Patent GB-868082-A (GB)
Title: Improvements in and relating to systems for presenting information
Inventor: JONES KENNETH
IPC: H04H60/94
Filed: 1958-05-09
Abstract: 868,082. Electric selective signalling systems. TELEVISION AUDIENCE MEASUREMENT Ltd., and JONES, K. June 10, 1959 [May 9, 1958; July 16, 1958], Nos. 15027/58 and 22807/58. Class 40 (1). A signalling system comprises a central station and a plurality of responder stations which receive interrogation pulses from the central station and each responds, after a specific number of pulses, by returning at least one pulse indicative of the operative state of the responder with or without a further response pulse or pulses indicative of the state of the apparatus with which said responder is associated. General operation.-Three pulses W1, W2, W3, are produced from a basic time pulse P1, at the central station, by multivibrator circuits, and are timed such that W3 steps a uniselector to allow W1 to be transmitted, W2 then operates a relay which switches the station to a receive condition. Each responder counts the interrogation pulses on a uniselector, and on reaching a predetermined count, n, is switched from a receive to a transmit condition. The nth pulse steps the uniselector to a marked contact, a self-drive mechanism is energized and the next group of contacts is stepped rapidly. These have previously been given positive potential by a handoperated switch and return pulses P3 are produced and transmitted to the central station where they are counted. The relays of the transmit/receive switches are timed to release before a further interrogation pulse is sent. A final negative pulse from the central station energizes self-drive systems in all the responder uniselectors and drives them back to a zero position. The central station.-A basic time pulse P1 from a multivibrator circuit V4, V5, Fig. 4, is applied to the grid of a valve V11 and to the cathodes of valves V11, V12 in a monostable multivibrator circuit. Valve V12 produces an interrogation pulse W1, which is applied to the contacts of a uniselector 5. Output pulse P2 of this multivibrator triggers another mono-stable multivibrator V15, VI 6 causing a pulse W2 to energize a relay RL5 whose contacts RL5A change the connections of an output transformer T2 from an outward transmission position to couple the transmission lines to a response signal amplifier V17. Pulse P2 is also applied to a mono-stable multivibrator V8, V9 to provide a pulse W3 which actuates a relay RL4 to complete a drive circuit for the solenoid of a uniselector 5. The pulses are timed such that the pulse W3 steps the uniselector 5 to allow the pulse W1 to pass along the transmission line. Pulse W2 then operates the relay RL5 setting the central station for receiving signals; RL5 is arranged to release immediately before the next interrogation pulse. The twenty-fifth step of the uniselector arranges that a negative restoring pulse is sent along the line. The responder.-Pulses from the central device pass from an input transformer T1, Fig. 5, to the grid of a valve V1 allowing the valve to conduct and energize relays RL1 and RL6. The former operates contact RL1A to disconnect V1 from the transformer T1 and to connect the return pulse generating valve V3 to it instead, whilst the latter closes its contacts to energize a drive magnet UDM of a uniselector switch 13. The uniselector steps once for each pulse, all relays being timed to release before a further interrogation pulse is received. If the device has been set to respond to the thirteenth pulse, the thirteenth contact on the uniselector energizes a relay RL3 operating switches RL31, RL32, a self drive circuit is completed, and the uniselector arm is driven over the next group of contacts. It then stops and awaits a reset signal. A manually operated switch MS has previously applied positive potential to one or more of these contacts, so that during the stepping process rapid positive pulses are applied to a valve V3, coil L1 and capacitor C4 which produce a respond pulse for each application of marking potential. The response pulses are timed to return to a counter, at a central station, between interrogation pulses. Reset of responder.-The last pulse transmitted along one line, by the central device is received by the input of valve V1 as a negative pulse; a positive pulse is generated at the anode of V1 and is applied to V2, which conducts and energizes a reset relay RL2. The latter is slow to release and its contacts RL21 connect the circuit of RL3 to a reset bank, relays RL3 and RL6 interact to energize the drive UDM and drive the switch to its reset positions. In a modified central station (not shown) the interrogation pulses are distributed over the connecting-lines by means of two distributer switches. The return signals are amplified, passed to a bank of rotary switches, and each pulse from one responder is counted on one switch. The switches are reset by the energization of their drive solenoid. In a modified responder the uniselector is replaced by a cam which is stepped round one position for each pulse by a relay to close a contact after a specific number of pulses. An arm passes over three further contacts to pass one, two, or three respond pulses (as before), dependent upon the state of the associated apparatus.