Patent GB-205783-A (GB)
Title: Improvement in cable telegraphy
IPC: H04L25/46
Filed: 1923-03-29
Abstract: 205,783. Western Union Telegraph Co., (Assignees of Benjamin, G. R., and Angel, H.). Oct. 23, 1922, [Convention date]. Type-printing telegraphs.-The receiving equipment of a synchronous type-printing telegraph system comprises a line relay, a printer including selecting magnets and a co-operating distributor, a vibrated fork provided with a synchronizing actuating magnet controlled by the signal impulses through a fork relay, and a printer relay coacting with the fork to control the impulses passing to the printer, the line relay controlling the fork relay and the printer relay. The fork is tuned to a multiple of the transmission speed, making preferably one complete vibration in the time of sending to line a single impulse of unit length. The speed of transmission is such that only impulses of longer duration than that of a single unit affect the cable relay at the receiver, and the fork serves to interpolate the missing impulses. The transmitting tape 12 is fed across a table 15 provided with holes disposed above pins 14 the number of which is that of the units in the code, e.g. five as shown, and these pins are attached to levers 16 held up by springs 18 against levers 20 which are operated successively against the returning action of springs 23 by cams 25 equally spaced on a shaft 10 driven by a phonio wheel PW controlled by a fork F. The pins 14 or the tape perforations are staggered to enable each pin to rise at the proper instant to enter the corresponding perforation. A pivoted table 32, held against the upper surfaces of the levers 16 by a spring 34, carries a pole changer PC movable between contacts 30, 31 to transmit marking and spacing impulses to transmitting relays 42, 43 through contacts 38, 39. Curbing at transmitter.-The duration of the transmitted impulses is curbed by cams on the periphery of a disc 47 on the shaft 10, the spaces between the cams allowing the contacts 38, 39 to separate. A similar transmitting arrangement utilizing a Wheatstone perforated tape is illustrated at T'. Siphon-recording devices.-A local record is produced at the transmitting station by connection of the pole changer PC through contacts 51, 52 to a siphon recorder 56, the impulses being curbed by a cam disc 58 on the shaft 10 controlling the separation of the contacts, and, to facilitate reading of the message on the tape 60 of this recorder, means are provided for spacing the successive code characters. For this purpose the shaft 10 carries a cam 70 serving, once in each revolution after actuation of the fifth lever 16, to close contacts 72, 73 in a circuit in which a solenoid 67 and a magnet 63 are arranged in parallel, thus clamping the tape 60 between the armature and the pole-pieces of the magnet 63. This magnet is simultaneously moved forwards owing to connection of its support 64 to the sliding plunger 65 of the solenoid 67, thus advancing the tape between successive code characters. The tape is released just before the end of the stroke of the plunger 65 by the engagement of a hook 80 carried by the support 64 with a spring arm carrying a contact 78 which is thus separated from a contact 76 to break the circuit of the magnet 63. Restoring or modifying imperfect signals and distribution to printer. Transmitted impulses of the type indicated at a, Fig. 4, are received by the cable relay CR in the form shown at d, Fig. 4, since transmitted impulses of unit length do not affect the relay and the length of the longer impulses is curtailed. A fork TF, tuned to make one complete vibration in the time of sending to line a single impulse of unit length, is maintained in synchronism and in correct phase with the transmitter by the energizing of a magnet 150 from a relay FR whenever a spacing impulse is received by the relay CR. The relay FR and the stronger winding 125 of the printer relay PR are arranged in a circuit 120 from a battery 108 through the marking relay 105 or the spacing relay 106 controlled in accordance with the position of the contact arm 101 of the relay CR on its rotating drum 102. One tine f<1> of the fork TF moves between a contact 130 connected to the armature of the relay PR and a contact 131 connected to the weaker winding 126 of this relay. The other tine f<2> closes at each vibration contacts 132, 133 in the circuit of a magnet 115 which, through a lever 113 and pawls 112, 116, rotates a ratchet-wheel 114 on the shaft 110 of the distributor D half a tooth at each energization and deenergization. Spirally-arranged lugs 109 on the shaft 110 act successively to move levers d<1> - - d<5>, connected respectively to the selecting magnets 1 - - 5 of the printer P, against contacts d<0> connected to the marking contact of the relay PR, and a switch lug 109 thereupon moves a lever d<6> to close the circuit of the printing magnet 118. When the tine f' comes against the contact 130, a condenser K is charged positively or negatively according as the armature of the relay PR is against its spacing or its marking contact. When the tine comes against the contact 131, the condenser discharges through the winding 126 of the relay, and this discharge is only effective to move the armature when the stronger winding 125 is deenergized owing to the relay CR being unaffected, the effect being thus to interpolate the missing single unit impulses and transmit them to the distributor D. A spihon recorder 56<1>, similar to the recorder 56 at the transmitting station, is adapted to be connected by a switch 111 either in shunt on the circuit 120 to record the impulses affecting the relay OR or in shunt on the lead connecting the contact 130 to the armature of the relay PR to record the impulses sent to the printer. The circuit of the magnet 63<1> and solenoid 67<1> of this recorder is closed for spacing the successive code characters by the action of a lug 109<1> on the shaft 110 moving a lever d<8> against a contact d<9>. To eliminate the usual allowance of line time for printing, each impulse received over the lever d' traverses a coil c<1> of a relay OR, causing the armature of this relay to close a circuit through the magnet 1, coil c<2> of the relay lead 154, and a lever d<10> to a contact d<12>, and this circuit remains closed until a lug 109<11> on the shaft 110 raises the lever d<10> off the contact d<12>. Each impulse received by the magnet 1 is thus locked until the printing magnet 118 has registered the preceding character, and the printing of one character may therefore be effected simultaneously with the reception of the first impulse of the preceding character. The impulses received by the magnet 2 may also be locked similarly. Synchronous movements.-The fork TF maintains the shaft 110 in synchronism with the shaft 10 during the transmission of signals, and the distributor may be stepped into phase by operating a key 119. To maintain synchronism when the end of the tape 12 has.passed through the transmitter, a lever 162, Fig. 3, is arranged to drop into a slot in the table 15, thereby closing contacts 164 to energize a magnet 161 which moves a lever 160 on to the levers 16. The lever 160 is formed with a notch over the central lever 16, thus allowing this lever to rise to transmit a synchronizing impulse to line once in each revolution of the shaft 10.