Patent GB-295428-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04M3/26
Filed: 1927-05-11
Abstract: 295,428. Automatic Telephone Manufacturing Co., Ltd., end Simpson. L. M. May 17, 1927. Autoamatic exchange systems.-Routine testing apparatus for testing the operation of a coder at all stages sends five-digit numbers into a coder and responds to the resulting code-impulses. The effect of the compensating digits is tested by connecting a differential relay to the + and - leads from the coder and inserting in one lead a resistance equal to that inserted by the coder in the other lead in response to the particular digit sent. Non-response of the relay indicates that the coder is working correctly. The coders are connected up in turn by distributors which move one step at the successful termination of each test cycle. If the coder next to be tested is busy the apparatus waits a reasonable time for it to become idle, but if the busy condition persists a switch in the routiner hunts for the coder, flashes its identifying lamp and causes the distributor to move on. If a second coder is found permanently busy the test is stopped. Faulty operation of a coder at any stage also stops the test an alarm being given whenever this occurs. Lamp signals indicate the stage of the test, the nature of the fault and the coder being tested. If it is necessary to test a particular coder, the distributors are made to hunt for it by inserting a plug in a jack asscciated with its identifying lamp and throwing a " continuous routine " key. Further keys are provided for re-starting the test and for eliminating any of the tests. Specification 229,371 is referred to. Starting test. Operation of key 10, Fig. 6, energizes magnet DM1 of the primary distributor PD and also relay ST which pulls up sluggishly, releases magnet DM1 allowing the wipers to move to their first terminals over which magnet DM2 or secondary distributor SD is energized, and entergizes relays STR, CRR the latter of which releases magnet DM2 after a short interval. If the coder selected is busy, relay A, Fig. 5, pulls up over wiper 32 to delay the test by holding open the circuit of relay B. Seizing coder and transmitting 44444. Relay B, Fig. 5, energizes relay SSD, Fig. 6, and connects relay PS, Fig. 3, to the coder release wire over wiper 32 of distributor SD. Relay PS short-circuits its upper winding to prepare the coder and' mark it busv. If relav PS fails to pull up, relay SDD, Fig. 6, which pulls up sluggishly energizes relay PSS, Fig. 3, in series with lamp 405 and relay PSS locks up and operates the alarm relay FA. Relay SS causes the switch CS to move off normal, energizes relay RA Fig. 6, and connects impulse springs. 81 to relay PA which pulls up in two steps and extends the impulse circuit to magnet DM3 of the sending switch SES which as soon as it moves off-normal energizes relay SA, Fig. 4, Relay SA lights a lamp, connects relay RA to synchronous impulsing springs 413 and energizes relay RB, Fig. 6, which connects ground over a back contact of relay RA and wiper 105 to the pulse wire of the coder. After four impulses have been sent, the sending switch extends ground from wiper 106 of switch CS to relay SZ, Fig. 4, which holds relay RA, makes a homing circuit for the sending switch, unlocks relay PA, energizes the back stroke magnet of sending sequence switch CS and connects impulse circuit 413 to two-step relay QX which extends it to the magnet DM8 of the pause-timing switch PTS. When the sending switch gets home, relay SA releases relay RB and holds relay RA. After six steps, the switch PTS unlocks relay SZ which stops the switch PTS, releases relay QX, allows magnet DM4 to advance the wipers of switch CS and allows relay PA to pull up again to initiate transmission of the next digit. After 5 digits wiper 106 energizes relay SC, Fig. 5, which disconnects springs 81. Pause before receiving coded number. Wiper 106 also energizes relay SDR, Fig. 6, which lights a lamp and connects 4-second impulses on 146 to relay DLP, Fig. 3, which pulls up in two steps and extends the impulse wire to relay DL which at the next impulse disconnects battery and earth connections through the retard TR, Fig. 4, from the line leads to the coder to enable it to begin sending, and locks itself. The coder, before sending, grounds the release wire and if it does this prematurely, the resulting lapse of relay PS, over a back contact of relay PL, lights lamps 405 and energizes relay PSS which locks up and energizes relay FA which gives an alarm. Receiving coded member 4444. Relays LP, HN, LN, Fig. 8, are now connected in series with relay IC across the + and - wires from the coder. The number sent to the coder was 4444, consequently the first code impulse which is " light - " energizes relay LN which connects the grounded wire 169 to relay QS, Fig. 4, and to a two-step relay QA which at the end of the impulse remains locked up by relay QS. The next impulse is " light + " and energizes relay LP which energizes relay MY, Fig. 1, which locks up. The final impulse is again " light - " and relay LM energizes relay XM, Fig. 1, and partly energizes relay QZ which at the end of the impulse releases relay QS and thus itself and relay QA. Relay XM remains locked up at the end of the impulse in series with relay MS which then transfers the operating wires to the 2nd set of storage relays CW - - CZ and relays XC, CS which respond in a similar manner to the next digit. Relay US at the end of the final digit energizes relay S, Fig. 4, which lights the selected lamps in the number indicator and connects 2-second impulses on 191 to a two-step relay TS which transfers them to a two-step relay TSR which in turn transfers them to a relay CD, Fig. 5. The latter locks up under control of relay SS which it releases, extinguishes the lamps and energizes magnet DM5 of switch TES. On the relapse of relay SS relays TS, TSR, CD fall back and the wipers of test-sequence switch TES move to their 2nd terminals. Faults in connection with transmission by coder. (1) Premature sending. This is dealt with in the. last paragraph but one. (2) No sending. Relay Q which is connected to wire 191 by relay DI on pulling up extends it to twostep relay QR this circuit being broken by relay S when relay US pulls up after the last digit is registered. If no digits are sent relay QR locks itself and energizes the alarm relay FA in series with lamp 228. (3) Sending incomplete. Relay QR pulls up as before, but since relay MS is energized, lamp 236 takes the place of lamp 228. (4) Wrong number. Relay WN Fig. 4, which is energized in series with any number indicator lamp other than 4, energizes relay FA in series with lamp 243. (5) Failure to ground release wire during sending. Relay MS energizes relay Z, Fig. 3, which locks up and connects relay ET to the release wire. If the trunk is not grounded, relay CS after the second digit energizes relay FA in series with lamp 284. If it is grounded, relay ET opens the alarm circuit and locks up. (6) Failure to ground pulse wire after sending. This ground energizes relay EP to release relay Z. If relay Z remains energized, relay TSR on pulling up energizes relay FA in series with lamp 289. Transmission, reception, and display of 48888. In position 2 of switch TES, relay SDD is replaced by relay DC, Fig. 8. The relapse and re-energization of relay SS cause the switch CS to go to its 9th position from which, in conjunction with relay DC, it determines the transmission of 48888 to the coder, relay SC falling back to re-connect the impulse springs 81 to relay PA. Relay SDD being un-energized, relay DL pulls up in parallel with SC immediately the last digit has been sent to signal the coder to begin. With relay DC energized, all the lamps but 8 are fed over the wrong number relay WN. The code in this case is " light +," "heavy -," "heavy - " and results in the operation of the W, X and Z relays in the storage groups after which the switch TES goes to its 3rd terminals. Testing effect of compensating digits. In position 3 of switch TES, relay NC pulls up, holds relay DC, connects relay LD in the loop to the coder in place of relays LP, HN, LN and arranged for the transmission of 47777. The code for 7 is " heavy -," " heavy - " and the first of these ;mpulses energizes relay LD which locks up and replaces itself by the two windings of a differential relay CRF which are connected to battery and ground respectively. Since the preliminary digit 4 should not cause the coder to insert any resistance, relay CRF should not respond to the remaining impulses. Relay IC, however, repeats the impulses to magnet DM6 of a counting switch CGS which thus goes to its 9th terminals and energizes relay LI, Fig. 5, which causes relays EP, CD to pull up as soon as the coder grounds the pulse wire. The switches CS, CGS then move to their next starting positions and the switch TES to position 4 in which relay CRA pulls up, holds relay NC, arranges for the transmission of 3 instead of 4 as a compensating digit and removes a shunt from resistance 297 in the negative lead, this resistance being equal to that inserted by the coder in response to the digit 3. In a similar manner, relay CRB in position 5 inserts resistance 306 and arranges for a preliminary digit 2, and in position 6 both relays are energized and the digit 1 is sent. If at any stage relay CRF does pull up, relay CFA energizes the alarm relay FA in series with lamp 337, and locks itself to resetting key 231. Selecting coders in turn. When the switch TES reaches its 7th terminals, relay TSH, Fig. 6, sends it home and relay SDS, Fig. 5, releases relay B to free the coder and energizes magnet DM2 of the distributor SD. When the switch TES reaches normal relay SDS falls back and the distributor wipers move on. When all the coders selected by the switch SD have been tested, it energizes relay DH, Fig. 4, which sends it home, energizes magnet DM1 of the distributor PD, and then falls back allowing the latter to move on. Blank terminals in