GB532584A - Arrangements for indicating the identity of a faulty unattended repeater at a terminal or attended station - Google Patents

Abstract

532,584. Repeaters. STANDARD TELEPHONES & CABLES, Ltd., JACOBSEN, B. B., ROCHE, A. H., and TERRY, V. J. July 21, 1939, No. 10910/40. Divided out of 532,523. [Class 40 (iv)] In a submarine or other unattended repeater, heat-sensitive means is associated with a filament circuit and gives a signal characteristic of the repeater. For example, a selfinterrupting thermal relay may be associated with a valve filament so as to remain inert until the filament breaks and then to send impulses at a characteristic rate, Figs. 2 and 3 (not shown). Alternatively, the filament supply circuit is bridged by a circuit comprising a resistance R in series with two branches, the current on each of which heats a " thermistor " in the other branch. (A " thermistor " is a resistance element, e.g. of silver sulphide, of which the resistance is gradually reduced with rise in temperature up to a critical temperature at which any further rise causes an abrupt diminution of resistance.) While the filament circuit is intact this is without effect but when it breaks the resulting rise in current, if the left hand branch has at the time a lower resistance than the other, causes the resistance of the right-hand path to be lowered when the heater of " thermistor " B becomes effective and that of the left-hand one to increase when, as a result, the current through " thermistor " A is reduced. The condition is then reversed and so on at a rate depending on the rate of heat transmission from the heaters to their " thermistors " and the periodic impedance change gives a signal at an attended station.