US2186898A - Telegraph storage system - Google Patents

Description

Jan. 9, 1940. F. E. D'HUMY ET AL 2,186,898

TELEGRAPH STORAGE -SYSTEM Original Filed Sept. 5, 1935 3 Sheets-Sheet l M: fi Q m In h.

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II v INVENTOR F.E. dHUMY BY 1 .w. FRANKLIN i A ORNEY 'Jan. 9, 1940- F. E. DHUMY El AL TELEGRAPH STORAGE SYSTEM Original Filed Sept. 5, 1935 3 Sheets-Sheet 2 MEW Cum 2 on; V

N m W K m fia mm N W d F M M v w W F L M m Y B 2 on N m E 0mm Sm u 1 8o 80 E Jan. 9', 1940. F E HUMY 5T M 2,186,898

TELEGRAPH STORAGE SYSTEM Original Filed Sept.' 5, 1935 3 Sheetssheet 3 F Rm F5 Rl6 I7 RIB AT ORNEY Patented Jan. 9, 1940 Fernand E.

Lawrence W. Franklin, Delawanna, signors to The Western York, N. Y.,

pany, New York Application 7 Claims This invention relates to a telephone-telegraph system of communication and more particularly to such a system in which storage of signals is effected either prior to or subsequent to the transmission thereof over the telephone system.

It is possible to transmit telegraph signals over a telephone circuit at much higher speeds than can be employed for the operation of ordinary start-stop code telegraph recorders, telautograph equipment or similar telegraph apparatus. It is also desirable to be able to transmit or set up such telegraph messages facsimile telegraph signals, etc., on a storage device at times when a telephone channel is not immediately obtainable and as soon as such channel is obtainable to transmit the subject matter thereover at the high speed of which the telephone circuit is capable. It is also desirable in certain systems to receive these messages at the high speed of transmission obtainable over the telephone circuit and to record. them at leisure at ordinary telegraph recorder speeds.

Oneof the objects of the present invention is, therefore, to provide storage of the audio frequency signals utilized in telephone-telegraph communication intermediate their production and their visible recordation decoding.

Another object is to provide means for producing telegraph signals at one rate and for transmitting them over a standard telephone system at the same or at a different rate and to record them, if desired, at a still different rate.

Another object is to provide means for permitting the telephone transmission of signals to occur in timed space relation tothe production thereof or to the visible recording. thereof. 7

Other objects and advantages of the invention will hereinafter appear.

Three systems of telegraph communication are disclosed in the present application relating, respectively, to a code telegraph system, a telautograph system and a facsimile recording system. The term telegraph communicationor telegraph system is employed herein to refer to each of these different systems, and the term telegraph signals is employed in reference to the signals utilized in each of these various forms of telegraph systems.

In accordance with the present invention,- a source or sources of electrical oscillations are employed, which oscillations are keyed, modulated, or otherwise varied in accordance with the subject matter to be transmitted whether code telegraph, facsimile reproduction, or telautograph signals. a d a t norma rate o peration of v and dHumy, Scarsdale, N. Y., and

N. J., as- Union Telegraph Coma corporation of New September 5, 1935, Serial No. 39,332 Renewed August 3, 1939 the transmitting mechanism of such telegrap systems. The signal oscillations may be converted as they are produced into sound, light, magnetic or similar forms of energy, and stored upon suitable storage devices such as'phonog'raph records,

photofilms, magnetic wires, etc. The stored impulses may be subsequently reproduced at the same or at a different rate, translated into sound or audio waves and transmitted over a standard telephone system. At the receiving terminal of the telephone system, the received sound signals maybe again stored upon a sound storage device or transmitted into another form of energy such as light, heat or magnetism, and stored upon suitable storage devices from which the signals may again be reproduced at "a desired rate for the operation of a telegraph recorder such as a code printer, a facsimile reproducer or a telautograph receiver. Storage of the signals may be omitted at the transmitting station and the signal oscillations as produced translated directly "into tone signals which are applied to the transmitter of the telephone system or, if desired, storage may be omitted at the receiving station into electrical current variations which may be directly applied to the receiving recorder,

Fig. 1 is a circuit diagram of a code telegraphicl,

a telephone transmitting and receiving system employing phonographic storage;

Fig. 2 is a circuit diagram of a facsimile telegraph system employing magnetic wire storage;

Fig. 3 is a circuit diagram of a telautograph system employing photographic or photofilm storage of the telegraph signals.

Referring first to Fig. 1, a vacuum tube VI is shown having its output circuit connected to the primary winding LI of a transformer Tl in such a manner that continuous oscillations will be produced by the feeding back into the grid circuit through the secondary winding L2of the transformer, of the energy from the plate circuit through winding Ll. The frequency of oscillation is mainly controlled by the constants of the tuned circuit including the inductance L2 and the capacity Cl, and is within the audio range of eflicient telephone line transmission, which is approximately from 200 to 3000 cycles per second. A resistance BI is shown inthe filament return circuit of the vacuum tube Vi for the purpose of properly biasing the grid of the and the telephonically received-signals converted tube relative to the cathode, although other conventional methods of obtaining this bias, such as grid leak and condenser, battery bias, etc., may be used. The output of this oscillator or frequency generator is fed through the condenser C2 and the resistances R2 and R3 to the grid of an amplifier tube V2. A tuned circuit including the inductance L3 and capacity C3 is used in place of the conventional grid leak for the amplifier tube V2, the purpose of whi h is to properly shape the signals in the output circuit of the tube V2 so that they may be more efficiently transmitted over a telephone circuit with a minimum of interference with adjacent circuits. The output circuit of the amplifier tube V2 is coupled by means of an inductance L4 and a condenser Ct to a sound producing device S. A variable resistance or potentiometer R6 is placed across the sound producing device S for adjusting the amplitude of the outgoing signals.

Keying of the oscillations is accomplished by opening and closing'the connection between the junction of the resistances R2 and R3 and the negative pole of the battery. A tape controlled telegraph code transmitting distributor TD is included in the connection just referred to for keying the oscillations in accordance with a permutation code. However, in place thereof any suitable type of telegraph transmitter may be employed or a relay having its contacts in said connection and controlled by various types of sig nals, such as standard speed start-stop signals, multiplex signals, etc. can be used to key the oscillations supplied to the sound producer S. The transmitter TD may be a standard startstop transmitting distributor of the type shown in U. S. patent to. Rothermel No. 1,805,374, granted May 12, 1931. In transmitting distributors of this type the rest contact R is closed when the transmitter is idle, so as to apply steady marking battery to the usual telegraph line.

Keying is accomplished by grounding the junction point of R2 and R3 to the negative battery, or other unipotential point. When this point is grounded, the energy stored in the tuned circuit L3-C3 is dissipated into R3 over the next few succeeding cycles. When the transmitter contacts are opened, the tuned circuit has to charge up through the resistances R2 and R3, so consequently require a few cycles to reach the maximum value. Consequently the signals which are applied to the grid of V2 will be sufiiciently rounded to cause no interference to adjacent circuitsythis rounding being a function of the sharpness of tuning of the L3--C3 circuit as well as of the values of R2 and R3.

As a result of the above connections the code signals produced by the transmitting distributor T are inverted, no signals appearing in the plate circuit of the tube V2! when the contacts are closed, that is, in response to marking conditions and an oscillating current flowing in the plate circuit of tube V2, when the contacts of the transmitting distributor are open or in their spacing positions.

Consequently, during idle periods of the transmitting distributor, there will be no tone signals over the telephone circuit and therefore the operator at the distant end of the system may send on the same circuit, without recourse to the use of different frequencies and the filters required for use therewith and without necessitating the use of manual send-receiving switches or other complications.

As is well understood in the art, the rest contact R of the transmitting distributor T opens when the distributor sends a start signal of spacing character, remaining open during the successive closing of the code contacts 1 to 5.

The tone producing device S connected across the resistance Rd produces a tone of the frequency of the oscillations of the curr nt in the input circuit of the tube V2 and keyed in accordance with the telegraph code.

The tone producer S is acoustically shielded and coupled to the transmitter TT of a telephone system terminating at a distant point in a telephone receiver TR, in turn acoustically coupled to a shielded microphone M. The acoustic shielding and coupling is shown diagrammatically in Fig. 1 by the casings ill and H, of sound insulating material enclosing the sound producer S, and the microphone M, respectively. By virtue of the acoustic shielding it all extraneous noises are precluded from afiecting the diaphragm of the telephone transmitter and substantially all of the tone from the sound producer S is effective upon the diaphragm. Consequently the level of the tone may be relatively low while still having an appreciable and uniform efiect on the diaphragm of the telephone transmitter. Due to the low intensity of the sound and the acoustic shielding of the sound producer, none of the tone signals penetrate into the room and the operation of the transmitter is, therefore, as quiet as ordinary telegraph transmitting apparatus.

The acoustic shielding H also protects the microphone M from extraneous noises and directs the received tone signals most efficiently to the diaphragm of the microphone.

If the microphone is of the carbon button type, a battery or other source of microphone current is necessary. A potentiometer or manual gain control R5 is included in the microphone circuit to adjust the input to the amplifier tube V3, coupled thereto through the transformer T2, so that the different transmission constants of different telephone lines can be readily compensated for and brought to the same volume level at the grid of the amplifier tube V3. The signals which have been amplified by the tube V3 are applied to a phonograph recording unit RU which re cords the tones as picked up by the microphone M on a Wax cylinder CY! in a manner similar to that used in the common dictaphone or phonograph recorder. Thus it will be seen that the signals may be recorded at the high speed of transmission of which the telephone circuits is capable, which may be several times the ordinary speed of the printer system used.

After the transmission is completed, the wax cylinder is placed in reproducing position shown at CY? and operated at a lower speed corresponding to the normal rate of operation of a standard telegraph printer. Speed relationship between the recording cylinder CY] and the reproducing cylinder CY2 is the same as the relation between the transmitting speed of the transmitting distributor TD and the normal speed of transmission for which the printer P is adapted, whether it be start-stop, multiplex, or other type of telegraph printer.

The signals stored in the wax cylinder are reproduced by the phonographic pickup unit PU and applied through a potentiometer R6 to the input of amplifying tube V4. The signals amplified by the tube V4 are applied in push-pull to the grids of tube V5 and V6 through a transformer T3, which has a center-tapped secondary. The functon of tubes V5 and V6 is to rectify the ground return, or negative battery, as shown.

Tubes V 5 and V6 obtain their plate voltage from a point on this voltage divider 0r bleeder circuit through the coupling resistor RI2. This point is the junction of resistances R9 and RIO and is also the point of the filament return of the output tube V1. The rectifier tubes V5 and V6 have their filament return connected to the junction of resistors RIB and RI I. The grid return from the center-tap of the secondary winding of transformer T3 is made to the negative end of the bleeder circuit. Therefore, the negative grid bias on tubes V5 and V6 is the voltage drop across the resistance RH; the plate voltage applied to tubes V5 and V5 is the voltage drop across the resistance RIIl, less the voltage drop across resistance BIZ (if any). The grid bias on the output tube Vl is the voltage drop across resistance RIZ (if any) and the plate voltage applied to tube V! is the voltage drop across resistance R9, less the voltage drop of the selecting magnets PM] of the standard telegraph printer P. The value of resistance RII is such that the plate current with no signal applied to the grids is cut off or nearly so in tubes V5 and V6. With this plate current interrupted, or nearly so, there is little or no current flow through resistance BIZ and therefore little or no negative bias on output tube V'I. Maximum plate current will flow through the printer selecting magnet PM at this time, the value of the current being determined by an appropriate choice of the values of resistances R9 and BIZ and the characteristics of tube V'I. I

When a signal is received from the record cylinder 0Y2 indicating what is normally a spacing or no-current signal, this signal is amplified in the tube V4 and applied to the grids of tubes V5 and V5. On one half cycle the grid of tube V5 is either positive, or at least less negative than before. Therefore, plate current will flow through this tube and through resistance RI2. 0n alternate half cycles the grid of tube V6 becomes less negative, and also passes current through resistance RIZ. A small condenser C5 is connected between the paralleled plates of tubes V5 and V5 and the filament or other unipotential point. The value of this condenser is such that the charging of this condenser during the time that neither tube is passing current through resistance RI 2, and the discharging of the condenser during the time that either tube is passing current through resistance BIZ, will effect a filtering action which will hold the voltage on the grid of the output tube V! at an essentially constant value during the period of any pulse, without seriously afiecting the general shape of the printer signal.

In Fig. 2 a facsimile telegraph system is shown in which the facsimile telegraph signals produced at the normal rate of operation of the facsimile system are stored at the transmitting station on a magnetic wire and subsequently transmitted at a high speed over the telephone system. The picture or message to be reproduced is prepared in conducting ink or other conducting medium upon' an insulating background I3, such as paper, which is wrapped about a cylinder II]. A stylus I4 is moved longitudinally along the drum I 0 in any suitable manner as by a screw (not shown) as the drum rotates, so as to trace a helical path on the sheet I3. The drum III is of metal or other conducting substance and is insulated from the stylus I4.

The system of the invention operates most effectively when transmitting from subject matter embodying an image-bearing surface upon which the images, such as words or pictures, are delineated by alternate conductive and non-conductive area. Such subject matter may be provided,

.for example, by printing, writing or drawing with a conducting ink or other conducting substance upon a non-conducting or dielectric substance, such as paper. Matter written with an ordinary graphite or lead pencil or like conductive mate rial deposited upon the paper may also be employed. Messages typewritten with a ribbon impregnatedwith conducting ink or by carbon paper is another form which the subject matter may assume.

Subject matter of this character comprises areas of a conductive layer or coating, for example, the letters or words of a telegram, separated by areas Which are substantially non-conductive, as the blank portions of the papersheet on which the telegram is written. The conductive areas are for the most part separate individual areas varying through a widerange of sizes from a minimum useful size upward, which minimum useful size may, in the case of printed or ,written matter, be regarded as the dot for a small letter i or a period.

In accordance with the invention, the area of subject matter of the character described is disposed upon or brought near a conductive surface of appreciable size, such as the cylinder I0 or other metallic plate, with the conductive surface areas spaced from the larger surface or plate byv adielectric substance, as the paper of the telegraph blank. In this manner each of the individual conductive areas of the subject matter together withthe plate form the two plates of a small condenser. When the metallic drum I9 is connected to one side of the grid circuit, and the electrode or stylus I4 is connected to another side of the grid circuit and is disposed in opposed position to the plate and arranged to engage the image surface of the subject matter between it and the plate, and when relative movement between the stylus and subject matter is eifected of negative voltage of the tube V9 is replaced by a tuned circuit comprising the inductance L6 and the capacity existing between the-scanning stylus I4 and the sending drum Ill. The value of the inductance L6 is chosen relative to the value of the capacity existing between the stylus I4 and the drum I0,'when the stylus is on a nonconducting or background portion of the image bearing surface, so that this circuit is tuned to the frequency of the oscillator FI. When the stylus crosses a conducting portion of the image, the capacity of this tuned circuit increases, re-

-sulting in the ,circuit being tuned to-a lower frequency than Fl. Since in this latter case the impedance of the tuned circuit is less at the frequency of the source Fl, the voltage applied to the grid of the vacuum tube amplifier V9 will be less with the stylus on a conducting portion of the image bearing surface than when on the nonconducting or backgroundportion thereof. Consequently, the amplitude of the oscillating currcnts of the frequency of source Fi will be less when the stylus M traverses the conducting portions of the characters or images being transmitted than when it traverses a non-conducting portion. As in the system shown in Fig. l, the inertia. effect of the tuned circuit formed by the inductance L5 and the capacitance between the stylus it and the cylinder 10 prevents abrupt changes in the signals and produces rounded signals of a character that can be accurately recorded and transmitted over a telephone circuit without interference with adjacent circuits.

The output of the tube V9 is coupled through the radio frequency transformer T4 to the input circuit of a vacuum tube Vlll. The amplifier tube V9 may be biased to slightly beyond cut-off, by the resistances Bit and RM so as to suppress the low amplitude oscillating currents corresponding to the scanning of conducting areas of the image. A second source of high frequency oscillations F2, the frequency of which may be by Way of example 997,250 cycles per second, is also impressed on the input circuit of the tube VIE] through the radio frequency transformer T5. The oscillations from the sources Fl and F2 are mixed in the tube Viki, producing in the plate circuit of the tube oscillating currents of the frequency of Fl, F2 Fl plus F2 and F! minus F2, or frequencies of 1,000,000, cycles 997,250 cycles, 1,997,250 cycles, and 2750 cycles. The plate circuit of the tube L Vi is coupled through the audio frequency transformer T0 to a recording coil SI of a signal storage device. The 2750 cycle oscillations are the only ones which will be passed by the audio transformer T to the recording coil Si, the remaining or higher frequencies being suppressed.

The drum I0 is driven at a constant predetermined speed by a phonic motor ,I I having a driving coil l5 supplied with alternating current from an oscillator or frequency source F3. The source F3 may be of a frequency of 2250 cycles per second although of course, any other suitable frequency may be employed. The desired scanning speed of the drum [0 may be obtained by selection of the proper number of teeth on the rotor of the phonic wheel or by appropriate gearing between the motor I l and the drum ID.

The synchronizing oscillations from the source F3 may also be applied through the transformer T0 to the recording coil Si.

The recording mechanism A shown is of the Poulsen wire type where the moving wire W is magnetized with different intensities by the alternating current impressed upon it by the current through the coil Si, as it is sent from one spool E 3 to the other spool H. The recording of the picture on this wire may take place at a relatively slow speed and the subsequent transmission over the telephone circuit may be carried on at a much higher speed.

After the picture signals have been stored on the wire, the spool with the wire thereon may be placed on the transmitting mechanism B which is essentially similar to the recording mechanism A. If desired, the wire may be rewound so that as it is run off of the spool, the signals will be reproduced in the same sequence in which they were recorded, although this is not necessary with facsimile transmission providing the receiving recorder is rotated in the proper direction.

In the use of this form of storage for code telegraph signals, it is necessary to rewind the wire before transmission is started.

The Wire W containing the stored facsimile signals, .either with or without previous winding, is passed through the transmitting pickup coil S2 of the reproducing mechanism B, the variations of magnetism of the wire creating variations in current through the coil S2. These current variations are then amplified by the tube VH and applied to a sound producing device S disposed in acoustical relationship to the transmitter TT of a standard telephone system. The sound signals are transmitted over the telephone system and at the distant end thereof actuate the diaphragm of the telephone receiver TR.

Thereceiver TB is disposed in sound transferring relation to a microphone M in turn coupled through a transformer Tl to an amplifier Al and thence through a transformer T8 to the band pass filters BPFI and BPFZ. Filter BFPI is designed to pass only the signals which constitute the picture itself, while the filter BPFZ is designed to pass only the synchronizing signals frornthe frequency source F3.

The facsimile signals transmitted by the band pass filter BPFI are applied through an amplifier A2 to the stylus E i and drum 60 of the facsimile receiver. The synchronizing signals passed by the band pass filter BPF2 are applied through an amplifier A3 tn the driving coil 15' of the phonic wheel H to drive the receiving drum H3 in synchrcnism with the transmitting drum 10.

It is to be understood that while the motors I l and Ill have been shown driven directly by the oscillating current supplied by the frequency source F3, other means of controlling the speed of operation of the drums l0 and Hi from these signals may be employed. For instance, the 2250 cycle oscillations may be modulated by a sixty cycle current and a sixty cycle current may be used to operate or control the phonic motors.

Another variation of the invention is shown in Fig. 3 in which recording is on a light sensitive film in connection with a telautograph method of transmitting intelligence. Briefly, this method consists of varying the amplitude of currents of two separate frequencies in accordance with the writing to be transmitted and interrupting current of a third frequency for performing the function of lifting the pen from the paper as between Words, while a combination of the above with suitable relays performs the function of paper feeding, as will be apparent hereinafter. Currents of all three of these frequencies are recorded optically on a light sensitive film as they are controlled by the movement of the transmitting stylus. The film may then be run at a high speed and the intelligence stored thereon converted into tone signals and transmitted over an ordinary telephone system.

The three sources of oscillations F4, F5 and F6, shown diagrammatically, are within the audible range of transmission over telephone circuits, that is, between 300 and 3000 cycles per second. The output of the source F4 is connected to the outside terminals of a potentiometer RH and the arm 55 of the potentiometer is connected through suitable linkage mechanism so that as the Writing stylus passes horizontally across the paper, the movement is transmitted to the pothe potentiometer arms.

light sensitive device.

tentiometer'arm l6. Similarly, the potentiometer RIG is connected across the output of the frequency source F5 and the arm I! of this, potentiometer is linked to the writing stylus in such .a manner that vertical movements thereof are transferred to thepotentiometer RIB. Thus any movement of the writing styluscorresponds to the writing movement of any one or both-of These two potentiometer arms vary the amplitude of the signals from the sources F4 and F5. The third source of oscillations F6 isprovided with a switch l8 in series with the output, which switch is adapted to be operated whenever the 1 penis raised from the paper. The manner ,of operating the potentiometer arms l6 and I1 and the switch l8 by movement of the transmitting stylus is well known in the art and therefore is not shown in detail herein.

The output currents from the three sources of oscillation, F4, F5 and Ft, are'coupled through a transformer T9 to the movement element I9 of alight valve'2ll. The light from the source 2| is reflected through'a narrow slot 22 onto a moving' photographic film F, the amount of light which will reflect on the'filn'l being determined by the opening of the light valve 20 under the control of the current; from-the sources F4, F5 and F6. The developing mechanism 23 for the photographic film may, be included in the recording assembly. After development, the film is passed through a suitable drying chamber 24 and rewound on a take-up reel 25. It is to be understood that the sprocket wheels 26 for conveying the filmthrough'the developing tanks and drying chamber are geared together to rotate in unison at the proper speed for recording. After the telautograph signals have been recorded on the film, the film is rewound and then placed on a transmitting unit 24 for transmission over the telephone circuit. The film is driven at a constant speed which may be in excess of that of the recording mechanism and passes between a light source 25 and a photoelectric cell 26' or A narrow slot 2! isprovided so that only a narrow portion of the film is exposed to the light. The photoelectric cell is responsive to the variations of the light and dark portions of the film and the variable current produced .by the cell is amplified by the vacuum tubes VIZ and W3 and then appliedto a sound producing device S in acoustic relation to the transmitter TT of the telephone system. The audible tones transmitted over the telephone system are picked up fromthe telephone receiver TR at the distant station by a microphone They are then amplified by the tube VM and applied to bandpass filters BPF4, BPF5 and BPFB. These filters pass the frequencies corresponding to. those fromthe sources" F4, F5 and F6, respectively. I

The output side of thefilter BPFd is coupled through a transformer to a diode rectifier tube W5. The rectified voltage generated across the resistance RII of the rectifier tube W5 is applied to the grid of an amplifying tube VIB.

. nals from the tube VlBare applied to the grid of an amplifier tube V! thereby producing essening current'of a frequency corresponding to the The siesource E5, and of an amplitude varying with-the;-

other component j motion fot the transmitting stylus. The oscillations passed by the filterBPFB are rectified and amplified in the same manner, the output currentfrom this amplifier being of a 1 frequency corresponding to the frequency of the sourceFli and of a constant amplitude but being keyedbfi' whenever the controlling contacts [8 the usual form comprising a pairof pen tracingf' solenoids 28 and 29, a paper feed relay 30, associat'ed paper feed magnetil, and a pen lifting magnet 32.

The frequency which is passed by the filter B PF and'which corresponds to the frequency of the source F 3 is applied to the horizontal move ment-magnet 28 of the telautographic recorder and the currents which are passed by the filter BPFil corresponding to the frequency of the source F5 are applied to the vertical movement magnet 29 of the telautographic recorder. The.

oscillations from the source F6 which are con-..'

trolled by the switch l8 and operated by thelifting of the pen from the paper at the transmitting end of the circuit passes through 'the filter EFF; and after demodulation to the pen' lifting magnet 32. The pen lifting function may be controlled either by opening or-closing the switch 18,

but as shown, the switch"; is closed while the j pen is in contact with the paper. Variations in signals caused by the lifting of the pen from the paper result in the magnet 32 being deenergized.

The paper feed function isaccomplished moving the transmitting stylus out of the regular writing field to one corner thereof. This movement produces a minimumoperating current for the magnets 28 and 29.

The paper feed relay 30 has three windings, one each in series with the magnets 28, 29 and 32. that it will be released when the transmitting stylus is off the paper and in the aforesaid outof-writing position so that the v rrent passing through the magnets 28, 29 and 32 is at a minimum value. The paper feed function. maybe performed directly by the relay 3U but-prefer- This relay is adjusted so ably through the medium of the heavier operating 'may be produced and recorded at normal telegraph operating speeds and transmitted over a line at an entirely different rate, due to the provision of storage means intermediate the transmission line and the signal source and/or the point of destination thereof. It is to be understood that the invention is not limited to operation over a telephone system but is applicable to the transmission over radio beams, etc. Neither is it restricted to the use of signals of a frequency within the audible range, but the principles thereof may be applied to the storage and transmission of signals of any desired frequency.

What is claimed is:

I 1. A method of telegraphic communication which comprises producing a plurality of electri- .cal oscillations of different frequencies, varying said oscillations in accordance'with subject matter to be transmitted, recording said oscillations on a storing device at one rate, reproducing said oscillations from said device at a different rate,

utilizing said oscillations to produce tone signals, transmitting said tone signals over a standard telephone system and making a visible record in accordance with telephonically received signals.

2. A method of telegraphic communication which comprises producing a plurality of' electrical oscillations of different frequencies, varying said oscillations in accordance with subject matter to be transmitted, recording said oscillations on a storing device at one rate, reproducing said oscillations from'said storing device at a different rate and making a visible record in accordance therewith.

3'. A method of telegraphic communication which comprises producing a plurality of electrical oscillations of different frequencies Within the audible range of frequencies, varying said oscillations in accordance with subject matter to be transmitted, recording said oscillations electrically'on a storing device at one rate, reproducing said oscillations from said storing device at a different rate; transmitting said tone signals over a standard telephone system and making a visible record in accordance therewith.

4. Incombination with a telephone system, a plurality of sources of oscillations of difierent frequencies-within the audible range of frequencies, means for modulating said oscillations in accordance with sub ect matter to be transmitted, a storing device for recording said oscillations at a predetermined rate, means for reproducing said oscillations from said storage device at a different rate, means for producing tone signals in accordance with said last produced oscillations, means for applying said reproduced tone signals to a standard telephone system and a visible recorder associated with the receiver of said telephone system responsive tosaid received signals.

5. In combination, a plurality of sources ofoscillations of different frequencies within the audible range of frequencies, means for modulating said oscillations in accordance with telegraph signals, a storing device for recording said oscillations at a predetermined rate, means for reproducing said oscillations at a different rate and a telegraph recorder responsive to said reproduced signals.

6. In combination, aplurality of sources of scillations of different frequencies within the audible range of frequencies, means for modulating said oscillations in accordance with subject matter to be transmitted, a transmission channel, a storing device at one end of said channel for recording said modulated oscillations at a predetermined rate, means for reproducing said stored oscillations at the same or a difierent rate and a recorder responsive to said reproduced signals.

'7. A communication system comprising two sources of supersonic frequency currents, means including said sources for'producing signals having audible frequency components corresponding tothe subject matterto be transmitted, means for storing said signals at a predetermined rate, means for reproducing said stored signals at a different rate and a recorder responsive to said reproduced'signals;

FERNAND E. DHUMY. LAWRENCE W. FRANKLIN.

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