Patent GB-430685-A (GB)
Title: Improvements relating to telegraph signalling apparatus
IPC: H04L1/08
Filed: 1934-03-23
Abstract: 430,685. Wireless signalling. CABLE & WIRELESS, Ltd., HIGGITT, H. V., and WOOD, K. L., Electra House, Victoria Embankment, London. March 23, 1934, No. 9153. [Classes 40 (iii) and 40 (v)] To eliminate the effects of atmospherics or fading in a double-current cable-code system in which a dot is denoted by (+ +), ), dash by ( - - ) and a space by (+ - ), signals are sent two or more times. The invention is applied to a diplex system of the kind described in Specification 384,691, in which the elements from two transmitters are interleaved by means of synchronized switches, the dot-transmitting and dash-transmitting contacts being operative alternately so that dots and dashes are sent out of phase. At the transmitter, (Fig. 1, not shown), the original transmission of the signals takes place over the A channel. The signals are simultaneously stored in condensers through a rotary distributer and a little later the condensers are discharged so as to cause the signals to be repeated in the B channel after a delay. The receiver shown in Fig. 2 is similar to that shown in Fig. 4 of Specification 386,784. Dots and dashes respectively are received in the A channel by relays 37A, 38A, and in the B channel by relays 39B, 40B. Signals in the A channel are stored in condensers 55 through distributer brushes 48, 50, which are for dots and dashes respectively ; the condensers are later discharged through brushes 53, 54, at the moment when the repeated signals are being received in the B channel through relays 39B, 40B. The intermediate relays 60A, 61A and 64B, 65B are shown so interconnected that they co-operate to eliminate the effects of fading from the signals sent by the final dot and dash relays 70, 71. Thus the marking (dot) contacts 74A, 75B which control the dot final relay 70 are in parallel, while the spacing (dash) contacts 79A, 77B which control the dash final relay 71 are in series through the armature 78A. The reverse arrangement (Fig. 3 not shown), is adopted when atmospherics are expected, and a sunflower switch may enable the connections to be changed from one state to the other, according as fading or atmospherics are to be provided against. Delaying signals by telegraphone. In a modification (Fig. 4, not shown) the signals, instead of being applied to condensers, are applied to a soft-iron strip for the purpose of producing the required delay. They are interrupted by a rotary interrupter before being applied to the strip, are rectified after being picked up from the strip, and are then removed by an A.C. magnet. The strip moves continuously so that each part of it is affected alternately by the dot signals and the dash signals. Instead of a magnetic strip, a magnetic disc may be used. Dot and dash signals may be impressed at different radii, or different discs may be used for dots and dashes. Modification using storing-relays. Instead of the condensers 55, neutral polarized relays may be employed (Fig. 5 not shown). Modification using displaceable pins. The condensers may be dispensed with and each of the relays associated with them may include a pin drum for producing the necessary delay (Fig. 9 not shown). Thus an armature 106, Fig. 6, may be rocked by the signals about an axis 108 so that a cam portion 107 comes into position to displace one of the pins 103a as the drum 102 revolves. After a delay this pin rocks a contact lever 109 to reproduce the signal, after which it is restored by the fixed cam 116.