GB333262A - Improvements in or relating to radio telephone and the like systems - Google Patents

Abstract

333,262. Mathieu, G. A. May 9, 1929. Repeating and amplifying systems.-Relates to twoway repeater arrangements for combined line and radio communications, or for similar systems in which the energy-level of the outgoing signals greatly exceeds that of the incoming-signals, and wherein blocking-means are provided for cutting-out the amplifier handling the incoming signals when the amplifier for outgoing signals is in operation, and similar blocking-means for cutting-out the outgoing amplifier when signals are being received. The invention consists in interlocking the two blocking-devices E, D by means of a biasing battery 1B, which connects the grid circuit of the first valve V3<1> in the blocking device E with a resistance R3 in the output circuit of the valve V5 in the blocking device D, and prevents momentary false working of the relays at the beginning of each message. Means are also provided for automatically short-circuiting signal-intensity reducing-means SP, Fig. 2, normally inserted in the transmitting circuit, as soon as speech commences in either direction. The valve VC1, Fig. 1, of the amplifier B is connected to the input of the blocking-device D, and the receipt of incoming signals builds up a voltage across resistance R3 in opposition to a biasing battery EF, and so operates a relay RL to short-circuit the primary winding of the transformer Tr2<1> of the transmitter amplifier C. Similarly when the local subscriber is talking, current from the output of valve Vc1<1> of the amplifier 0 is fed to the input of set E to operate a relay RL1, which short-circuits the primary winding of the transformer Tr2 in the amplifier B. The grid of the valve V3<1> of the set E is connected through the biasing battery IB to the resistance R3 in the set D. This interlocks to the blocking sets and prevents a false operation of the set E by any unbalanced speed components passing through the hybrid coils particularly if the " gain " of the amplifier C has been increased to bring feeble outgoing signals up to normal strength. Fig.2 shows the arrangement for removing during speaking periods an intensity-reducing means SP, normally in the transmitting channel. Resistances R6, R<1>6 are inserted in series with the relays RL, RL1, and are in turn shunted by the windings W, W1 of auxiliary relays AR, AR1. When signals are being sent out, a third relay AR3 is energized, through relays AR, AR1, and the attenuation pads SP are rendered ineffective by the switches S1, S2, S3. A switch S4 is also closed to insert a delay circuit C, R across the windings of the relay AR3, so that the latter is not operated by short pauses in the conversation.