GB1356875A - Remote conttrol - Google Patents

Abstract

1356875 Selective signalling ZELLWEGER Ltd 3 Feb 1972 [29 March 1971] 5036/72 Heading G4H Remote control is performed using n-bit commands, all having the same number of "ones", the commands being individual commands corresponding to particular receivers, and collective commands, receivers intended to respond to collective commands not testing some of the bit positions of the received commands, these bit positions including at least two of opposite binary value. The receivers responding to collective commands, can also respond to individual commands (those which are the same in the tested positions). The use of the same number of "ones" in individual commands as in collective commands, and taking the non-tested positions to be pairs of opposite binary value, reduces the ability of interference to produce incorrect control actions. In the receiver of Fig. 2, the bit values of the command are received at 24, preceded by a start pulse which starts a motor 26 controlling contacts 29, 30, 33 and stepping switch 40. Contact 30 switches on an SCR 50. A reversing switch 36 is positioned according to each successive bit value to apply pulses to lines S1, S2 and stepping switch 40 selects, in turn, bit positions in a command "key" 23. In the event of disagreement between a bit of the command received and the corresponding bit set up in the command "key" (assuming the latter bit is not set to neutral, as shown by dashed lines at 75, 74), the current is shunted through the command "key" away from SCR 50 which ceases to conduct. Finally, switch 33 is closed, and if SCR 50 is still conducting, an impulse switch 59 is actuated and the control function is performed (operation of a switch). Switch 59 reverses switch 77, 78, so that the next command to which the receiver is responsive is the bit-by-bit inverse of the previous one. A command and its inverse are respectively used for switching on and off the controlled switch. The command "key" may be a replaceable printed circuit, or reversing switches controlled by punched cards. In a first modification, the reversing switches 77, 78 are eliminated by duplicating the components 50-54, and using a bi-stable impulse switch 59 with two outputs. In another modification, the lowest fifth of Fig. 2 is common to a plurality of units each like the rest of Fig. 2, diodes being used for decoupling.