Patent GB-344462-A (GB)
IPC: H04L12/40
Filed: 1929-09-04
Abstract: 344,462. Selectors responsive to code signals. RISTOW, A., 13, Wiesbadenerstrasse, Friedenau, Berlin. Sept. 4, 1929, No. 26848. Convention date, Nov. 19, 1928. [Class 40 (iv).] In a selector responding to a definite code in which the lengths of the received impulses are measured by relays or groups of relays, an initial signal of correct duration followed by a space of correct duration must be received before the stepping switch moves from its normal position. The zeroizing circuit includes contacts operated by the impulse-receiving relay and by a relay operated periodically by a local timing means, and this circuit is opened for a predetermined and regulable time, a predetermined and regulable time after each step of the selector switch. As described the selector responds to a code comprising a dash of 4 seconds, two dots each of 1À5 seconds and a final dash of 4 seconds, the impulses being separated by 1À5 second spaces. When the first dash, which must have a current strength exceeding 10 milliamps., is received L energizes completing a circuit for T which has a slow operating lag of 4 seconds. If the signal lasts for 4 seconds, T completes a circuit for V through the primary of induction coil 9. When the dash terminates L and T release breaking the circuit through V which starts to fall away. A pulse is then induced in the secondary of 9 which operates WRI, changing over f2 to break Q, S and make Q1, S1. V has a release period of 3 seconds for its contact a5 and 1À5 seconds for contacts a2, a3 and a4, a2 and a4 closing slightly before a3. After 1À5 seconds from the termination of the dash a2 recompletes the circuit for L which energizes if a dot is coming in. Contact a3 completes the circuit for Z to step the switch and off-normal contact g closes. Contact a4 completes the zeroizing circuit through interrupter 13 if L does not energize. After a further 1À5 seconds a5 makes its upper contact energizing M of WRII, allowing f and e to make contact, re-operating V. When a5 makes its lower contact M1 energizes breaking e, f and V re-commences to release. A space should now be in progress and during this period the zeroizing circuit is open at a4 and the impulsing circuit at a2. After 1À5 seconds contacts a2, a3 and a4 make as before, stepping the selector if a further dot is received. The conclusion of the second dot and the third pause are similarly timed and then the final dash arrives. This first operates as a dot and the selector moves to position 3. After 1À5 seconds a5 makes its top contact and V re-operates. At this time, however, the circuit of L is maintained by g1 which shorts a2 when the selector is on contact 3. After a further 1À5 seconds contact a3 again makes and the selector steps to position 4. One second later T energizes completing the circuit for W and a6 moves over ringing the alarm. Arm a6 remains in this position until it is reset by hand. T energizing re-operates V which releases L and T and V again commences to release. After 1À5 seconds a4 makes and as no signal is now coming in, L is de-energized completing a circuit for Z, through interrupter 13, to step the selector to normal. During the homing motion wiper y completes a circuit for WRI to reset f2 to its normal position. If the first space and dot differ from the second space and dot the relay V will be replaced by a group of relays operated automatically and in turn by controls such as WRII.