GB745139A - Improvements in or relating to transmitting apparatus for signals recorded on tape - Google Patents

Abstract

745,139. Telegraph transmitters. STANDARD TELEPHONES & CABLES, Ltd. Oct. 2, 1953 [Oct. 9, 1952], No. 25321/52. Class 40 (3). A transmitting apparatus for code signals having their elements recorded longitudinally on a tape comprises a sprocket wheel for feeding the tape-past a reading head for detecting the signal elements, means for transmitting the signals, and further means operating independently of said detected signals for arresting said sprocket wheel for a predetermined interval during the passage of a stop element under said head so that the time interval of the transmitted stop element may be increased to any desired length. In the recording apparatus, Fig. 1, the tape 42, preferably magnetic, is fed by a sprocket 41 on a shaft 40 carrying a wheel 1 having 24 teeth and rotated at speed such that during one revolution 24 seven-unit signals are recorded. In the rest position, a detent 2 on a pivoted bell crank 3, controlled by the armature 5 of the electromagnet 6, engages a tooth, such as 9. The start element rocks the lever 3 to release the wheel 1 so that signal elements are recorded on the tape, and the beginning of the stop element rocks the detent so that the wheel 1 is arrested at the end of 140 ms. assuming code elements of 20 ms. and a stop element of that duration. In the transmitting apparatus, Fig. 2, the tape 22 is fed to a reproducer head by a wheel 21 on a shaft 20 carrying a wheel 14 having 24 teeth and rotated as in the case of the wheel 1 of Fig. 1. In the stop condition of relay 16 the detent 15 on bell-crank 17 engaging a tooth such as 18 or 19 arrests the wheel 14. With the switch 8 in the stop position, the relay 16 energized by marking current from the battery B holds the detent in the arresting position. When the switch 8 is moved to the start position, marking current over contact M still holds lever 17 so that the detent 15 is in the arresting position. A cam 12, which makes a complete revolution in 150 ms., moves a tongue 23 to a contact S and spacing current through relay 16 rocks the lever 17 so that detent 15 is released. The tongue 23 is returned to the position shown by a spring. Subsequently the detent 15 is raised by relay 16 to engage the next tooth on the wheel 14 and the tape 22 is arrested with the stop element being transmitted. The stop condition is transmitted for a further 10 ms. after the tape 22 has been arrested until the projection 13 on the cam 12 again operates the tongue 23 to the contact S so that the relay 16 moves the detent 15 downwardly to release the wheel 14 and sprocket 21 to feed the tape to read off a further code combination of signal elements.