transmitter(redirected from Longwave transmitter)
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(Russian, transmitter).(1) A telegraph transmitting device in which code combinations of the characters in the text of a telegram are automatically converted into a series of electric current impulses that are sent to a communication line. The code combinations are represented by holes in a perforated paper tape.
During the initial stage in the development of telegraphy the electromechanical transmitter invented by C. Wheatstone in 1858 was used, and the Morse code, a type of unequal-length code, was employed. By the end of the 1950’s an electromechanical transmitter employing an equal-length five-element code had come into general use. In such a transmitter the perforated tape is advanced one step for each rotation of the transmitting distributor, and brush arms “read” the next code combination from the tape; by actuating contacts the brush arms produce the corresponding five-element combination of current and no-current signals. Telegraph transmitters are designed either as an accessory for automating the operation of the keyboard of telegraph transmitting equipment or as an independent unit. The use of a transmitter makes it possible to increase the output of transmitting equipment and the efficiency with which a communication channel is used.
(2) A transmitting device in remote-control and remote-signaling systems that is used in railroad transport to transmit coded electrical signals over a track circuit.
REFERENCESOsnovy telegrafii i telegrafnye stantsii. Moscow, 1970.
Kogan, V. S. Telegrafiia i osnovy peredachi dannykh. Moscow, 1974.
V. V. NOVIKOV