Patent GB-611083-A (GB)
Title: Improvements in or relating to intelligence relaying systems
IPC: H04B7/155
Filed: 1946-03-19
Abstract: 611,083. Automatic exchange systems. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. March 19, 1946, No. 8546. Convention date, Jan. 18, 1944. [Class 40 (iv)] [Also in Groups XL (b) and XL (c)] A remotely controlled H.F. relay station for connecting together two of a number of points around the station comprises a transmitter modulated by the output of a superheterodyne receiver whose beat oscillator steps cyclically in frequency until a modulated signal producing a frequency corresponding to the I.F. of the receiver is received from one of the points. Figs. 1 and 2 show a radio relay station in the standby condition with aerials W, N, E, S (facing neighbouring stations) and coupling transformer 6, connected in parallel to a standby receiver 7 and to converter 14 of the main receiver. Transformer 6 connects to a transmission line which may lead to a broadcast aerial if required. When a signal is received, for example, from the station opposite aerial W, standby receiver 7 whose frequency bandwidth is sufficient to accept signals from any of the surrounding stations, causes discharge valve 9 to fire, thus completing the circuit from the positive terminal of H.T. power unit 11 through contact 13 of relay 66 (Fig. 1) to operate relay 10. Contact 12 of this relay connects power to the main receiver (by means not shown), earths the negative terminal of H.T. unit 11 via wire 43 and contact 36 of relay 35, and provides a holding circuit for itself. The current valve 9 develops a voltage across resistor 86 which is applied to the grid of valve 59 to start an electronic distributer 55-59 (see Group XL (b)). Beat oscillators 15-19 are by this means cyclically set in operation until the oscillator corresponding to the received signal is reached when the distributer is stopped. The I.F. signal produced is amplified and detected in unit 20 and the modulation after amplification in unit 21 is fed through transformer 22 to transmitter 24 and also to tone-filters 28, 29, 30, 31 of frequencies f1, f2, f3 and f4 respectively. The frequency f 1 with which incoming. signal is modulated is rectified at 75 to produce a bias which is fed from the centre tap of transformer 76 to the grids of valves 55-59 and it is this bias which stops the distributer. In this stationary condition valve 56 corresponding to aerial W passes a sustained anode current, causing relay 62 to operate. The associated contacts short circuit relay 82 ensuring the continued connection of aerial W to the receiver and also apply, via contact 78; an increased suppressing bias to the distributer. At this stage slugged relay 13 whose operation was initiated when the signal was first received, now completes the circuit of relays 81, 83, 84, 85, thus connecting the idle aerials to transmitting aerial selector 34. A second tone modulation f2 passes through filter 29 to fire valve 32 causing relay 27 to connect power unit 26 to the transmitter. Station W now sends a series of impulses of a tone frequency f 3 which after rectification at 42 step selector 34 to connect the required aerial to the transmitter. On completion of traffic, a disconnect tone f4 is received and this, after filtration in unit 31 and rectification at 38, momentarily operates relay 36. Contact 96 of this relay causes selector 34 to return to its normal position and contact 36 causes relays 10 and 27 to release disconnecting power from the receiver and transmitter respectively.