Patent GB-845463-A (GB)
Title: Submerged repeater switching system
IPC: H04B3/44
Filed: 1958-02-21
Abstract: 845,463. Submarine repeaters. STANDARD TELEPHONES & CABLES Ltd. Feb. 21, 1958 [Feb. 28, 1957], No. 5715/58. Class 40 (4). In a submarine cable telegraph system at least two repeaters are connected in circuit in a cable conductor at the receiving end of the cable, a first one of these repeaters being at a substantial distance from the shore and having switching means with at least two positions, one of which connects the repeater in circuit and another of which connects the cable circuit to by-pass the repeater, while a second one of these repeaters is at a considerably greater distance from the shore and has switching means with a plurality of testing, amplifying and operating positions, switching signals being sent from the shore over the cable conductor to cause selective setting of either of the switching means to any of its positions. In the arrangement shown there are two repeaters, the outer one of which has three stages consisting of tube 26, tube 28 and six tubes 30 to 31 (Fig. 1) in parallel, respectively. Spare tubes 26<SP>1</SP>, 28<SP>1</SP>, and 30<SP>1</SP> to 31<SP>1</SP> are provided. The output impedance is suitable for direct coupling to the intermediate section 36 (Fig. 2) of the cable. The long section 11 (Fig. 1) of the cable is connected via conductor 10 to the wiper arm S1 of a rotary switch (Fig. 2) which in the normal condition (contact 1) extends it via conductor 15 to the input and signal shaping circuit 16 (Fig. 1). The output of this amplifier is resistancecoupled to the cable section 36 via the heater circuits 68, switch bank S2, resistor 65, rectifier 66 and the grounded conductors 40 and 44. With the polar switch 75 (Fig. 2) of the inner repeater in its normal condition the signal output of the outer repeater is applied to an isolating transformer 82 having a shaping network 86 connected to its secondary winding via which it is applied to the amplifier of the inner repeater. This amplifier is substantially identical to that of the outer repeater, but has its output transformer-coupled to the short cablesection 45. Switching operation.-The control apparatus at the shore receiving station includes a switching battery 110 feeding a potential divider 111, the tap of which is connected via a pulse counter 118 to the key 112. With the reversing switch 114 thrown to the right and with switch 49 on its contact 2, depression of key 112 causes positive potential to be applied via milliammeter 109 to the cable conductor 43; the negative pole of the battery 110 being connected to earth via conductor 113. The polar switch 75 operates, thus cutting out the inner repeater and extending conductor 43 directly to conductor 35, and at the same time provides a discharge circuit through conductor 80 for capacitors 83 and 108. The voltage of this initial switching signal is made insufficient, by adjustment of potential divider 111, to fire the cold cathode tubes 79 (Fig. 2) at the outer repeater. The potential divider is then adjusted to increase the potential to the firing potential, so that one of the tubes 79 fires to each subsequent depression of the key 112. Each time a tube 79 fires the electromagnet 13 is energized and rotates the ratchet wheel 14 one step, ten such steps moving the wiper arms S1, S2, S3 from one contact to the next of their respective banks. Depression of the key 112 with the reversing switch 114 thrown to the left restores the polar switch 75 to the condition shown. The switch S1-S3 has six positions, in the first or normal one of which the repeater is in circuit with the first set of tubes operative. In position 2 the heater circuit of this first set of tubes is opened by S2 which connects up the heater circuit of the second set (26<SP>1</SP> to 31<SP>1</SP>) in its stead. Position 3 connects a test resistor 67 in place of the heaters to permit testing of a normal outer repeater with the tubes in non-operating condition. In position 4 everything in the outer repeater is disconnected except the stepping circuit, thus giving an open circuit condition of the cable out to the outer repeater to enable testing for a cable fault to take place. The fifth position switches the cable through, by-passing the outer repeater except for the low-pass filter 120 (Fig. 2) which provides a low resistance path for the heater current. The inner repeater may then be switched back into circuit and the system may thus be operated in the event of failure of the outer repeater. In position 6 the outer repeater is by-passed, the cable being connected through without either repeater being in circuit. The cable may then be tested or it may be operated in either direction at the normal non- repeatered speed, or at higher speed in the reverse direction with repeaters connected in at the distant end.