GB1205504A - Improvements in or relating to line-communication systems employing repeaters - Google Patents

Abstract

1,205,504. Pilot gain control. SIEMENS A.G. 26 July, 1968 [28 July, 1967], No. 35752/68. Heading H4R. In a pilot-controlled line-communication system including controlled repeaters 1 and intermediate preset repeaters 2 in which the output signal level from the controlled repeaters is varied in dependence on measured attenuation or temperature, constant amplitude information signals 5, Fig. 3a, and a main pilot P are applied to a four-terminal level setting network 4 in which the level is set by for example a temperature sensor 3, and a constant amplitude auxiliary pilot H is coupled to the output of the network 4, the controlled repeaters 1 being controlled by an associated pilot receiver tuned to the auxiliary pilot frequency and a four-terminal level readjusting network 5 in the receiver B being controlled by the main pilot signal. The system may use underground cables and a resistance measurement of an auxiliary wire may be used for terminal control. The system may include a branch exchange 7 with a four-terminal network on each side of the branch, the pilot P acting on network 5a to produce a constant signal level for the exchange. The networks may effect equalization and the pilot frequencies may be close one to the other. In a four-wire system between two terminals the received levels may control the transmitting levels through commonly controlled transmitting and receiving networks.