Patent GB-1080160-A (GB)
Title: Improvements in or relating to electric signal pulse detecting systems
IPC: H04M15/04
Filed: 1965-10-21
Abstract: 1,080,160. Automatic exchange systems. SIEMENS A.G. Oct. 21, 1965 [Oct. 21, 1964 (2)], No. 44538/65. Heading H4K. Metering pulses on a plurality of lines are detected by scanning, a pulse being judged present on the basis of a comparison of the scanning results of three successive scans, a pair of storage elements (cores or magnetic drum areas) associated with each line being employed to record the scan results for a preceding scan and the scan before that, the state of these elements being switched to a characteristic state when a pulse is judged present and being held in that state regardless, of further scanning results until the elements are interrogated in a meter pulse collection cycle of a subscriber's metering total storage arrangement. As shown in Fig. 1 the lines on which metering pulses occur are scanned at AM and the presence of a pulse produces a pulse e in a time position identifying the line of origin. A store MSP contains the pairs of storage elements recording the result of the previous scan and the scan before that and in the time positions associated with the lines these results are presented as outputs m1 and m2 for inspection by a logical circuit AS1 along with the current scan result e. Normally the circuit AS1 produces outputs a1 a2, to update the storage elements in MSP, but when e and m1 indicate a pulse present for two scans and m2 indicates that the pulse was absent before that, the outputs a a2, and their corresponding outputs m1 m2, circulate the result 0, 1 regardless of the result e. As shown in Fig. 2 a pulse tj is analysed by scanning pulses AWM, peculiar to the line bearing the pulse, to produce the locked-up conclusion 0,1 for the outputs m1, m2. Periodically, and between scanning pulses AWM, scanning pulses AWZ occur to collect detected pulse for registration in a subscriber's metering total store in ZSP. The occurrence of a pulse AWZ causes the record in the pair of storage elements in MSP to produce its output signals m1, m2, for inspection by a circuit AS2 and, if the locked-up condition 0,1 exists, this circuit produces an output ad. The subscriber's total is at this time passed through an add-one circuit AD but without increment unless the signal ad is present. If the inputs m1, m2, to circuit AS2 are other than 0,1 the circuit provides outputs a1, a2 to reinscribe the same result back into the storage element pair in MSP. If, however, the inputs are 0,1 and a metering pulse is collected for storage in ZSP, circuit AS2 inscribes 1,1 into the storage element pair in MSP to break the locked-up circulating condition. When next circulated through circuit AS the outputs m1, m2 are converted to 00. The relative pulse rates are set out at the foot of Fig. 2. If mutilations are to be taken into account the pulse rates are increased to allow for one scanning result to be missed. Instead of watching the passage of the leading edge of a pulse the system may be modified to decide on the presence or absence of a pulse by watching the passage of its trailing edge. An alternative arrangement, Figs. 4 to 6 (not shown), has a combined circuit AS1, AS2 Collecting pulses (equivalent to AWZ) in this system coincide with scanning pulses AW and the circuit is gated to allow an ad output whenever a collecting pulse occurs. An ad output is produced whenever m1, m2 are locked-up with values 01 and the circuit AS immediately clears the values to 00. If the e, m1, m2 outputs are currently 110, and before the locked-up values 01 of m1, m2 circulate, coincidence with a collecting pulse produces an ad output and the values of m1 m2 are converted to 11 which circulates until the pulse ceases. If the values of ml, m2 were converted to 00 at this time the pulse could be counted twice. Fig. 7 (not shown) explains how meter stores are arranged on a magnetic drum. The stores are disposed in m tracks and each track has x stores each m bits in length. The provision of m bits allows two tracks to store the signals a1 a2 and produce the signals m1 m2; each of the stores in the m storage tracks thereby having an associated bit position in each of the two additional tracks. Storage may be made in a magnetic core matrix instead of a drum.