Patent GB-339265-A (GB)
Title: Improvements relating to electric receiving and/or signalling apparatus
IPC: H04L15/26
Filed: 1929-09-03
Abstract: 339,265. Siemens Bros. & Co., Ltd., and Humphries, H. E. Sept. 3, 1929. Code - signal transmitters.-For intercalling between wireless stations or for other purposes, a signal consisting of a sequence of long and short marks is transmitted or received by apparatus in which the length of a mark is measured by counting the beats of a timing element, means being provided for allotting either a long or a short value to any m a r k of the sequence. The apparatus shown provides for a sequence of three marks, giving a choice of 8 signals, but by strapping certain terminals it will deal with signals of two marks or one. When used as a transmitter it sends marks of 8¢ or 12¢ seconds separated by spaces of 1 second, but when used as a receiver it accepts any mark within the limits 7¢-10¢ or 11¢-14¢ seconds and any space not exceeding 1¢ second. The apparatus consists entirely of relays; the timing element is a pair of relays Y, Z which beat with a ¢ second period; the beats are counted on a chain-register A - - J; spaces are measured during transmission by the same register, but during reception by a separate chain of sluggish relays PA - - PD; the sequence of correct and correctly-spaced marks is recorded by relays MA - - L. During transmission the determination whether the three marks are to have long or short values is effected by the depression or not of keys AK, BK, CK. During reception the determination whether the three marks are to be judged by long or short criteria is effected by the strapping or not of terminals AT, BT, CT to ZT. Time measurement of marks. The unit of time is the beat period (¢ second) of a pair of interacting relays Y, Z, the relay Z having a condenser QA in parallel and a choke ZC in series. The time can be adjusted by a series of resistances YA. During a mark, relays S, SA fall back (SA being shorted by S so as not to be affected by a momentary signal), Y, Z are put into action, and the beats of Y are recorded on a relay register A - - H of the type described in Specification 221,316. The relays A, B perform a cycle of twice the period of Y, and control a second pair C, D which cycle at a period twice as great again, and so on. The period of the complete chain A - - H is therefore 8 seconds, and the addition of a relay J which records that one cycle has been completed allows measurements to be made up to 15 seconds. At every half-second a different combination of the relays A - - J is energized and may be arranged to close a distinctive time-indicating circuit. On the cessation of a mark, S, SA fall back, the register A - - J is restored, and Y, Z are put out of action, QA being disconnected from Z and connected to YB to secure its own quick discharge and the quick release of Z. Operation as receiver : first mark. It will first be assumed that the station signal consists of three short marks. At 7¢ seconds G falls away while H remains energized, so that a circuit is closed for J (i). An instant later H falls away and opens a short round K (i), which energizes in series with J (i), locks itself over winding (ii), and energizes MA which energizes PA. Relay PA opens a circuit by which R would otherwise be energized at the termination of the mark, and thereby certifies the mark as having the prescribed minimum duration. At 10¢ seconds, C, E, K would all be energized and close a circuit for R, to indicate that 'the mark has exceeded the prescribed maximum, but if the mark is correct SA re-operates and unlocks the register A - - J in time to prevent this circuit from being closed. First space. Relay K is also unlocked by SA and allows MB to energize in series with MA and PB in series with PA, and PC, PD are also energized. Relay PD shorts PA, which shorts PB, which shorts PC, which shorts PD, and after 1¢ seconds a circuit would be closed by SA, PA, PD for R, but if the space is of permissible length SA falls away again in time to prevent this. Second mark. At 7¢ seconds K again operates, closing a differential circuit MA (ii) to release MA while holding MB, and MC is energized and locks. At the end of the mark SA unlocks relays A - - K and MB is de-energized. Third mark. At 7¢ seconds K energizes MA, and at the end of the mark K falls away, MB is energized in series with MA, and L is energized to ring the call bell CB and to prevent SA from being shorted by further signals. Incorrect and jambing signals. If a space is too long or a mark too short, R is energized over a front contact of SA and back contacts of PA, PD and unlocks MA, MB, MC to obliterate any partial record that may have been effected. If a mark is too long, R is energized (as described for the first mark) over front contacts of E, C, K and locks itself under control of K alone, which remains energized as long as the mark continues. At 16 seconds. Hand K being operated and G released, a differential circuit J (ii) is closed to release J, and at every succeeding energization of A (i.e. once a second) a circuit is closed for a buzzer BZ to indicate that the station is being jambed. Signals involving long marks. Assuming that the station signal consists of a. long, a short, and a long mark, terminals AT and CT but not BT would be strapped to ZT. At 7¢ seconds in the first mark, when the release of H would otherwise remove a short from K (i), K remains shorted over AT, and the short is not removed until G again operates at 11¢ seconds. Thus 11¢ seconds (instead of 7¢) must elapse before K is energized to certify that the mark is of the requisite minimum duration. The next energization of C and E occurs at 14¢ seconds, so that 14¢ seconds (instead of 10¢) must elapse before R can be energized to indicate that the mark is impermissibly long. During the second mark MB is energized to connect BT in place of AT, but without effect since BT is not strapped. During the third mark MB is de-energized and MC energized, whereby CT is connected and the criteria of a long mark are again applied. Operation as transmitter. The code of a wanted station is set up on keys AK, BK, CK (keys corresponding to long marks being depressed) and a start key SK is momentarily pressed. The apparatus then transmits marks and spaces of correct nominal duration, 8¢ or 12¢ seconds for a mark and 1 second for a space. The timing operations are much the same as in receiving, except that spaces are measured on the register A - - J, the relays PA - - PD functioning idly. It will be assumed first that three short marks are to be sent, so that none of the keys AK, BK, CK are depressed. Relay W is energized by SK, locks up, and energizes WA. Relay TO is energized to start transmission and SA is de-energized to put the timing relays into action. At 7¢ seconds K operates and energizes MA, and at 8¢ seconds C operates and de-energizes TC to terminate the mark. At 9¢ seconds C falls away and re-energizes TC to start the second mark, and at the same moment E operates and energizes R which energizes SA (i) to unlock A - - K, whereupon R, SA fall back. Owing to the release of K, MB is now energized in series with MA and connects key BK in place of AK. The second mark is terminated in the same way, the operation of K de-energizing MA and energizing MO and the release of K de-energizing MB, so that key CK is connected, and the third mark is started. At 7¢ seconds K operates and energizes MA; at 8¢ seconds transmission is stopped; at 9¢ seconds K is de-energized, R, MB, L are energized, and W is unlocked to bring the operations to a close. Relay R is locked by W and L until W has had time to fall back. The bell CB rings momentarily to notify the operator that transmission is completed. If any of the keys AK, BK, CK are depressed the effect is the same as that of strapping the terminals AT, BT, CT to ZT in receiving, that is to say 4 seconds is added to the criterion of the corresponding marks. Modifications. (1) By connecting terminals 23, 24 together the apparatus serves for signals of two marks (choice of 4 stations) and by connecting 21 to 20 instead of 22 it serves for single-mark signals (choice of 2 stations). (2) By connecting relay Q as shown, the times at which G, H, J and K operate are advanced by 4 seconds, whereby the apparatus is enabled to deal with marks of 4¢ and 8¢ seconds duration instead of 8¢ and 12¢. (3) The capacity of QA may be reduced to shorten the nominal duration of a mark, in which case relays W, TC may introduce a supplementary condenser during the space periods of transmission to prevent a corresponding shortening of the spaces.