GB873147A - Improvements in or relating to automatic telephone systems - Google Patents

Abstract

873,147. Automatic exchange systems. AUTOMATIC TELEPHONE & ELECTRIC CO. Ltd. Dec. 19, 1957 [Feb. 19, 1957], No. 5530/57. Class 40 (4). Subscribers of two different categories are charged different metering fees, metering pulses of one kind affecting the meters of both categories and metering pulses of another kind affecting the meters of only one category. A subscriber's meter MTR, Fig. 3, may be connected through a rectifier MR either to positive battery or to earth according to whether the subscriber is on a business tariff B or a residential tariff R. In the former case the meter responds to both +100 and + 50 volt pulses. In the latter case the meter responds only to the higher voltage pulses. Detailed description, Figs. 1, 2. The first dialled digit besides being repeated over junction JN also drives a fee discriminating uniselector FD. The uniselector FD starts at position 1 and advances two steps for each impulse. It is guarded against interference by subsequent digits. When the called party answers relay D operates to energize DD. The first subsequent " S " pulse on lead SP energizes DA. The next " Z " pulse operates DB. Metering pulse terminals MP1-MP6 during this " Z " pulse delivery 1-6 pulses over strappings to appropriate odd-numbered contacts of bank FD5 and even-numbered contacts of bank FD6. Since the wipers of FD stand at an oddnumbered contact only FD5 is effective to energize metering relay J an appropriate number of times. FD3 supplies a corresponding number of +100 volt pulses over contacts J1 to the P wire of the calling line. This is the basic metering fee and is effective on the meters of both residential and business subscribers. At the end of the " Z " pulse DA and DB release and uniselector FD advances one step to an even-numbered position. An " S " pulse reoperates DA and the next " Z " pulse reoperates DB. Wipers FD6 and FD4 are now effective, one to supply pulses from the appropriate terminal MP1-MP6 to relay J, and the other to supply a corresponding number of +50 volt pulses to the P wire. This is the supplementary fee and is effective only on the meters of business subscribers. At the end of this " Z " pulse DA restores but DB holds up whereby subsequent " S " pulses have no effect on the metering relay.