Patent GB-764077-A (GB)
Title: Improvements in or relating to television entertainment distribution system
IPC: H04N7/16
Filed: 1951-08-29
Abstract: 764,077. Selection signalling; magnetic recording and reproducing heads. INTERNATIONAL TELEMETER CORPORATION. Aug. 29, 1951 [Oct. 9, 1950], No. 20377/51. Classes 40 (1) and 40 (2). [Also in Groups XVIII, XIX, XXXIX, XL (b) and XL (c)] Selective signalling. Sequences of pulses transmitted in the inaudible range over the sound channel accompanying a vision channel in a television distribution system (see, Group XL (b)) are employed to..position a stepping switch in a coin-collecting apparatus (see Group XVIII) at a receiver so as to necessitate the deposit of a particular sum of money before the programme can be received. Further impulses conveying a four-digit number identifying the programme are recorded on a magnetic tape (see Group XIX) stepped between the recording of pulses by yet further pulses from the transmitter. The pulse sequences are repeated continuously throughout the programme so that a receiver coin-collecting apparatus may be set up and reception commenced at any time during the programme. The transmitted pulses are as shown in Fig. 3A and occupy five different frequency channels. Those in channel f 1 extend throughout the first part of the cycle which is occupied by pulses in channels f3 and f4 conveying the number indicating the programme. The pulses in the f3 channel are in four groups 101, 103, 105, 106, each of up to nine pulses so as to convey a four-digit number (4213 as shown) and each group is separated by a single pulse in the f4 channel. The remainder of the cycle is occupied by a group of pulses 111 in the f2 channel indicating the price of the programme. The pulses in channels #1-#4 are generated by means of a transmitter having contacts closed through holes in a four-track punched tape, Fig. 5 (not shown). The #5 channel is employed for a release pulse which is transmitted manually at the termination of the programme. When a receiver is tuned to the transmitter, the first f pulse thereafter is applied to a solenoid 358, Fig. 17, driving the stepping switch in a coin-collecting apparatus. The solenoid operates through a ratchet-andpawl mechanism 357, 361 and the f pulse causes a contact arm 353 to be moved from its rest to its zero position. This initial movement also changes over contact 369 connected in a control circuit, Fig. 4 (not shown), and thereafter the solenoid is connected in a circuit receptive to the f2 channel pulses. When these arrive the solenoid responds to each pulse and steps the arm 353 round over a corresponding number of contact studs 352. The apparatus now remains in this condition until an amount of money has been deposited in a coil-collecting box. This results in a second switch arm disposed on the opposite face of plate 345, and moving over contacts 352 which extend through the plate, being moved by an amount corresponding to the money deposited. When the amount corresponds to the price determined by the f2 pulses, the two arms engage the same stud and a circuit is completed to permit reception. A switching operation then also takes place in the control circuit whereby the first following train of f pulses are applied to an electromagnet operating a step-by-step drive of a twin-track magnetic tape recorder. The f3 and f4 pulses are also applied to the two recording heads and produce a corresponding record on the tape. The f3 and f4 pulses are timed as shown in Fig. 3A to occur between the f pulses so that the tape is stepped between recordings. At the termination of recording a further switching action takes place in the control circuit and the apparatus is disconnected from the control pulses and remains thus until the termination of the programme. At this instant a release pulse received on the #5 channel energizes solenoid 363 and withdraws detent 362 and pawl 361 to allow arm 353 to restore to its rest position under the action of a helical. spring (not shown). The control circuit is also released and the apparatus resets in readiness to respond to a subsequent programme. Magnetic recording and reproducing heads. The recording head, Fig. 20, in the twin-track magnetic recorder comprises a magnetic anvil 402 over which the tape passes under two recording polepieces 403, 404 having energizing windings 407, 408 fed with pulses from the #3 and f4 channels respectively. The television receiver incorporating the coin - collecting apparatus and magnetic recorder also forms the subject of Specification 764,079, [Group XL (b)]. Specification 764,076 also is referred to.