Patent GB-877516-A (GB)
Title: Improvements relating to automatic telephone systems
Inventor: LONG DOUGLAS PERCY
IPC: H04M15/38
Filed: 1959-02-16
Abstract: 877,516. Automatic exchange systems. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. Feb. 5, 1960 [Feb. 16, 1959], No. 5354/59. Class 40 (4). In an automatic telephone system, comprising a line finder, a selector and a call charge storage circuit located between them and adapted to register, up to a limited number only, metering impulses transmitted back towards the line-finder from a point ahead of the selector, a recording equipment common to a plurality of line-finders and hence of call charge storage circuits is coupled to the storage circuit when the limited number is reached or the call is terminated so that the number of metering impulses in the storage circuit may be recorded, the identity of the line, determined by the identity of the line-finder and its setting, being recorded in the equipment in the form of a printed record; this method of call charge recording dispensing with the need for subscribers' individual meters. When a connection has been established via the line-finder (Fig. 1) and selector (Fig. 3), relays H and HH are held over the P wire from the supervisory circuit of Fig. 4. Metering.-It will be assumed that 16 metering impulses are transmitted from the supervisory circuit to the call charge storage circuit (Figs. 2A, 2B) which has a maximum storage of 10 impulses, the call then being terminated. A metering impulse sent by the operation of contact mp1 (Fig. 4) brings up relay MM (Fig. 2B) which energizes the reverse drive stepping-type electromagnet MSDM of an impulse counting uniselector MS in the call charge storage circuit, and also operates relay R. This relay locks up and opens the homing circuit of MS. On the release of relay MM at the end of the first metering impulse, MS advances one step. The same procedure is adopted up to and including the tenth impulse. At the conclusion of the 10th metering impulse, relay N is energized over wiper MS2 and operates latch electromagnet SFLM (Fig. 5B), thereby causing the coupling switch SF1 to hunt for the outlet of this call charge storage circuit, test relay T coming up on finding, followed by relay TA. This relay marks in the bank of wiper MF of an identification switch MF the particular outlet that corresponds to the setting of the line-finder (i.e. the tens and units digits of the calling subscriber's number), applies earth to the start wire 27 of the recording equipment RMM, energizes latch electromagnet MFLM and earths wipers SF5, SF6, SF2 and MS3. The identification switch is driven to the marked outlet where it is stopped, and wipers MF2 and MF3 earthed, by high speed relay X. Recording equipment RMM is thus able to record the calling subscriber's four digit number and the number of metering impulses (10 in this case) in the call charge storage circuit. The finish wire 28 is then earthed and winding II acting in opposition to winding I of relay R is energized, thus releasing relay R, whereupon the impulse counting uniselector is homed. Releasing relay R also de-energizes relay N and hence relays T, TA and X, thus releasing the recording equipment for further use. The impulse counting uniselector is stepped to its sixth position by the next six metering impulses, the call then being terminated. The consequent removal of earth from the P-wire (contacts b1 opened) removes the short-circuit from the right-hand winding of relay N (Fig. 2A), which thereupon pulls up in series with H. The line-finder is thus held, and the operation of N initiates association of the recording equipment with the call charge storage circuit and recording of the stored metering information as previously explained. On the subsequent relapse of R; relays N and H fall away and the call charge storage circuit and the line-finder are released.