US1351989A - Telegraph system - Google Patents

Description

J' H. BELL.

TELEGRAPH SYSTEM.

APPLICATION FILED NOV. 25, 1919.

Patented Sept. 7, 1920.

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transmitting telegraphic sign is over long JOHN H. BELL, OF SOUTH ORANGE, NEW JERSEY, ASSIGNOR TO WESTERN ELECTRIC P AI'ENT OFFICE.

GOIVLPANY, INCORPORATED, 9F NEW" YORK, N. "55., A CORFORATION O1? NEN YORK.

TELEGRAPH SYSTEM.

Specification of Letters Eatent.

iatcnted Sept/7, 1920.

To all whom may concern:

Be it known that l, Jenn ll. BELL, a citizen of the United t ltates, residing at South Orange, in the county of Essex; State of New Jerseyhave invented certainnew and useful Improvements in Telegraph Systems, of which the following is a Tfllll, clear, con cise, and exact description. 7

'lhis invention relates to telegraph systems and are particularly to svstems tor submarine cables or other conductors having high electrostatic capacity.

its object is a transmitting system suitable for duplex working and one which will produce, so far as .ssible, no cnn'inlatire charging of the cable and the consequent signal distortion known as wandering zero. 7 I

ln duplex operation where the main transmission line is balanced by an artificial line it is essential that the impedance of the artificial line be made to approximate very I closely the impedance of the real line. While it is comparatively easy to obtain this bal ance for steady currents, it is decidedly more diiiicult to compensate for the momentary unbalance which occurs for example when the sending voltage is suddenly ap plied to the cable for the reason that the artificial line cannot be made an exact copy ofthe real line for these transient effects. The result is thataduplex jar or, in other words a momentary disturbance-of the local receiving relay by the locally transmitted impulses is produced whieh'canses mutilation ol signals being received from the distant station.

To prevent this duplex jar, it has been proposed to use sinusoidal current impulses sages in the Baudot code or in similar codes over ocean cables.

The invention comprises an alternatin" current generator or preferably a pair or such generators which produce approximately sinusoidal waves; These generators are associated through a common driving mechanism with a transmitting distributor in such a way that the passage of tie distributor brush over each distributor segment coincides in time with the duration oi a. single hall. wave ol? the alternating current. The impulse sent to the line from any one distributor segment may be either a positive hall wave or a. negative halt wave, depending upon the selective operation or a pair of polarized relay. associated with the alternating current source.

The specific embodiment of the invention herein disclosed pro-rides live pole-changing switches for transmitting telegraphic inipulses in accordance with the l audot code. These pole-changing switchesiare connected to a set of di'l'le'rential relays which cooperate with a set of segments on the distributer to determine the character of the impulse to be sent to line from the transmitting segments of the distributor.

The invention will be more clearly understood by reference to the accompanying drawing in which Figure 1 illustrates in diagrammatic form an embodiment of the invention arranged for multiplex ope 'ation. Figs. 2 and 3 represent characteristic signal combinations with the corresponding currentimpulses necessary for their transmission, and Fig. l shows an alternative arrangement whereby a single alternating em rent generator may be used instead of two alternating current generators.

Referring to Fig. 1, the transmitting apparatus for one channel B of a multiplex system is shown together with portions of the adjacent multiple): channels A and (I. A distributor X, preferably of the rotary type, is shown in extended form and is understood to be driven by suitable driving mechanism which also serves to drive the two alternating current generators l and 2 and to maintain a definite fixed phase relation between the alternating current generators and the distributer.

The alternators l and 2 are furthermore arranged to produce currents lSl) degrees other of its windings.

out of phase with each other so that a positive half cycle produced by one alternator coincides in time with a negative half cycle produced by the other. The output of the alternators 1 and 2 is controlled by polarized relays 3 and 41- rcspcctively, relay-3 being polarized to connect alternator l. to the conductor 8 when a positive impulse flows through conductor 5 and relay i being arranged to connect alternator 2 to the con tery to the segments 11, 13' and 15, while pole changers 32 and 3-1 connect positive battery to segments 12 and 14-, and that when any of the pole changers is operated to produce a desired code combination, the polarity applied to its corresponding distributer segment will be reversed. 'Each pole changer moreover is connected to two of the differential relays 4:0 to 4:6, for example, pole changer 31 is connected to one winding of relay 41 and one winding of relay 4L2, pole changer 32 is connected to one winding of relay I2 and one winding of relay 43, etc. Thus each of the relays e0 to 416 depends for its operation on the character of two adjacent impulses from the pole changers. If all of the pole changers are in the unselected position, as shown in the drawing, each of the differential relays is unenergized, for example, relay 1 receives positive current from pole changer 30 through one of its windings, and negative current from pole changer 31 through the Consequently this relay through its back contact connects ground to the transmitting segment 21 and will apply 2. ground to the line L through the common ring 27 when the distributor brush 19 passes over the segment 21. Similarly each of the other relays, being unenergized, applies ground to the line through its corresponding distributer transmittingsegments 20 to 26.,

The operation of the system may best be understood from the consideration of a typical code combination in which the first, third and fourth impulses of a five impulse code are marking impulses, while the second an d fifth impulses are spacing impulses, and let us also consider t at the last impulse sent out by the preceding channel A was a spacing impulse. The term marking impulse is here'applied to an impulse which is intended to perform some selecting action at segment 23 with conductor 8.

a distant station, whereas a spacing impulse is one which produces no selecting action. V a

In ordinary Baudot' operation, the marle ing impulses are ordinarily positive impulses, while the spacing impulses are negative impulses. The terms positive and negative are hardly applicable in the present instance, however, because of the particular arrangement of the pole changers and the code employed. Considering the specific code combination above'referred to, however, the signal combination taken for an example, is shown by curve D in Fig. 2. Inasmuch as the last impulse of channel A was a spacing impulse, the pole changer 31 will be in the position shown. The first impulse in channel B is, however, to be marking impulse so pole changer 31 will be moved to the right and will thus connect positive battery to segment 11 and to one winding of relay 11. The other winding of relay 41 will receive positive battery from pole changer 30. Consequently relay will be operated and move its armature to the forward contact, thus connecting seg- 'ment 21 to the conductor 8 which leads to the contacts of relays 3 and 4. When distributer brush 9 reaches segment 11, positive current will therefore flow from the distributor contact 11 by way of common ring 1'7 to the relays 3 and 1. This positive impulse causes relay 3 to operate and close its contact, thereby connecting the alternator 1 to the segment 21 and inasmuch as brush 19 is now connected to se ment 21 with the common sending ring '27, a positive half cycle of current will be sent to line L.

The second impulse of the series being a spacing impulse, pole changer 32 will not be operated but will be in the position shown. This connects positive current to segment 12 and also to one windin of relay 412. The other winding of relays-2 is also receiving positive current from pole changer 31, therefore relay is operated and C011 nects, through its forward contact, segment 22 with the conductor 8. This positive cur rent again causes the operation of relay over the conductor 5 when the brush 9 reaches segment 12 and connects it to ring 17. In this second position of the distributer the alternator 1 will send out a negative half cycle of current to'the line L. Thethird impulse being a marking impulse, pole change 33 will be moved to the rightand will thus connect positive current to se ment 13 andalso one winding of relav 13. The other winding of relay 43 is alsh receiving positive current from the back contact of pole changer 32, consequently re lay 13 is operated and connects distributer The positive current again causes the operation of relay 3 and in this position of the distributer causes a positive half cycle of current to be sent to line L. The fourth impulse being a marking impulse, the pole changer 34 will be moved to the right and will connect negative battery to segment 14 and also to one winding of relay 44. The other winding of relay is however, receiving positive current from pole changer 33, therefore relay 44 does not operate, but instead ground will be connected to segment 24 through the back contact of relay 44. The fifth impulse being a spacing impulse, the pole changer 35 is not operated butjremains in the position shown and connects negative battery to segment and also to one winding of relay The other winding of relay 45 is receiving negative battery from pole changer 34,consequently relay 45 operates and connects segment 25 to conductor 8. This negative current also causes the operation of relay 4 when the distributer 9 connects segment 15 with common ring 17 and causes a negative half cycle of current to be sent to line by way of conductor 8 and segment 25. this is shown diagrammatically in Fig. 2, wherein the curve E represents current generated by alternator 1, curve F represents the current generated by alternator 2, and

the shaded portions indicate the signal impulses actually sent to line.

As a second example of the operation of the system, the code combination illustrated in curve D of Fig. 3 may be considered. In this instance the last impulse sent out from channel A is assumed to have been a marking impulse, while the code combination to be sent out from channel B is one in which the first, third, fourth and fifth are marking impulses and the second impulse is a spacing impulse. In this case pole changer will have been moved to the right and will connect negative battery to one winding of relay 41. Pole changer 31 will also be moved to the right and will connect positive battery to the other winding of relay 41 and to the segment 11. Therefore, relay 41 is not operated and the line will be grounded during the time the brush 19 is passing over the segment 21.

The second impulse being a spacing impulse, pole changer 32 remains in the position shown and applies positive battery to one winding of relay 42 and to the segment 12. The other winding of relay 42 is also receiving positive current from pole changer 31, consequently the relay 42 operates and when the distribnter brush 9 reaches segment 12 relay 3 also operates to connect a negative half cycle of current to the line by way of distributor segment 22. v

The third impulse being a marking impulse, the pole changer 32 is moved to the right and connects positive battery to one winding of relay 43 and to the distributor segment 13. The other winding of relay reaches segment 13, relay again ooerates to connect, in this ea. c, a positive h 2 cycle of current to the line L through distributor segment The fourth impulse being a marking a pulse, pole changer 34 is moved to the 1 ght and connects negative battery to one winding of relay and also to segment 14. The other winding of rela 44 is receiving positive battery by way of pole changer 33, Consequently relay 44 does not operate but connects ground'to segment 24 through its back contact.

The fifth impulsc'being a marking inipulse, pole changer is moved to the ht and connects positive battery to one windof relay 45 and segment 15. The other winding of relay 45 is receivin negative battery through pole changer 44, consequently relay 45 does not operate but connects ground to the line through its back contact and segment 3-5 of the distributor.

If new the first impulse to be sent out from channel C is to be a marking impulse, the line will continue to be grounded, whereas if this first impulse to be a spacing impulse, a negative half cycle of current will be sent to the line, as illustrated in curves E of Fig. 3.

Inspection of these curves shows that an impulse is sent to line only when the permutation to be transmitted calls for a reversal in the character of the impulse and that when two or more succeeding impulses of the same character are called for in a permutation, the line will be grounded after the first of these first impulses has been transmitted.

The transmitting system above described is thus seen to send out a perfectly symmetrical series of current impulses, that is, each impulse is followed by an impulse of the same length but of opposite polarity so that there is no opportunity for the cable to build up a cumulative charge of either positive or negative polarity. Furthermore, the frequent grounding of the cable insures that any accidental charge on the cable will be drained ofi.

Owing to the fact that the impulses transmitted are sinusoidal in character, it is furthermore readily seen that the system is one which is particularly well adapted to duplex operation and should produce a minimum of disturbance from duplex jar.

In the alternative arrangement shown in Fig. 4, a single alternating current generator l is used instead of the two generators 1 and 2 of Fig. 1. The two terminals of this are connected to the armature contacts of relays 3 and 4 respectively, so that each half cycle may be sent to line in one direction or the other depending on the selective operation of relays 8 and l.

hat is claimed is:

1. In a telegraph transmitting system, a set of pole changers, a source of alternating current, a distributor having two groups of commutator segments, a pair of polarized relays connected to said. source of alternating current and selectively controlled by the cooperation of said pole changers and one "of said groups of segmentsior sendlng positive or negative hall cycles of said alternating current to line through said second group of segments.

2, In a telegraph transmitting system, a set of pole changers, a corresponding set oi diiierential relays, each oi? which is under the joint control of two of said pole changers, a distributor having two groups of commutator segments, each segment of one of said groups being arranged to ground the line through the normally closed back con tact on a corresponding one of said relays and to send a half cycle of alternating current to line through the front contact of said relay when operated, and means under the joint control oi" said pole changers and said other group of segments for determin ing the polarity of the half cycle so sent.

I In a telegraph transmitting system,

a group of permutation pole changers, alternate pole changers being normally con nected to the positive pole of a direct our rent source, the intermediate pole changers source with said distributor.

l. In a telegraph transmitting system, a group of permutation pole changers, alternate pole changers being normally connect ed to the positive pole of the direct current source, the intermediate pole changers be ing normally connected to the negative pole of the direct current source, a differential relay having two windings connected to two adjacent pole changers respectively, and ar ranged to be operated Whei either of said pole changers is operated individually, but

to-remain uuoperlated iii neither or both of said pole changers are operated, an alternating current source, a sending distributer, and means under the joint control of said distributor and said pole changers to determine the phase of said alternating current. t

in Witness whereof, I hereunto subscribe my name this Qlst day of November A. D., 1919.

Jenn BELL.

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