US1857259A - Transmission system - Google Patents

Description

May 10, 1932. w. T. REA

TRANSMISSION SYSTEM 2 Sheets-Sheet Filed June 24, 1931 INVENTOR W. ZIEew BY I ATTORNEY May 10, 1932. w, REA 1,857,259

TRANSMISSION SYSTEM Filed June 24, 1931 2 Sheets-Sheet 2 INVENTOR ATTORNEY Patented May 10, 1932 UNETED s'rnrss PATIENT! OFFICE wiL'ron r. REA, or rnnsnnvs, NEW YORK, Assienonronivmnroien TELEPHONE AND TELEGRAPH COMPANY, CORPORATION OF YORK rnsnsivrrssron sysrniw Y Application filed June 24,

This invention relates to telegraph systems, and more particularly to improved arrangements whereby signals may be originated and received on such systems at a high signaling speed and whereby such high speed signals may be transmitted between stations over lines suitable only for low speed signals.

To distinguish between low speed andhigh speed telegraph signals and low speed and high speed telegraph transmission channels for the purpose of this invention, it is pointed out that the speed of the signals may be defined as the number of dots or impulses originated per second. The shortest impulse of a set of message impulses would be utilized to fix the maximum speed of the message signals. The number of these shortest impulses that could be transmitted per second could be termed the speed of the signals or could be characterized as the maximum fundamental frequency of the signaling current.

A. telegraph line interconnecting two Jstations would usually have associated therewith certain selective devices, such as filters or composite sets, and these filters or composite sets might be designed to out 0E frequencies above to cycles. Accordingly, such a circuit would be suitable for the transmission of telegraph signals having a maximum speed of less than 60 to 7 0 impulses per second or, in other Words, for a signaling current below such frequencies. This type of circuit might, for the purpose of illustrating this invention, be termed a low speed telegraph circuit. Obviously, it may be desirable to originate and receive signals at a speed faster than 60 to 70 impulses per second and this would result in the utilization of a current of a higher frequency. The use of a higher frequency current would not be possible on the type of circuit heretofore termed a low speed circuit because of the cut-ofi' characteristics of the filters or other, apparatus associated with the line. Accordingly, to accommodate high. speed signals, the filters or other devices in the line would have to be re-' designed to have a higher frequency cut-off characteristic so that the line mi ht be termed a high speed circuit. Obviously, this would necessitate the reconstruction or [redesign of 1931. Serial No. 546,624.

the low speed circuit into a high speed circuit.

Oneofthe primary objects of the arrangements. of-the invention is to make it possible to utilize the low speed circuit without anychange'therein for the transmission of high speed telegraph signals. In the arrangements of the invention thisis accomplished by resolving a series of high speed signals into a plurality of series of signals of approximately half the original frequency. The signals of this lower frequency may then be transmitted over a plurality of low speed telegraph circuits and may be recombined at the other end of the line to form the original high speed signals.

In the arrangements of the invention the translating means for resolving the high speed signals into low speed signals for transmission over the lines comprise a plurality of polar relays. The translatingmeans at the other end of the line for recombining the transmitted low speed signals to form high speed signals again also comprise a plurality of polar relays. In the arrangements of the invention means are provided'for combining two low speed telegraph circuits into one high speed circuit, for combining threelow speed telegraphcircuits into one high speed cfrcuit,-andfor combining four low speed circuits into one high speed circuit. Other objects and features of the invention will appear more fully from the detailed description thereof hereinafter given.

The invention may be more fully understood from the following description together with the accompanying drawings in the Figures 1, 2,3 and 4 of which the inven-.

tion is illustrated{ Fig. 1 shows arrangements of, the invention whereby two low speed telegraph circuits may be combined to form one high speed. telegraph circuit. Fig. 2 is a: modification of the arrangements of Fig. l. Fig. 3 shows arrangements of the invention wherebythree low speed telegraph circuits may be combined to form one high speed telegraph circuit. Fig. 4 shows arrangements of the invention whereby four low speed telegraph circuits may be combined to form one'high Speed telegraph circuit.

Similar reference characters have been used to denote like parts in all of the figures.

In Fig. 1 is shown a system in which two low speed telegraph circuits may be combined into a high speed telegraph circuit. Two stations are shown interconnected bythe lines 15 and 16. These lines might'be used for both telephone and telegraph service and might have included therein selective devices such as filters or composite sets. If the lines 15 and 16 were used as compositedtelephone and telegraph lines, the selective devices might be designed to have a cut off frequency of to cycles and telegraph signals having a greater speed than 60 or 70 dots per second, or in other words requiring a sig naling current with a fundamental frequency above 60 or 7 0 cycles, could not besent over such lines. Lines of this type may, for the purpose 0f illustrating this invention, be termed low "speed'telegraph circuits. Devices other than selective circuits might obviously be associated with these lines to cause then to tally in the category of low speed circuit-s. At the sending end of the system is shown loop circuit 1 with the key K and the relay 17. Controlled by relay 17 is a circuit including the nolar'relays .A and 13. These relays will resolve the high speed signals originating in the loop circuit 1 into two series :01 low speed signals for transm'ssion over the transmission channels 15 and 16. At the receiving end of the system are the polar relays 18, I19 and 20. These relays will be responsive to the low speed signals transmitted over the transmission channels and will combine these signals into a ser es of high,

speed signals to actuate the sounder '22 in the receiving loop circuit 21. I

Y The operation of the arrangements of Fig. 1 is as follows: In the followingcircuit descriptions it will be assumed that current flowing through a relay winding from terminal 3 to terminal 6 will tend to operate the relay armature to the marking contact, and

' current flowing from terminal 6 to terminal 3 will tendto operate thearmature to the spacing contact. Assume the key K inthe sending loop 1 to be closed and the relays A, B and 17 to be in the mark ng condition, as

shown in the drawings. Under these conditions negative marking battery will be connected over the armatures of relays A and to lines 15 and 16 and the relays 18, 19 and 20 will be in the position shown. 'Negative or marking battery will thus be connected over the contact of relay 19 and markng contact of relay 18 to the loop circuit 21 and sounder 22. V

If the key K is now opened'the armature of relay 17 will be operated'to its spacing contact, thereby applying ground to terminal [6 of windin-g 3-6 of relay B. 7 Since negative battery is connected over the armature or" i relayA to'termi-na13 ofwinding 8-6 of relay B, relay B will be caused to operate to its spacing contact. It will be maintained on its spacing contact by current flowing line 16. Atthe same time negative marking battery is being applied from the armature of relay A to line 15. Under such conditions, namely when negative marking battery is applied to line 15 and positive spacing battery is applied to line 16, relay 18 will remain on marking .and relays 19 and 20 will operate to spacing. Under such conditions positive spacing battery will be applied from spacing contact of relay .19 and marking contact and armature of relay 18 to the receiving loop 21 and sounder 22.

If the key Kis now closed again, the armature oi relay 17 will move to its marking contact. This .applies ground to terminal 3 of winding 6-3 of relay A and causes the armature 01 said relay to operate to its spacing contact. This'is because spacing battery is applied from the armature of relay B to terminalfi of winding 6--3 of relay A. The armature of relay A-will be maintained on its spacing contact by the spacing current transmitted through its holding winding 72 to ground. This will apply positive spacing battery from the armature of relay A to line 15: Thus a condition exists where positive spacing battery will be applied to both lines 15 and 16. Under these conditions relay 18,19 and 20will operate .to spacing and negative battery'will be applied from the contact and armature of relay 20 and spacing ing due to current through its holding winding 72. This will apply negative marking current to line '16.' Under such conditions, namely when positive spacing current isgapplied to line 15 and negative marking current is applied to line 16, relay 18 will be operated to spacing and relays 19 and 20 to marking. This will cause positive current to be applied over the contact and arma- 'ture of relay 20 and spacing contact and armature of relay 18 to the receiving loop 21 and sounder 22.

When the key K is closed again the relays will assume the position shown in the drawings.

the sounder 22 in the receiving loop will follow the operation of the key K in the sending loop 1. When the key K is closed to transmit a marking signal, negative marking current will be applied to sounder 22; when key K is next opened to transmit a spacing signal, positive spacing current will be applied to sounder 22; when key K is next closed to transmit a marking signal, negative marking current Will be applied to sounder 22; .and when key K is next opened to transmit a spacing signal, positive spacing current will be applied to sounder 22. The sounder in the receiving loop will thus operate at the same or high speed as the key in the transmitting loop, whereas the signals passing over lines 15 and 16 will be of approximately half that speed.

In Fig. 2 is shown a modification of the arrangements of Fig. 1. The sending arrangements are identical in both figures. in the receiving arrangements of Fig. 2 only two polar relays 21 and 22 are used instead of three relays as in Fig. 1. As the sending arrangements in both figures are identical in operation no description thereof will be given. In Fig. 2 the right hand Winding of relay 21- is reversed with respect to the left hand winding of said relay.

The operation of the arrangements of Fig. 2 is as follows: Vb-en both of the telegraph circuits 15 and 16 have marking current applied thereto, relays 21 and 22 will be operated to marking. Under these conditions negative battery will be connected to loop 21 and sounder 22. When spacing current is applied to line '15 and marking current to line 16 relay 21 will be spacing and relay 22 marking. Under these conditions positive battery will be connected to theloop 21 and sounder 22. When spacing current is applied to both lines 15 and 16 relay 22 will be operated to spacing and will connect line 15 over its spacing contact to the right hand winding of relay 21. As this winding is reversed with respect to the other winding, relay 21' will be operated to marking and negative battery will be connected to loop 21 and sounder 22. With marking current applied 5 to line 15 and spacing current applied to line 16. negative marking battery from line 15 will be applied to the right hand reversed winding of relay 21. This will operate relay 21' to spacing and connect positive battery to loop 21 and sounder 22.

Thus it will be seen that the operation of the sounder 22 in the receiving loop will follow the operation of the key K in the transmitting loop.

Fig. 3 shows a system in which three low speed telegraph circuits may be combined into one high speed telegraph circuit. Two stations are shown interconnected by the lines L L and L These lines might, as in the cases heretofore referred to, be used for both telephone and telegraph service and might have included therein selective devices or composite sets, which would for the purpose of this invention cause them to fall into the category of low speed circuits individually. At the sending end of the system is shown a loop circuit 1 including the key K and the relay 17. Controlled by relay 17 are circuits including the polar relays A A B B2, C and C These relays will resolve the high speed signals originating in the loop circuit 1 into a plurality of series of low speed sig-- nals for transmission over the lines L L and L At the receiving end of the system are the polar relays A A B B and C,,. These relays will be responsive to the low speed signals transmitted over the lines'and will recombine these signals into a series of high speed signals to actuate the sounder 22 in the receiving loop circuit 21.

The operation of the arrangement of Fig. 3 is as followsi Assume key K to be closed. Current will then be flowing in loop circuit 1, holding the armature of relay 17 on the lower contact. Assume also that relays A A B B C and C are operated to their marking contacts M and are maintained thereon by current flowing in holding windings 27. These holding windings are so arranged that when marking battery is applied to them from the armature of the relay they will maintain that armature on the marking contact M and, when spacing battery is applied, they will maintain the armature on the spacing contact S. Current will also he flowing from the marking contact M and armature of relay B through operating windings 6-3 of relays C and C through the armature and marking contact M of relay A and the lower contact and armature of relay 17 to ground. However, the effect of this current will be such as to aid the holding windings of relays C and C to maintain their armatures on the marking contacts. Current will also flow from the marking contact M of re lay A through windings 36 of relays B and B through the armature and marking contact of relay C and the lower contact and armature of relay 17 to ground. The effect of this current will be to maintain the armature of relays B anl B on the marking contacts.

Under these conditions, negative battery will be applied to lines L and L and positive battery to line L thereby operating relays A A B B and C to their lower contacts. Current will fiow from negative battery through the lower contact and armature of relay A the armature and lower contact of relay B and the lower contact and armature of relay C through loop circuit 21 and sounder 22, thereby holding the sounder in the marking condition.

If key K is now opened, current will cease to flow in loop circuit 1 and the armature of KO I ' 3 upper contacts.

ielay 17 will move to the uper contact, therecd ntact M and armature of relay B to windings 68 of relays A and A Since these windings have negative battery applied to them from the marking contact M and armature of relay C current will flow in suchia direction as to cause the armature of relays A and to operate to the spacing contacts S. Positive battery will thereby be applied to line L operating relays A and A to their upper contacts and causing positive battery to be applied from the upper contact and armature of relay A through the armature and lower contact of relay B and the lower contact and armatureof relay C to loop circuit 21 and sounder 22, thereby operating the sounder to the spacing condition.

If key K is again closed, the armature of relay 17 will move to its lower contact, applying ground through the marking contact and armature of relay C to windings 3-6 of relays B and B Since these windings now have positive battery applied to them from the spacing contact S and armature of relay A they will cause the armatures of relays B and B to operate to the spacing contacts S. Negative battery will thereby be applied to line L operating relays B and to their Since relays A and A are still maintained on their upper contacts and since relay (3;, is still maintained on its lower contact, negative battery will be applied from the upper contact and armature of relay A through the armature and upper contact of relay B and the lower contact and armature of relay C to loop circuit 21 and sounder 22,

r o aeratin the sounder to themarkin condition.

If key K is again opened, the armature of relay 17 will move to its upper contact, and ground will be applied through the spacing contact S and armature of relay A to windings 63 of relays C and C Since negative battery is applied to these windings from the spacing contact S and armature of relay B relays C and C will be operated to their spacing contacts S, thereby applying positive battery to line L and operating relay C to its upper contact. Positive battery is thereby applied from the upper contact and armature of relay A through the armatures and upper contact of relay B and the upper contact and armature of relay C to loop circuit 21 and sounder 22, thereby operating the sounder to the spacing condition.

If key K is again closed, relay 1'? will operate to its lower contact, applying ground through the spacing contact S and armature of relay B to windings 6-3 of relays A and A Since positive battery is applied to these windings from the spacing contact S and armature of relay C the armatures of relays A and A will be operated to their marking contacts M, applying positive battery to line L applying ground through the marking and operating relays A and A to their lower contacts. Hence, negative battery will be applied from the lower contact of relay A through the armature and upper contact of relay B am the uper contact and armature of relay C to loop circuit 21 and sounder 22, thereby operating the sounder to the marking condition, 7

If key I: is again opened, releasing relay 17, ground will be applied through the ing contact S and armature of relay C to windings 3-6 of relays B and B Since negative battery is applied to .these windings fron the marking contact M and armature of relay, A the armatures of relays B and B will operate to their marking contacts M, applying positive battery to line L and operating relays B and B to their lower contacts. Positive battery will thus be applied from the lower contact and armature of relay A through the armature and lower contact of relay B andthe upper contact and armature of relay G to'loop circuit 21 and sounder 22, operating the sounder to the spacing condition.

If key K is again closed, the armature of relay 17 will move to its lower contact, thereby applying ground through the marking contact M and armature of relay A to windings 6-8 of relays C and C Since these windings now have positive battery applied from the marking contact M and armature of'relay B the armatures of relays C and C will be operated to their marking contacts M, applying negative battery to line L and operating the armature of relay C to the lower contact. All relays will thus be returned to their original positions, and loop circuit 21 and sounder 22 will be operated to the marking condition.

It will thus be evident that sounder 22 will follow. the signals transmitted by key K, whereas the fundamental frequency of signals passing over transmission channels L L and L will be approximately one-third the frequency of those transmitted by the key and received by the sounder.

It will be noted that the armature of one relay of any pair, such as A supplies battery to the operating winding of the next pair of relays, in the sequence, such as B and B and that the other relay of the first mentioned pair supplies ground from the contacts of the main operating relay 17 to the windin s of the second pair of relays in sequence, such as G and C It will also be noted that the battery polarities connected to the marking and spacing contacts of successive relays are reversed and that likewise the operating and the holding windings of successive pairs of relays are reversed. In a like manner, the contacts of the left-hand relays of each successive pair are oppositely connected to the contacts of relay 17. By adding pairs of relays and still maintaining '7 spacthe conditions above imposed, the sending relay chain may be extendedto any odd number of relay pairs. The receiving relay chain may be likewise extended by inserting in the loop circuit pairs of relays whose armatures are connected in a reversing switch arrangement, and connecting the windings of each pair of relays to one of the lines extending to a pair of sending relays.

In Fig. 4 is shown a system in which four low speed telegraphcircuits may be combined into one high speed circuit. Two stations are shown interconnected by the lines L L L and L These lines might, as in the cases heretofore referred to, be used for both telephone and telegraph service and might have included therein selective devices or composite sets, which would for the purposes of this invention cause themto fall into the category of low speed circuits individually. At the sending end of the system is shown a subscribers loop circuit .30 including the key K and the relays E and E Controlled by these relays are circuits including the polar relays A B C and D These relays will resolve the high speedsignals originating in the loop circuit 30 into a pluralityof low speed signals for transmission over the lines L L L and L At the receiving end of the system are the polar relays A A B B C C and D These relays will be responsive to the low speed signals transmitted over the lines and will recombine these signals into a series of. high speed signals to actuate the sounder 22 in the receiving loop 21.

The operation of the arrangements of Fig. 4: is as follows: Assume key K to be closed. Current will then be fiowingin loop circuit 80, holding the armatures of, relays E and 2 on their marking contacts M. Assume also that relays A B C and D are operated to their marking contacts M and are maintained thereon by current flowing in holding windings 2 7; Current will also be flowing from the marking contact M and armature of relay A through operating winding 36 of relay B and the marking contact M and armature of relay E to ground. The eifect of this current will be such as to aid the holding winding of relay B to maintain the armature on the marking contact. Current will also flow from the marking contact M of relay C through winding 3-6 of relay D and the marking contact M and armature of relay E to ground. The effect of this current will be to maintain the armature of relay D on the marking contact M.

Under these conditions negative battery will be applied to lines L L L and L thereby operating relays/A A 13 ,13 C C and D to their lower contacts. Current will flow from negative battery through the lower contact and armature of relay A the armature and lower contact of relay B the lower contact and armature of relay C and the lower contact and armature of relay D through the loop circuit .21 and sounder 22, thereby holding the sounder in the marking condition. I

If key K is now opened, current will cease to flow in loop circuit 30 and the armatures of relays E and E will move to the spacing contacts S, thereby applying ground to winding 6-3 of relay A and to winding .3-6 of relay Since negative be. tery is applied from themarking contact M andarmature of relay D to winding 63 of relay A this relay will be operated to its spacing contact, applying positive battery to line L and operating relays A and A to their upper contacts. The application of ground to the windingof relay C only causes the armature to be maintained on the markingcontact M. Positive battery will now be connected from the upper contact and armature of relay A through the armature and lower contact of relay 13,, the lower contact and armature of relay C and the lower contact and armature of relay D5 to loop circuit'21 and sounder 22, thereby operating the'sounder to. the spacing condition.

If key K is again closed the armature of relays E and E will move to the marking contacts M, applying ground to windings 3-6 of relays B and D Since the winding of relay D is connectedto negative battery through the marking contact M and armature ofrelay C the armature of this relay will not be operated. However, positive battery is now applied from'the spacing contact and armature of relay A to winding 3-6' of relay B The armature of relay 13 will, therefore, be operatedto the spacing contact S, applying positive battery to line L and operating relays B and B to their upper contacts. Negative battery will thereby be applied from the upper contact and armature of relay A through the armature and upper contact of relay B thelower contact and armature of relay C and the lower contact and armature ofrelay D to loop circuit 21 and sounder 22, thereby operating the sounder to the marking condition. y I

If key K is again opened relays E and'E will be permitted to release and their armatnresfwill move to the spacing contacts S. applying ground to winding 63 of relay A and winding 36 of relay C Since the winding 6-3 of relay A is still supplied with negative battery from the marking contact M and armature of relay D relay A will not operate. The winding 3-6 of relay C however, is now supplied with positive batbattery will thereby be applied from the up- If key K is again closed, the armatures of relays E and E will be caused to move to their marking contacts M, applying ground towindings-36 of relays B and D respectively. Since winding 3-6 of relay B is supplied with positive battery from the spacing contact S and armature of relay A its armature will remain operated to the spacing contact S. However, since the previous operation of relay G applied positive battery to winding 36 of relay D thearmature of this relay Wlll operate to the spacing contactS, applying positive battery to line L and operating the armature of relay D to the upper contact. Negative battery will, therefore, be applied from the upper contact and armature of relay A through the armature and upper contact of relay E the upper contact and armature of relay'C and the upper contact and armature of relay D to loop circuit 21 and sounder 22, thereby operating the sounder to the marking condition.

If key K is again opened relays E and E will release, applying ground to winding 63 of relay A and winding 36 of relay C Since the latter winding still has positive 5 battery applied to it from the spacing contact S and armature of relay E the armature of relay C will remain upon its spacing contact S. The winding of relay A however, has positive battery applied to it from the spacing contact S and the armature of relay D and since it is a reversed winding the armature of relay A will .be caused to move to its marking contact M, thereby applying negative battery to line L and operating relays A and A to the lower contacts, Positive battery will thereby applied from the lower contact and armature of relay C through the armature and upper contact of relay B the upper contact and armature of relay C and the upper contact and armature of relay D to loop circuit 21 and sounder 22, thereby operating the sounder to the spacing condition.

If key K is again closed the armatures of relays E and E will be operated to their marking contacts M, applying ground to windings 3-6 of relays B and D The winding of relay D still has connected to it positive battery from the spacing contact S and armature of relay C whereas the winding of relay B now has negative battery connected to it from the marking contact M and armature of relay A Relay B will hence be operated to the marking position, applying negative battery tothe line L and operating relays B and B to their lower contacts. Negative battery will, therefore, be

applied from the lower contact and armature of relay A, through the armature'and lower contact of relay B the upper contact and armature of relay C and the upper con tact and armature of relay D to loop circuit 21 and sounder 22, thereby operating the sounder to the marking condition.

If key K is again opened relays E and E will release, applying ground to windings -6-3 of relay A and windings 3-6 of relay 0 Since the winding of relay A is still supplied with positive battery from the spacing contact S and armature of relay D it will remain in the'marking condition. lVinding 3.-6 of relay G is now supplied with negative battery from the marking contact M and armature of relay The armature of relay C will, therefore, be operated to its marking contact'M, applying negative battery to line L and operating relaysC and C to their lower contacts. Positive battery will be applied from the lower contact and armature of relay A}, through the armature and lower contact of'relay B the lower contact and armature of relay C and' the upper contact and armature of relay D to loop circuit 21 and sounder 22,thereby operating the sounder to the spacing condition;

If key K is again closed, operating the armatuies of relays E and E to their marking contactsM, ground will vbeapplied to winding 3+6 of relay D and sincethe other terminal of this winding is now supplied with negative battery from the marking contact M and armature of relay C the armature of relay D will operate to the marking contact M, applying negative battery to line L; and operating relay D to the lower contact. All relays are thus returned to their original position, and sounder 22 will be operated to the marking condition. 7 It will thus be evident that sounder 22 will follow the signals transmitted by key K, whereas, the fundamental frequency of signals passing overtransmission channels L L L and L will be approximately one fourth the frequency of these transmitted by the key and received by the sounder.

It will be noted that in the sending arrangement each relay in the sequence obtains its operating battery from the armature of the preceding relay and that alternate relays obtain their ground from the spacing and marking contacts, respectively, of control relays such as E 'and E By adding pairs of relays to the sequence and still supplying each relay with battery from the armature of the preceding relay, and by adding a controlrelay for each pair of sequence relays,

the sending relay chain may be extended so as to transmit into any even number of lines. The receiving relay chain may be likewise eX- tended by inserting in the loop circuit pairs of relays whose armatures are connected in a reversing switch arrangement and coni necting the windings of each pair of relays in series with one of the lines extending to a sending relay.

Accordingly the principle embodied in the arrangements of the invention, whereby low speed circuits may be combined to form a high speed circuit, are not limited to the use of two circuits. By varying the relay combinations at the sending and receiving ends of the transmission system a greater number of circuits may be utilized in the combination if desired. The principles of the invention may furthermore be utilized in connection with secret transmission systems, since the transmitted signal is not understandable except in the presence of all of its components. The arrangements of the invention may be utilized on lines which do not include filters or composite sets it the frequency characteristics of the lines themselves make it desirable. The arrangements of the invention are furthermore applicable to other types of telegraph systems from those illustrated, such for example as carrier telegraph and radio systems.

WVhile the invention has been disclosed as embodied in certain specific arrangements which are deemed desirable it is understood that it is capable of embodiment in many and other widely varied forms without departing from the spirit of the invention as defined by the appended claims.

What is claimed is V 1. A. telegraph system comprising two lines interconnecting two stations, sending apparatus at one of said stations comprising two polar relays each having its armature connected to one of said lines and having sources of marking and spacing current connected to the contacts of said armatures, operating circuits for said polar relays, a single switching means for controlling said operating circuits. said operating circuits being so arranged that the initial positioning of said 1- switch will cause marking currents to be applied to both of said lines. the subsequent operation of said switch wlll cause marking current to be applied to the first of said lines and spacing current to the second of said lines, the subsequent operation of said switch will cause spacing current to be applied to both of said lines, and the subsequent operation of said switch will cause s acing current to be applied to the first of said lines and marking current to the second of said lines; and receiving apparatus at the other of said stations. said receiving apparatus comprising polar relays in each of said lines, a receiving loop circuit, and means controlled jointly by said polar relays for applying signals of different polarities to said loop circuit, said last mentioned means being so arranged that the application by said sending apparatus of marking currents to both of said lines will cause marking current to be applied to said loop, the subsequent application by said sendingapparatus of marking current to thefirst of said lines and spacing current to the sec'ondof said lines will cause spacing current to be applied to said loop, the subsequent application bysaid sending apparatus of spaoingcurrent to both of said lines will cause marking current to. be applied to said loop, and thesubsequent application by said sending apparatus of spacing current to the first of said lines and marking currentto the second of said lines will cause spacing current to be applied to said loop. 4

2. The combination of a high speed telegraphcircuit with a plurality of low speed telegraph circuits, a translating device for resolving the original high speed signals into a plurality of series of low speed signals for transmission over said low speed circuits, said translating device comprising a chain of polar relays arranged in pairs and having operating circuits so arranged that the armature ofone relay of any pair supplies battery to the operating windings of the next pair of relays in the sequence and the armature of the other relay of the first mentioned pair supplies ground over the contacts of a relay inthe high speed circuit to the windings of the second pair of relays therefrom in the sequence, the battery polarities connected to the marking and spacing contacts of successive relays beingreversed and contacts of the other relay of each successive pair being oppositely connected to the contacts of the relay in the high speed cir cuit.

3. The combination of a high speed telegraph circuit with a plurality of low speed telegraph circuits, a translating device for resolving the original high speed signals into a plurality of series of low speed signals for transmission over said low speed circuits, said translating device comprising a chain of polar relays arranged in pairs and having operating circuits so arranged that the armature of one relay of any pair supplies battery to the'operating windings of the next pair of relays in the sequence and the armature of the other relay of the first mentioned pair supplies ground over the contacts of a relay in the high speed circuit to the wind ings of the second pair of relays therefrom inthe sequence, the battery polarities connected to the marking and spacing contacts of successive relays being reversed and contacts of the other relay of each successive pair being oppositely connected to the contacts of the relay in the high speed circuit, and receiving arrangements'for said system comprising a plurality of polar relays included in said low speed circuits and controlled by the series of low speed signals transmitted thereover, a receiving loop circuit, and means controlled by said last mentioned relays for applying signals of'difierent polarities to said receiving loop circuit.

4. lhe combination of a high speed te egraph circuit with a plurality of loW speed 1 telegraph circuits, a translating arrangement for resolving the original high speed signals into a plurality of series of low speed signals for transmission over said low speed circuits, said translating arrangement comprising a plurality of control relays included in said high speed telegraph circuit and a chain of polar relays, each of said polar relays being connected to one of said low speed circuits, each of said relays in said chain 0btaining its operating battery from the armature of the preceding relay in the chain and alternate relays in said chain obtaining their ground from the spacing and marking contacts respectively of said control relays.

In testimony whereof, I have signed my name to this'specification' this 22nd day of June, 1931. j I i WILTON T. REA.

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