| 摘要 |
<p>974,244. Pulse signalling; transistor time delay switching circuits; supervising unattended repeaters. BRITISH TELECOMMUNICATIONS RESEARCH Ltd. April 12, 1962 [April 17, 1961], No. 13790/61. Headings H3T, H4L and H4R. In a signalling system comprising send and receive channels each employing a plurality of repeaters SR1 to SRn and RR1 to RRn, Fig. 1, including pulse regenerators, wherein the repeaters are fed with D.C. power in series from a terminal station TSR over the signalling channels, the send and receive channels are connected together by relay-operated contacts S in each repeater station when the system is not energized, and timing equipment T controlling the relays is set in operation when the power is applied to any repeater and breaks the connection S between the channels after a predetermined time whereby the power is supplied to the succeeding repeater. Constant current power is supplied from a source CCF, and a test signal which is applied at the same time as the power passes through the regenerators and is transmitted back to the terminal station TRR over the loop at each repeater in turn and operates an alarm if an incorrect signal is detected at D. The reading of a voltmeter V across the power source CCF increases by discrete steps as the relays of successive repeaters are energized and thus provides an indication of the location of a fault. The slitht breaks in transmission as each repeater switches over may be arranged to give an audible signal. The delay device T, Fig. 3, comprises a transistor T feeding a relay S in its emitter circuit, the transistor conducting to operate the relay when the capacitor C is sufficiently charged through the resistor R.</p> |
