Patent GB-343503-A (GB)
Title: Improvements in or relating to automatic or semi-automatic telephone systems
IPC: H04Q3/58
Filed: 1929-10-16
Abstract: 343,503. Automatic exchange systems. STANDARD TELEPHONES & CABLES, Ltd., Columbia House, Aldwych, London. -(Hatton, W. ; 18, Rue de Boudewyns, Antwerp, Belgium.) Oct. 16, 1929, No. 31404. [Class 40 (iv).] Calls originated in a satellite or sub-satellite cause the automatic seizure of a two-way junction from the satellite to a manual position at the main office but do not operate a signal there if the call is local, the junction being released unused. If the call is not local, the local discriminator responds to the whole of the wanted number and then gives the calling signal. No record is made of the value of the number. The main office is provided with register controllers which, however, if the call is external to the office cause it to be extended to an operator's position from a second selector, the register controller being released by a signal sent back from the operator's position. Call finder at satellite, Fig. 2. In response to the operation of starting relays Lsr, Str, the call finders of all idle links are driven by their magnets SMF. The successful one is stopped by its relay Lt which energizes A and makes a driving circuit for SMS which drives the selector to an idle junction being stopped by Jt which energizes Mc. Lb is then operated and makes a circuit for E in series with the cut off relav Cor which stops the other finders. Association of discriminator with junction circuit, Fig. 3. Dlr which pulls up in parallel with the test circuit is followed by Lbr, Ar, Dr, Isr in the out-going end of the junction circuit and Asrt, Brt, Art at the incoming end. Common starting relays Strm, Crm cause the idle discriminators to hunt for the calling junction circuit. Jtrm stops the successful one and Arm makes a series circuit for Er, Clr, only the latter operating at this time. Cr then extends the talking loop and dialling tone goes back from DT at the main office. Discrimination. The first digit is repeated to SM1. Dialling relay Lmrm releases Clr, Cr. As soon as SM1 moves off, SMT starts to follow it, being stopped by Lirm on the group marked by wiper es. At the end of the digit, Cnrm switches the impulse circuit to the magnet SMT for the second digit. Wiper at or bt of SMT is selected according to the condition of the even thousands relav Etr. At the end of the second digit Cnrlm pulls up. If the terminal selected by SMT does not denote a local call, the next two digits cause the operation in turn of Dcrlm, Dcr2m after which a circuit is made for Er which operates Mtr and connects battery over Cslr to the upper junction wire, energizing Bsrt<1> to give the calling signal. If on the other hand the call is local, Mcrm is operated when Cnr1m pulls up at the end of the second digit. If one digit is enough to determine the destination, a is connected to Ltrm3 and Mcrm is operated over Is. Mcrm energizes Ler which removes the test battery, releasing Jt, Mc in the link circuit to free the junction. In the case of zero calls Er is operated to signal the operator over fs and its tenth terminals. Operation of Er on external calls or release of the junction on local ones releases Jtrm which restores the discriminator. Completion of local call. This proceeds as described in Specification 331,223, [Class 40 (iv), Telephones &c.]. Call originated at main office-associating register controller and registering number. When the finder, Fig. 4, of the link circuit finds the calling first finder (not shown) Ar, Cr, Br, Dr, Hr, Sr pull up and also Str, Csr, Fig. 5. PR associates the register controller with the calling second finder whereupon Rtr, Tclr, Tcr are operated and dialling tone is sent back. Rbr pulls up energizing SMA which releases Rbr and on its relapse moves off normal re-operating Rbr which re-energizes SMA causing it to make a further step. The digits are repeated in succession to the registers SMTH .. SMU series relay Ser controIling the sequence switch SMA. Rbr at the beginning of the first digit energizes C, Er in series, releasing Cr to cut off dialling tone, Rtr falls back but Tc1r holds up. Transmission by register controller. When the second digit has been received Tar connects ground over B to the a-wire and battery to the b-wire and assuming the selector is ready B pulls up over the forward loop and energizes Lr which starts the sending switch P1, shunts out B and locks itself. The digits are terminated by Nir. The digit marking control is transferred from one register to the next by sequence relays D1r, D2r, D3r energizers from the later terminals of the sending switch. Just before the switch gets home Lr, Nir are released to allow a new digit to be sent. First selector, Fig. 6. Battery placed on the b-wire by the register controller when it is ready to send energizes Ara. Ecr follows and SMB drives the marking switch in search of the calling link. Bcr stops the switch and is followed by Fcr which sends SMB home and J1r which associates the selector with the common circuit. Bcr falls when the switch moves on and Gcr pulls up when it reaches home putting Bra across the trunk to signal the register controller to send the digit. Bra pulls up energizing Gclr and subsequently repeats the digit to SMB. At the end of the digit, Gcr is released by Ira and opens the loop. PJ now drives the selector until Hcr finds a circuit via ab, dj, cj and test potential in an idle second selector of the wanted group. Hcr locks in series with Scr which energizes J2r to switch the talking circuit through. J1r then frees the control circuit. Completion of outgoing call and release of register controller. In this case the second selector extends the call to an operator's position. Drr lights a calling lamp and energizes Arr which sends back ground to operate Gr, Fig. 4. Gr releases Dr, Er, Cr and cuts out the feed bridge and Tcr, Tc1r release the register controller.