Patent GB-331581-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04Q1/20
Filed: 1929-04-05
Abstract: 331,581. Automatic Telephone Manufacturing Co., Ltd., and Simpson, L. M. April 5, 1929. Drawings to Specification. Automatic exchange systems.-A routine tester for selectors gains access to the switches to be tested over switches of the preceding rank which are also available for routing exchange traffic and operate differently dependent on the route over which they are seized. These access switches are provided with one additional relay controlled by the tester only, which, when operated, enables the routiner to hold the switch. The access switch responds to vertical and rotary im- - pulses from the routiner connecting the tester in turn to all (or to a particular one if necessary) of the switches to which it leads. Rotary type switches are provided in the tester for the following purposes : connecting to a particular access switch, controlling the impulses sent to operate this switch to a particular level and contact in that level, for connecting a particular test, sending impulse trains, providing a pause when necessary between two impulse trains and for timing the operating times of the " B " and " ring trip relays. A tuned valve circuit is provided for amplifying tone signals. The embodiment describes the invention as applied to a final selector routine tester, the routiner gaining access to the final switches over exchange group selectors. When the test is originated a rotary type switch steps on to the first access switch terminals and if this switch is free the routiner sends ten impulses to step the switch to the top level and then, after a pause controlled in length bv the movement of a rotary switch over six terminals, one impulse is sent moving the wipers of the access switch on to the first final selector. Lamps in the routiner indicate the access switch in use and the level and contact on which its wipers are stationed. If the final switch, or the access switch, is busy the testing is held up and if busy for a predetermined time an alarm is given. If the final selector is free the direction of current flow in and the ability to operate of its line relay are tested, and if these are correct the final switch is stepped to its ninth level and to the eleventh terminal in that level. These terminals connect to the routiner and consequently as the terminals are arranged to test free, the output of ringing current can be tested. Ring back tone is also checked by amplifying the tone through a tuned valve circuit to enable the tone, if correct, to operate a relay. The called circuit is then looped and a rotary type switch tests the time taken by the ring trip relay to pull up. The routiner now tests the correct battery reversal over the calling loop and if this is correct thf final selector is released, the time between release and the removal of the guarding earth being checked on a rotary switch. The final switch is again stepped to the eleventh contact on-the ninth level which is now arranged to test busy and the return of busy flash and tone over the calling loop is checked, the tone signal being amplified in the valve circuit previously mentioned. If this test is correct the switch is released and then stepped to the eleventh contact of the first level to check the correct response of the final switch to these impulses and if this setting is correct the final switch is released and the access switch moved forward one step to connect the next final selector to the routiner. When all the final switches accessible from the top level of the access have been tested, the access switch is allowed to restore to normal and all switches on the first level, and then on the second level &c. are tested. When all the final selectors to which the access switch leads have been routined the access switch is released and a rotary switch in the tester connects to the next access switch. If P.B.X. type final switches are to be tested the rotary digit sent to the final selector is ten impulses only, this contact being marked busy and auxiliarly to the eleventh contact so that the hunting facility of the switch is tried. Relays in the routiner check the operation of the switch in each test and when a particular test fails to obtain the correct response a lamp signal lights in the routiner to indicate the test on which the apparatus has failed, the testing is stopped and an alarm is given. Facilities are provided for retesting a selector and for continuously routining a particular switch.