US2150781A - Telegraph system - Google Patents

Description

"March 14, 1939; M l. Pupm TELEGRAPH SYSTEM '4. sms-sheet .1

Filed July 9,'1956 @WSU ESR Tk mi ATTORNEYS .Marh 14,1939, MLPUPN -`2,150,781

TIELEGRAPH SYSTEM y @mi ATTORNEYS March 14, 1939.

TELEGRA'PH SYSTEM 4 Sheets-Shet 4 Filed Julyl 9, 1936 A'ITORNEYS VIi() Patented ai'o 14 i939 ausl Application if s, i936, eriai No. defied se crains. (et.

This invention relates to telegraph communication systems and has for its principal object the provision of an improved system or long distance telegraphy.

The system may be employed in either land or submarine cable telegraphy, but is especially ape plicable to the latter because the problems and limitations involved therein are much more severe than in the former. It provides a more perfect method of relaying than has heretofore been developed and makes more emcient use of the cable by increasing the signalling speed and reducing the time heretofore lost in synchronizing the var ious units. In addition, the equipment is greatly simplified, thereby reducing the maintenance erf;-` pense and the number oi delays due to apparatus failures. The systemes a Whole is very reliable and comparatively simple to operate.

The system may also be employed in teleg raphy by means of modulated high frequency waves. When used in wireless telegraphy it oilers great advantages with regard to secrecy, and j,

therefore is very desirable to both comercial companies and to military forces. y

Broadly stated, the invention provides im proved transmitting or sending apparatus for iin= pressing on a cable or other communication chan nel, such as a submarine cable or overhead or conf duit conductors in land telegraphy, signal pulses having a definite, regular shape and uniform periodicity. An alternating synchronizing voltage is impressed. on the 'same cable for the purpose of effecting synchronisin between the send-n ing and relaying units. over the cable or conductor a composite wave comprising the alternating-synchronizing voltage with signal pulses superposed thereon.

When this waves arrives at the relaying station it is separated into its two components and the alternating voltage-used to drive a synchronously operable relaying unit. This relaying unit funcn tions to completely retransmit the received signal pulses, which are much distorted due to the attenuation characteristic of the cable, in their original shape as sent out from the sending stef1 tion.

As a primaryaid in securing more perfect relaying, and in increasing the speed and reliability of the system as a. Whole, I provide a novel signal reshaping or conforming unit. By means of this conforming unit it is possible to convert and translate a received signal yWave of greatlydistorted form into a series of signal pulses, each having a `deiinite, precise shape and the succession Aof pulses having e. uniform periodicity. The

Thus there is transmitted pulses.

proper functioning oi this conforming unit depends upon only a portion of each received signal pulse and utilizes this portion to impress a constant voltage of corresponding polarity across a timing circuit. The portion of the signal pulse 5 so utilized is of denite duration and may be preselected to be the most characteristic portion of the pulse, that is, that portion having the maximum deviation from aero.

The timing circuit includes relay means actuf1'0 ated by the impressed voltage for repeating the impressed signal pulses in their conformed shape, and a time delay circuit for continuing the actuation of the relay means a predetermined length of time after the voltage is removed. Th'eelec- -15 tromagnetic constants ci the time delay circuit may be proportioned so as to give repeated signal pulses of the desired duration.

lIn order to select the desired portion of the v received signal pulses, `a contact'maker is pro- 20 vided which makes a uniform, continuous series of contacts, with the interval between successive contacts equal to the interval between successive signal pulses, that is, the periodicity of the series of contactsis the same as that of the signal pulse A2&5 intervals. The duration of each contact is the y same, and is equal 'to the predetermined fraction oi the signal pulse which it is desired to utilize. This fraction may be chosen as desired, but 'a suitable value has been found to be one-fourth. 18 0 The contact maker operates jointly with relay means responsive to the received signals to impress the voltage across the timing circuit.

It will be apparent that the operation of the contact maker is such as to impress a. constant .'35 voltage of definite duration across the timing cir-l cuit foreach received signal pulse, and that the voltage will be impressed at uniform intervals equal to the, interval between successive signal l The magnitude and duration of this volt- 40 age is independent of the received signal pulse, but the polarity is determined by the polarity of the selected portion of the signal. Therefore, the duration ci successive contacts of the repeating relay means will be independent of the received signal pulses, but the sequence of contacts will depend upon the corresponding polarities of the received signal pulses. The repeating relays may then be used to control the operation of apparatus for impressing corresponding signal 50 pulses on the cable.

'I'hus the relayed signal pulses will be of preoise shape and uniform periodicity despite the severe distortion of the received signals occa.-l sioned by the attenuation characteristic oi the ,65

2 cable, which markedly increases with the frequency an'd therefore cuts olf the higher harmonics in the signal wave.

. Another advantage of this method of relaying is its inherent stability of operation in the presence of electrical disturbances on theV cable, due to electrical storms, etc.. and its comparative freedom from the effects of zero wende This is due to. the fact that the correct functioning of the relaying unit depends only upon the portion of the signal pulse selected, and therefore it makes no diilerence what the shape of the incoming signal wave is,` solong as the selected portions are of the correct polarity. Since these selected portions-may be chosen from the most characteristic part of the signal pulse, a maximum deviation from the mean value of the signal train is permitted while still maintaining perfect relaying.

For the correct operation` of the conforming unit it is necessary that the contact maker operate in vsynchronism with the received signal pulses, and therefore in synchronism with the sending unit. At the present time a well-known method of synchronization is the clockhand correction method. The units at the various stations are driven or controlled by phonic wheel motors, each motorenergizcd With a direct current interrupted by a tuning fork. Since it is impossible to adjust the several tuning forks to vibrate in exact synchronism over an extended period of time, the fork at the transmitting station is adjusted to run either slightly faster or slightly slower than those at the other stations, and provision is made to restore periodically the units to exact synclironism. Thus continuous synchronism is not maintained hut, instead, there is a periodic progressive departure therefrom, which'may be undesirable when high signalling speeds are employed. Furthermore, this method of synchronization requires a tuning fork with associated corrective aptus at conch station, the frequency of which must be carefully adiusted, and therefore introduces apparatus which is expensive, may get out of order, and requires considerable time for correct synchronization after an idle period.

In the present system I provide apparatus for synchronization by means of .a continuous alternating voltage sent over the same cable or communication channel as the message signals. This voltage is impressed on the cable by the transmitting unit, and the signal pulses superposed thereon. At the relaying station the synchronizing voltage is separated from the signal pulsesby appropriate methods, preferably by a thermionic amplifier selectively tuned to the synchronizing frequency, and is used to control the operation of a phonic wheel motor.

The composite wave is also passed into another channel which contains a substantially distortionless amplifier. The synchronizing voltage may be eliminated from this channel by impressing thereon a voltage of like magnitude and frequency but of opposite phase, by means of a voltage generator similar to the one at the transmitting station, or by an appropriate voltage obtained from the synchronizing voltage amplifier.

The received signal pulses so separated are used to control the operation of the conforming unit in the manner hereinbefore described, and the contact maker of the unit ls driven by the synchronously rotating phonic wheel motor. The phonic motor also drives the signal pulse generating equipment controlled by the conforming escoger unit, for impressing corresponding signals on the cable to the receiving station.

\ The conforming lunit is also useful at thereceiving station if it is desired to record signals by automatic printing equipment, and in that case a synchronizing voltage is sent overl the cable from the relaying to the receiving station.

In a simplex system it is preferable to send out the synchronizing voltage from the signal transmitting station and relay the voltage to the receiving station, if desired, although it might be 4sent out from the relaying or receiving stations. In a duplex system the voltage may be impressed on the cable at either terminal station and relayed to the other terminal statiini.4 'In either case all the synchronously operating units are controlled by means of a single unit at one of the stations and operate in synchronism therewith, so that only a single tuning iorlr is required for the entire system. For this reason it is not necessary to provide elaborate corrective apparatus to insure a constant frequency, such as is required when two or more forks vibrate at slightly different frequencies.

Thus this method of synchronization has many advantages over previous methods; it effects continuous synchronization of units separated by a long cable, instead of a periodic progressive departure therefrom; it permits controlling the units at the sending, relaying, and receiving stations by the use of, only a single tuning fork,

thereby eliminating apparatus which is expensive, may get out of order, and requires careful adjustment; and after the necessary adjustments are made at the time of installation no further adjustments are required for synchronizing the units after an idle period, thereby eliminating the time required for synchronization by present methods.

Since the signal pulses areimpressed on 4the cable by the synchronously rotating apparatus, the frequency of the synchronizing voltage is always definitely related to the signalling speed. The term signalling speed is a convenient way to designate the rapidity with which. successive signal pulses follow each other, and the phrase frequency of the signal pulses may be tal-zen to mean the frequency of e continuous succession of signal pulses. it will be apparent that the signalling speed, or the frequency of the signal pulses; determines the speed with which any desired sequence of signal pulses may be transmitted. The relative frequencies and magnitudes of the synchronizing voltage and the signal pulses may be varied hetween wide limits but it has beenfound that a synchronizing voltage having one-foiuth the frequency and one-third the magnitude of the signal pulses is very satisfactory, although magnitudes varying from onetenth to one and one-half times the signal pulses have been employed with success.

As is well known, an inherent limitation on the speed of signalling is the attenuation characteristie of the cable, which markedly increaseswlth frequency. Due to this discriminatory eifect, signal pulses transmitted at too high a speed become practically indistinguishable, and are especially unsuited for automatic relaying. In order to enable the signals to he distinguishably received and therefore make possible a higher signalling speed, I preferably employ' signal pulses conslstingof a marking pulse of desired' polarity followed by a curbing pulse of opposite polarity. The eilectof this curbing is vto define',

. so that in the received signal wave each pulse will appear as a decidedv hump. y Advantage is taken of this in relaying bys'electing the hump for the portion of the signal pulse which controls the conforming unit, therebyinsuring reliability and accuracy of operation, and freedom from small disturbances. The employment of curbed signals also prevents charging the cable by a succession of like signal pulses, and so minimizes zero Wander effects.

As a further als al improving the distinguishability of the signals, and the reliability and precision of operation, l employ the above-described conforming unit to control the signal pulse generating equipment at the transmitting station.4

A tape transmitter is used for converting spaced code punchings in a telegraphic tape into electric current pulses of corresponding polarity. it is evident that if there is any irregularity in the size and spacing of the holes, or irregularity in the operation oi the tape transmitter, these pulses will not be of desired uniformity. Therefore the conforming unit is employed to insure impressing on the cable signal pulses-of dednite,

circuit, including a battery, will be closed. When used with the conforming unit this transmitter gives excellent results and possesses the great advantages of simplicity and reliability. The feeding of the tape, the operation of the conforming unit, and the operation of the signal pulse generating apparatus are all controlled by the phonic wheel motor at the transmitting station so that proper phase relations may be readily maintained.

The following is a detailed description of a preferred embodiment of my invention:

In the drawings, Fis. l is a schematic diagram showing the relationship between the various units at the sending, relaying, and receiving stations;

ape; Fie. 3 is a side elevation of the tape transmitrating and amplifying the signal pulses and the synchronizing voltage at the relaying station;

Fig. 'l is a diagram to illustrate the advantages of using the conforming unit in relaying; and

Fig. 8 is a tabulation showing the wave forms found at various points in the system for a given sequence of dots and dashes.

Referring to Fig. l, the various steps in the transmitting, relaying, and receiving of the message signals are shown in schematic form. For purposes of clearness, all electric ccnnectionsbe- Fis. 2 shows a fragment of the telegraphic tween units are shown by a single, heavy line, y

and the units themselves are shown as separate and distinctpieces Aof apparatus with their rotating elements coupled together, although in practice many of the units -will be combined. In the box representing each unit, the gure is indicated in which a more detailed showing of that L unit may be found.v s

At the sending station the phonic motor drives the tape transmitter, which converts telegraphic tape punchings into corresponding .electric pulses; the conforming unit, which produces corresponding pulses of definite shape and uniform periodicity; a signal pulse controller and genere.- tor, controlled by these pulses and impressing corresponding` signalpulses on the cable; and a synchronizing voltage generator for impressing that voltage on the cable.v

When the composite wave, comprising the sienal pulses and the synchronizing voltage, reaches the relaying station it passes into two amplifiersthe message channel amplifier, and the synchronizing channel amplier. The latter is selectively tuned to the frequency of the synchronizing voltage and its output is used to `control the relaying phonic motor. This motor drives a synchronizing voltage eliminator which bucles out that voltage from the message channel, thereby leaving only the signal pulses, which are then fed into a conforming unit and completely reshaped to their original form. 'These reshaped pulses control a signal pulse controller and generator exactly'as at the sending station, and impress corresponding signals on the succeeding cable section. The relaying phonic motor also drives a synchronizing voltage generator as at the sending station.

- At the receiving station the two components of the composite wave are separated as at the relaying station, and a. conformingunit reshapes the'signal pulses for operating recording appa.- ratus, such as an automatic printer. Of course, ifa. siphon recorder is used it will not be neces-- sary to reshape the received signals and the synchronizing voltage need not be sent over the cable to the receiving station, thereby eliminating the corresponding apparatus.

Fig. 2 shows a fragment of telegraphic tape Ill which may be used to transmit'messages by the International Cable Code, in which a pulse of current in one direction, say positive, signifies adot, and a pulse of corresponding duration but of opposite polarity, a dash. The holes Il reprewith holes I8 to feed the tape at the desired,

speed. Spring elements 2l! are fastened to 'a suitable support 2I and carry at ltheir lower lends contact elements 22 and 23.. These contact elements press lightly on the tape t0 and are so positioned that when holes Il or l2 pass thereunder the inner contact elements pass throughl the holes and make contact with the drum il,

thereby completing a suitable circuit and'generating' a. corresponding pulse of current. Since itis customary to employ a tape which is waxed or parafdned, occasionally particles oi.' wax are caught between the inner contactelements and 'pressing on said channel a. continuous alternating voltage having a. frequency bearing a denite ratio tothe frequency of the signal pulses, a synchronousl-y operable relaying unit connected to said channel, means for causing said voltage to maintain said relaying unit in continuous synchronism. therewith, and means for controlling the opera tion of said relaying unit by the signals received during deilnite portions of the signal pulse inter-I vals, said relaying unit recreating signal pulses corresponding to those received during said inter vals for retransmitting corresponding signals, the

said rreated signal pulses having ,definite .the frequency of the signal pulses bearing a denite ratio to that of the alternating voltage,

passing the impulses received at the other end oi said communication channel into two channels, selectively amplifying the alternating voltage in one of said channels to the substantial exclusion of the signal pulses, utilizing said separated voltage to maintain the relaying unit in synchronism therewith, eliminating the alternating voltage in the other of said channels by an equal and opposite voltage impressed thereon by means oi said separated voltage, and utilizing the signal pulses so separated to control the operation oi the relaying unit for retransmitting corresponding signals.

8. In a 'telegraph system including a sendingunit and a synchronously operable relaying unit operativelyl connected to a communication channel, the method of transmission which comprises impressing on said' channel by said sending unit a continuous alternating voltage and signal pulses, the frequency of the signal pulses bearing a definite ratio to that of the laternating voltage, passing the impulses received at the other end of said communication channel into two channels, selec:- tively amplifying the alternating voltage in oneoi said channels to the substantial exclusion of the signal pulses, utilizing said separated voltage to maintain the relaying unit in synchronism therewith, utilizing said synchronously operated unit to generate and impress a voltage in the other oi saidchannels substantially equal and opposite to the alternating voltage contained therein, and utilizing the signal pulses so separated to con- 'trol the operation of the relaying unit for retransmitting corresponding signals.

9. In a telegraph system including a sending- A unit and a. synchronously operable relaying unit operatively connected to ay communication channel, the method of transmission which comprises impressing on said channel by said sending unit a continuous alernating voltage and signal pulses,

the frequency of the signal pulses bearing a definite ratio to that of the alternating voltage, passing the impulses received at the other end of said,

-communication channel into two channels, selectively amplifying the alternating voltage in one of said channels to the substantial exclusion of the signal pulses, utilizing said separated voltage to europei maintain the relaying unit in synchronism there# other of said channels by an equal and opposite Voltage impressed thereon by means of said separated voltage, and utilizing the portions of the signals received during only deilnite portions of the signal pulse intervals to control the operation of the relaying unit for retransmitting corresponding signals.

l0. In a telegraph system including a sending unit and a synchronously operable relaying unit operatively connected to a communication channel, the method oi transmission which comprises impressing on said channel loy said sending unit a continuous alternating voltage and signal pulses, the frequency of the signal pulses bearing a definite ratio to that of the alternating voltage,

' passing the impulses received at the other end ci said communication channel into two channels, selectively amplifying the alternating voltage in one oi said channels to the substantial exclusion of the signal pulses, utilizing said separated volt. age to maintain the relaying unit in synchronism therewith, utilising said synchronouslyoperated unit to generate and impress a voltage in the other oi said channels substantially equal and opposite to the alternating voltage Acontained therein, and utilizing the portions of the signals receved during only denite portions of the sign nal pulse intervals to control the operation of the relaying unit ,for retransmitting corresponding signals whose lengths are substantially greater than the said portions of the signal pulse intervals.

ll. in a telegraph system, apparatus ior reshaping signal pulses comprising relay means responsive to said signal pulses, contact means malring a uniform series oi contacts having the perisaid contact means, a repeating relay having an actuating coil, said energizing circuit being adapted to energize said actuating coil when closed by the joint action of said relay means and said con tact means, and means continuing actuation of said repeating relay for a preselected interval after said circuit is opened including a capacitance in parallel with said actuating coil, said capacitance being charged by the closing of said.

energizing circuit and discharging through the actuating coil after the energizing circuit is broken 'to continue the actuation of said repeating relay vfor said preselected interval.

l2. in a telegraph system, apparatus for re'- shaping signal pulses comprising relay means responsive to said signal pulses, rotary contact means making a uniform series, o contacts having the periodicity of a continuous succession of signal pulses, said contacts being oi equal duration lessthan that of a signal pulse interval, an

o energizing circuit under joint control of said relayy source of voltage under joint control of said receiving relay and said contact maker for applying said voltage to the first-mentioned circuit when the energizing circuit is closed by the closure of both receiving relay and contact' maker and thereby actuating said repeating relay and charging said capacitance, said voltage, resistance, inductance and capacitance being selected so that upon the opening of said energizing circuit the capacitance will discharge through the actuating coil of the repeating relay and continue the actuation thereof for a selected interval thereafter, thereby generating repeated signals which persist for said selected interval,

14. In a telegraph system, a communication channel; Aa tape transmitter converting telegraphic tape punchings into corresponding electric signal pulses; and transmitting means controlled `by means. of .only a portion of each of said pulsesv to impress corresponding signals on t pulses, a contact maker for making a uniform i said channel, said transmittingmeans comprisp ing a relay selectively responsive to said signal series of contacts having the periodicity of 'a continuous succession of signal pulses, said contacts being of equal duration substantially less than that of a signal pulse interval, an energizing circuit under joint control of said relay and saidcontact maker, a repeating relay having an actuating coil energized upon closure of said energizing circuit by the joint action of said relay and said contact maker, a repeating relay having an with the actuating coil of said repeating relay, said capacitance being charged by the closing of said energizing circuit and discharging through the actuating coil of said repeating relay after the energizing circuit is broken so as to continue actuation thereof for a selected interval after said circuit is broken', whereby signals which persist for said selected interval may be generated.

15. In a telegraph system including a communication channel, means for impressing upon said channel uniformr signal pulses which comprises a feeding mechanism for feeding a tape perforated in accordance with the signal pulses which it is desired to transmit, a contact element positioned Y passing under said contact element, acontact. 'maker correlated-with said feeding mechanism for making a uniform series of contacts-having the periodicity of the signal pulse intervals, said contacts being of equal duration substantially less than that of a signal pulse interval, an energiz- 1 ing circuit under joint control of said relay and said conta-ct maker, a repeating relay having an actuating coil, said energizing circuit being .adapted to energize said actuating. coil when closed by the joint action of said relay and said being charged by the closing of said energizing circuit and discharging through the actuating coil after the energizing circuit is broken to continue the actuation of said repeating relay for said selected interval.

l16. In a telegraph system including a' ccmmunication channel, means for impressing upon said channel uniforml signal pulses which c'omprises a feeding mechanismfor feeding a tape perforated in accordance with the signal pulses which it is desired to transmit, a contact' element positioned and constructed to continuously bear against a tape in said feeding mechanism,

a relay controlled by said contact' element so as A to be actuated inac'cordance with the perforations in said tape passing under said contact element, a contact maker correlated with said feeding mechanism for making a uniform series of contacts having the periodicity of the-signal pulse intervals, said contacts being of equal duration substantially less than that of a signal pulse interval, a repeating relay having an actuating coil, a capacitance in parallel with said actuating coil', the circuit including said. 4capacitance and said actuating coil having resistance, inductance "and capacitance, an energizing circuit'including a source of voltage under Joint control of the first-mentioned relay and said contact maker for applying said voltage to the first-mentioned circuit when the energizing circuit is closed by the closure of both the first-mentioned relay and the contact maker and thereby actuating said repeating relay and charging said capacitance, said voltage, resistance, inductance and capacitance being selected so that upon the opening of said energizing circuit the capacitance will.

for receiving said signal pulses and synchronizing voltage at the other end of said communication channel, means synchronized by the received synchronizing voltage for selecting definite portions of the signal pulse intervals, and means i vcontrolled by the signals received during the said 'selected portions for recreating corresponding signals of definite length substantially greater than the said selected.l portions of the signal pulse intervals.

18. In a submarine cable telegraph system, in combination, means for impressing on a submarine cable signal pulses and acontinuous alternating synchronizing voltage, the frequency of said synchronizing voltage bearing a definite ratio to the frequency of the signal pulse intervals, means for receiving'said signal pulses and synchronizing voltage at the other end of said cable, a contact maker synchronized by the received synchronizing voltage for-making a uniform series of contacts having the periodicity of the signin pulse intervals, the duration of said contacts being substantially shorter than said intervals, and asignal repeater under the joint control of the received signal pulses and said contact maker for recreating signals. corresponding tothe signal portions received while said contacts are made, the signals recreated by saidsignal repeater having lengths substantially greater than the duration of' said contacts.

19. In :a-submarine cable telegraph system, in combination,I means for impressing on a submarine cable signal pulses and a continuous alternating synchronizing voltage, ,the frequency for making a uniform series of contacts having the periodicity of the signal pulse intervals, the

duration oi said contacts being slibstaritially shorter than said intervals, an energizing circuit under joint control `of said receiving relay and said contact maker, arepeating relay having an actuating coil energized upon closure of saidem1 ergizing circuit by the joint action of said receiving relay and said contact maker, and a capacitance in parallel with the actuating coil,

of said repeating relay, said capacitance being charged by the closing of said energizing circuit and discharging through the actuating coil of lsaid repeating relay after the energizing circuit is broken so as to continue a tuation thereof for a selected interval after said circuit is broken.

` 20. In a submarine cable telegraph system, in

combination, means for impressing on asub marine cable signal pulses and a continuous alternating synchronizing voltage, the frequency of said synchronizing voltage bearing a definite CERTIFICATE Patent No 2;, l 50,781.,

ratio to the frequency of the signal pulse intervals, means for receiving and separating said signal pulscsand synchronizing voltage at the other end 'oi said cable, a receiving relay selectively responsive to the received and separated signal pulses, a contactl maker synchronized by the received and separated synchronizing voltagefor making a uniform series of contacts having the periodicity ci the signal puise intervals, said contacts being of equal duration substantially-less than that o a signal Apulse interval, a repeating relay having an actuating coil, a capacitance in parallel with said actuating coil,

ythe circuit including said capacitance and saidv actuating coil having resistance, inductance and capacitance, an energizing circuit including a source of voltage under joint control of said receiving relay and said contact 4maker for applying' said voltage tothe first-mentioned circuit* when the ,energizing circuit is closed by the closure ci both said receiving relay and the contact maker and thereby actuating saidl repeating relay and charging said capacitance, said voltage, resistance, inductance and capacitance being selected so that upon the opening oi said energizing circuit the capacitance will'discharge through the actuating coil oi the repeating relay and continue the actuation thereof for a. selected interval thereafter, thereby generating repeated signals persisting for saidselected interval.

, venirmi ement si, Administratif@ of the Estate of Michael idwrslcy Papin, Deceased.

0F contractione e March lil, 1959 VARVARA PUPIN Sl'll'IH, ADMINISTRATRIX or MICHAEL IDvoRsKY PUPI'N, DEGEASED@ It is hereby certified that error appears in the printed specification lofthe above numbered patent requiring correction as follows: Pegel, first column, line 58, for the word "waves" read wave; page 5, first col, line "(5for "electric" read electrical3 page 5, second column, line 8, for "wil" read will; page 6, first column, line )4.9, for message read'meesage; page 7 first column, line 65, claml, and second colmi-1n, line 6, claim`2, after "superpovsing" vinsert signal pulses; line 10,'claim 2 strike out vianciig page 8, first column, `line 11,9, claim8, for "laternating" read alternating; page 9, first column, line h2., claim llufor "a repeating relay having an" readand a capacitance in parallel; and that the.. said Letters Patent should. be

, read with this correction y,therein that the sarnemay conform to the record` of thel case in the Patent office. y

signed and sealed this 9th day 'or Mama. D. 1959.

Henry Van Ar edele (Seal) Acting ,Commissionerof Patente.

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