US2039629A - Telegraph repeater - Google Patents

Description

y 1 936. E. 'r. BURTON 2,039,629

TELEGRAPH REPEATER Filed Oct. 23, 1930 3 Sheets-Sheet l CHARGE. "E I A A A V IMPULSECOIIL OUTPUT V CONDENSER VOLTA 6E INVENTOR E. T. BUR TON ATTORNEY May 5, 1936. E. "r. BURTON 2,039,629

TELEGRAPH REPEATER,

Filed Oct. 25, 1933 3 Sheets-Sheet 2 FIG. 8 A A J v V A A A 42 V IMPULSE COIL OUTPUT \r FIG Q CONDENSER VOLTAGES FIG. 10

lNVE/VTOR 1:. 7T BURTON By j A TTORNEV y 1936- T. BURTON 2,039,629

TELEGRAPH REPEATER Filed Oct. 23, 1930 3 Sheets-Sheet 3 IIII 3 FIG, 12 I67 -g g fg-las AAA IV FIG. 13

- INVENTOR E. 7'. BURTON.

"5 jibe/M Patented -May 5, 1936 UNITED STATES" 2,039,629 TELEGRAPH anrrn'rna Everett T. Burton, Mlllburn, N. J... asslgnor to Bell Telephone Laboratories,

Incorporated,

New York, N. Y., a corporation of New York Application October 23, 1930, Serial No. 490,585 20 Claims. (01. 178-70) s This invention relates to telegraph systems and 'more particularly to repeaters for regenerating impulses for further transmission in telegraph and similar impulse transmission systems such as picture transmission and television systems.

An object of this invention is to reduce distortion in telegraph signals.

Another object is to reshape attenuated anddistorted signals of irregular amplitude into corresponding signals having a substantially flattopped wave of uniform amplitude.

Heretofore, two general types of repeaters have been employed, i. e., electromagnetic relays and thermionic or vacuum tube amplifiers. Electro-' 16 magnetic relays have been commonly used for reproducing square-topped waves such as are used in telegr'aphy, while vacuum tube amplifiers have been preferred for reproducing without distortion, waves of varying intensity.

20 However, a repeating circuit for telegraph signals has been proposed which utilizes vacuum tubes in place of electromagnetic relays and which may produce in its output circuit a substantially square-topped wave. United States patent to Krause 1,537,682, May 12, 1925 discloses such a system in which fiat-topped waves are produced in the output circuit of a vacuum tube whenever the input voltage exceeds a certain value. 'Nega tive grid voltages in excess of that value produce no further change in the output voltage because the space current is completely blocked. On the other hand, positive grid voltages in excess of that value produce no further change in the output current'because of filament saturation. A disadvantage of that arrangement is that disturbing currents of small value are amplified greater proportionally. than the signal impulses. I

It is, therefore, a further object of this inven- 40 tion to eliminate, by means of a thermionic repeater, disturbing currents of less than a predetermined amplitude.

' A sum further object of thls'invention is to provide a thermionic repeater in which the polarity of the repeated impulses is independent oi-the characteristics of the thermionic or vacuum tubes, and dependent only upon the establishment or definite values of voltage of the received signals.

In accordance with the above stated objects,sig-

naling impulses are received in the form of a wave which a greatly overloaded magnetic circuit is utilized. The impulses or kicks may be selected to occur within any desired range of intensity ofv current upon the rise and fall of current intensity.. This method is described more fully in U. S. 5 Patent 1,936,153, granted to E. T. Burton on November 21, 1933. As a next step, these sharp discrete impulses are lengthened by means of a vacuum tube arrangement which reproduces waves corresponding to the incoming line signals 10 in polarity, but having a substantially flat top. The impulse coils serve as mutual impedances in the input circuits of said vacuum tube arrange ment. 7 I

Another object of this invention is to provide 5 a repeater of the type described which is capable of operating at a high speed. In the present invention, mechanical relays, which are subject to chattering at high speeds, are rendered unnecessary. 20

'The arrangement for lengthening the impulses may be embodied in any one of several forms. According to one embodiment, the output circuit of the impulse coil is connected to the grid circuits of two thermionic devices, such as vacuum tubes, 25 wherein are provided condensers for storing the signals. The thermionic devices may be described as rectifying or unidirectlonally conducting de- 'vices., Each condenser becomes charged to one polarity on the receipt of an impulse from the 30 impulse coil and maintains a charge upon the grid until a change of signal polarity occurs, at which time the condenser is discharged. A feature of this'arrangement resides in means for reproducing three-element signals, that is, sig-, 35 nals consisting of positive, negative and zero impulses. a 1

According to another embodiment of this invention, two three-electrode devices, such as vacuum tubes, are arranged so that the grid circuit 40 of each tube is coupled to the plate circuit of the other, whereby an increase of current in the plate circuit of one tube is eflective-to decrease the plate current in the other tube until the latter plate current is blocked. This system is stable 45 in two positions, in which there is a steady plate current inone tube or the other, depending on the polarity of the last received impulse. The threeelectrode devices may also be described as rectitying or unidirectionally conducting devices. 50

Other objects and features of this invention will appear more clearly from the following de-&

scription' taken in connection with the accom- 7 mm: drawings and appended claims.

schematically a circuit including a storing condenser and embodying the present invention;

Fig. 2 is a simplified diagram showing the connections to the storing condenser of Fig. 1;

V Fig. 3 illustrates a signaling wave received by the repeater circuit of -Fig. 1;

Fig. 4 shows the current in the secondary trans former windings of the circuit of Fig. 1;

Fig. 5 shows the condenser voltage for corresponding points on the incoming signal curve shown in Fig. 3;

Fig. 6 is a modification of the circuit of 1 1g. 1, which constitutes a three-element relay;

Figs. 7 to 10 inclusive, illustrate a repeated signal at different stages in its retransmission by the circuit of Fig. 6;

Fig. 7 shows an incoming signal;

Fig. 8 shows the outputvoit'ages of two windings of the transformer;

Fig. 9 shows the voltages of the two respective condensers;

Fig. 10 shows the voltage of the two condensers in series;

Fig. 11 is a schematic diagram of another modification of the present invention and shows a regenerative locking repeater; and

Figs. 12 and 13 are still, further modifications which embody the features of the circuit shown in Fig. 11.

Referring to Fig. 1, a repeater is connected to retransmit from the incoming line III, to the outgoing line "I I. Connected to the incoming line" II is the primary winding of a transformer 12. The transformer is of a type having ahigh permeability core which becomes saturated at a very low magnetizing force. A transformer of this type is commonly referred to as an impulse coil, and is described in U. 8. Patent 1,936,l53, supra. The impulse-coil I! has two secondary windings l4 and 2l. The winding I4 is connected serially with a condenser II and resistance It, while. the winding 24 is similarly connected in a series circuit with a condenser 25 and a resistance 28. Two space discharge devices such as vacuum tubes l1 and 21 each have their grid circuits connectedin parallel with the condensers I5 and 25, respectively. The grid circuits plate circuits of these vacuum tubes are arranged so that the condenser 30 is in series with each plate circuit. A B battery II is interposed in the plate circuit of vacuum tube ii. The output voltage of the above described vacuum tube arrangement is supplied from the plate andfilament respectively of vacuum tube l1, and is impressed on the grid circuit of amplifier tube 33 whose plate circuit is connected to the outgoing line ii; The C batteries i8 and 29 are desirably of sufllcient voltage to block the plate current to zero when a plate voltage equal to that of battery 3| is applied to either tube.

The function of the condenser 30 can best be understood by reference to Fig. 2. When the grid of vacuum tube i1 is positive and the grid of 21 negative, the current flows through the plate circuit of vacuum tube I I to charge'the condenser 30 to the voltage of the B battery ii. The

I capacity of the condenser 30 is small and, there- .fore, the condenser becomes charged to the full battery voltage almost immediately. when the grid of vacuum tube 21 becomes positive and that of i1 becomes negative, a discharge path for the again becomes positive. The grid circuit of vacuum tube II is connected in series with condenser and the B battery Ii. It follows that the grid voltage of vacuum tube 33 is equal to the voltage of battery 3i minus the sum of the condenser voltage and any "0 battery voltage that may be employed. (when the condenser is fully charged, the condenser voltage neutralizes the voltage of the 3" battery II and the grid voltage of the amplifier tube 33 becomes equivalent to the voltage of the "0 battery alone. when the condenser is discharged the grid voltage is equal to that'of battery 3i minus the 0" battery voltage.

The manner in which a received signal is transferred from the incoming line II to the outgoing line II will now be explained. In Fig. 3 is illus-v trated the waveform of a somewhat distorted signal made up of one positive, one negative, two positive and one negative impulses. The two lines A and B in Fig. 3 represent the current values at which the transformer becomes saturated. It is apparent that the only time any current is induced in the secondary winding of the transformer or impulse coil l2 occurs when the current strength of the received signal lies between the values Band A.- It will be seen that only a short time elapses during the change in current strength from B to A or vice versa." The electromotive force induced in the secondary windings of the impulse coil is shown diagrammatically in Fig. 4. The secondary windings of the impulse coil induce discrete impulses of short duration which are of one polarity when the incoming signal passes from the value B.to A, and of the positive when the incoming signaling current changes. from minus to plus (B to A), the con-- denser '30 begins charging and therefore becomes fully charged whenever the incoming current is positive. and above the saturation point. The condenser is discharged during the time that the incoming impulse is correspondingly negative.-

The outgoing mum the line H has a shape" corresponding to the signal shown in Fig. 5. It will be observed that the signal of-Fig. 5.1a squaretopped as contrasted with. irregular signal shown in Fig.3. The square-topped eflect is due to the fact that the voltage of the condenser 30 has but two alternative values and quickly changes from one value to the other whenever the received signal current passes between the values A and B.

The circuit of Fig. 1 may be modified as shown in Fig. 6 to make a three-element relay. The impulse coils 42 and "of Fig. 6 each replace the impulse coil l2 of 1 and are oppositely biased. The impulse coil 42 has a pair of secondary windings 44 and 54- corresponding in function to the pulse coil 52 has a similar pair of secondary windsecondary windings l4 and 24 of Fig. 1. The imings 64 and 14. The secondary windings are 7 connected to the grid circuits of vacuum tubes ll, 51, t1 and", respectively, which are connected to the windings in a similar manner to the corresponding elements in the circuit of Fig. 1. A condenser I similar to the condenser ll of Fig. 1 is connected in series with the plate cir- 2,039,629 cult of .either tube" or 51. Similarly, condenser II is connected in series with .the plate circuit of either tube 61 or 11. The condensers 60 and I are connected in series with each other and with a battery 12 and the grid circuit of an amplifler tube 13. The vacuum tubes or similar triodes 41, 51., 61 and 11 are supplied with plate voltage by the common B battery "which connects the plates of tubes 51 and 61 tocondensers 00 and 10.

The operation of the circuit shown in Fig. 6 can best be understood by reference to the curves shown in Figs. 7 to inclusive. The incoming signal wave, as before, isshown in Fig. '7 as consisting of a positive, negative, two positive and one negative impulses. The impulse coil 42 is biased so that it is saturated for any current value below the line D or above the line C. The impulse coil 52 is biased in the opposite direction and this impulse coil is saturated at current values below the line E or above the line F.

As shown in Fig. 8 (see curve 42") an electromotive forceof high amplitude and short duration is induced in the secondary windings of impulse coil 42 when the received current strength passes between the values C and D; and an electromotive force is induced in the secondary windings of impulse coil 52 (see curve 52') when the incoming signal passes between the values E and F. The polarity of the induced electromotive force is, of course, determined by whether the signaling current is increasing or decreasing as it passes between the values C and D, and E and F,

respectively.

Fig. 9 shows the voltages of the condensers 60 and I0, respectively. The curve 60' corresponding to the condenser 60 resembles somewhat the curve shown in Fig. 5. The condenser 60 is 'charged in the same manner as the condeser 30 of Fig. 1, but on account of the bias of the impulse coil 42 the zero voltages are of longer duration than the positive voltages. The curve 210' corresponding to condenser i0 shows two voltage values, one of which is gem and the other negative. The condenser I0 is connected to the battery II in a different manner from the condenser 00 and, in response to the incoming signal of Fig. 3, the negative voltage conditions in condenser 10 are of shorter duration than the zero voltages.

The total voltage of condensers 00 and I0 connected in series isas shown in Fig. 10. Comparing the output voltage shown in Fig. 10 with'the input'currentor voltage of Fig. '7, it will be seen that the device of Fig. 6, like the circuit of Fig. 1 produces flat-topped. signals. Furthermore, it will be noted that the incoming signal in passing between the current value E and the value C produces a zero voltage in the output circuit. The advantage of converting the current strengths between the values E and C into zero voltage is that signals between these values are mitted signal. The device of Fig. 6 avoids the possibility of transmitting-stray pr interfering disturbances, by suppressing all signals not sufficiently strong to reach the valueC or E A type of two-elementthermionic tube relay employing the regenerative locking principle is illustrated inFigi 11. A pair of three-electrode devices such as vacuum tubes are provided and the polarity .of the repeated i nal is. determined by the tube which is supplying current through its plate circuit. Y

I Referring more particularly to Fig. 11, the incoming line H0 is connected to the primary winding of a high permeability transformer or impulse coil H2 adapted to become saturated at a comparatively low current value. Connected to the, secondary transformer winding in a manner to be describedpresently, are a pair of vacuum tubes ill and I21. A pair of resistances I and I30 are connected in series with each other, the resistances forming a part of the plate circuits of the vacuum tubes II? and I2! respectively.

The grid circuits of the vacuum tubes Ill and I211 respectively are connected so that when space current flows in the plate circuit of either tube, the grid'of the other tube is blocked toe. negative polarity by the potential drop through the resistance I20 ,or 030 in the plate circuit of the first tube. The grid circuit of vacuum tube II'I is connected across resistance l30, while the grid which is connected to the output line i I l, is supplied with the potential drop across resistance iii], although, as an alternative arrangement, this grid circuit may be connected across the resistance I30.

The circuit shown in Fig. 11 has only two points oi stability. In one stable condition, current flows through the resistance I20 "and not'through resistance I30, while in the other stable condition current flows through resistance I30 and not through I20. The repeater of Fig. 11 remains in one or the other stable condition until the grid voltages are reversed by an impulse from the transformer M2. By employing a transformer delivering a very short high amplitude impulse. the time of signal crossover-or reversal of polarity-in the output circuit of the-repeater may be reduced almost to zero. When such a transformer is employed the crossover point on the incoming wave, at which the repeater changes from one stable condition to another, is independent of the characteristics of the vacuum tubes and dependent upon the permeability and saturation points of the transformer.

A three-element relay operating on the same principle as the two-element relay of Fig. 11 is shown in Fig. 12. Essentially the circuit of Fig. 12 comprises .two circuits similar to that of Fig. [111 with their outputs connected in series. A pair of biased impulse coils I42 and I52 are used to operate the relay, each impulse coil controlling the operation of the repeater for one polarity of the incoming signal. Assuming an incoming wave of the shape shown in Fig. 7, the impulse voltages of the secondary windings I44 and I64 of the impulse coils, I42 and I52 respectively will be as indicated by the curves 42' and 52 respectively of Fig. 8 and their directions are indicated by arrows shownadjacent to their respective windings in Fig. 12. The'vacuum'tubes I41 and I51 respond to the impulses received from impulse coil I42 and cooperate in' a mutually locking arrangement similar to that of Fig. ll, to-control the voltage across resistance I40. Similarly vacuum tubes I01. and I'll control the voltage across resistance I50. The resistances I and I are connected in series, and the output terminals I and I10 areselectedto. obtain the combined voltasedropacrossbothresistances. Itwillbe noted that vacuum tubes I" and III are connected to the secondary winding I in opposite relation to the connection of vacuum tubes Ill and I" to the secondary winding III. In other words vacuum tubes In and III are connected to the lower end of winding Ill whereas the vacuum tubes I" and I" are connected to the upper end of winding III. Therefore, a polarity of an impulse shown in curve I! will have, when impressedon the grid of vacuum tube I41, the op- .incurvell'oil lg.8,isoccurringinsecondary winding I due to the incoming signal wave shown in Fig. 7, passing through the range 01 intensities between lines 0 and D. This positive impulse causes the grid oi vacuum tube Ill to become negative, thereby blocking the space current in tube I" and causing space current to flow in vacuum tube III. The space current in tube I51 produces a voltage drop across resistance Ill. This voltage counteracts an equal drop across resistance III produced by the previous impulse in secondary winding III. The eiiect therefore 01' the voltage drop across resistance III is that terminal I'll goes from negative to zero potential as indicated by the ilrst zero section in the curve shown in Fig. 10. s When the incoming signal wave rises to the positive side and passes through the values between the lines E and FiFig. 7), a positive impulse occurs in secondary winding I" to impress a positive potential on the grid of tube I"; This results in changing the stable co I dition of tubes I11 and it! established by the p vious impulse in winding III, so that space current now flows in tube I11 causing a voltage drop across resistance III, and the space current in tube III-is blocketL- At this time the stable condition 0! tubes I" and I I1 is such that avoltage drop'ex-- ists across resistance I due to the first impulse shown in curve (of Hg. 8, and no voltage drop exisis across resistance III. The eilect oi simultaneous voltage drops across resistances III and I and of no voltage drop across resistance III is to impress a positive potential on terminal "I and the output voltage'ot the circuit goes from zerotopositiveasindicatedby theflrstpodtive section of the curve shown in Fig. 10.

When the incoming 818ml wave decreases in intensity and returns through the values between the lines 1' and E (Fig. '1), a negative impulse occurs in secondary winding I impressing a negative potential on the grid of tube Ill. The stable condition of tubes I11 and III due to the flrstimpulse shownincurve I2'ot1'lg.8,is againchangedsothatthespacecurrentin the tube I" is now blocked and space current flows intube lIlproducingavoltagedropacrossresistance III. At this time the stable condition .oitubesIl'landIIIisthesameasstatedlnthe previous paragraph, that is, a voltage drop exists across resistance I.

V The eil'ect oi simultaneous voltage drops across resistances III and III isto-restosethepotenflalontermlnal I'Iltoaa'o voltage of thecircuit goes mm creases in intensity, becomes negative and through the values between lines 0 and D (Fig. 'I), a negative in winding I to impress a positive potential onthe grid of tube I". The positive potential on the grid changes the stable condition of Iaibes Ill and III 7 sothatspacecurrentnowflowsintube Ill and the space current in tube III is blocked. The space current in tube ll'l produces a voltage drop across resistance III and no voltage drop now exists across resistance I. At this time the stable condltion'o! tubes I" and III is such that 'avoltagedropexistsacromreslstance IIlandno whentheincomingsignalwave (FlgL'Dispassing through intensifies between lines D and If,

the potential diflerence between terminals Ill.

and III is zero. when the intensity is above line 1",thep0t0ntlal attermlnal I'|l,withrespectto terminal m, is positive and when below lineD the potential at terminal III is negative.

The output voltages across terminals III and III are of a shapesimilar to that oi! the curve shown in Fig. 10 that is, oi! positive, negative and zero polarity and constitute a\ three-element signal wave. The reproduced signals are flattopped, and those impulses which have a leuer s'tiengththanlorcarenotretransmitted.

InFig.l3isshownaslightmodiilcationoithe" -The lllandlllareinthesrid ircifl of both tubea'llland II'I.

Theiollowingieaturuoitherelaysoil'lgs. 11, 12and13areinsfimnentalineilectimreliabiliiw oioperation: J

Intheilrstplace,the'inputvolta gessupplled to the grid circuits are obtained from impulse coilsratherthandirectlytromtheincaningline.

Bymeansorthei uipiulaecoilsthleviilueofincomingcurrentstreiutpbelowwhichasianalis canbewlthaccuracy .bysimplyvarylnlflleflaalngcurrentintheimpulsecoila. Whentbeeurruitvaliiecrossesa predeterminedlinetheimpulseeoilsproducea .impiflaeorwwhieh'instantlychanses tbcvacmmitubeflate circuits Irom a-stable conditionotonepolarltytooneotanotherpo- 'larity. Thusthetlmetakeniortheoutgoingsig- .naltochange'nomonepohritytoanotherisvery smallandisturthermi'netotanyvarlationsinthecharaete'rlsticaclthevacuumtubes. lithegrldcircuitsottbsvacuumtuhswereconnecteddirectly'totheincnminglinewithoutthe interpositionotimpuhscolhtheresponsetoa .cha aeinpola trorit eosthottheneeivedsisnaiwouldbeneitber asnfldnorasresularasinummmmmmmnm impulsecdls. v'lhe-responseoi'thegridcircuits with when, on the other hand, impulse coilsare employed the relay may operate indefinitely without requiring adjustment or the vacuum tubes.

The plate impedance of the vacuum tubes of Figs. 11, Hand 13 is comparatively low when the grid is locked to the positive polarity for the reason that no grid biasing batteries are used. Thus the plate circuit resistance and the B battery voltage become the chief factors in determining the output voltage. The output being taken from two o! the four plate resistances only, at most two B battery units are instrumental in determining the output voltage. In the circuit of Fig. 13, the question of battery matching is eliminated since a single B battery unit furnishes both output polarities. When a grid is locked to the negative polarity the voltage is 'suihcient to reduce the corresponding space current to zero.

ing and an outgoing line, instrumentalities connected to the incoming line for producing a succession of short, sharp, discrete impulses in response to the establishment of definite magnitudes of voltage 01 each incoming signal impulse,

space discharge devices responsive to said discrete impulses, a plate circuit for eachQ said devices, a single space discharge device interconnecting said plate circuits and the outgoing line, and impedance means in one of said plate circuits for controlling the output voltage in the other of said plate circuits. s

2. In a repeater for signal impulses, an incoming circuit, two space discharge devices each having a cathode and a control element connected to its input circuit, anode-cathode output circuits, an outgoing line to which impulses from an incoming line are to be repeated, polarizing sources for equally and symmetrically polarizing each.

control electrode with respect to its associated cathode, said control electrodes being coupled by equal mutual impedances, but oppositely, to said incoming circuit, and a potential storing device connected in common to said anode-cathode circuits and having impedance equally and oppositely coupled to said anode-cathode circuits, said device being also coupled to said outgoing line'.

13. In a communication circuit, a signal repeat- 'er comprising instrumentalities for producing-in response to each received signal impulse, a sucsession of short, sharp, discrete impulses of opposite polarities, mutually locking devices adapted to change from one stable condition to another in response to each of said discrete impulses, and a space discharge deviceadapted to remain stable in one of a plurality of conditions and solely responsive to said -discrete'impulses11or changing from one of its conditions to another.

4. In a signaling system, a repeater'comprisinga plurality of space discharge devices, a plate circuit to; each of said devices, a condenser connected in series in each of said plate circuits, an instrumentality responsive to a received impulse of one polarity and arranged to cooperate with one'of said devices in charging said condenser, another instrumentality responsive to a received impulse oi! the other polarity and arranged to cooperate with another of said devices in discharging said condenser, and a space discharge amplifying device for transmitting signals or a polarity determined by the voltage of said condenser.

5. In a, signaling system, a repeater comprising a condenser, means responsive to a received impulse of one polarity for charging the condenser, means responsive to an impulse of another polarity for discharging the condenser, said discharging means comprising a space discharge device having a control electrode responsive to received signals, and means for transmitting signals of a polarity determined by the polarity of the voltage of the condenser.

6. In -a signaling system, a repeater comprising a condenser, means responsive to a received impulse of one polarity for charging the con; denser, means responsive to a received impulse of another polarity for discharging the condenser, and means, for transmitting signals comprising a thermionic amplifier having a control electrode connected to the condenser, whereby to prevent rapid discharge of the condenser through the transmittingmeans.

7. In the operation of asignaling system, a method of reshaping incoming distorted signal impulses which comprises converting each of the distorted signal impulses into a plurality of impulses oishort duration and of opposite polarity, and subjecting each of said impulses 01 short duration to a relatively high, impedance to produce a voltage sustained until the next succeeding-short impulse is produced, to i'orm a twoelement square topped wave.

- 8.'l'n the operation of a signaling system, a method oi. reshaping incoming\dist0rted "signal impulses of positive and negative polarity which comprises converting each or the distorted impulses into a plurality of impulses ofshort duration and of positive and negative polarities, subiecting alternate pairs of said short impulses of opposite polaritiesto a relatively high impedance to produce a voltage sustained until thenext succeeding short impulse alone and of the opposite polarity is produced, subjecting other alternate pairs of, said short impulses of opposite polaritiesat different intervals'from those of the first mentioned alternate pairs whereby ,the voltage produced by one of the impulses oi! said other alternate pairs is sustained until the next succeeding short impulse of said other alter-- nate pairs is produced, and combining the sustained voltages in their time relation to form a three-element square topped wave.

9. In a signaling system a circuit arrangement for reshaping distorted signals comprising electromagnetic devices forconverting each of the distorted signal impulses into a plurality of voltagedmpulses of short duration and of positive and negative polarities, unidirectionally conducting means for selecting certain of said voltage impulses to produce sustained voltages of a polarity dependent upon the polarities of the voltage impulses of short duration, impedancemeans for further sustaining the voltages of the output of said unidirectionally conducting means, and means for repeating the further sustained voltages as undistorted signal impulses corresponding to those received by' said electromagnetic Ierences across the two impedance elements being devices, the repeated signal impulses having a polarity determined solely by the polarity of the corresponding sustained voltages.

10. In a communication system, a signal repeater comprising two space discharge devices, a condenser, a charging circuit for said condenser including one space discharge device and a discharge circuit i'or the condenser includingthe other space discharge device, each space discharge device having control means for succes-v sively blocking and permitting space current in 7 response to received i nals.

11. In a communication system, a signal repeater comprising two triodes, each having an anode, a cathode and a control electrode, a condenser, a charging circuit for the condenser including the anode and cathode of one triode, a discharge circuit for the condenser the anode and cathode of the other triode, inductive circuits including the control electrodes for controlling the current through the triodes in re-' sponse to received signals, and a spacedischarge device for transmitting repeated signals having a polarity determined by the charge oi! the condenser.

12. In a signal on system, a repeater for suppressing signals having' less than a predetermined magnitude, comprising a first impedance element, mutually locking devices responsive to incoming signals for maintaining in approximately constant potential difierence across said impedance element only while the incoming signal strength exceeds a predetermined positive value, a second impedance ele other mutually locking devices for maintaining an approximately constant. potential diiierence across said second impedance element only while the incoming signal strength exceeds in negative polarity a predetermined value, the potential difopposite in polarity, and a transmitting device connected;s in series with both impedan' ce elemen 13.1nasignalrisystemarranged to receive two element slgnal waves,a repeater 1'or supp signals having less than a predetermined magnitude, comprising a condenser, means responsive to incoming signalsior suc- 50 cessively charging and the condenser fierandsopoiedtlnteurrentinoneampllfier "is efi'ective to block current in the-other ampli- -fier, inductive device for controlling the input in mm tbeestabliahmmtol definite inasnitudes or voltage of the incoming signals.

15. Inasignalingsystem,'arepeatercomprising J5 apairotthermionicampiiflermmhblvi lm ment in series with the first impedance element,

system,asignalrecircuits oi the amplifiers, said devices being, adaptedtoproduceshort,sharp,-disereteimpulses output circuit comprising an impedance element and an input circuit supplied with voltage from the output impedance element of the other thermionic'amplifier, the input circuits being so poled that output current from one amplifier blocks output current in the other amplifier, inductive devices responsive to signals received from a line for controlling the input circuits of the thermionic amplifiers, and a transmitter for repeating the incoming impulses, said transmitter being connected to the two output impedance elements in series.

16. In a signaltransmission system arranged to receive two element signal waves, a repeater comprising oppositely biased inductive devices arranged to eiIect the suppression of signal intensities of a pmitive polarity and of anegative polarity except those within a predetermined range and .to convert the rising and falling portions of a signalwave within said range into short, sharp, discrete impulses of opposite pol'arity, a plurality of mutually locking space discharge devices responsive to said short impulses, a pair oi. impedance elements respectively connected in the output circuit oi each 01' said locking devices whereby each pair of short impulses oi opposite polarities produces potential differences across said impedance elements alternately, a

transmitting device connected in series with the pairs of impedance elements whereby each 0! the short impulses-is efiective to cause said transmitting device to transmit or repeat an impulse of positive, negative or zero voltage to form a threeelement signal wave.

17. In a repeater for signal an incoming and an outgoing circuit, devicu for receiving from said incoming circuit signal wave impulses of slowly varying intensities and for producing a' succession of short, sharp, discrete impulses in response to the establishment oi definite magnitudes of voltage in each incoming signal wave im'-. pulse, a pair of thermionic valves. each having a cathode, anode and an impedance control element, circuit means'conecting the anode oi one valve and the impedance control element of the other valve to said devices, and additional circuit means interconnectingthe input and output circuits of said valves and said outgoing repeater circuit whereby said valves assume two stable conditions alternately in response to said discrete impulses.

18. In a repeater for signal impulses, according to claim 17, said additional circuit means-comprising a connecting lead between the impedance control element oi said other valve to the plate fcircuitoi'saidone valve,completing'circuitmeans whereby an electrical impulse of one polarity applied to the impedance control elemmt of either valvecauses a change of plate circuit current in that valve wherebythe piatecurrentotonevaive isreducedandzthatottheothervalveincreased until one of said stable conditions is attained and maintained until an applied impulse oi! opposite 'p larityreversesthe processactuatingsaidvalm to assume the other and opposite stable condition. I v

19. In a system for communication of intelligence arepeater having and outgoing circuits, means in said incoming circuit and responsive to incoming distorted signal waves for producingasuccessionofshortdiscreteimpulsee inresponse tochangcsoi'magnitudeotvoltage of said waves througha fixedrange of magnitudes, the polarity-of said discrete impulses being determined by the direction of change 01 laidvoltage through said fixed range, thermionic discharge means alternately and oppositely responsive to impulses of positive and negative polarity,

an impedance element connected in common to' said thermionic discharge means and arranged to cooperate therewith in producing for each pair of short discrete impulses of positive or negative polarity by themselves, a sustained voltage wave of square topped shape and equal in duration to intervals between the impulses of the corresponding pairs, and another thermionic discharge device connected to said outgoing circuit ior amplifying said sustained voltages for retransmission.

20.,In a repeater for signal impulses, an incoming circuit connected to a source of signal impulses, two space discharge devices each having a cathode and a control element connected to its input circuit, and an anode-cathode output circuit, an outgoing line to which the impulses from an incoming l'ne are tovbe repeated, a path com mon to both anode-cathode output circuits and in shunt to said outgoing line, and electrostatic I EVERETT T. BURTON.

' means arranged in said common path to cooperate v

Images