Patent GB-468968-A (GB)
Title: An electrical statistical apparatus peculiarly suitable for use with telephone systems
IPC: H04M3/36
Filed: 1936-01-16
Abstract: 468,968. Automatic exchange systems. SIEMENS BROS. & CO., Ltd., and HUMPHRIES, H. E. Jan. 16, 1936, No. 1448. [Class 40 (iv)] [Also in Groups XIX and XL] The percentage occupancy over an arbitrary period of time of a group of units of apparatus such as telephone junctions is determined by associating the units in turn and in repeated cycles with apparatus which stores one unit of occupancy for each unit of apparatus found occupied and when a predetermined number of such units has been stored effects the operation of a register. For example, if 7200 observations are made in an hour, i.e. the tests for occupied condition are made at ¢-second intervals, the register will be operated once for each 72 occupied-conditions found and the reading of the register at the end of the hour will give the percentage occupancy. The apparatus shown provides for observations on groups of from one to seven junctions which are connected to corresponding positions in the banks 1 .. 7 of a step-by-step switch. Observation on such a group is started by closing a key K individual to the group, marking the position in switch bank 8 and energizing the driving magnet DM. When the marked position is reached relay T operates energizing relay A to start the timing mechanism which is similar to that described in Specification 446,433, [Group XL], and involves a slowrelease relay B and a slow-to-operate relay C which interact in cycles. At each operation of B, before C pulls up, condensers QA, QB, QC, are charged in parallel by the operation of relay J(i) if an occupied condition is encountered and on the release of relay B the condensers discharge in series to a reservoir condenser QD. When the latter has accumulated a predetermined charge it discharges through the gas-discharge tube DT to operate relays D, E which advance register OR by one step, light lamp ORL, and release relay A to restore the condenser &c. circuits to normal. A lamp L illuminates the tube DT to cause it to strike always at the same potential. The successive connections of relay J(i) to wipers 1 .. 7 are effected by a relay chain U .. ZA controlled by relay C. At the first operation of C, when the junction connected to wiper 1 has already been dealt with, relay U(i) operates over contacts za2,.. v2 and v3 .. za1 in series with relay ZB, and connects up wiper 2. At the release of C, relay V(ii) operates over contacts r2, u2, in series with U(i), and removes the short-circuit from its winding (i). At the second operation of C, relay U releases to connect up wiper 3, and relay W(ii) operates over contacts za2 .. v2, v3 and u4, and locks over its winding (i). Operations continue similarly to the end of the chain when after the seventh release of relay C, relays ZA, ZB are released and the original circuit for U is again prepared so that the cycle is repeated. Calibration is effected by operating winding (ii) of relay J over plug TJ to simulate 100 per cent occupancy and adjusting resistance CR to provide the required time interval between two operations of register OR. To observe a group of less than seven junctions, a battery connection is made over the key K to the " commence " wire, if the group does not start at wiper 1, to operate the appropriate relay in the chain, whilst, if the group does not extend to wiper 7, a connection is made over the " finish " wire whereby relay R operates at the correct stage in the operation of the chain to restore the chain to normal. An extension arrangement is described by which groups of up to 21 junctions may be observed three at a time.