要 |
823,833. Multiplex systems. STANDARD TELEPHONES & CABLES Ltd. Jan. 8, 1958, No. 710/58. Drawings to Specification. Class 40 (4). [Also in Group XL (b)] In a multi-channel carrier current system in which the channels occupy equal width contiguous frequency bands of the frequency spectrum, an arrangement for combining or separating the channels consists in dividing the channel band-pass filters into two groups comprising those of the odd- and even-numbered channels, respectively (the channels being numbered in order of increasing frequency of the channel frequency bands), the two groups of channel band-pass filters being connected to a single transmission circuit by respective bandstop filters through means, such as a hybrid transformer, preventing interaction between the two band-stop filters, each band-stop filter having a plurality of stop bands centred on frequencies such that the pass band of each channel band-pass filter of its group lies between two adjacent stop bands. An embodiment of a suitable band-stop filter is described.
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