GB862562A - Improvements in or relating to systems for the two-way transmission of intelligence between two stations - Google Patents

Abstract

862,562. Inductive signalling. SIEMENS & HALSKE A.G. March 19, 1959 [March 19, 1958], No. 9570/59. Class 40(5) In an inductive system for communication between a fixed station and a moving lift cage, the energy of the carrier wave from the fixed station powers the transmitter in the cage. In the embodiment described a fixed station FR, Fig. 2a, is inductively coupled by a toroidal transformer œ1 and the lift cable L to the two similar cage stations, KI, Fig. 2b, being an example having further toroidal transformers œ2, of ferrite or C core construction. At the fixed station a microphone Ml, Fig. 2a, carrier generator G1 and modulator Mo and call generator G2 with call key RT1 are employed in a known single sideband unsuppressed carrier system. The cage equipment, Fig. 2b, includes a known demodulator, amplifier and telephone receiver, and microphone and amplifier, the transmitting and receiving amplifiers V3, V5 being powered by the carrier frequency passing through the demodulator DMo. A safety arrangement, included within dotted lines in Fig. 2a, includes a bridge whose arms are respectively transformer œ1, resistor R 3 , resistor R 2 and resistor R 1 and choke J in parallel (Fig. 3): Under no fault conditions equal potentials exist at points a and b. When a fault in œ1 occurs, transistor T 1 , which is normally conducting is cut off, T 2 conducts, and amplifier V 2 is short circuited via diodes GI 3 , GI 4 , and relay A operates, short circuiting œ1 with contact al, and fault lamp S lights. When the fault is cleared the circuit is reset by key ET.