GB1130131A - Electric pulse signalling system - Google Patents

Abstract

1,130,131. Measuring temperature electrically. ENGLISH ELECTRIC CO. Ltd. Feb. 25, 1966 [March 1, 1965], No. 8747/65. Heading G1N. [Also in Division H4] In a system for collecting information at a receiving station 5, information from a plurality of sources is transmitted via transducers 6, including thermocouples 15, and a common channel 7 as signals having a duration proportional to the amplitude of the output signals from the thermocouples 15. Details of one transducer 6 are shown. The common channel 7 comprises lines 8 to 12 and a group of lines 13. When information is required to be trahsmitted, a signal is sent to all the devices 6 via line 12 which sets the magnetic core of the type having a square hysteresis loop, of a device 26 in each transducer at saturation point, each signal from thermocouples 15 having charged a corresponding capacitor 18 accordingly. A signal on line 10 is then sent to all the devices 6 simultaneously which renders the transistors 27 conductive and the voltage across the capacitor 18 is applied to the winding 25 of the device 26 thus reducing the flux level of the core at a rate dependent on the applied voltage level. The signal on line 10 is arranged to exist for a predetermined short time and when it ceases the flux level in each core represents the output of the corresponding thermocouple. Diodes 41 to 44 are connected to different combinations of lines 13 for each device 6, the lines 13 normally being energised with positive potentials so that the diodes 41 to 44 conduct and all the transistors 39 are cut off. When it is desired to transmit to the receiving station 5 the value of the information stored in a particular core 26, the appropriate lines 13 are energized with negative voltages so that the diodes 41 to 44 are cut off and the transistor 39 conducts, causing diode 30 to conduct. In this way a predetermined voltage from voltage divider 32, 33, 34 is applied across winding 28 to drive the flux at a constant rate back to the saturation point. When the flux reaches saturation point the voltage across winding 28 will fall effectively to zero and the diode 30 will cease to conduct so that a voltage pulse of duration proportional to the magnitude of the input signal is produced on line 45 and transmitted via line 11 to the receiving station 5. The diode 46 prevents interaction between the various devices 46. The line 12 may be omitted and all the cores reset to saturation by energizing all the lines 13 simultaneously. In a modification suitable for small signal inputs, Fig. 2 (not shown) the voltage across capacitor (18) is supplied via an additional transistor gate and an amplifier to the winding (25) an additional winding on the core(26) providing negative feedback for the amplifier. A normally open relay contact may be connected in parallel with the additional transistor or it may be a field effect transistor to prevent any error due to its base emitter voltage.