Unipolar Telegraphy

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Unipolar Telegraphy

 

a direct-current telegraphic method in which the coded signals consist of unipolar current pulses, for example, of a positive polarity, and of intervals in which a flow of current is absent. A start-stop multivibrator telegraph apparatus is used as a transmitter, and a nonpolar electromagnet serves as a receiver. In unipolar telegraphy in which signals are transmitted over open-wire lines, the electromagnet is more sensitive to current leakage and to interference that are induced in the line that it would be in a bipolar system. These effects are especially noticeable in damp weather. Thus, unipolar telegraphy is used with open-wire lines only if the lines are comparatively short—from 200 to 350 km. It is also used in lines that connect telegraph apparatus to telegraph offices in cities.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
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