GB1462052A - Information communication system - Google Patents

Abstract

1462052 Electric selective signalling PLESSEY CO Ltd 26 June 1974 [27 July 1973] 35899/73 Heading G4H An information communication system, e.g. for use in a car, ship or aeroplane for the passing of information to control accessories each of which comprises an actuator device WSS, &c. and a responder device WSWM, &c., comprises a plurality of pairs PWA, PWR &c. of peripheral stations interconnected by a common path CLP controlled by a timing unit MTU arranged to generate polling cycles comprising a plurality of frames of timing pulses; each pair of accessory actuator and responder devices is served by a pair of peripheral stations, each of which pairs is allocated a unique address defining a particular frame in each cycle. As described there are 128 frames in each cycle, each frame containing ten 5 Ásec slots bounded by 1 Ásec timing pulses, the first and last slots being start and stop slots SS, ES (Fig. 2, not shown). The other eight slots are divided into groups of four, slots 1-4 for command and data signals and slots 5-8 for speech signals (units SCPSA, SCPSB). The accessories shown in Fig. 1 are: headlights (HL), direction indicators (RF, LF), screen wiper (WS), oil pressure (OP), speedometer (S), tachometer (T), coolant (TG) and fuel level (FG). HL, RF and LF, and WS are switch operated and insert a 1 or 0 in one of slots 1-4 of their allocated frame; FL and T are sampled voltages; S is a variable frequency generator for which four frames (and hence four addresses) are allocated; and OP is an oscillator with variable M/S ratio. In addition there are headlamp and direction indicator "tell-back" peripheral stations having the same address as their corresponding station pairs: the responder station in each pair transmits a status signal bit to its tell-back station in slot 3 or 4 of the corresponding frame to light lamps RTFLHLFTL. Speech is handled by passing direct voltage samples over path CLP; sampling occurs during each frame and each direction of speech transmission is considered as a separate function. Two of slots 5-8 are used for each "communication call." Each station pair (e.g. PWA, PWR) is connected to its accessory pair (WSS, WSWM) by means of interface circuits (WST, WMD) which may include sample and hold circuits for transmitted analog values. Each station contains a frame counter which enables buffers BTB &c. (Fig. 3, not shown) during the frame allocated thereto. A clock extraction circuit (CEM) causes input and output of data in the buffers during the correct time slots for the frame. Instead of an electrical closed loop CLP, transmission may be by radio or optical fibres.