Automatic telephony; a comprehensive treatise on automatic and semi-automatic systems (1921)
Smith, Arthur Bessey, b. 1875, Campbell, Wilson Lee · New York : McGraw-Hill · leaf 98
US 81 While a trunk holder is useful, the inter-office trunks are often solong and their resistance so high that in the interest of good impulsingthe regular form of repeater is used. Quad-Level Trunks.—Sometimes the trunking between certain officesis light. There may not be enough traffic to fill… … Fig. 73.—Conditions for quad-level trunks. Suppose (Fig. 73) that the total busy-hour traffic from office A tothe four offices numbered 1, 2, 3, and 4 is such that from ten to 20 trunkswill carry it. But because each office is called from a different level onthe selectors at A, it is ordinarily…
Telephone
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