Electronic transmitter - receiving circuit having a clock-controlled serial - parallel - serial converter for according to the duplex - method operated remote write machines

摘要

1,119,009. Telegraphy. CREED & CO. Ltd. 28 March, 1967, No. 13951/67. Heading H4P. A telegraph apparatus for simplex operation comprises a shift register which receives serial code combinations when the apparatus is receiving and, when the apparatus is transmitting, receives parallel combinations the elements of which are shifted out to line. The state of the line is sampled during each element and the sample inserted in the stage of the register left vacant due to the shifting. In the embodiment described, when the keyboard 52 gives a parallel signal to a register comprising BS1- BS5 a clock 54 is started. The clock feeds bitrate pulses to the logic circuit shown which locks the keyboard, blocks the receive line R and sets BS8 to send a Start bit on line S. Shift pulses are applied to the register and the line S is sampled at the mid-bit points by gate 28, the samples being inserted in BS1. When a complete character has been sent a Stop bit is added and gate 43 is enabled so passing the contents of the register, which is the combination actually transmitted, to monitor-printer 53. The keyboard is unblocked. If, after a time set by delay 46, no further key has been operated the receive line is unblocked. The Start bit of a received combination starts clock 54 and the bits are mid-bit sampled at 28 as before, the samples passing to the register which is subsequently read out to the printer during the Stop bit.