US2256487A - Data transmission and control system - Google Patents

Description

' Sep 1941- F. L. MOSELEY ET AL DATA TRANSMISSION AND CONTROL .SYSTEM :5 Shets-Sheet 1 Filed Oct. 7, 1956 mm m g I l L I] fiozmm T E T k W W m w B H mm v w/Jm 77 Z w k l A R B T mE N EEEQQQ m oh II 1% RN mm W N K i ,u In R HM- Q Sept. 23, 1941. F. 1.. MOSELEY ET AL DATA TRANSMISSION AND CONTROL SYSTEM 5 Sheets-Sheet 2 Filed Oct. 7, 1936 V1 2% NM W N m flan c a mY m HRB E F v P 1941- F. L. MOSELEY ET AL 2,256,487

DATA TRANSMISSION AND CONTROL SYSTEM Filed Oct. 7, 1956 5 Sheeis-Shet 5 Q *m INVENTORS fimnla/a M70511 EY 3 ERIC J. Isa/arm r H/ iliNI-JYQ 'l'atenteilsephnlfll DATA MR AND m srs'rnr franeislsloselenlelhamanllblelmc, mitfqaflgnerliosperrym 'Co-pany, llrooklymlt't aoarperathn oiNewieek Application October 7, 1.3, SEEING. 1m 15 Claims. (Cl. 171-831) This invention relates, generally, to transmission systems and .he invention has reference, more particularly, to a novel two wire data ton and control system employing A. C. voltages of fixed selected frequenciu and constant magnitude, but of variable phase position.

Date transmission systems, i. e., electrical systems employed for transmitting various data such as angular data or data that are susceptible of indication on a suitable sheet, card or other member having relative movement with respect to a pointer or other designating means, as heretofore constructed, have generally required five or more wires extending between the transmitting or field station and the receiving or central station for transmitting a single channel of data. The use oi this relatively large number of wires not only greitly increases the installation and maintenance expenses, but ofttimes the desired number of wires are not available for use in transmitting data, as during army maneuvers, where it is not practicable to string five or more wires from a' transmitting station, such as an outpost, to a receiving or central station which may be several miles away.

In our copending application Serial No. 83,844

there is disclosed a novel data transmission and control system that employs but two wires extending between the remotely located transmitting and receiving points, the said system employing means for producing a synchronizing signal voltage of fixed frequency that is sent out from the receiver to the transmitter, at which station means is provided for converting such signal voltage to one of different frequency and variable phase position corresponding to the data transmitted, such diiferent frequency voltage being sent back to the receiver, which latter is arranged to select the returning signal voltage and detect its phase position for use either in operating a follow-up indicator or, through use of a torque amplifier, to control a servo motor to effect the positional control of a heavy object.v

The principal object of the present invention is to also provide a two-wire data on sentovertwowireasuchasacommerciai teie- 7 phone line, to the receiver, which latter is provided with means for separating said voltages anddetectingthephaseshiftofthedata transmitflng voltage for use either in operating a follow-up indicator or, through the use of a torque amplifier, to control a'servo motor to effect the positional contrd of an object.

Another object of the present invention lies in the provision of a novel data transmission and control system of the above character that is entirely self-synchronous and continuously rotatable, the said system requiring but one data transmitting frequency voltage for each channel of data transmitted, and being adapted to provide additional channels, if desired, over the same pair of wires by employing corresponding additional data transmitting frequencies at the transmitter, these additional frequencies being separated from one another and from the synchronising frequency by use of suitable filter means at the receiver.

Still another object of the present invention is to provide a novel data transmission and control system of the above character that is easy to operate and is reliable in use, the said system empioying a small and compact transmitter that can be readily carried from place to place.

Other objects and advantages will become apparent from the specification, taken in connec- Y tion with the accompanying drawings wherein one embodiment of the invention is illustrated.

In the drawings. Fig. 1 is a schematic view showing a two-channel, two-wire data transmission systemof this invention arranged for automatic follow-up.

Figs. 2a. and 2b are a wiring diagram of the system of Fig. 1, and Fig. 3 shows the system adapted for radio transmission.

40 Similar characters of reference'are employed and control system using a variable phase, constant frequency signal voltage for transmitting the desired data, the present system, however, employing means at the transmitter for producing the data transmitting fixed frequency voltage of variable phase position and a synchronising or timing voltage of diiierent frequency and fixed phase podtion, both of which voltages are 55 generator set I in the above views to indicate corresponding parts.

Referring now to Fig. 1 of the drawings in connection with a brief description of a two-channel system arranged for automatic follow-up, the reference numeral 1 designates a storage battery connected to supply motor operating current to a motor-generator set 2 that has generator windings adapted to supply a single phase output of one frequency through leads I and two three-phase outputs of different through cables I and I.

It more than two channels of data transmission are desired, the generator portion of motoris provided with additional windfrequencies is: data,if desired.

I" are shown extending from motor-generator set 2, indicating that this set is-capable of providing transmission frequencies for four channels Leads I extend to thesingle phaserotor windingsrof transmitter inductive devices I and t having three-phase stator windings connected respectively to cables 4 and I. Leads 3 are also shown broken off to indicate that the same are.

adapted to extend to the single phase windings of additional transmitter inductive devices (not shown) similar to i and 6', having three-phase stator windings connected respectively to the cables l and I, should two additional channels of data tron be desired, thereby providing four channels of data transmission over two wires. Four channels of on are particularly convenient in the operation of anti-aircraft and seacoast defense fire control equipment since the same permit one to one and multiple speed transmission in both train or azimuth and elevation.

From inductive devices 8 and 6' of the transmitter the leads 3 extend to the two-wire transmission line 3', which may be a commercial telephone line. Thus. the single phase current of, for example, 100 cycle frequency constituting the synchronizing or timing signal and supplied by leads 1, passes through the rotor windings of devices 6 and 6' in series to the line 3' and over this line, which may be several miles long to the receiver or receiving station.

At the receiver there is provided a line amplifier I that restores the received signal voltage to a suitable value, which signal is then passed to a band pass filter 8. If the rotor of either of the inductive devices 8 or 6' is angularly shifted or turned by suitable means, such as shown in our above mentioned copending application, causing a similar turning of indicator discs ill or ill attached to the rotors thereof, then a single phase voltage of changing phase position is applied to leads 3 at the rotor terminals of the shifted device, which voltage has a frequency depending upon the frequency of the three-phase supply to the stator winding of such device. If the frequency of the three-phase supply through cable 4 to the stator of inductive device or Selsyn 6 is 150 cycles, then the single phase voltage applied by this device to leads 3 will also be of 150 cycles frequency. The phase position of the voltage thus applied to leads I will be shifted one degree for each degree the rotor of the device is turned.

Thus, there is supplied to line 3' (in the absence of additional inductive devices connected to cables I and 5) three frequencies, a timing' frequency of, for example, 100 cycles, and two signalling frequencies of, for example, 150 and 250 cycles, the phase positions of which latter frequencies may be shifted at will by turning the rotors of devices 6 and 6'. At the receiver or receiving station a. band pass filter B separates these three frequencies, passing the timing frequency through leads I! to an amplifier II that builds'up this frequency to a voltage value suflicient for operating the synchronous driving motor of a motor-generator set l2, thereby causing this set to run synchronously with the motorgenerator set 2 at the transmitter. The band pass filter 8 passes the 150 cycle signal voltage received from inductive device 6 through leads taining detecting and amplifying apparatus.

At the receiving station there is provided ree ceiving'inductive devices I! and I3 similsihto' devices i and t". The three-phase stator of device I3 is supplied from motor-generator set 12 device 8, for example, 150 cycles, whereas device I1 is similarly supplied through cable It with three-phase current of the same frequency as that supplied to the stator of device 6'. The rotors of devices II and I! are respectively connected through leads II and I. to the detectoramplifiers II and 22, which latter are connected through cables II and 2| .to motors 23 and 23' that are connected through suitable gearing I. ford tunrning the respective rotors of devices IS an Any turning of the rotor of transmitter device 6 shifts the phase of its output signalling voltage with respect to the timing voltage and the phase shift is supplied through leads II and appears at the device ii of the receiver, within which this voltage is compared with the phase of that supplied through leads I! from the receiver inductive device II. Any departure from predetermined flxed relative phase positions of these voltages corresponding to the synchronous positioning of transmitter indicator disc II withits output to phase alignment with the incoming signal, thereby causing indicator 21 to follow the movements of indicator ill.

The second channel of transmission acts in like manner so that as transmitter inductive device indicator disc III is turned, the motor II is caused by detector-amplifier 21 to turn indicator disc 21' by a like amount. Cables I4 and it are shown extending from motor-generator I! for supplying three phase current to two additional receiver inductive devices in the event that four channels of transmission are desired, the respective signalling voltages of differing frequencies for the detector-amplifiers (not shown) of said additional receiver inductive devices being supplied from filter 8 through leads 3!! and l l. Referring now to Figs-2a. and 2?), showing the wiring diagram of the system of Fig. 1 in detail, the motor 28 of the motor-generator set 2 is shown provided with a centrifugal speed control device 33 and has a single phase, inductive type generator rotor 34 on its drive shaft and a plurality of three-phase generator rotors 35, 36, 31 and 3B. Rotor 34 is associated with singlephase generator winding 39 for the generation in the latter of the low frequency synchronizing or timing signal which in the example previously given was assumed as cycles. Rotors 35 and 36 are associated with three-phase generator windings 40 and ll for the generation in the latter of three-phase voltages of different frequencies, assumed as and 250 cycles in the example previously given, which voltages are respectively communicated to the stator windings 42 and 43 of the inductive devices, 6 and 6'. The single-phase rotor windings I4 and 45 of these inductive devices are connected in series with it to a box 4! containing detecting .andyampli fying apparatus; Likewise the' fllter I passes the 250 cycle signal voltage received inductive device 8' through leads I! to another box ilconand 58'.

greater eachotberthroughtbeslipringsshowntoihe windingll,andthroughthetelephoneorother two-wire line 8' to the receiving station.

Atransformerltatthereoeivercouplesthe line 8' to an attenuator II which, in turn, is coupled by transformer 48 to the push-pull amplifier I that serves to amplify the noblenizing and signal voltages which are delivered through output transformer ll to the band pass filter l. A voltmeter or volume indicator SI is shown connected across the output of transformer It. By adjusting the attenuator 41 to get a desired reading of meter", variations in the length and hence attenuation of line I may be compensated for.

Section II of the band pass filter I selectsthe timing frequency and supplies the same through leads I and thermionic amplifier II to the synchronous motor I of the motor generator set It. Motor 52 is illustrated as a single-phase machine provided with a D. C. excitaflon winding on the rotor. In practical use. a starting winding is provided on motor I! to make it self-synchroniaing. Motor 52 has a plurality of three- .phase inductive type generator rotors on its drive shaft two of which, designated 53 and it, are shown in the drawings, which rotors cooperate with three-phase windings I5 and '58 for the generation in the latter of three-phase voltages of frequencies corresponding respectively to those produced by windings ill and ll of motor-generator 2.

Section 51 of the band pass filter I selects the signalling frequency put into the line I by inductive device 0- and supplies the same through leads lltoaninputtransformerflofthephase,

detector-amplifier Ii. Transformer SI this signal in 180 out of phase relation to the plates of diode phase detector rectifier tubes I! The plates of diode tubes 59 and i! are also supplied with the single .phase voltage output of the receiver inductive device I! by means of leads II and transformer I. When the voltages across transformers ii and I are 90 out of phase with each other, their vector sums applied to the plates of tubes 59 and 59' are equal, and the rectified voltage drops obtaining across resistors ii, II in the external cathode-plate circuits of these tubes are equal. and opposite. A low pass filter I! is connected across resistors ii and ii so that with the voltage drops across these resistors equal and opposite, there is no net voltage drop across points 82 and 62' at the output of this filter. However, when the rotor of the transmitter inductive device i is turned with respect to the rotor of inductivedevice ll, causing the phase of its output signalling voltage to shift relative that of device ll, the voltage across transformer 58 will shift from its 90 relation with that across transformer lll; causing the voltages across resistors I and I to become unequal, since one of the tubes 5! or 59' will pass more current than the other depending upon the direction in which the device listurned,andaD.C.signalvoltagedropwil1' appear across points 62, I. This voltage is dividedthroughresistors il andfl'andiscommunicated to the control grids of modulator tubes 68 and 68' arranged in push-pull. An A. C. bias voltage is also supplied from a transformer I through resistors I, N to the control grids of tubes It, i. The plates of tubes ii, ii are supp ed with a D. C. voltage through the divided primary of output transformer il. Tubes 6 and II are provided with a degenerating network I former I! and tubes II and II.

prevent oscillation, and II designates a fixed bias resistor With a D. 0. signal voltage applied to tubes it, It together with an A. C. bias voltage from transformer II, there appears in the plate circuits of these tubes A. C. voltagw through the halves of transformer 61. When the currents drawn by tubes It, 88' are unequal, a net A. C. voltage passes through transformer 81 and to the grids of amplifier tubes 10, II that are arranged in push-pull and are connected to the output terminals or transformer ll. The plates of tubes II and ll are supplied with A. C. voltage from a transformer 81 connected to commercial frequency supply leads It that also supply transformer II. A phase correcting network 8' is included in the connection between trans- The net A. 0. signal voltage applied to tubes II and 10' causes these tubes to draw unequal plate currents through the halves of an inductance H and resistors ll, it. Since the plate supply to these tubes is A. 0., the drop across the plate circuit impedance contains both an A. C. and a D. C. voltage component. The A. 0. component is improved in wave form by condenser II and through condensers II, I! to the grids of grid controlled, guseous rectifier tubes 16, ii. A phase bias voltage is applied to the grids of tubes 16-, 16' from secondary winding I! of transformer 8! through the use of phase shift condenser and resistor, II, II. The A. C. voltage component appearing across resistors 82, 82' thus adds vectorially with the bias A. C. voltage so as to advance the phase of the voltage appearing at one of the rectifier grids while simultaneously retarding the phase of the voltage at the other. The plate currents drawn by these tubes from supply Il through the differentially wound motor a are thereby unbalanced, causing this motor to operate through gearing transmission 29 to turn the rotor 85 of receiver inductive device II in the proper direction to move receiver indicator disc 21 into synchronism with transmitter indicator from motor 23, may thusly be controlled from the Y transmi itter by turnin g the rotor of inductive device The operation of the second channel of transmission is similar to that just described in connection with the first channel, the signalling voltage supplied from transmitter inductive device i' through line 3' passing through section ill of filter l and feeding into detector-amplifier 22, which detector-amplifier maybe used to control motor 23' for automatically positioning the receiver indicator disc 21', as shown in Fig. 1 or as shown in Fig. 2b, where manual operation of the receiver indicator disc is desired, the output voltage of diode Phase detecting rectifiers 59, II,

maybedispensedwithandaradiotransmitter.

installed at the transmitting station and a radio receiver installed at the receiving station. Such an arrangement is shown in Fig. 8, wherein an amplifier 84 is shown connected to leads i at the transmitter, which amplifier feeds the amplified timing and signalling voltages to a modulator 85 that is supplied with a radio frequency carrier voltage from the oscillator, II. Modulator 05 feeds the transmitter antenna BI and the signals received by receiver antenna I! are led to demodulator 93, the audio output 0! which is supplied to amplifier I of the receiving station, which in turn supplies the same to filter l, as before.

It will be apparent that, if desired, a power transmission line may be used for conveying the signal potentials, preferably at a frequency higher than the frequency 01' the power current oi. the line, from the transmitting to the receiving station, and in such case the transmission oi a timing potential is not essential since synchronous motor-generator sets supplied from the line may be used at the transmitter and receiver for supplying three phase currents to the inductive devices.

As many changes could be made in the above construction and many apparently widely diil'erent embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. In some instances a 'single wire and ground may be used in lieu of two wires, although the operation would not ordinarily be so good, so that the expression "two wire transmission line in the claims is intended to cove such a possible structure. 7

What is claimed is: I

1. In a control system of the character described, a two-wire transmission line, a transmitting station connected to said line, a receiving station connected to said line remote from said transmitting station, controlling means at said transmitting station including an A. C. generator and an inductive device energized therefrom for delivering electric signal impulses of changing phase to said line in accordance with desired data for transmission to said receiving station, means at the latter station for detecting the phase oi said signal impulses and including an A. C. generator operating synchronously with said transmitting station generator, and controlled means including an inductive device at said receiving station energized from said receiving station generator and operable from said detecting means in synchronism with said controlling means.

2. In a data and control system, a transmitting station, an A. C. voltage supp y. a two-wire transmission line supplied with a single phase timing voltage from said supply, a transmitter inductive device supplied with polyphase voltage from said supply and operable to deliver a single phase signal voltage continuously variable as to phase position, the single phase signal voltage output 01 said inductive device being supplied to said line, and areceiving station connected to said line ata remote point, a receiver inductive device, filtering means for selecting said single phase timing voltage for use in supp y n said receiver inductive device with polyphase current that is synchronous withthat supplied to said transmitter inductive device, a detector-amplifier connected tor-receiving the single phase signal voltage output of. said receiver inductive device, said filterassess? age output 01' said transmitter inductive device for application in said detector-amplifier tor comparison and combination with said receiver inductive device signal voltage output, and means controlled from the output oi! said detector-amplifier for use in synchronizing said transmitter and receiver inductive devices.

3. In a data on and control system. an A. C. voltage supply, a radio transmitter having its carrier modulated with a single phase timing voltage from said supply. a transmitter inductive device supplied wtih polyphase voltage from said supply and operable to deliver a sinile phase signal voltage variable as to phase position, the single phase signal voltage output of said inductive device being also supplied so as to modulate said radio transmitter carrier with a variable phase signal, a remote radio receiver, a receiver inductive device, filtering means supplied irom said radio receiver, said filtering means selecting said received and detected single phase timing voltage for use in supplying said receiver inductive device with polyphase current that is synchronous with that supplied to said transmitter inductive device, a detector-amplifier connected for receiving the single phase signal voltage output oi. said receiver inductive device, said filtering means selecting said received and detected single phase signal voltage output or said transmitter, inductive device for application to said detector-amplifier i'or combination with said receiver inductive device signal voltage output, and means controlled i'rom the output of said detector-amplifier for use in synchronizing said transmitter and receiver inductive devices.

4. In a data transmission and control system, a transmitting station comprising a constant speed generator, a transmitter inductive device supplied with polyphase voltage from said generator and operable to deliver a single phase signal voltage variable as to phase position, a two-wire transmission line supplied with single phase timing voltage from said generator, the single phase signal voltage output 01' said transmitter inductive device being supplied to said line, and a receiving station connected to said line at a remote point, said receiving station comprising a synchronous motor-generator set, filtering means for selecting said transmitter generator single phase timing voltage, for use in operating the synchronous motor of said set, whereby a polyphase voltage output 01' the generator of said set is synchronous with that supplied to said transmitter inductive device, a receiver inductive device supplied with said polyphase voltage output oi! said set, a detector-amplifier for receiving the single phase signal voltage output of said receiver inductive device, said filtering means selecting said single phase signal voltage output of said transmitter inductive device for application to said detector-amplifier for comparison and combination with said receiver inductive device signal voltage output, the output of said detector-amplifier serving for use in synchronizing saidtransmitterand receiver inductive devices. A

5. In a data transmission and control system, a transmitting station comprising a constant speed generator, a transmitter inductive device supplied with polyphase voltage from said generator and operable to deliver a single phase signal voltage continuously variable as to phase position, a two-wire transmission line supplied with single phase timing voltage from said gening means selecting said single phase signal volterator, the single phase signal voltage output of said transmitter inductive device being supplied aasaear plifier for receiving the single phase signal voltage output said receiver inductive device, said filtering means selecting said single phase signal voltage output or said transmitter inductive device for application to said detector-amplifier for comparison and combination with said receiver inductive device signal voltage output, and motive means operated from said detector-amplifier for maintaining said receiver inductive device in synchronism with said transmitter inductive device.

6. In a data transmission and control system, a transmitting station having means for supplying an A. C. timing voltage, a movable control member, and means responsive to movement of said control member for supplying a variable phase signal voltage, a remote receiving station, means for transmitting said timing and signal voltages to said receiving station, said latter station having thermionic control means, a movable controlled member operated therefrom, and means energized in response to said timingvoltage and responsive to movement oi. said controlled member for supplying a variable phase receiver voltage, and means for causing said remeans for transmitting said voltages, and means near said controlled object and connected therewith ior receiving said transmitted voltages and for determining the movement 01' said con trolled object in accordance therewith.

10. In a data transmission and control system for multiple channel transmission, a transmitting station having means for producing a synchronizing A. 0. single phase voltage and a plurality oi polyphase voltages 01' different frequencies. a plurality of transmitters for receiving said Po yphase voltages and for delivering variable phase signal potentials of corresponding frequencies, transmission means comprising but two wires for transmitting said single phase voltage and said signal potentials, a remote receiving station for receiving said voltage and potentials, said receiving an A. C. timing voltage, a movable control,

member, and means responsive to movement 01 said control member for supplying a variable phase signal voltage, a remote receiving station, a controlled member at said receiving station, means for transmitting-said timing and signal voltages to said receiving station, said latter statlon having push-pull phase detector-rectifier ceiver voltage to act jointly with said signal voltage to determine the operation of said thermionic control means, and hence 01' said controlled member.

7. A' data transmission and control means as defined in claim 6, wherein said thermionic control means comprises push-D ll Phase detectorrectifiers having their plates supplied-not only with said variable phase receiver voltage in in-- phase relation, but also supplied with said variable phase signal voltage in 180 out of phase relation, the vector addition of said voltages serving to determine the action of said detector-rectifiers, and hence of said controlled member.

8. A data transmission and control means as defined in claim 6, wherein said thermionic control means comprises push-pull phase detectorrectifiers having their plates supplied not only with said variable phase receiver voltage in inphase relation but also supplied with said variable phase signal voltage in 180 out of phase relation, the vector addition of said voltages serving to determine the action of said detector- 9. In a data transmission and control system, I

' a timing voltage and a signal voltage variable in phase with movement or said controlling object,

means, meter means operated therefrom, and means energized in response to said timing voltage and responsive to movement or said controlled member for supplying a variable phase receiver voltage for acting jointly with said signal voltage to determine the operation 01' said detector-rectifier means, and hence of said meter means.

, 12. A data transmission and control system comprising a transmitter and a remotely located receiver, said system comprising a two-wire transmission line as the only conducting means interconnecting said transmitter and receiver, said transmitter having means for delivering a fixed phase timing voltage and a variable phase signal potential that is variable without limit and corresponding to the data transmitted to said line for transmission to said receiver, and said receiver having means for selecting and detectingthe phase position of said signal potential with respect to a version of said timing voltage for use in visually indicating the data transmitted.

13. In a control system-oi! the (character described, a two-wire transmission line, transmitting means lor delivering'a fixed phase timing voltage to said transmission line, said transmitting means including a variable phase transmitter having a controlling member and arranged for delivering electric signal impulses oi. changing phase to said line, said signal impulses being variable without limit as to phase in accordance with the position oi said controlling member, receiving means for receiving said fixed phase timing voltage and comprising a variable phase receiver connected to said line for receiving said changing phase signal impulses, and a controlled member located at said receiver, said receiver having means for detecting the phase position 01' said signal impulses with respect to a fixed phase voltage derived from said timing voltage and for operating said controlled member in response thereto, whereby said controlled member is moved synchronously with said controlling member, said two-wire transmission line constituting the only electrical connection between said transmitter and receiver.

14. A signalling system comprising in combinatlon a transmission line consisting of but two conducting paths extending between a transmitting point and a receiving point, means including generating means and the line for providing at both points, fundamental electric waves of substantially the same constant frequency and phase position, means at the transmitting point utilizing output from said generating means for delivering to the line, waves of the fundamental frequency but in any phase displacement within 360 degrees relative to the phase of the fundamental waves. the displacements being proportional to indications to be transmitted, and means at the receiving point for detecting and indicating the amount of the phase displacement.

assess? 15.Asignallingsystemeomprisihginccmbinationatransmissionlineconsistingofbuttwo conducting paths extending between a transmitting point and a receiving point, means including generating means and the line, for providing at both points fundamental electric waves of substantially the same constant frequency and phase position, angularly movable means at the transmitting point, utilising output from said generating means for delivering to the line, waves of the fundamental frequency but in any phase displacement within 360 degrees relative to the phase of the fundamental waves, and proportion. al to the angular movement of the said angularly movable means, the angular movement being the signal data to be transmitted and means at the receiving point for detecting the phase displacements and for translating the displacements into proportional angular movements.

FRANCIS L. MOSELEY. ERIC J. IBBIBTER.

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