| 摘要 |
1,012,462. Unattended repeaters. PHILIPS ELECTRONICS & ASSOCIATED INDUSTRIES Ltd. March 15, 1963 [March 20, 1962], No. 10381/63. Heading H4R. For the location of a faulty repeater in a carrier system, each repeater station includes an oscillator 4 for sending a signal to an indicator 7 at a terminal station, and the oscillators are controlled over an auxiliary line 9 which has Zener diodes 11, 14 in series and in parallel at each station so that as an increasing direct voltage is applied from a source 10 the oscillators are activated one at a time in succession. If, for example, in a one-way system, Fig. 1, the amplifier at VS3 is faulty, no indication is given until the oscillator at VS4 becomes operative. In a 2-way system, Fig. 2, the go and return paths are coupled as regards signal currents through an amplifier 15, so that high level signals are transmitted as long as the amplifiers in the go path are operating correctly. In order to reduce the direct voltage required for testing a large number of repeater stations, the line 9 is reversed between the stations, which are also provided with diodes 17, and the voltage is applied to the line over a change-over switch 16, so that half the oscillators are controlled in each position of the switch. A suitable transistor oscillator is described with reference to Fig. 3 (not shown). |
