Polarential telegraph system

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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]

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References[edit]

  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).