Patent GB-1002298-A (GB)
Title: Improvements in or relating to electrical signal distributing systems
IPC: H04N7/16
Filed: 1960-08-08
Abstract: 1,002,298. Distributing music, &c. BRITISH RELAY Ltd. and K. A. RUSSEL. Nov. 8, 1961 [Aug. 8, 1960], No. 27457/60. Heading H4R. In a system for distributing television or other electrical signals to subscribers having payment or credit meters, the price charged per unit time of a programme may be varied by control signals controlling the effective price rate of subscribers' meters, such control signals being transmitted over the wires at a frequency below the lowest frequency used for the distributed television signals. A central station 10 (Fig. 1) feeds vision and sound signals by wires 13 to subscribers' stations 11, 12 . . . &c., each having sound and vision reproducing equipment 14, a switch 15, a capacitor 16, an electromagnetic escapement mechanism 17 and a low-pass filter 18. The sound signals may be transmitted at audio frequency. The video signals may be transmitted at video frequency but are preferably superimposed on a carrier. Preferably several feeders distribute different programmes and a subscriber can select the required programme by operation of a selector switch. At the central station 10 audio-frequency input signals at terminals 19 are fed through an audiofrequency transformer 20 and combined in a radio-frequency transformer 21 with video signals on a carrier obtained from terminals 22. Escapement mechanism.-The escapement mechanism 17 at each subscriber station is associated with a differential gear 23 (Fig. 2) having one input shaft actuated by a coin box unit 24 so that it is turned by an amount dependent on the coins fed into the coin box whilst the other input shaft is driven by low. frequency pulses (e.g. D.C. pulses of duration between one and fifty seconds) from the central station. This shaft is connected through a gearbox 25 to the escapement mechanism 17. The output from the gear 23 actuates the switch 15 such that the switch 15 is closed for the prepaid period. The escapement mechanism 17 is actuated by the charging and discharging of the capacitor 16. The charging pulses are produced by cyclic operation of a switch 26 at the central station 10 which alternately connects the wires 13 to a source of direct potential 27 to charge the capacitors 16 and to a current integrating meter 28 to discharge the capacitors 16. A lowpass filter 29 prevents the pulse generator affecting the audio or vision signals. Discharge of the subscribers' capacitors provides a means of measuring the total money collected. Main distribution centre.-Audio signals are fed by an input circuit 31 (Fig. 4) through an amplifier 32 to a matching transformer 34. Video signals at input circuit 35 are applied to a modulator 36, amplifier 37 and thence into a combining network 38 which also receives the audio signals. The signals are fed out on subscribers' feeders 39 and through filters 40 to links 41 leading to sub-stations. A clock 50 transmits pulses to a timer 51 which is controlled by a rate-per-hour input 52 to produce control pulses for a switch 53 which applies pulses to the distribution network from a battery supply 54 via a low-pass filter 55 and the transformer 34. The returning discharge pulses pass through filter 55 and switch 53 to a current integrator and meter 56. The output of integrator 56 is converted to digital form by a counter 57, the output of which is recorded by a printing device 58. The output of the counter 57 is also fed to an adder 59 together with signals from telemeter receivers 60 which receive signals from sub-stations via links 41. Time division multiplex is used for combining the information from the sub-stations. The combined output from the adder 59 is fed to a multiplier where the total is multiplied by the rate-per-hour factor to give the total money collected, which total is fed to a print-out device together with date and time information from clock 50. Sub-station.-Signals applied over link 41 (Fig. 5) are fed to a filter 70 which passes the vision carrier to an amplifier 71 and thence to a combining network 72 for recombining with audio signals and pulse signals. All signals are applied to subscribers' feeders 73. The substation also feeds signals to a further link 74. Audio signals and pulses from filter 70 are applied to transformer 75, the audio output of which is fed to combining network 72 whilst the charge pulses are passed to a delay timer 76 which, after delay, feeds them to a switch 77 controlling a battery 78 to provide direct voltage pulses. These are fed to the secondary of transformer 75 and thence to the combining network. The discharge current from subscribers' stations is measured by an integrator 79 and converted to digital form by a counter 80. The counter output is printed by a print-out device 81 and also goes to a telemeter modulator 82 and amplifier 83 for feeding back to the main distribution centre over link 41. Pulses.-An interrogation cycle 95 (Fig. 7) for the central station consists of a charging pulse (6 seconds) and a discharging pulse (6 seconds), the total cycle 95 taking 15 seconds. Later, price control pulses 96 are sent out, up to 59 in number. Interrogation cycles 97, 98, 99 for sub-stations occur at different times.