GB1345516A - Data transmission systems - Google Patents

Abstract

1345516 Data transmission systems MOTE DISTRIBUTORS Ltd 29 April 1971 [29 Jan 1970] 4356/70 Heading G4H A data transmission system for transmitting information relating to the condition of each of a number of stations comprises a scanned memory board MB for producing cyclically and in sequence data signals each of which represents in analogue form the condition of a station, threshold devices S1-S3 for assessing the magnitude of the data signal corresponding to each station, gating circuits for producing a pulse train, wherein the presence or absence of one or more pulses is indicative of the condition of a station, a coaxial cable for transmitting the pulse train to a remote location and an interrogating circuit for decoding the information relating to the condition of a station. The memory board MB containing the information relating to the condition of each station is scanned by a method similar to that described in Specification 1,223,422 so that there appears at the output of an amplifier L the sequence of analogue signals representing the conditions of the stations. Each threshold amplifier S1-S3 produces an output when the analogue signal is equal to a certain value or none of the amplifiers produces an output when the analogue signal is zero. The outputs of the amplifiers S1-S3 are fed to the gating circuits, Fig. 2 (not shown), which combine the outputs to form a pulse train comprising two pulses, the presence or absence of one or both pulses of which is indicative of the condition of the station. To display the information relating to a selected station, a keyboard in the decoding circuit, Fig. 3 (not shown), is manually operated to set a counter to a value corresponding to the selected station. When the counter has been reset to zero by clock pulses from the memory board scanning system, gates are opened to energize one of four lamps for displaying the condition of the selected station.