| 摘要 |
<p>347,687. Two-way repeaters. VIARD, G., 254, Rue de Vaugirard, Paris. Jan. 29, 1930, No. 3083. Convention date, Feb. 15, 1929. [Class 40 (iv).] A uni-directional amplifier, employed in a twoway repeater, is arranged to amplify the speech transmitted in either direction, the connections to the amplifier, which has a bias in one direction, being reversed when necessary by the transmission over the circuit of a frequency outside the normal speech range. The amplifiers 3, Fig. 1, are normally connected to transmit in the direction 1-2. When transmission in the opposite direction takes place the speech currents pass into delay network 6 and also energize relay 10 which connects to the circuit a current of frequency outside the normal transmission range. This current is amplified by amplifiers 7 which are tuned to this frequency only and energizes slow-acting relay 4 which reverses the connections to amplifiers 3 and enable them to amplify the currents in the direction 2-1. The control frequency is rejected by the band-pass filters 5, 5<1>. To prevent the operation of relay 10 by current flowing in direction 1-2 the device 9 may be arranged either to reject all frequencies passed by the filter 5<1> or the arrangement shown in Fig. 3 may be used. Currents flowing from 2-1 energize relay 14 whilst those flowing from 1-2 energize relay 13, the operation of 13 by currents from 2-1 being prevented by the delay device 6 which enables 14 to pull up before the operating currents have passed through the delay network.</p> |
