. The Bell System technical journal. Telecommunication; Electric engineering; Communication; Electronics; Science; Technology. CARRIER SYSTEMS ON TELEPHONE LINES 623 which, as has been noted, acts to separate the carrier currents from the regular speech currents on the common line circuit. It consists of a high-pass and a low-pass filter paralleled on the line side. Currents entering these terminals from the line circuit pass through the high- pass circuit to the carrier apparatus or through the low-pass circuit to the circuit terminal or repeater. The transmission characteristics of these fil
. The Bell System technical journal. Telecommunication; Electric engineering; Communication; Electronics; Science; Technology. CARRIER SYSTEMS ON TELEPHONE LINES 623 which, as has been noted, acts to separate the carrier currents from the regular speech currents on the common line circuit. It consists of a high-pass and a low-pass filter paralleled on the line side. Currents entering these terminals from the line circuit pass through the high- pass circuit to the carrier apparatus or through the low-pass circuit to the circuit terminal or repeater. The transmission characteristics of these filters are shown on Figure 41. It will be noted that frequencies 1001-. CHAWNEL-J CtMNNEL-2 CHANNEL-1 CHANNEL-2 CHANNEL-I CHANNEL-J I £ 3 4 5 6 7 8 5 10 II le 13 14 15 16 17 18 19 20 21 £2 23 24 £5 26 27 28 29 30 FREQUENCY KILOCYCLES Figure 41—^Typical line filter characteristics above approximately 3,300 cycles are transmitted in the high-pass circuit and frequencies below about 2,800 cycles are transmitted through the low-pass circuit. It is common to equip a few line circuits with line filter sets, in addition to those which are normally in use for carrier transmission. This makes it readily possible in case of an emergency or for other reasons to use the spare wires thus equipped for carrier transmission. Non-linear effects may be produced in the coils and condensers in the circuit. The design of the filter parts must be made so that these effects will be a minimum. This requires the use of non-magnetic cores in the coils, and also that the containers be of non-magnetic material. Condensers in magnetic containers must be located so that they will not lie in the field of the coils and thus contribute to the modulation products. The modulation in the line filters, telegraph composite sets, and office and cable loading units, must also be con- Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
