Patent GB-287292-A (GB)
Title: Multi-channel systems of telegraphy
IPC: H04L5/22
Filed: 1927-02-15
Abstract: 287,292. Pernot, F. E. Feb. 15, 1927. Addition to 265,806. Diplex and multiplex telegraphs; automatic telegraph; automatic transmitters; curbing at transmitter; restoring or modifying imperfect signals; repeating systems using contact-making relays.-The parent Specification relates to code telegraphy wherein the " dot " and " dash " elements are of different polarity but of equal duration, and describes means whereby signals from two or more transmitters running at different but related speeds are aggregated at the transmitting station for transmission as a simple message and segregated and re-shaped at the receiving station, synchronism being maintained throughout the system. According to the present invention a similar result is obtained with apparatus involving a single commutator ring at each station. Aggregating means. In the example illustrated a transmitter A, Fig. 1, runs at twice the speed of the transmitter B, so that two signals A1, A2, are sent by the former for each signal B of the latter, as shown in lines C, D, Fig. 3. One terminal of transmitter A is connected to both distributor segments a1, a2, Fig. 1, while the transmitter B is connected to the segment b, and one revolution of the distributor corresponds to the emission of two code elements from A or one from B. The effect of interruption by the brush 8, however, is that the signals sent to line are evenly spaced as at A1, B, A2 in line G, Fig. 3. Segregating means. The receiving station, Fig. 2, includes a regenerator and synchronizer 17, of the kind described in Specification 213,302. Signals from the line are regenerated by means not shown and control the contact arms 26, 33, so that the apparatus 17 retransmits dash ' signals through the contact arms 26 to the magnets 22, 23, which pertain respectively to the receivers SB, SA, while 'dot' signals are retransmitted through the arm 33 to the magnets 24, 25. The signals are delivered by the distributor 18 to the appropriate receivers SA, SB, which reproduce and reshape the segregated messages by means of hold-on mechanism. The signals received from the line are shown at H, Fig. 4, while the restored signals are shown at Q and R. Thus if a ' dash ' A1 be received while the brush 21 is on the segment a1, a circuit is closed from the battery 61 through the windings 55, 55<1>, in parallel, armature 37 (the ' dash ' magnet 23 being energized by the signal), brush 21, distributor ring a1 and contact 59, at the moment (t1, Fig. 4), when the cam 53 closes that contact. The " flick " magnet 55<1> closes a hold-on circuit, and the magnet 55 remains energized (A1, line M) after contact is broken at the distributor (t5) and until contact is broken by the cam 53 at time t3. The magnet 55 acts to depress the selector rod 81, Fig. 5, into the path of the lever 82 so that when (at time t2) this lever is moved to the right, the rod 81 is moved thereby and pushes over the lever 86 and separate slide rod 84, the lever 86 being then held by the arm 87 which drops behind its top, while the rod 84 closes a ' dash ' contact 85 for initiating an outgoing dash signal. The contact 85 remains closed until (at time t4) the arm 87 is re-set by the cam 79 acting through the lever 88. A similar mechanism is provided for the ' dot ' magnet 56, which is controlled by armature 39 of magnet 25, and the apparatus SB is similar to SA except that the cam 54 rotates at the same speed as the commutator 18 whereas the cam 53 rotates at twice that speed. Generalization. In the general case there may be more than two channels, the signalling speeds therein having any suitable relation : thus there may be three channels, A, B, C, having speed ratios 5: 2 : 1, the number of segments on each commutator being equal to the sum of these three numbers and arranged in the order A1, B1, A2, A3, B2, A4, C, A5.