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* GB786079 (A)

Description: GB786079 (A) ? 1957-11-13

Improvements in or relating to monitoring devices used in carrier-wavetelephone systems

Description of GB786079 (A)

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BE535541 (A) CH326378 (A) DE1010111 (B) FR1122282 (A) NL184989 (B) US2851529 (A) NL99204 (C) BE535541 (A) CH326378 (A) DE1010111 (B) FR1122282 (A) NL184989 (B) US2851529 (A) NL99204 (C) less Translate this text into Tooltip

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PATENT SPECIFICATION Date of Application and filing Complete Specification: Feb 4, 1955. 786,079 No 3400/55. r, 1 Application made in Netherlands on Feb9, 1954. ___ Complete Specification Published: Nov13, 1957. Index at acoeptance:-Class 40 ( 4), R 3 D, R 11 (D:F 1:G). International Classification:-HO 4 b, j. COMPLETE SPECIFICATION Improvements in or relating to Monitoring Devices used Telephone Systems We, PHILIPS ELECTRICAL INDUSTRIES LIMITED, of Spencer House, South Place, Finsbury, London, E C 2, a British Company, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The invention relates to monitoring devices used in carrier-wave telephone systems for supervising (for example, by remote control) amplifiers used in a repeater station for traffic in each direction In carrier-wave telephone systems the use of such monitoring devices has particular advantages, since it makes possible the immediate indication of specific deviations from the normal operating conditions in the repeater station, so that these can be corrected at an early stage. The risk of interruptions of the transmission due, for example, to the break-down of a repeater station, is thus reduced. Such monitoring devices are of particular importance when the transmission path includes one or more unattended repeater stations, as it frequently does in carrier-wave communication over coaxial conductors, cables, or the like It is advantageous that the monitoring signals emitted by monitoring devices associated with different repeater stations should be transmitted to a terminal station, so that it may be possible to supervise the operating conditions of the entire carrier-wave telephone system, or of a section of it, from one position In this case the monitoring signals may be transmitted through the carrier-wave cable itself; for example, over separate pairs of conductors. The invention has for its object to provide a monitoring device for a repeater station in a carrier-wave system in which one or more of the following requirements may be met: ( 1) A change in anode current beyond a given limit, or the break-down of an amplifying tube is to be indicated by the monilPrice 316 l in Carrier-wave toring device, which, if desired, may actuate an alarm device in a terminal station. ( 2) If the monitoring signals are transmitted over the carrier-wave telephone cable, they and the intelligence and dialing 50 or other signals sent over the cable are substantially not to affect one another. ( 3) The transmission of the monitoring signals is to be based on the principle that normally such a signal is transmitted and de 55 terioration or failure is to be indicated by cessation or alteration of the monitoring signal. ( 4) Monitoring signals received from different repeater stations are to be distinguish 60 able. ( 5) The monitoring device is to be capable of indicating inadmissible differences between the signal levels for traffic in the two directions and of actuating an alarm device 65 ( 6) The monitoring device to be capable of indicating deterioration of the voltage supply of the repeater stations. The invention comprises a monitoring system for supervising the operation of ampli 70 fiers in a two-way repeater in a carrier-wave telephone system, characterized in that the frequency of a monitoring oscillator associated with the repeater can be discontinuously changed by a relay circuit whose ener 75 gizing circuit is differentially connected to the anode circuits of tubes which are incorporated in different amplifiers, in such a way that in the event of a tube becoming faulty the frequency of the monitoring signal 80 emitted by the said oscillator provides a tube-test signal for indicating which of the said amplifiers contains the faulty tube; and in that a frequency-change indicator, responsive to changes in the frequency of the said 85 monitoring signal, serves to provide at a supervisory station, which may be remote from the repeater, a corresponding tube-test indication. The expression " tube-test ", in this speci 90 786,079 fication, means a test which indicates whether the anode current of a discharge tube has attained a value associated with a fault in the tube. One embodiment of the invention will now be described by way of example with reference to the accompanying diagrammatic drawing, in which:Fig 1 shows a repeater station intermediate between two terminal stations; and Fig 2 shows a terminal station. The repeater station and terminal station shown in Figs 1 and 2 respectively form part of a carrier-wave telephone system, in which intelligence signals, pilot signals, supply voltages, monitoring signals, service messages and the like are all sent over one coaxial cable For these signals the following frequencies may be allocated: for 960 intelligence channels, 60 kc 1 s to 4 Mc /s; pilot signals, 60 kc /s: service signals from 15 kc./s to 21 kc Is, monitoring signals from 6 to 12 kc Is; supply voltage 50 c /s. The repeater station shown in Fig 1 handles two-way traffic; the cables 1, 1 ' carry the incoming signals and the cables 1, 2 ' carry the outgoing signals The ends of the cables 1, 1 ' are connected to high-pass filters 3, 3 ' and low-pass filters 5, 5 ' The ends of cables 2, 2 ' are connected to high-pass filters 4, 4 ' and low-pass filters 6, 6 ' These filters serve for separating the higher from the lower frequencies The high-pass filters 3, 4 and 3 ', 4 ' pass only the intelligence signals and pilot signals, while the low-pass filters 5, 6 and 5 ', 6 ' pass only the service messages, monitoring signals, and supply voltages. The signals selected by the high-pass filters 3, 3 ' from the cables 1, 1 ' are respectively supplied through equalizing networks 7, 7 ' and input transformers 8, 8 ' to amplifiers 9, 9 ', which are connected through output transformers 10, 10 ' and the high-pass filters 4, 4 ' to the outgoing coaxial cables 2 and 2 ' The amplifiers 9 and 9 ' are respectively constituted by two cascade-connected stages 12, 13 and 12 ', 13 ', each of which comprises two parallel-connected pentodes whose cathode circuits include negativefeedback impedances. The service messages, monitoring signals, and supply voltage pass from cables 1, 1 ' to cables 2, 2 ' through the low-pass filters 5, 6 and 5 ', 6 ' and conductors 14 and 14 ' respectively The conductors 14 and 14 ' convey supply voltages of mains frequency in phase opposition, and are connected to the primary windings of transformers 15, 15 ' whose secondary windings are connected to rectifying circuits 16, 16 ' The circuits 16, 16 ' are connected in parallel to the input terminals of a smoothing filter 17 whose output terminal 18 delivers a positive direct voltage for the anodes and screen grids of the amplifying tubes The filament voltages for these tubes are obtained from secondary windings 19, 19 '. The winding 19 supplies the filament voltage for one of the amplifying tubes in each of the amplifying stages 12, 13, 12 ', 13 ', and 70 the winding 19 ' supplies the filament voltage for the other tube in each of these stages. Thus if a breakdown occurs in one of the supply voltages across the conductors 14 and 14 ', the amplifying stages 12, 13, 12 ', 13 ' con 75 tinue to operate. The repeater station includes a device for remote monitoring, at a terminal station for example, of the amplifying stages 12, 13 and 12 ' 13 ', respectively, and this is effected for 80 traffic in each direction. The monitoring device includes a monitoring oscillator 21 whose frequency can be changed discontinuously by means of a contact voltmeter or relay 20 The energizing 85 winding of this voltmeter is connected differentially between conductors 22 and 23 which convey anode voltage to the amplifying stages 12, 13 and 12 ' 13 ' respectively The monitoring signals from the oscillator 21 con 90 trol a frequency-indicator at the terminal station The voltmeter 20 responds to changes of voltage and has fixed contacts 27 and 27 ' and a pointer contact 26 The ends of its energizing winding 28 are connected 95 to terminal 18 through resistors 24 25 which are included in the anode conductors 22 and 23. The monitoring oscillator 21 is a resistance-capacity oscillato