Patent GB-423526-A (GB)
Title: Improvements in or relating to printing telegraph systems
IPC: H04L1/08
Filed: 1933-08-24
Abstract: 423,526. Type-printing telegraphy. MARCONI'S WIRELESS TELEGRAPH CO., Ltd., Marconi House, Strand, London.-(Assignees of Mathes, R. E. ; 755, Belvidere Avenue, Westfield, New Jersey, U.S.A.) Aug. 24, 1933, No. 23603. Convention date, Sept. 15, 1932. [Classes 40 (iii) and 40 (v)] Relates to the reinsertion of start and stop impulses in messages which are received from a start-stop transmitter, sent on by a system which employs synchronized impulses and is protected against parasites by the Verdan method, retranslated into start-stop characters, and distributed to a group of stock-tickers or printers. The translation may be effected by means of a reperforator or of an impulse-repeater. A master transmitter sends characters each comprising six code impulses together with start and stop impulses to a reperforator B, Fig. 1, which perforates a 6-hole tape and feeds this to the transmitter C. The latter feeds a distributer and relay D which stores the signals and sends them three times at intervals over the line or wireless circuit a, for the purpose of eliminating parasites by the Verdan method. The signals are received by a synchronized distributer and relay V which automatically compares the three versions of the message, and feeds a reperforator W. The reperforated tape is passed to a transmitter X which sends on signals through a distributer Y (Fig. 5, not shown), which inserts start and stop impulses, to line L or to a series of relays which distribute the impulses to a group of printers. In a further modification (Fig. 2, not shown) the signals received from line L are of the cadence type instead of the start-stop type, and a contact-making repeater is used instead of a reperforator. The parts W, X, Fig. 1, and relay SOR, Fig. 4, may be replaced by storing relays or condensers ; and the selector magnets of the receiver B may operate sending-on relays instead of punches (Fig. 3b, not shown). Reperforating receiver. The receiver B, Fig. 1, is of the start-stop type shown in Fig. 3, and produces a six-hole tape for retransmission without the start and stop signals. The start signal received from armature a operates the start magnet M2, and impulses are then distributed to the six selector magnets SM. The energized magnets lock up, so that when the punch magnets PM are energized through the stop segment SS so as to pull down the selector bars SB, Fig. 3a, the selected armatures SMA enter notches N and permit the corresponding punches P to be operated. The locking circuits of the selector magnets SM are eventually broken at m<1> owing to an impulse sent by a segment between the stop and start segments. Means are provided for punching centre-holes only when transmission ceases, during an interval long enough to prevent punched portions of the tape from being held idle in the loop. Elimination of parasites by the Verdan method. The transmitting distributer and relay D, Fig. 1, and the receiving relay and distributer V are shown in Fig. 4. Each six-impulse character is sent three times by means of the first eighteen segments of distributer MDT, the remaining two segments serving for synchronizing-signals. The connections for only the first of the six impulses are shown. The first impulse passes to line L from tape-transmitter contact TTC through brushes B1, B2, and segments 1D, 1A. At the same time, charges representing the impulse are stored in condensers C1 and C2 through segments 1G, 1E and 1H, 1F respectively. Subsequently the condensers are discharged through the line relay via the brushes and segments 1E, 1B and 1F, 1C, respectively, so that each impulse is sent three times. At the receiver, the receipt of a marking impulse or a parasite throws armature RR on to its upper or dead contact, while a space signal connects up the battery B. Therefore for the first of the six impulses, a disconnection at RR must be received three times at the receiver, if condenser C3 is to escape being charged through one of the segments 1AR, 1BR, 1CR. If the condenser becomes charged, it is discharged at the third transmission through the sending-on-relay SOR. The first of the six impulses is thus dealt with, and circuits are provided for the remaining five impulses. The Verdan principle may alternatively be carried out by means of pin drums or discs, magnetic-tape records, or storing-relays or condensers, and the impulses may be jumbled for secrecy.