GB539105A - Improvements in carrier frequency relay communication systems - Google Patents

Abstract

539,105. Wireless and wired-wireless signalling. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. Oct. 28, 1939, No. 28919. Convention date, Oct. 29, 1938. [Class 40 (v)] [Also in Groups XXXV and XXXVI] A relay station for a frequency modulated carrier comprising an amplifier oscillating at the frequency of the incoming signals, is provided with means for deriving the modulating frequencies and for modulating the carrier by a local modulating frequency. The relay station may be part of a wireless or wiredwireless chain. At each relay station three stages of amplification 10, Fig. 4 are used of which the second is shown in full. The primary coil of an input transformer feeds two tuned secondaries 12 coupled to push-pull oscillating valves 11. One circuit 12 is flatly tuned slightly, above and the other below the mean frequency of the input. The frequency modulated output is passed through a transformer 14 to the next stage. Feed back from the output circuit to the input circuit, indicated by dotted lines b, causes oscillation of the amplifier, the frequency being controlled by the incoming signals. The variations in anode current fed to the valves 11 represent modulation frequency and this is made use of for modulating or demodulating at the relay station. The anodes of the valves 11 are connected through the transformer 14 to a centre-tapped primary winding of a transformer 15, the anode current being supplied to the centre connection. The secondary of the transformer 15 is connected to windings 17 of a further transformer 16. A modulation output amplifier 19 is connected to centre tappings of the two windings 17. Modulation input, after passing through an amplifying stage 21 is supplied to a further winding 20 of the transformer 16. A balancing network 18 is connected to the winding 17. In a modified arrangement the input and output circuits of an oscillating amplifier and two-way repeater c, Fig. 5, are coupled to a bi-directional antenna system 9 and balancing network 23 through a balancing transformer 22. Specification 533,147 is referred to. The Specification as open to inspection under Sect. 91 describes (1) modified arrangements of the antenna system and (2) means for automatically keeping several oscillators @ed at different relay stations in synchronism. For the latter purpose, the push-pull oscillator 50, 52 tunable by motor 63 is coupled by a loop 71 to the transmission line leading to the antenna system and to concentric conductor lines 59, 60 (one above and the other below a quarter wave-length) associated through elements 73 with the grid circuits of valves 61, 62, the anode circuits of which cause relay 64 to energize the reversible motor 63 to retune the oscillator 50, 52. This subjectmatter does not appear in the Specification as accepted.