Patent GB-582996-A (GB)
Title: Improvements in and relating to telegraphic receiving apparatus
IPC: H04L15/28
Filed: 1944-06-16
Abstract: 582,996. Electric telegraphs. OLSEN, L. C. June 16, 1944, No. 11537. [Class 40 (iii)] A strip-perforating telegraphic receiver for land-line morse signals is sensitive to incoming changes from marking to spacing and vice versa during alternate time intervals of length equal to that of a dot, the acceptance and blocking intervals being distinguished by mechanical means. The effect of interference is thus diminished; a momentary interruption in a dot, for instance, will not be registered since it occurs during a time interval in which the receiver is insensitive to changes from marking to spacing. The marking and spacing punches 7, 8, Fig. 3 (section on III-III on Fig. 1, looking down) are actuated by punch hammers 27, 28, but only if at the moments when these are being moved forward by cam-driven levers as 16, Fig. 1 (plan), the heads as 35a of selectors as 35 are respectively interposed between the ends of the punches and the sides of slots -31 in the hammers. The cam groove 13 is so shaped that the marking hammer 27 is actuated at the end of each of the periods during which a mark can be received, a feed-hole being punched by the punch 55 each time the marking punch 7 advances. The spacing punch is similarly actuated, in opposite phase to the marking punch. The punches are restored by springs 42 and preferably also by claws 34. The selector 35 when in the operative position is held there by its hooked end 35b, Fig. 5, engaging the plate 4, through a slot 37 into which it projects. It is unhooked, on a change of line and condition from spacing to marking, by the tongue 43a of a lever pivoted at 46, when the lever 49 of the receiver magnet moves to the left, Fig. 5. This operation becomes effective to punch a marking hole provided that it occurs while the cam-driven bell-crank 19, Fig. 1, has moved clockwise so that its roller 44 has released the spring 40, which moves the selector 35 into the operative position. The marking crank 19 and the corresponding spacing crank move in phase opposition, so that the receiver is open to register marks and spaces during alternate signal periods, the selector 35 being retracted by the lever 19 during the closed period. If the marking selector 35 is retracted (e.g. at the middle of a dash) while the magnet 50, Fig. 5, is still in the marking condition, the tongue 43 is flexed as shown in Fig. 1. When once unhooked by a tongue 43a or 43b, a selector remains unaffected by the line signals until it has been able to effect the punching of a hole and been retracted by the corresponding bell-crank roller such as 44. In a modification, Figs. 12, 13 (not shown), levers such as 19 are dispensed with, the marking punch hammer is in the retracted position during the mark-registering period and can then receive the marking selector, but is in a forward position throughout the space-registering period and cannot then receive the marking selector, which is restored and hooked in the inoperative position by a ramp at the end of the punching stroke. The action of the spacing punch and selector 'is similar. In a further modification, each of the two selectors, as 35, tends to be reciprocated by its spring, as 40, Fig. 1, unless it is retained by its end 35b, Fig. 15, engaging a bell-crank 66 which corresponds to the crank 43 and is operated by the line signals, so that the selectors are released into the operative position alternately on changes of line! condition. A marking hole is punched when the marking hammer 27, Fig. 17, moves forward, if the selector 35 has been able to enter the slot 31 in the hammer fully ; but the selector is prevented from doing so by the latch obstructing its nose 62 unless the latch has been set to the appropriate position in response to a preceding change of line condition of the opposite polarity. Hence marking and spacing holes must alternate.