Polarential telegraph system

A polarential telegraph system is a direct-current telegraph system employing polar transmission in one direction and a form of differential duplex transmission in the other.[1]

Two types of polarential systems, known as types A and B, are in use. In half-duplex operation of a type A polarential system, the direct-current balance is independent of line resistance. In half-duplex operation of a type B polarential system, the direct current is substantially independent of the line leakage. Type A is better for cable loops where leakage is negligible but resistance varies with temperature. Type B is considered better for open wire where variable line leakage is frequent.[2]

See also

References
  1. Frank Jay (1977). IEEE Standard Dictionary of Electrical and Electronics Terms. p. 501. A direct-current telegraph system employing polar transmission in one direction and a form of differential duplex...
  2.  This article incorporates public domain material from the General Services Administration document: "Federal Standard 1037C". (in support of MIL-STD-188)
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