Patent GB-685240-A (GB)
Title: Improvements in or relating to telegraph repeater systems
IPC: H04L25/42
Filed: 1950-09-28
Abstract: 685,240. Code telegraphy. SIEMENS & HALSKE AKT.-GES. Sept. 28, 1950 [Oct. 8, 1949], No. 23816/50. Class 40 (iii). In a telegraph system of the start stop type, an arrangement for releasing a distributer in a receiver or a repeater operates so that the releasing means is insensitive to the nature of the current prevailing and is operated solely by a change of the current condition, and means is provided for stopping the distributer when it reaches its normal or stop position independently of the current condition then prevailing in the receiving circuit. In the repeating arrangement, Fig. 1, the movement of the armature e to battery - TB in response to the start impulse causes the winding of the magnet A to be without current for a short period so that a pawl is actuated by a spring to release the control cam disc K of the distributer having discs N<1> ... N<5> which close contacts in timed succession to pass the impulses received by the relay E to a relay S effecting their repetition over the outgoing line a<2>, b<2>. In a modification, Fig. 2, the receiving arrangement is generally similar to that shown in Fig. 1, but the received impulses are stored on condensers C<1>... C<5>. The impulses are repeated over the line a<2>, b<2> under control of cam contact discs M<1> ... M<5> associated with a control disc L released by an electromagnet B under the conjoint control of a cam disc F of the receiver cam assembly and of a synchronous cam disc T. In a further modification, Fig. 5, the receiving distributer is released solely by the change of current in a predetermined direction. When the armature e changes over from the position shown, the capacitor C is oppositely charged and current flows through the rectifier G1 and the winding of the magnet A which rocks a pivoted pawl so that the control cam disc K is released. The movement of the armature e from the contact - TB to the position shown, produces current which flows through the rectifier G<2> to ground, the rectifier G<1> blocking current flow through the winding of the magnet A. A cam disc H opens the circuit of a slow-operating relay U and a cam disc F closes the circuit of a magnet B which on operation releases the control disc L of the repeating cam assembly, the received impulses being stored on condensers C<1>, C<2> ... and repeated by cam discs M<1>, M<2> ..., and the repeating circuit being completed by a contact member closed by a cam disc J. If the armature e of the receiving relay E is against the contact - TB when the distributer reaches its rest position relay, U is energized and at the operated contact u applies negative battery over a contact closed by the disc J in its rest position to the retransmitting relay S which applies a negative impulse to the line a<2>, b<2>. When contact e returns to the position shown, relay U releases, and at contact u positive voltage is applied over the contact closed by the disc J to relay S and over its contact s to the line a<2>, b<2>. Other differentiating arrangements include a condenser connected between the armature and the winding of the releasing magnet, Fig. 3 (not shown), or a primary winding of a transformer connected between the armature and earth, the secondary being in series with the winding of the release magnet, Fig. 4 (not shown). A further arrangement comprises a rectifier bridge with two corners connected respectively to earth via a condenser, to the armature of the receiving relay, the other two corners being connected to the ends of the winding of the release magnet. In a further arrangement, Fig. 7, the armature e<1> in either of its operative positions equalizes the potential on the grid and cathode of the valve R, the resistance W<1> being short-circuited, but during transit, allows the grid to become more negative than the cathode so that the valve R conducts and operates a magnet effecting the release of the distributer. The release of the distributer may be effected consequent upon the received signal exhibiting a change of amplitude accompanied or not by a change in polarity.