GB249057A - Improvements in submarine and the like cable signalling systems - Google Patents

Abstract

249,057. Western Electric Co., Ltd., (Western Electric Co., Inc.). Dec. 6, 1924. Restoring or modifying imperfect signals; duplex telegraphs. -A submarine cable repeater is adapted to compensate at the repeating point for distortion caused by both the incoming and outgoing cable sections. Such compensation, which is preferably not complete in respect of the outgoing section, may be effected by amplifying various components of the signal wave to different degrees depending on their frequencies. The figure shows a two-way bridge duplex repeater between cables 230 and 231. Conjugate points of the bridge M are connected through a filter network 236, a shaping network 237, a shielded transformer 235 and a repeating amplifier ER to the apex of the bridge N, and conjugate points of the bridge N are similarly connected through a filter network 267, a shaping network 268, a shielded transformer 269, and a repeating amplifier WR to the apex of the bridge M. The network 236 which suppresses the higher frequencies is a balanced ten-section network, each section being constituted by resistances 238, 239 and a condenser 240. The shaping elements connected across the primary of the transformer 235 comprise an inductance 241 and a resistance 242. A balanced transformer constructed as described in Specification 248,822 may replace the network 236 and transformer 235. The secondary of the transformer 235 is connected to a potentiometer 243 and the current from this is amplified by a series of four valves 8A1, 8A2, 8A3, and 8A4. An inductance 244 and a polarizing battery 246 are arranged between the potentiometer and the grid of the valve 8A1 with a condenser 245 crossconnected as shown to the filament. The plate circuit includes battery 8B1, variable resistance 247, and a portion of an inductance 270 with a variable shunting condenser 248, these elements constituting a shaping network. This plate circuit is connected to the grid valve 8A2 through condenser 249, inductance 244, and grid polarizing battery 263, a leak resistance 250 being connected to ground and a condenser 245 to the filament. Similar circuit connections are provided between the valves 8A2 and 8A3 with the addition of a variable resistance 252 in the shaping network. The plate circuit of the valve 8A3 is provided with a further shaping network and is connected to the grid of the valve 8A4 through a condenser 259 and polarizing battery 265. The plate circuit of the valve 8A4 includes battery 8B4, variable resistance 261, and inductance 260, and is connected through condenser 262 to the apex of the bridge N. The shaping elements associated with the amplifiers are adjusted to effect a greater amplification of the higher than of the lower frequencies. To enable maximum amplification in each of the amplifiers ER, WR to be effected without causing the amplifiers to sing different speeds of signalling are preferably employed in the two directions.