US2274638A - Telautograph system - Google Patents

Description

March 3, 1942. 4 v E. R'osENE 2,274,638

I TELAUTOGRAPH SYSTEM I Filed Nov. 15, 1959 7 Sheets-Sheet 3 406 4/3 STA TIO/V B IN V E N TOR V. 5. R05 ENE I 3 mm ATTOR/VE V I March 3,1942. v. E. ROSENE 7 2,274,638

TELAU'IOGRAPH SYSTEM 'Filed Nov. 15, 1939 7 Sheets-Sheet 4 STA T/ON A l/Vl/EA/ TOR 1 E. ROSE/VL- B HhXM ATTORNEY -March 3, 1942.

v. E. ROSENE TELAUTOGRAPH gYSTEM Filed Nov. 15, 1939 7 Sheets-Sheet 5 l l l k FIG. 7

.m 7 rfa- 0 4 M 0 7 0 w w M 1. H

STATION 8 I lNVENTOR 1 E. ROSE NE 8) WW, 2 ATTORNEY March 3, 1942. i I v. E. ROSENE 2,274,638 TELAUTOGRAPH SYSTEM Filed Nov. 15, 1939 7 Sheets-Sheet 6 smr/o/v a INVENTOR E. ROSENE ZMM' A TTOR/VEY Patented Mar. 3, 1942 UNITED STATE s PAT NT OFFICE I 12,214,638 rrzmu'roemrn SYSTEM Victor E. Rosene, Jamaica, N. Y., assignorto'Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application November 15, 1939. Serial No. 304,455

This invention relates to systems for transmission of intelligence over wires or radio' circuits and particularly to a telegraph system in which the movements of a stylus or writing point,

at a transmitting station, are recorded in facsimile at a distant receiving station.

An object of the invention is to improve-transmission in a telegraph system of this type, and this is accomplished by utilizing the changes in frequencies of transmitted electric current rather than the changes in intensities, for reproducing in facsimile in a recording station the transmitted intelligence.

Heretoforein systems of this type, the movement 'of a directing, or writing, point at the transmitting station was resolved into two component motions which in one case varied the frequencies of two signal currents'being transmitted over the line circuit and in-another case 'varied the phase angle of an alternating current voltage applied to the line.

.In 'onetype of system; the signal currents of varying frequencies were utilized to produce cor-' responding movements of the directing, or writing, point at the receiving station. The two signal frequencies, however, were preferably cut cuits and the receiving pointsfollowed the movement of the sending point.

In another case, heretofore known, wherein the component motions varied the phase angle of 'an oscillating potential applied to the line,

the varying phase angles of the receiving signals a were utilized to move a receiving pen or stylus to reproduce the motions of the transmitting point.

According to the present invention, the movement of the directing, or writing, point at the in separate concentric grooves on the \same phonographic record and the variations in these frequencies corresponding to the movements of the transmitting writing point were obtained by moving reproducers along the grooves to increase or decrease the relative speed of the rec 0rd with respectto the reproducer stylus. At the receiving station the line frequencies were separated and each was modulated with a local frequency which was obtained from a record similar to the one at,the transmitting station. Each of the frequencies generated atthe receiving stationdiffers.normally'from the corresponding line frequency by a predetermined frequency for which the receiving circuitis balanced in such a way that no motion of the receiving, or

- recording, point is produced but any slight change in the line frequency-due to the motion of the transmitting point unbalances the receiving circuit and moves the receiving, or recording,- point and the associated reproducers until the balanced condition was restored. -By setting up the receiving circuit for a balance, when the difference between the line frequencies and the locally generated frequencies was small as compared with the line frequencies, the changes in ,line frequency "corresponding to even slight movements of the transmitting points produced large unbalancing effects in the receiving'cirthe transmitting station, rents of different frequencies are generatedby circuits.

transmitting station, is resolved ino two component -motions which likewise vary the frequencies of two signal currents being transmitted over the line wire or radio circuit. These currents are varied in frequency, and are uti- Iized to produce, or indicate, corresponding movements of the writing point at the receiving StBtlu'lL. gI-Iowever, the present invention differs from the systems heretofore known in that at two alternating" curmeans of oscillators and transmitted over a wire line orradio circuit to a receiving station where the' two currents are separated by means of filters. Each of the currents passing through a filter is then impressed on a vacuum tube mod,-

ul'ator circuit together with an alternating cu'rrent of a distinctive frequency from a local oscillator. Each of the modulator circuits is balanced so as to eliminate in the output the frequency of its local oscillator. The lower or high.-

er side-band products of, the modulator circuit outputs are introdllced into special vacuum tube The two special vacuum tube circuits are preferably tuned to the same frequency and respectively operate two receiving elements. On each of two rotatable shafts of the receiving elements is mounted a variable air condenser which controls the-frequency-of one of the local oscillators and thereby maintains a fixed side-band.

frequency in the output of each of the modulator circuits. The positions of the receiving elements correspond to the frequencies of the currents received from the transmitting stations. Since the position of the receiving elements is the unbalance in the outputs of the special vacuum tube circuits which outputs cause the recording pen to take a position corresponding to the position of the transmitting pen.

A feature of the invention is the adaptability of the system to transmission over a wire line or radio circuit.

Another feature is the adaptability of the system to a telephone plant for remote control of the various devices or for the transmission of alarms from an unattended repeater station to an attended station.

Still another feature resides in its use for telemetering purposes by maklnguse of one transmitting oscillator and one receiving element with its associated vacuum tube circuit.

In the drawings:

Fig. 1-shows the relative arrangements of Figs. 3, 4 and 5; s

Fig. 2 shows the relative arrangements of Figs. 6, '7 and 8; v 4

Figs. 3, 4 and 5 are a schematic circuit arrangement of a facsimile telegraph circuit according to the invention, wherein line conductors are employed between interconnected stations;

Fig. 3 shows a transmitting station connected to a line circuit;

Fig. 4 shows a line circuit equipment at the receiving station connected to balanced modulator circuits and special vacuum tube circuits;

Fig. 5 shows the receiving elements responsive to the outputs of the special vacuum tube circuits for operating 'the recording pen; I

Figs. 6, 7 and 8 are a schematic circuit arrangement of a facsimile telegraph system according to the invention, wherein a radio circuit is employed between stations; a

Fig. 6 shows a transmitting station including the radio transmitter;

Fig. 7 shows a radio receiver operating into balanced modulatorsv and special vacuum tube circuits;

Fig. 8 shows the receiving elements responsive to the outputs of the special vacuum tube circuits of Fig. 7 foroperating the recording pen; Figs. 9.and 9A are side and end elevation views, respectively, of the transmitting pen and operating contacts;

Fig. 10 is a plan view of the operating arms and magnet therefor of the recording pen; and v Fig. 11 is' an elevation view of the recording pen and the operating arms and magnet therefor.

Like parts in figures are designated with like reference numerals, that is, the parts in Figs. 6, 7 and 8 which are like their corresponding parts in Figs. 3, 4 and 5 have the same reference characters except for the prefixes which correspond to the number of the figure in which the parts are Tocated.

In the arrangements of Figs. 3, 4 and. 5 the 2,274,038 rotated about its longitudinal axis operates a comprises only two stations, stations A and 13, either one of which may send to or receive from the other over line conductors such as those designated 30! and 302. Although the system only shows transmitting apparatus at station A and receiving apparatus at station 13, it is understood that each station may comprise both transmitting and receiving equipment. Furthermore, by employingeither automatic or manually operated switching, facsimile messages may be transmitted to any one or a plurality of stations or to two or more stations for broadcast purposes.

phone art and therefore are not shown or de-' scribed herein.

A transmitting unit and a receiving unit may be provided at each of stations A and B. The transmitting 'unit such as that designated T comprises a table 90I (shown in Fig. 9) a transmitting pen handle 902 which when manually operated through its swivel bushing 903 closes contacts 904 and brings transmitting pen or stylus 905 into engagement with a sheet of paper (not shown) affixed to table 90I. "Ihe transmitting pen can be made to leave a record on the paper. The transmitting pen is fastened to two sliding arms 303 and 304 which are respectively connected by means of rotatable shafts 305 and 306 to variable air condensers 301 and 308. The receiving unit, such as designated R, at station B comprises a table IIOI (shown in Fig. 11)- and a recording pen or stylus H02 which is automati- \cally operated in response to the incoming signal frequencies. The pen, or stylus, H02 is securely fastened to a bracket I I03 which in turn is fixedly mounted on disc H04. Disc H04 is fixedly secured to a disc H05 in the manner shownvin Fig. 11 by a-machine screw H06. To the lower side of disc H04 are mounted in the manner shown in Fig. 11 four rollers I I 01 and in a similar manner tothe upper side of disc I I05 are mounted four rollers I I08. Slidably arranged between rollers II 01 is longitudinally movable arm HIO and similarly arranged between rollers H08 is longitudinally movable arm H09. The recording pen and movable arms therefor are shown assembled in the schematic circuit arrangement in Fig. 5.

The movable arms H09 and I H0 are respectively connected by means of rotatable shafts IIII and 50I to variable air condensers 502 and 503 and the-rotor members of receiving elements 504 and 505. The recording pen H02 is caused in response to the incoming signal frequency to take 7 the circuits operating at each station and to remove the pen from the paper at the receiving station when the pen is lifted from the table at the transmitting station. When a wire line circonnecting a transmitting and a receiving station 7 system illustrates one form of the invention and will now be described.

The automatic and manually operated switching equipments are well known in the tele-' System employing thewire line circuit for transmission The operation of the system is started by closing the start switch 309 whereby direct current is furnished at boththe lower and upper contacts of the switch to operate the oscillators 3|0 and 3H and to close the operating circuit for start relay 3|2. Relay 3I2 operates and closes a cir-- of resistance'3l8 which of comparatively high value, the relay does not operate at this. time.

Relay 404, however, operates and closes a conditioning circuit from grounded battery, armature and contact of relayj404j conductor 406, conductors 401 and 400 in parallel, vacuum tube filaments, to ground, thereby lighting-the filaments of the vacuum tubes in the oscillators .4I6

and 435, balanced modulators 409 and M0 and.

the filaments -.of the full wave rectifier-amplifier vacuum tubes in the special circuits 4| l and M2. The conditioning circuit including conductor 406 also extends over conductors 506 and 501, in parallel, to ground through the windings of the rotors of the receiving elements 505 and 504, respectively. The system is now conditioned to receive the signals transmitted by transmitting pen.

905. Any pressure on the'transmitting pen 905 closes contacts 904 which establishes a circuit extending from ground, conductor 3|6, through the winding of relay 3", togrounded battery. Re-

lay 3I1 operates and establishes at its armature A and contact a shunt path around resistance 3|8 whereby relay 405 is operated. [Relay 405 in opcrating} closes a circuit from grounded battery,

' the armature and contact of' relay 404, contact and armature of relay 405, conductor 4 I 3, through the winding of magnet I2, to ground. As hereinbefore explained the transmitting station apparatus changes the capacitance of two variable air condensers 301 and 308 and causes the receiv-y ing station apparatus to assume a similar position.

Two oscillators 3I0 and 3| I are provided at station A for transmitting and are capable of generating current oscillations of different fre- .quencies, onecf which is of a-higher range than the other. V .The movement of transmitting pen 905 on a P sheet afflxed to table 90| causes arms 303 and 304 to move correspondingly. Arms 303 and 304 are in Figs. 3 and 9. Each of the arms is'slotted for approximately its full length to engage an oblong-shaped member that :is fixedly mounted on the top of each of the rotatable shafts 305 and 306. so that any movement of, the transmitting pen 905 resolves itself into two' component motions which through the corresponding motions of arms 303 and 304 rotates shafts 305 and 306 to vary the capacities of condensers 301 and 308 and consequently the frequencies of the two oscillators 3 I 0 and 3| I whereby'two variable signal currents are transmittedby thaosciillators through the primary'windings'of transformer 3I3. a

Condensers 301 and '308 are respectively shunted by variable condensers 3 I 9 and 320 which pivotally mounted on swivel bushing 903as shown are-used to adjust the frequencies of oscillators 310 and 3 when condensers 301 and 308 are in their minimum positions as shown in Fig. 3. The

two ranges, or bands, of frequencies of oscillators 3|0 and .3I leach made variabl within its range by the movement of transmitting pen 905 are impressed simultaneously on the wire linecone ductors 30I and 302 through'the windings of f transformer 3|3. At receiving station B the 1 variable frequency in the higher range which is produced by oscillator 3|0,-is' passed through transformer 402 and high-pass filter 4| 4 and impressed -on balanced modulator 'circuit 409 through the transformer 5. A carrier frequency 14 from a local oscillator MB is introduced into the modulator circuit 409 and combines with the variable frequency received from the transmitting station through high-pass filter M4 to generate side-band frequencies in the modulator output. The carrier frequency f4 from oscillator-416 is higher than the band of transmitted frequencies andis suppressed in the modulator circuit and the lower side-band is transmitted to transformers 4H and M8. The frequency ft from oscillator 4I6 may be adjusted by the variable condenser 403. The differential character of the plate circuits of the balanced modulator prevents voltage of the frequency of the unmodulated carrier current generated by oseillator MS from being induced in the outputcircuit. The output or lower side-band. transmitted to transformers MT and H8 is impressed on a. spe cial vacuum tube circuit 4| I. Transformer 4|| is tuned to' a frequency fa by condenser 419 and I transformer M8 is tuned to-a frequency I2 by condenser 420. The frequencies are referred to herein as the lower side-band although the upper side-band could be used. The side-band frequencyfi from the modulator is approximately midway between the frequencies 12, and I: when the circuit is balanced. 1

The special vacuum. tube circuit 4|| comprises an inputwhich represents a variable condition to be recorded, two vacuum tube full-wave rectitier-amplifiers, and a. receiving element of the galvanometric type having two windings connectedfpr differential energization by the output of the rectifier-amplifiers. Any change in the output frequency ii of the modulator-409 causes. a corresponding change in the output of special circuit 4| I. If we assume that the modulator output frequen'cy'h approaches nearer to the frequency f: of the tuned transformer 4|8 and at the same time is farther away from the frequency is of the tuned transformer M1, the

" output of vacuum tube 42| will increase while the outputof vacuum tube. 422 will decrease. The energization of the two differential windings of the receiving element 505 is consequently-caused to be unbalanced and thereby produces movement of the rotor of the receiving element. 505 and the movable element of condenser 503 until the oscillator 4|6 has changed its frequency f4 to a value which will combine with the frequency from the transmitting station through high-pass filter M4 to restore the side-bandjrequency ii to its normal value. When this condition is restored the outputs of vacuum tubes MI and .422

are again balanced and the receiving element 505 I will come to rest.

The receiving element or galvanometer 505 comprises rotor 508 energized by a circuit in eluding conductor 503, a field structure 599 having two differential windings therecn adapted to be respectively energized by the output of fullwave rectifier-amplifiers 42| and 422, and rotatable shaft 50! which is fixedly mounted on rotor 508 for varying the capacity of condenser 503 in accordance with any unbalance in the currents respectively fiowing through the two windings on field structure 509. The rotatable shaft 50!, when rotated, causes the movement of arm Hi and the consequent movement of receiving pen H02 as hereinbefore stated. Rotor 508 has no restoring spring or other biasing means; It

moves only when the current in either of the differential windings exceeds the current in the other.

resistance 425 will be decreased thereby increasing the negative voltage on the grid of rectifieramplifier 422 and decreasing the negative volt- ,age on the grid of rectifier-amplifier 42L Rapid fluctuations of voltage on the grids of the rectifier-amplifiers 42l and 422 are prevented by resistances 429 and 43| and condensers 430 and The direction of motion depends on. which of the two differential windings carries This circuit is tuned by condenser 419 to-a frequency slightly. below the normal frequency of, output of modulator tube 423. The rectifier circuit of tube 422 includes the right-hand winding, or secondary, of transformer H8 and the cathode and two like rectifier elements in the upper part of the tube. This circuit is tuned by condenser 420 to a frequency slightly above the normal frequency of the output of modulator tube 424. The grid elements of tubes 42I and 422 are connectedto the midpoints of the secondary, or right-hand, windings of transformers 4i! and 8, respectively, so that the pulsating direct current resulting from the 432. The plate current of rectifier-amplifier 42! will be increased and the plate current on rectifier-amplifier 422 will be decreased thereby setting up a magnetic field in the field structure 509 'of the receiving element 505 which will cause the rotor coil 508 to turn in a direction to increase the capacitance of condenser 563; The change in capacitance of condenser 503 lowers th frequency of oscillator 410 to a point where the of arm 303 attached to shaft 305, at station A,

the latter arm having been operated through the movement of the transmitting pen 905. The

- movement of arm 'I I [0 will operate in conjuncfull-wave rectifying action of the diodes causes a drop in the potential across resistors 425 and 425 through which the grid elements of tubes 42l and 422 are respectively connected to the grid biasing batteries 42'! and 428. Resistor 429 and condenser430 are provided to delay change in the potentialof the grid of tube, 42!; and resistor 43l and condenser 432 are provided to delay change in the'potential of the grid of tube 422. The output circuit of tube 42l includes one winding of field structure 509 of the receiving galvanometer 505 and the output circuit of 422 includes the other winding on field structure 509. These windings,'as hereinbefore stated, are differential so that with the input circuit of tube 42l tuned to a frequency as much lower than the normal frequency of the output circuit of modulabor-tube 423 as the input circuit of tube 422 is tuned to a frequency higher'than the normal frequency of the output circuit of modulator tube 424,. the current in one winding on field structure 509- will balance the current'in the result.

As soon as there is current in the circuit over v wire line conductors 30! and 302 caused by the movement of transmitting pen 905 and the consequent movement of the rotatable element of nearer the frequency f: of thetunedcircuit of transformer 4H and farther away from the frequency fa of the tuned circuit of transformer 4|8. 'I'he'rectified current through resistance 428 will be increased and the rectified current through tion with a simultaneous movement of arm H09.

The movement of arm H09 like arm I0 .is controlled through intermediate equipment by the movement of its corresponding armat station A, the controlling arm in this case being that designated 304. The operation resulting from the movement of arm 304 will now be described. The movement of arm 304 like arm 303 is controlled by the operation of transmitting pen 905. The position of arm 304 which is attached by means of shaft 306 to variable condenser. 308 determines the frequency of oscillator 3| I. Condenser 308 is connected in parallel vwith the variable condenser 320 which is used to adjust the frequency of oscillator 3 when condenser 308 is in its minimum position. The frequency hereinbefore described. Tuned circuits and arrangements of the vacuum tubes in the special vacuum tube circuit 2 are similar to those ,of

the special vacuum tube circuit 4| I. -Although a normal frequency h from modulator 0 has been chosen similar to that of f1 from modulator 403 so that circuit 2 may have the'same characteristics as circuit 4, this arrangement is not necessary. Circuit 2; may be designed to have circuits tuned to frequencies difierent from those of the tuned circuits of vacuum tubes 42| and 422; The receiving element 504 is similar to the-receiving'element 505 and condenser 502 is in the minimum position when condenser308 is inits minimum position. The action of the fredescribed. The positions of the arms 303 and 304, respectively control the condensers 301 and 300, will determine the frequency transmitted over wire line conductors 30l and 302, and will cause arms Hi and H09 of the receiving pen H02 totake up positions corresponding to these frequencies. The cross-point of the arms at the transmitting tabl 90l will therefore determine the position 'of the cross-point of the arms at the receiving table H0l. In this way the receiving, or recording, pen will follow the motion armature H09 moves downward until the receiving pen, or stylus, H02 engages the paper on table H 0| Arm H09 is pivotally fixed on top of shaft HH and is therefore permitted to operate in a see-saw fashion under the influence of magnet IH2. The iron pole-piece HI3 may be arcuate in shape in order that shaft [III in rotating under the influence of rotor 5l0, may rotate arm H09 and still maintain the receiving pen H02 in an operated position. When the magnet H I2 is deenergized coil spring Hi4 will hold the recording pen H02 suspended above the recording table H0l. 0

System employing the radio circuit for trans-,

- mission When a radio circuit is employed to transmitthe two control frequencies from the transmitting station, standard radio transmitters and receivers are used. The output of the radio receiver contains the two control frequencies such as described hereinbefore in the system wherein a wire line circuitwas used for transmission. v These control frequencies areseparatedby the high-pass and low-pass filters as hereinbefore described. There are, however, in addition to the control frequencies, two other pilot frequencies which must be respectively employed for starting the operation of the circuits at the receiving station and for controlling the recording pen. At the transmitting station in this case transmission will now be described in detail. Referring to Fig. 6 the start switch 609 at station A is operated to close at its upper and its lower contacts, respectively, circuits for operating oscillators M0 and 6H and start relay 6l2. Relay 612 on operating closes a circuit for impressing a frequency is on transformer 022. The system is now in condition to receive signals transmitted by transmitting pen 905. Any pressure on transmitting pen 905 closes contacts 904 which establishes a circuit extending from ground, conductor BIB, through the winding of. relay 6|! to grounded battery. Relay 0|! operates and closes a circuit for impressing a frequency f7 on transformer 62L As hereinbefore described a transmitting pen 905 upon being moved over table 90l changes the capacitance of two variable air condensers such as those designated 60! and 600 of Fig. 6 and consequently the frequencies of oscillators M0 and GH'are varied to correspond to the movement of transmitting pen 905. Two different ranges, or bands, of frequencies are respectively produced by oscillators H0 and 6.

By moving transmitting pen 905, the frequencies -of each of the oscillators 6l0 and-6H are'made variable within their respective ranges and these variable frequencies are impressed on the secondary windings, connected in series, of transformers GM and 622 at the same time that the fixed pilot frequencies is and): of oscillators 623 and dare impressed .on the secondary able frequency produced by oscillator M0 is of a higher range than that produced by oscillator oscillators would be employed for generating the,

pilot frequenciesand their outputs would be r-' spectively controlled by the start and the pen relays. At the receiving station the pilot fre-Z quencies would be present in the output of the radio receiver and pass through, first, the output transformer and then, a band-pass filter. The band-pass filter passes a, band 'of'. frequencies which are between the cut-off frequencies of the high-pass and the low-pass filters Included 3 in the range of frequencies readily passed through the band-pass filter arethe higher pilot and the lower pilot frequencies added at the transmitting station. The higher pilot frequencies ,would be used to control a start relay for starting the'receiving circuit in-ope'ration and for furnishing grounded battery to light all the tube filaments and to energize the rotors of the receiving elements. The lower pilot frequency would be used to control a pen relay which when.

operated controls the pen magnet.

. The system employing the radio circuit for SH and the fixed frequency of oscillator 023 is higher than that of oscillator 024. The four frequencies in the output of transformers SH and 622 are impressed on a radio transmitter 025 together with a source 626 of carrier current having a frequency fa, the output of the transformers serving to'modulate carrier current for transmission to receiving station 13. At receiving station B the incoming modulated carrier current is received by radio receiver 136 wherein the demodulation takes place in the well-known manner, and the demodulator output of the receiver is impressed on transformer 131. The demodulator output now contains the two control frequencies that respectively originated in oscillators 910 and 0H and the two pilot frequencies which respectively originated in the oscillators 623 and 624. passes through transformer 13'! is impressed on three filters connected in parallel, namely, highpasslfilter H4 for readily passing the controlling frequency originating in oscillator 6l0, low-pass filter 133 for'readily passing the controlling frequency originating in-oscillator 6| l, and bandpass filter 138 for readily passing the frequencies originating in oscillators 023 and 524.

The controlling frequencies readily passing filter H1 control the receiving element 805 in the same manner as the controlling frequency The pilot frequencies readily passing the band-- pass filter I30 are impressed on high-pass filter 139 and low-pass filter 140. quencies of the band-pm filter are between the cut-off frequency of each of filtersl39 and H0. The frequency is readily passing high-pass filt r The demodulator output which The cut-off fre- 139 is impressed on a rectifier-amplifier tube Ml to operate start relay 142 and the frequency f1 readily passing low-pass filter 140 is impressedv H09 to change positions corresponding to the positions of the transmitting arms 604 and 603 at station A in the same manner as hereinbefore described for the system employing a wire line circuit for transmission between-stations.

. Telemeterz'ng Should it be desired to use the invention for telemetering purposes, one of the transmitting oscillators only such as that designated 3|0 in Fig. 3 and one receiving element only, such as that designated 505 of Fig. 5 would be employed.

. In this case the filters would be omitted since a transmitted. Since only an indicator is required at the receiving station for telemetering an indicating type wattmeter having a center-tapped potential coil could be used in place of the receiving element such as that designated 505.

The spiral spring usually furnished on the wattmeter potential coil should be replaced with flexible leads in this case.

- What is claimed is:

1. A telautograph system comprising a receiver having a scribing point, an electrostatic capacity, means whereby said capacity is varied as the scribing point moves in one direction of a coordinate system, means for establishing the frequency of an alternating current at said receiver by said capacity, means operableto transmit current of varying frequency from a transmitter, means for receiving said varying current at said receiver and producing under the control thereof a force for changing the capacity, which force is proportional to the instantaneous difierence of the transmitted current and the frequency of alternating current established at said receiver.

2. A .telautograph receiving system comprising a scribing point, a source of incoming waves and a local source of waves, means for causing said waves to interact to produce a force, means for applying said force to cause movement of said scribing point, and'electrostatic capacity controlled means determining the position of said scribing point at which no further moving force is applied thereto.

3. In a transmission system, a transmission circuit, means connected to said circuit and movable in a plurality of directions, an oscillator circuit and elements responsive to the movement of said means for varying the capacitance of said oscillator'circuit whereby the frequency of ourrent'from said oscillator circuit when impressed vanometric means in said receiving station re-- sponsive to said variations in the frequency of current from said source, and an indicator at said.

receiving station responsive to the operation of said galvanometric means for indicating the different positions through which said directing means is operated.

5. A facsimile telegraph system, having a transmitting station, a receiving station, and a transmission circuit interconnecting said stations, a directing point capable of assuming a plurality of positions, a signal frequency source and an electricity storing element cooperating therewith at said transmitting station to transmit over said circuit to said receiving station, current of a frequency corresponding to each of the operable positions of said directing point, a source of current at said receiving station, a balancing circuit for first simultaneously receiving the current from both of said sources and then suppressing current waves of the frequencies from said second-mentioned source whereby one of the sidebands of the frequency generated at the firstmentioned source is further transmitted, a rectifier-amplifier circuit for receiving said one sideband, a receiving element comprising a magnetized coil and responsive to the output of said rectifier-amplifier for indicating at said receiving station successive positions of said directing point.

6. In a transmission system, in combination with a transmitting station, a receiving station, a transmission circuit interconnecting said stations, a directing point at said transmitting station movable in any direction in a plane, a plurality of electricity storing elements controlled by said directing point, a plurality of sources of waves of different signal frequency ranges respectively controlled by said storing elements to vary the frequency of waves from each of said sources for transmission over said transmission circuit, a plurality of channels at said receiving station, means at said receiving station for selecting the different signal Wave frequencies received for transmission over said channels respectively, galvanometric means comprising a plurality of magnetizing elements respectively responsive to the different frequency ranges and an indicator responsive to said magnetizing element for indicating the plurality of positions to which said directing point is moved.

'7. In a transmission system, in combination with a transmitting station, a receiving station, a radio transmission circuit extending from said transmitting station to said receiving station, a directing point at said transmitting station movable in all directions in a plane, a plurality of electricity storing elements controlled by said directing point, a plurality of sources of. signal currents of different frequency ranges respectively controlled by said storing elements to vary the frequency of each of said sources for transmission over said transmission circuit, other taneously with current of the frequencies of the difierent signal ranges of said plurality of sources, a radio receiver at said receiving station, a plurality of networks connected to said receiver for respectively selecting for further transmission currents of the frequencies originating in the first-mentioned sources, a second plurality of networks connected to said receiver for respectively selecting, for further transmission, currents of the frequencies originating in said other lators for generating current of difierent frequency ranges, a transmission circuit for receiving current from said' oscillators, a switch and means controlled thereby for starting said oscillator to transmit over said circuit currents of different frequencies, a receiving circuit comprising a high and low-pass filter, two balanced modulator circuits respectively connected to said hi h and low-pass filters, a balanced rectifier-amplifier circuit connected to each of said modulator circuits, galvanometric devices respectively responsive to the output current waves of said rectifiersources, a receiving circuit, means responsive to the currents selected by said second plurality of said networks for conditioning for operation said receiving circuit,,means responsive to the currents selected by first-mentioned plurality of networks for operating said receiving circuit, and

an indicator responsive to the operation, of said receiving circuit for duplicating the movements of said directing point.

8. A telautograph system comprising two oscilamplifier circuits, a transmitting pen for controlling the frequencies transmitted from said oscillators over said transmission circuit and receiving pen controlled in its movement by said galvanometric devices, a writing surface in en- .gageable relation with each of said pens, electromagnetic means operatively responsive to the en- .gagement of said transmitting pen and writing surface therefor for causing the engagement between said receiving pen and said writing surface therefor. I i

, VICTOR E. ROSENE.

Images