GB1189919A - Improvements in or relating to Circuit Arrangements for Detecting and Indicating Changes of Signal State on Signal Lines - Google Patents

Abstract

1,189,919. Automatic exchange systems. SIEMENS A.G. 30 Sept., 1968 [29 Sept., 1967], No. 46260/68. Heading H4K. The state of lines is monitored by giving each line an arrangement of three ferroelectric or ferromagnetic elements K1, K2, K3; K1 being coupled to its associated line; both K1 and K2 being driven by interrogation pulses from a scanner AB1 and having outputs coupled in opposition to the third element K3; a change of state of the line resulting in a corresponding change of state of the element K3. Changes of state are signalled from K3 to a receiver EM. The currently existing state of the line is indicated by the state of K3 which may be read out to EM non-destructively by a scanner AB2. The elements K1, K2, K3, described, are ferromagnetic as shown in Fig. 1. Cores K1 and K2 may be non-remanent with a permanent bias so that unidirectional interrogation pulses from AB 1 switch the cores from saturation under bias to opposite saturation from which the cores revert to saturation under bias when the interrogation pulse ends. If the cores are remanent they are cycled from saturation to saturation and back by bipolar pulses. Output pulses generated in windings We of K1 and K2 for one direction of turnover are coupled to input windings Ws1, Ws2 of core K3. To obtain unidirectional inputs to K3 diodes D1, D2, may be used in the coupling loops or the resetting amplitude of the bipolar interrogation pulse may be so small as to produce no significant output from K1 and K2. Core K3 is remanent and its windings Wsl, Ws2 are in opposition. With no current monitored from the line both cores K1 and K2 turn over to interrogation, the output from K1 to K3 exceeding that from K2 so that K3 is always driven to a 0 state. If current is monitored it biases K1 and interrogation produces no output, output from K2 (which is invariable) driving K3 to a 1 state.