Monitoring of the remote alarm systems with means for localizing of noise sources

摘要

1,091,909. Repeaters. SUBMARINE CABLE Ltd. July 19, 1965 [July 23, 1964], No. 29667/64. Heading H4R. In a communication system incorporating a number of repeaters each repeater includes a noise location network, comprising a resonant circuit of inductors and capacitors, to provide a gain change at a frequency within the useful communication channel, the frequency of the peak differing for each repeater with compensating gain changes being introduced at the terminal station. The gain change at the repeater may be a dip in the gain frequency characteristic caused by a simple parallel resonant circuit in series with the signal path, Fig. 4 (not shown), or preferably a bridged T circuit with resonant elements which maintains a constant impedance, Fig. 5 (not shown), each dip caused by a repeater circuit being compensated by a complementary network at the terminal station. Alternatively a network may be employed at each repeater, Fig. 7, which gives a dip of trapezoidal form, Fig. 8 (not shown), and if the frequencies of the dips at each repeater are suitably chosen, as derived mathematically in the Specification, the total effect of all the " dip " circuits is a constant attenuation over the whole band, which may be compensated by providing an increase in gain at the terminal station. Faulty repeaters introducing an excessive amount of noise in the system are identified by noting those parts of the noise spectrum which have received the additional attenuation due to the " dip " circuits in repeaters following the faulty repeater.