Patent GB-701602-A (GB)
Title: Improvements in or relating to telegraph systems and apparatus
Inventor: MONTESSORI GIUSEPPE
IPC: H04L25/24
Filed: 1951-05-04
Abstract: 701,602. Code telegraphy; multiplex telegraph systems. ITALCABLE SERVIZI CABLOGRAFICI RADIOTELEGRAFICI E RADIOELETTRICI. May 4, 1951 [May 16, 1950], No. 10579/51. Class 40 (3). [Also in Group XXXV] In a telegraph system, means for achieving synchronism with the received signals and/ or for signal regeneration and/or multiplex operation comprises a cyclically operating time division unit forming a distributer and producing two or more impulses during the period of a basic signal element, said impulses being obtained by division from a constantly produced series of pulses of greater frequency, a correction unit which compares the beginning of a received signal with the pulse or pulses of the timing arrangement and operates to increase or decrease the higher number of impulses so that, following the subdivision process, the phase of the timing arrangement is altered to conform to the phase of the incoming signal. The synchronized timing arrangement controls the signal sampling instants, regenerating operation, and, in the case of multiplex systems, the channel distribution of the successive elements in Morse cable code. In the case of the five-unit code with multi-channel operation, a further valve distributer arrangement is added to separate the sets of five code elements and to insert the normal start and stop elements of the separate five-unit signals for the respective channels. Circuit arrangements. - The corrector arrangement, Fig. 3, is supplied at 31 with oscillations of the prescribed higher frequency, and the valves 32, 33 are operated normally to produce sharp negative pulses at the prescribed frequency. Leading or lagging correcting impulses apnlied at A. R cause the number of pulses appearing at the output of the valve 33 to be increased or decreased. The output pulses from the valve 33 are applied to a four-stage dividing circuit, Fig. 4 (not shown), whose output is applied at 57 to the timing distributer arrangement, Fig. 5, arranged and connected so that reversed potential changes occur at the pairs of points 51, 51<SP>1</SP> ... 56, 56<SP>1</SP> in succession in response to the train of pulses applied at 57. Neon tubes 511 ... 516 in the anode circuits of the right-hand sections of the double triodes may be connected by a switch 510 to a positive source so that they light up in synchronism with the changeover of the successive valves, or in the right-hand position of the switch 510, the positive source is connected when a signal element arrives so that the lamp illuminated indicates the phase of the signal relative to the timing distributer. Correction-determining circuit, Fig..6.-The impulses to be derived at A, R for application to the circuit, Fig. 3, are generated by the conjoint operation of a relay 67 responding to the signal elements received over the line S and a relay 64 controlled by a valve 65 to whose grid are applied negative voltages at points 51', 52<SP>1</SP>, 53' tied to the points on the first three valves of the distributer arrangement, Fig. 5. Normally the combined voltages at 51', 52<SP>1</SP>, 53' hold the valve 65 conducting so that the armature of the relay 64 is held on the contact 1. During the period of the first three impulses of the distributer, one of the voltages at 51', 52', 53' becomes negative so that the valve no longer conducts and the armature moves to the position r and if the line relay 67 changes over during this period, a correcting impulse is applied at R. If the changeover of the line relay 67 occurs during the second half of the distributer cycle, i.e. before the reversals take place at the first three valves of Fig. 5, since the voltages at 51', 52', 53' will all be positive, relay 64 will be operated to the 1 position so that a correcting impulse is applied over the connection A. The correcting impulses are successively applied until the distributer timing arrangement reaches the correct phase position and then are applied alternately at A and R. Regeneration and multiplex arrangements.- The received signals in the Morse cable code are applied to dot and dash relays, Fig. 7 (not shown), and the separate associated retransmitting relays have their operating circuits completed through a valve rendered conducting by connection at 53 or 54 to the third or fourth valve of the distributer arrangement. The relays remain in their operated position until an impulse arrives from the subsequent cycle of the distributer, so that the regenerated signals are of correct duration. The transmission of the successive signal elements into alternate channels is obtained by a double triode trigger valve which is switched from one position to the other during successive cycles of the distributer by a connection to the corresponding point 53' or 54<SP>1</SP> of the distributer timing arrangement, Fig. 5. A modification, Fig. 8 (not shown), describes an arrangement in which the timing distributer produces solely two pulses during the length of the basic signal element with consequent modification in the regenerating circuit, and a further arrangement, Fig. 9 (not shown), employs a double triode in place of a signal receiving relay and is entirely electronic. Inter-signal earthing arrangements. - For breaking up block signals or reinserting a short interval between signals of the same nature, e.g. successive dots or dashes, a valve controlling restoring windings of the output relays is operated by a connection to a point, such as 52, preceding the points 53 which controls signal sampling and regeneration so that the preceding signal element is terminated a short interval, e.g. a sixth of a signal period, before the beginning of the subsequent regenerated signal. In a further modification, Fig. 11 (not shown), for multiplex operation, the signals are regenerated in separate circuits so that signals from a teleprinter or the like at a repeater station may be fed to one of the channels. Multiplex arrangement for the five-unit code. -An additional distributer, Fig. 12 (not shown), separates successive five-unit signals for distribution to the alternate channels and controls relays for inserting the appropriate start and stop signal elements for the signals in the respective channels.