Patent GB-676393-A (GB)
Title: Improvements in or relating to the tele-selection of elements of electric signalling communication, remote-control and like systems
IPC: H04Q9/14
Filed: 1950-07-07
Abstract: 676,393. Electric selective signalling systems. SOC. D'ELECTRONIQUE ET D'AUTOMATISME. July 7, 1950. [July 18, 1949] No. 17039/50. Class 40 (i). A telecontrol system comprises a transmitting station sending directive signals which at the receiving end cause the generation of a series of local directive signals equal in number and characteristics to all the possible incoming directive signals, the incoming signals being compared with the regenerated signals in individual channels, so that one pair of signals will correspond causing the actuation of a particular executive element. In one embodiment (Fig. 1), the received signal at 1 is taken to an element 3 which causes a series of local generators 4 to produce the individual directive signal for each of N channels, which are then taken to a comparator 5 where they are compared with the incoming signal via a parallel branch lead 8, followed by a switch 6 which is unlocked when the output of the comparator 5 is zero, to allow the operation of an actuating element 7. Alternatively, the signal required to unlock a switch 6 may be one containing all the possible directive signals. The actuating element 7 could also be made to send a signal back to. the transmitter acknowledging receipt of the order. Several groups of actuating and executive elements may be combined in one transmission channel by using directive signals of two parts, a prefix part characteristic of the group and a body part characteristic of the individual executive element. Thus, in Fig. 2, the signal generator actuating element 3 and the local signal generators 4 are common to both groups, the comparators 5, 15 being fed with the incoming signal through a prefix analysing circuit 9, 19 which unblocks a circuit 10 or 20 to allow the directive signal from 1 to proceed to the. appropriate group of comparators 5 or 15. The prefix may be suppressed before reaching the switches 6, 16, which may be included in the actuating devices 7, 17. Fig. 4 gives more details of one channel in an embodiment wherein the coding comprises a series of pulses all subjected to a prior amplitude limitation.. The prefix code comprises two pulses spaced by an interval t and is fed through a transfer stage 21 to an open delay line 22 whose transmission time is t/2, so that the first pulse is reflected to be superposed onto the second to give a pulse of double amplitude which unlocks the valve 24 by overcoming its cathode bias. This pulse is applied to a delay line 26, which has an initial portion 27. to introduce a general delay to affect subsequent synchronisation and a further portion designed to reproduce the individual directive signal code by connections 28, whereas the initial impulse after passing through the delay line 26 is taken via an amplifier 29 to an integrating circuit 30 to produce a control voltage across a resistor 31. The individual directive code on lead 28 is applied across a resistor 34, to the other end of which is taken the input signal via lead 8, so that if the signals are identical no voltage appears across 34, whereas if the input directive signal is not that intended for that channel, a difference voltage appears across resistor 34, and is fed to a comparator circuit comprising a wave-form differentiator 35 and integrator.36 and connected to the other end of resistor 31. The resultant of the outputs of the two integrating circuits 30, 36 across resistor 31 is either a negative voltage, when there is an output from integrator 36, or a positive voltage, when there is no output. from integrator 36, the latter condition causing anode current in valve 32, producing the operation of actuating relay 33.