US1895107A - Telegraphic signal reproducing apparatus - Google Patents

Description

Jan. 24, 1933. R; D. SALMON 1,895,107

I TELEGRAPHIC SIGNAL REPRODUCING APPARATUS Filed Sept. 24, 1950 1H! WI A 5 C L} a I A" aw H K bgnx J '1 I I FWHZHWJW l- ,4/ 5/ 6/ 0/ 'f #2 (2F 02 axf ggf ATTORN Patented Jan. 24, 1933 NITED STATES PATENT OFFICE REGINALD DENNIS SALM ON, OF C'ROYDON, ENGLAND, ASSIGNOR T CREED AND COMPANY LIMITED, OF CROYDON, ENGLAND TELEGRABHIC SIGNAL REPRODUCING APPARATUS Application filed September 24, 1930, Serial No. 484,073, and in Great Britain October 9, 1929.

This invention relates to improvements in telegraphic apparatus in which signal reproducing means is actuated by mechanical power under the control of received signals.

1n co-pending application Serial No. 452,367 means is shown applied to telegraphic apparatus of the class referred to, whereby reproduction of false signal elements resulting from prolongation of received signals due to line conditions orother disturbing causes is avoided. The correction of these errors, in part, due to the selective power of such apparatus to reproduce as normal elements such portions of the received signals as may be represented only by fractions of elements therein. The invention therein described shows telegraphic apparatus in which a rotatable member is released by apparatus under the control of received signals to actuate signal reproducing means, and in which means is provided also under the control of received signals to prevent any further effect of the continuing rotation of the member on the signal reproducing means after the cessation of a received signal. By this means if a signal is prolonged an extra element is not reproduced provided the distorted signal terminates before the selecting period of the reproducing apparatus is reached. This selecting point is arranged to occur as nearly as possible in the center of a received signal element. If a. signal is prolonged beyond this point another normal signal element is reproduced.

The object of the present invention is to prevent the reproduction of false signal elements resulting from prolongation of received signals. in telegraphic apparatus in which a rotatable member is released under the control of received signals to release after an adjustably fixed portion of a revolution a second rotatable member for actuating signal reproducing means.

In one embodiment of the invention herein described the rotatable members are constituted by sleeves on which cams are adjusta-bly positioned to permit adaptation of the apparatus in a known manner to different speeds of working and to different signal shapes consequent upon variation in line conditions.

The invention comprises a relay responslve to received signals, a rotatable member released for rotation at the first response of said relay, a second rotatable member released for rotation by the first said rotatable member after an adjustably fixed portion of a revolution thereof, means actuated by said relay to prevent the release of said second rotatable member upon cessation of a received signal, and means actuated by said second rotiatablc member to reproduce received signa s.

The invention also consists of the provision of further features which simplify the constructional details, which features will be described with reference to the drawing and defined more particularly in the appended claims.

In the accompanying drawing, Fig. 1 represents diagrammatically one embodiment of the invention as applied to a cable code regenerator in which the signals are composed of a variable number of elements of equal length but of a different polarity, and in which the spaces are formed by intervals of no current. Figs. 2, 3 and 4 are diagrams for explaining the principle of the invention and are somewhat similar to Figs. 6, 7 and 8 of the above mentioned co-pending application. Figs. 5 and 6 show details of the clutch releasing mechanism, while Fig. 7 shows a section of the cam sleeves and driving shaft.

Referring to Fig. 1 of the drawing, 1 is a shaft driven by a motor not shown through a friction drive 3, whereby the speed of shaft 1 is set approximately to the speed of the received signal elements. 4 and 5 are two separate cam sleeves frictionally driven from shaft 1 by means of the spring pads 6 (Fig. 7) carried in radial slots in shaft 1. The rotation of these sleeves is controlled in a manner which will be described later. Sleeve 5 carries an adjustable cam 7 which through a cam roller 9 actuates rod 8 in the direction of its length during the rotation of cam 7. Rod 8 is deflectable laterally at the tip 811, by the armature 10 of a polarized power relay (not shown) in accordance with the polarlty of received signal elements through the medium of a spring link 11. The deflection of rod 8 to one side or other causes the extremity 8a to lie opposite the extremity of one or the other of two contact levers 12 and 13 which are held normally by springs 14 and 15 against adjustable contact screws 16 and 17 respectively. The armature 10 of the polarized relay remains in the position to which it was last actuated so that on rotation of the cam 7 one or other of contact levers 12 and 13 is moved over to its opposite contact screw 18 or 19 for a period of time determined by the length of the raised portion of the cam 7. A non polarized power relay (not shown) actuates its armature 22 carrying a detent 21 for each signal element regardless of the polarity of these elements. a

The. cam sleeve 4 has a tooth 20, formed thereon, which co-operates with the detent 21 formed on the extremity 22 of the armature of the non polarized power relay. A cam 23 having a notch 24 is also carried on sleeve 4. and may be adjustably fixed thereon in rela-' tion to tooth 20. A lever 25 having a step portion 26 rides on the cam 23 under pressure of spring 27. An extension 21a of the detent 21 actuated by the nonpolarized power relay is adapted to prevent lever 25 from dropping into the notch 24 during rotation of cam 23 if the detent 21 is subsequently in a position to arrest the rotation of sleeve 4 by cooperating with tooth 20. A second lever 28a is fixed to the same pivot shaft 29 as lever 25. A lever 28, pivoted to shaft 29, is forced into engagement with lever 28a by spring 28?) to maintain lever 28 yieldingly in position and oooperation with tooth 30 of sleeve 5, except when lever 25 is held out of notch 24 by either the cam surface of cam 23 or the extension 21a of-detent 21, as illustrated in 5 and 6. This lever 28 is adapted to release the second sleeve 5 through the disengagement of said lever from tooth 30 when lever 25 falls into .the notch 24 of cam 23 on the first sleeve 4. As previously stated sleeve 5 carries an adjustable cam 7 which actuates signal reproducing means.

The operation of the apparatus is as follows. When asignal of suflicient strength is received the non-polarized power relay operates and detent 21 moves outwardly (Fig. 5) in a radial direction and releases tooth 20, the extension 21a of detent 21 at the same time moving from the path of the'extension of lever 25. After an interval determined by the setting of cam 23 in relation to tooth 20, lever 25 drops into the notch 24, lever 28 thereupon releases tooth 30 and the second sleeve 5 commences to rotate. During the continued reception of s gnal elements detent 21 remains clear of tooth 20 and sleeves 4 and 5 continue to rotate in approximate syneach signal element. Upon termination of a signal the non polarized power relay de energizes and detent 21 arrests sleeve 4 through tooth 20, lever 25 is thereupon maintained in a position to cause lever 28 to arrest sleeve 5, which is eflected as soon as tooth 30 engages lever 28. If a signal is prolonged by line conditions or other disturbing causes beyond the time at whichit should have terminated it will be seen that tooth 20 will have passed detent 21 and an extra revolution of sleeve 4 will ensue. Provided however, that, the signal terminates and the non polarized power relay deenergizes so that detent 21 returns to the unoperated position before lever 25 drops into the notch 24, an extra revolution of sleeve 5- and consequently an extra reproduced element will not result as lever 25 will now be intercepted by the extension 21a of detent 21.

The mode of operation is perhaps better illustrated by reference to Figs. 2, 3 and 4 of which the explanation herewith given is somewhat similar to that for th'e'corresponding figures in the I, previously mentioned parent application.

Referring to Fig. 2 vertical lines'A, B, C, D, efc., represent signal periods as'used at the point of transmission. The entire line of signal periods may be said to represent the signal letters F I as transmitted by an automatic transmitter in Morse cable code. The signals will be received after transmission through a long line or cable substantially in the attenuated form shown in Fig. 3. If the distances of the horizontal lines 6 and c Fig. 3 from the zero line a be considered as the mini mum values of signal strength necessary to actuate or to hold actuated the nonpolarized power relay, it will be seen that cam sleeve 4 will be released at point (1 Figs. 3 and will be arrested for a full signal period only at point E performing successive revolutions during the reception of the signal elements representative of the letter E as shown b the periods A B C D E in 41 t pomt e, Fig. 3, the received signal current strength rotation of sleeve 4. The point E of Fig. 3, I

however, will be the exact pointat which sleeve 4 will be stopped. As shown at point 0- of Fig. 4, sleeve 5 is released for rotation.

say, three-eighths of a signal periodafter the release of sleeve 4.- Sleeve 5 will continue rotating until three-eighths of a signal period after sleeve 4 has been returned to its original starting position. Then lever 2 8 will again engage tooth 30. Thus, cam 7,

which rotates integrally with sleeve 5, may be adjusted to actuate cam roller 9 and rod 8 so as to cause the retransmission of a signal element immediately upon the commencement of rotation of sleeve 5, (i. e., threeeighths of a signal period after sleeve 4 begins rotating) and sleeve 5 may be made to stop rotating three-eighths of a signal period after sleeve 4 returns to its starting position. The period for which cam 7 actuates the retransmitting lever is, of course, independent of a complete revolution of sleeve 5 and depends only upon the amount of cam surface on the cam 7. In the case illustrated, the first sixeighths of the entire cam surface, starting immediately after its release with sleeve 5 by lever 28, is operative to cause this retransmission of signal elements.

The polar relay operates at its own margina1 current point which, for simplicity, we will assume to be the same as that of the non-polar relay. Thus, at n the polar relay will shift its armature from, say, the left or dot position to the right or dash position. At the point 11, Fig. 3, since 8a is locked in engagement by pressure against lever 12, the shifting of armature 10 from left to right causes flexible spring link member 11 to give and store the shifting energy as potential energy in the flexed sprin This potential energy is liberated between the points g and x Fig. 4. This is made possible by cutting the cam surface of cam 7 in such a way that lever 8 is released for, say, the final two-eighths of each retransmitting signal period, thereby releasing, in this specific case, 8a and lever 12 from their previously locked pressure engagement. This causes lever 8 to be thrown from engagement with lever 12 into a position for subsequent engagement of portion 8a with lever 13. In this manner, a negative or dash element is retransmitted by lever 13 upon the release of sleeve 5, as shown in Fig. 4, between intervals C and D and the first one-eighth of interval D 13 The raised portion or effective cam surface of cam 7 causes rod 8 to actuate either one of levers 12 or 18, upon release of sleeve 5, in accordance with the signal element received by the polarized relay, armature 10 of which is shown. Cam 7 is integral with sleeve 5 and, thus. both are simultaneously released Y and are, therefore, rotated by shaft 1 when step portion 26 of lever 25 drops into notch 24 of cam 23. This mode of operation causes lever 28 to be pushed upward by- levers 28a and 25 under pressure of spring 27, thereby causing lever 28 to release tooth 30 of sleeve 5.

As is customary in cable signal notation, the portions of the signal elements above the cen er line represent dots and those below represent dashes. The distance between each corresponding pair of vertical lines, such as 07 7 in Fig. 4. represents the time during which one of the levers 12 or 13 is actuated after selection by polarized relay armature 10 and selecting rod 8. This length of the reproduced signal elements is determined by the length of the effective cam surface on cam 7 and is represented in Fig. 4 as interpolating an earthing period, in order to reproduce elements of the same duration as are transmitted by the distant transmitter.

When signals of the same polarity follow each other. as in the case of the second dot of the letter F shown in Fig. 2, the armature of the polar relay remains to the left and lever 12 is again operated through the cam surface of cam 7 after a grounding period represented by a time interval g w I: sometimes happens, however, that a signal is prolonged, by line conditions or other disturbing causes, to a point beyond the time at which it should have terminated. Th s is shown diagrammatically on the termination of the second dot signal element in the signal I of 3. The dotted portion of the curve represents the distorted signal, while the full line portion represents the normal termination of the signal. It is obvious, from the figures. that, instead of the nonpolarized relay becoming (ls-energized at point m and arresting the motion of sleeve 4 by means of detent 21 when point 0 is reached, the nonpolarized relay is not deenergized until point 2 is reached. By this time tooth will have passed the detent 21 and, thus, sleeve 4 will make another revolution. The polarized relay, however, remains in the position to which it was last actuated, namely, to the left or dot position. Thus. if some means were not provided, an extra dot would be transn'iiited by lever 12. This would occur at point m, Fig. 4, if the signal were prolonged still further than that shown by the dotted lines, for at this point, as, the second cam sleeve 5 is released. This would cause contact lever 12 to be actuated as the polarized relay remains actuated to the dot side by the previous signal.

The .pre'sent invention obviates such errors, however, when signals are somewhat prolonged. for the armature 22 of the nonpolarized relay is released at point )7 oneeighth of a signal element before portion 26 of lever is ready to drop into cut 24 of cam 23, i. e., at point a Then. end portion 21a of armature 21 will lock with lever 25 and keep portion 26 from falling into cut 24. This, in turn, prevents lever 28 from releasing tooth 30 of sleeve 5. Sleeve 5, therefore, is kept from turning and cam 7, consequently, does not operate rod 8. Thus, a wide margin of safefy is possible with this apparatus and prolonged signals, caused by changing weather canditions and the like, will not necessitate constant adjustment of the receiving. reperforating. or retransmitting apparatus.

It will be evident that considerable modifications of the arrangement for receiving, retransmitting or otherwise reproducing the signals may be made and that although described as applied to a cable code regen'erator the method of control of two cam sleeves as described is not limited to this particular application or that particular code, but may be used in all cases where the two separate cam sleeves permit a greater degree of adjustment to varying line or signal conditions than could be obtained by one cam sleeve alone.

lVhat is claimed is:

1. Telegraphic signal reproducing apparatus comprising, a relay responsive to received signals, a rotatable member released for rotation at the first response of said relay, a second rotatable member released for rotation by the first said rotatable member after an adjustably fixed portion of a revolution thereof, means actuated by said relay to prevent the release of said second rotatable member upon cessation of a received signal before completion'of said adjustably fixed portion of a revolution, and means actuated by said second rotatable member to reproduce received signals.

2. Telegraphic signal reproducing apparatus comprising a relay responsive to all the elements of a received signal, a rotatable member released for rotation at the first response of said relay to any signal element, a second rotatable member released for rotation by the first said rotatable member after an adjustably fixed portion of a revolution, means actuated by said relay to prevent the release of said second rotatable member upon cessation of any received signal element before completion of said adjustably fixed portion of a revolution, a second-relay responsive to the polarity or character of received signal elements, and signal reproduc-' ing contact levers actuated by said second rotatable member and as selected by said second relay.

3. Telegraphic signal reproducing apparatus comprising a relay responsive to all the elements of a received signal, a driving shaft rotatable at a speed substantially identical with the speed of received signal elements, a cam sleeve independently mounted on said shaft and released for rotation at the first response of said relay to any received I actuated by said second rotatable member and as selected by said second relay.

4. In telegraphic signal reproducing apparatus a driving shaft rotatable at a speed substantially identical with the speed of received signals, a cam sleeve independently mounted on said shaft, a lever actuated during rotation of said sleeve to release a second cam sleeve independently mounted on said shaft, a detent actuated in response to received signals to release said first cam sleeve for rotation, and an extension of said detent which intercepts the movement of said lever when the detent is in a position to arrest the-motion of the first said cam sleeve on cessation of a received signal.

5. In telegraphic signal reproducing apparatus a driving shaft rotatable at a speed substantially identical with the speed of received signals a cam sleeve independently mounted on said shaft and yieldingly driven therefrom by frictional force, a lever actuated by a notch in said cam sleeve to release a second cam sleeve frictionally driven from said shaft, a detent actuated in response to received signals to release and arrest the first said cam sleeve through a tooth formed thereon, and an extension of said detent to prevent said lever falling into the notch in said cam when the detent is in a position to arrest said tooth.

6. In telegraphic signal reproducing apparatus a cam sleeve frictionally driven from a rotating shaft and released in response to received signals, a spring actuated lever cooperating with a notch in said cam sleeve to actuate a second lever, means to reproduce received signals, a second cam sleeve frictional- 1y driven from said rotating shaft and released on actuation of said second lever for operating said signal reproducing means, and yielding spring means to return said second lever to a position to arrest said second cam sleeve.

7 In a telegraph system, a rotating shaft, a plurality of sleeves frictionally mounted on and driven by said shaft, electromagnetic means effective upon the reception of signals for releasing one of said sleeves for rotation, and means actuated after said first sleeve has completed a predetermined portion of a revolution for releasing another sleeve for rotation, and signal reproducing means actuated by said last-mentioned sleeve.

8. In a telegraph system, a rotating shaft, a plurality of sleeves frictionally mounted on and driven by said shaft. electromagnetic means effective upon the reception of signals for releasing one of said sleeves for rotation, means actuated after said first sleeve has completed a predetermined portion of a revolution for releasing another sleeve for rotation, signal reproducing means actuated by said last-mentioned sleeve, said electromagnetic means being effective to prevent the rotation of any other sleeve except the first upon the cessation of a received signal when the cessation occurs before the first sleeve has completed the predetermlned portion of a revolution.

- In witness whereof I hereunto subscribe my name this fifteenth day of August, 1930.

REGINALD DENNIS SALMON.

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