American telegraphy and encyclopedia of the telegraph; systems, apparatus, operation (1909)
Maver, William, jr. [from old catalog] · New York, Maver publishing company · leaf 315
the contactpoiats of the pole-changer at A, when the distant key is open. A continuity preserv-ing pole-changer is employed, this having been found more serviceable than the usualdynamo pole-changer. A repeating sounder, es, also with contact on front stop, maybe used ad shown, to obviate aay… … SIEURS DIPLEX. THE SIEURS DIPLEX. By diplex transmission is meant the simultaneous transmission ot two messagesin one direction over one wire. The Sieurs diplex system is entirely different in principle from the duplex sys-tems already described. The writer is not aware that it has ever been in…
Telegraph
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