Patent GB-333300-A (GB)
Title: Improvements in or relating to testing arrangements for automatic or semi-automatic telephone systems
IPC: H04M3/32
Filed: 1929-05-14
Abstract: 333,300. Standard Telephones & Cables, Ltd., (Deakin, G., and Polinkowsky, L.). May 14, 1929. Automatic exchange systems. - Routine testers are provided for testing link circuits (comprising line finders and group selectors) and numerical selectors controlled by common control circuits. The routiner in each case controls the setting up of a call to a predetermined number which when reached causes the routiner to release the switch train and step on to the next switch to be tested. Routining is held up on busy switches and on switches with busy control circuits. When testing the link circuits connection is suspended if any finders in the group required are hunt. ing. Provision is made for testing the control switches in turn without testing all the conversation switches associated with them and for continuously routining a particular switch. General operation. The routiner T1 (Fig. 1) selects a link over TF and if all the line finders in the group are at rest the link to be tested connects itself to TL. A number routing to either trunk STL (representing an operator call) or to 1TL is dialled into the register controller which controls the setting of a switch train to the trunk dialled. When the routiner receives the call the train is released and TF selects another link for test. Routiners T2 and T3 control respectively settings over 2GF and FF and FF only to trunks 2TL and 3TL. The routiners are stopped and a signal given if the correct line is not selected. The routiners are described for testing switches of the type described in Specification 318,945. Testing link circuit (Fig. 2). When the start key AK is pressed, Tr pulls up and Cr energizes. If any of the line finders in the group are hunting Csr is operated and consequently Or energizes. When the finders come to rest Or falls back and Sr energizes followed by Lr. Relay Lr marks the link required over brush a of TF and energizes Hsr to start the line finders 2LF (Fig. 1) hunting. When the selected link is connected up Er energizes breaking the circuit of Lr and energizing Fr. Relay Br is con. nected to the register controller and if this has not yet been connected up Br energizes over front contact Ar. When the controller is seized Br releases and a circuit is completed for driving magnet IP of impulse sending switch IF. Switch IF can send either fast or slow impulse trains dependent on whether EK is operated or not the contacts wiped by c being smaller and nearer together than those wiped by e. The predetermined impulse series is transmitted over TL, Dr energizing to short circuit further impulses when the number required for each digit has been sent. The digit trains are counted by relays Gr-Jr and when all four have been sent (or two only if SK has been operated to simulate an " operator " call). The routiner waits for the completion of the test call. When the test line 1TL is seized Rr energizes breaking the forward loop and releasing the switch train. When booster metering battery is connected to the test wire, Mr energizes releasing all theenergized relays except Ar. A circuit is completed for PF which drives TF. When brush d leaves the terminal on which it is standing Ar releases and on reaching the next terminal Tr pulls up, breaking the circuit of PF and the test cycle is repeated. If this terminal is busy the tester stops but can be made to move another step by operation of DK. By operating keys TK and CK and then keys UK and OK the tester can be stepped to a particular link which can be continuously routined by the operation of key IK. By plugging into jack MJ transmission of dialling tone from the register controller can be checked. The keys GK, HK, JK enable a 20,000 ohm leak, a 1,000 ohm line and an extension set respectively to be introduced on the test line. Testing group selectors (Fig. 3). Key 2AK is depressed and 2Tr energizes as before. When the group selector selected and its associated control circuit are free relay Br energizes and 2Cr pulls up. Relays 2Ar and Kr energize. Revertive impulses are returned by the group selector and are repeated by Pr to RTS, the digits being counted out. first by wiper a and the last two by wiper d, the group selector and final switches being thus set to a predetermined position connecting with circuit 2TL. When this line is seized. relays 2Er, 2Fr and 2Or energize followed bv 2Gr. Relay 2Cr falls away restoring RTS and releasing all operated relays except 2Ar. The switch TGF steps to the next terminals as described before and the test cycle is repeated. If the group, selector or its control circuit is busy 2Br remains de-energized. The switch can be stepped to the next circuit by key 2DK. Keys 2TK, 2UK, 2CK and 2IK enable a particular selector to be continuously routined whilst key 2EK enables only one group selector in each control circuit group to be tested providing means for quickly testing the whole of the control circuits. If a line other than the predetermined line is connected up 20r operates when the called subscriber replies but not 2Er and 2Fr. The switch train is released and the routiner stopped. The key 2PK enables the line conditions in the fundamental loop to be varied. A similar switch which receives two digits only is described for testing final selectors. In addition to the above tests this switch tests the output of ringing current whilst a jack is provided by means of which ringing tone output may be verified. Arrangements for testing for the return of busy tone on engaged lines are also provided.