Patent GB-276587-A (GB)
Title: Improvements in or relating to telegraph circuits for diplex and quadruplex working
IPC: H04L5/04
Filed: 1927-03-31
Abstract: 276,587. Nielsen, T. C. V. March 31, 1927. Diplex and quadruplex telegraphs; perforated strip recorders.-In a diplex transmission the current changes necessary in the primary signals to produce the secondary signals are effected at such times as the transmission of the primary signals, irrespective of the secondary signals, requires a change of current over the signalling circuit. Fig. 1 shows a system in which the primary message is transmitted by changes of current strength and the secondary message by changes of polarity. The primary key 2 controlled by one Wheatstone transmitter connects 100 or 50 volts of the battery 12 to the line 14 according as it makes contact at 3 or at 4, and the secondary key 5 controlled by the other Wheatstone transmitter determines the polarity of the transmission. At the receiving station the line 14 is earthed through the windings of polarized relays I - - III in series, of which the armatures 31 - - 33 move between contacts 21 and 22, 23 and 24, 25 and 26- respectively connected to opposite poles of a battery 45 earthed at its mid-point. The armature 33 is unbiassed but the armatures 31 and 32 are biassed to remain against contacts 22 and 23 respectively, the former until a negative, and the latter until a positive voltage greater than 50 volts energizes the relay windings. The armatures 31 and 32 are connected through the winding of a relay IV of which the armature 34 moves between contacts 27 and 28 connected to opposite poles of the battery 45. The armature 33 is earthed through the winding of a relay V of which the armature 35 moves between contacts 29 and 30 connected to opposite poles of the battery 45 through magnets 37 and 38 respectively. The armature 34 is connected to earth through an undulator 47 which records the primary message, and also through a condenser 41 and a magnet 39. The armature 35 is connected to earth through a condenser 40. The magnet 39 actuates the feed-perforation punch and the magnets 37, 38 each actuate one of the signal - perforation punches in a tape for recording the secondary message, the tape being fed forward half the distance between two centreholes for each impulse through the magnet 39, and signal perforating punch being spaced a similar distance in front of the other. Fig. 3 shows modified circuit arrangements. The primary key moves between a spacing contact 62 and a marking contact 61 connected through the secondary key 63 to one or other pole of the battery 66 earthed at its midpoint. At the receiving station the line 67 is earthed through the windings of polarized relays VI, VII of which the armatures 70, 71 are biassed against contacts 73, 74 respectively and are each connected to earth through a separate winding of a polarized relay VIII and a condenser. The contacts 72, 73 of relay VI and 74, 75 of relay VII are connected as shown to batteries 82 and 83 respectively and to magnets 76, 77 respectively which actuate the punches for recording the secondary message. The relay VIII controls the recording of the primary message. Fig. 5 shows means for controlling the operation of two transmitters in accordance with the invention. The key 101 actuated by the primary transmitter 147 alternately connects line 104 to marking and spacing contacts 102, 103. The contact 102 is connected to + or - battery 105 according to the position of the armature 106 of a relay IX, and the winding of this relay is connected to + or - battery 113 through a condenser 109 and the key 110 actuated by the secondary transmitter, and is connected to earth through a contact 118 closed by the primary transmitter only when the spacing contact 103 of the latter is connected to line. The key 101 carries a tongue 126 earthed through a condenser 120 and moving between an earthed contact 124 and a contact 123 connected to battery 121 through a magnet 122. The condenser 120 is thus charged through contact 123 and magnet 120 at each marking contact and discharged through the contact 124 at each spacing contact made by the transmitter 101, and at each energization of the magnet 122 its armature disengages a stop 133 to permit a halfrevolution of a shaft 136 carrying cams 134. During this half-revolution one of the cams 134 actuates a follower 129 carrying a pawl 135 acting on a ratchet wheel 131 on the tape-feeding shaft of the secondary transmitter, thus feeding the tape one step.