US2340798A - Remote control system - Google Patents

Description

Fe'b. l, 1944, H. B. DEAL.

` REMOTE CONTROL SYSTEM Filed July 23. 1941 2 Sheets-Sheet 1l Feb. 1, 1944. H. B. DEAL REMOTE CONTROL SYSTEM Filed July 23, 1941 2 Sheets-Sheet 2 INVENTOR HARA/10N DEAL ATTORNEY Patented Feb. 1, 1944 UNITED STATES PATENT OFFICE REMOTE CONTROL SYSTEJVI'Y Harmon B. Deal, Glen Ridge, N. J.', assi'gnor to Radio Corporation of America, a corporation Application .any 2s, 1941, serial No. 403,736

10 Claims.

TheA present invention relates generally to re.- mote control systems, and more particularly to a remotecontrol. system wherein the operation of reproducer oiastandby radio receiver may be controlled from aJ remote point transmittingv a carrier wavev modulated by normalk or theultra-high frequency band. In accordanceY with the presentrinvention, controlsignalswhich are preferably, though not necessarily, generated! at the broadcast vstationare utilized to modulate the carrier of` thebroadcast. stationV which is to exercise control.. Of course, if desired, an auxiliary special. carrier mayA bey modulated.

Ilia remote receiveristobe controlledv as. de-

scribed above, and, thestations-regular carrier is--te bemodulated..bythe control signals, it is, immaterial. whether or not. the controlling-signals are audible since the. control. signals wouldv normally precede thestart, .and follow the termination of the specialbroadcast. However, it isevident that, under certain circumstances, an. in-

audible control signalisto, be preferred, as or exainplein the caser wherethere may have been in progress a program to which many people Were already listening. and towhom an. audible con.-

trolsignal would be.y objectionable, or in cases where a certain amount `of secrecy is desirable.

Inaudibility of the, control signal may be obtained by utilizing super-audibleV or sub-audibleV control frequencies. Since super-audible frequencies would encroacnon1 adjacent broadcasty channels, sub-audible control frequencies are preierred. Another.v reason for preferring. the sub-,audible frequency bandiorv the control frequencies is because it is. immediately available since it is not beingused presently. Theaverage radio receiver.` andloud-speaker cut off belowflocycles per second, andeven the very -best receivers with considerablebass compensation do` nottransmt frequencies below 50 cycles persecond to any appreciablevextent. that a band in which, controly signals will not affect program materialbeing broadcast simul taneously, lies below 50-cycles yper second Itis recognized,;of course'. that the 10W frequency* This.v indicatesy cut-off. of areceiver isnot abrupt, andthat there fore. the lowest usable :frequency andeamplitude ofy thecontrol.` signals will produce'. the -least 'prozgram interference.

Inaa series of tests lwhichhave beenconducted with devices `built .in accordance with. thegpresent. invention, it hasbeen found-that thevamplitude oi the control signals should be .kept asn small as possible for they reasonthat harmonics of the-control .requency-, whether originatingr-in the source or produced.in-thereceiven will 11e` in theacceptance bander the.k usual radio receiver: andlwill befaudible. The harmonicsmay be .produced inthe. receiver. by.v overload 'or b'yl-y cross-modulation of control frequencies andlprogram, .and it Vhas. been Adetermined 1 that bothofv thesev effects .are considerably; aggravated` by large'- control. signal amplitudes.

transmitter for 1: roducing\, the controllfrequen# torV tube and modulating. meanstor modulating# the carrierof the transmitterv withthe controh signals. At. the` receiver, .which-isdn standbyl condition means are provided for.receivingstlfieA modulated carrier anduti-lizing.- the derivedlsig'- nais for control. purposesf.

It. is -believed..that.-the.invention. willI belfbetter4v understood. and. its various .objects and` advanf= y tages will be more apparent. .from the following detailed. description `ofk a..prefferred-embodiment:

thereof .when readv in. conjunction; with the.. atf tachedA drawings. y

In the drawings:

Figure. l illustrates` in .diagrammatid formi a suitable control. .signal generating. .meanswhicli'l may be. usedY as a transmitting Ystationrior.-A niodur` lating the transmitter. carrierA byy the controlsigf 5 nals i-in, accordance .with the presentlinventioI-nv and, l

Figure` 2 isfa diagrammatic..illustration of al'- preferred .embodiment 4of arreceiver. unit adapted@ to be controlledin accordance with. receivedI consil trol signals.

Referring now more. particularly'. to.. Figure fl.

of the drawings', rtherexis .provided an electronc tube; I` which isemployedsas; an oscillatorvvto'ge'n'e' l rate.=the variousizdesi-redcontrol: frequencies.4 Fori' this. purpose,y a. novelA phase Vreversal circuitllarrangement ris used'f for .y providing. phase reversal between the grid andV plate oi' -theosclllatortubai I. The phase reversal network is conn'e'cted-lbetween the r anode and-cathode ofthe-tub'and comprises capacities yil j' 8,'-and 9U and resistor`s1-4 0'- y andfil l: Thisfln-etworkgl also,detern'iinesthelfre-V quency of the generated oscillations in accordance with the values of the resistances and the condensers. Feedback between the plate and the grid is provided by a circuit 2li which connects point 26 of the phase reversing circuit to the input grid of tube I through a coupling condenser 3. In order to avoid undesirable phase shifts in the resistance of the grid coupling circuit, ahigh resistance grid leak resistor 2 is provided.

Preferably the resistance of resistor 2 should be large as compared to the reactance of condenser 3. Two control push buttons I and 20 are provided. Push button 2i] acts upon depression to close a switch 2i, and thereby connects the output of the oscillator I to the ampliiier 23. Push button I5, on the other hand, acts when depressed to open switches I7 and I8 and close switch I9. Normally resistor I3 is connected in parallel with resistor II, and, likewise, resistor I4 is connected in parallel with resistor I0. Under these conditions the net resistance between points 25 and 2G of the network is decreased.v This results in a higher frequency of oscillation. Consequently, with push button I6 not depressed, and push. button 25 depressed, control oscillations of a certain frequency are impressed upon the amplifier 23 through closed switch 2I and conductor 22. i

.When push button I5 is depressed, the parallel resistors I3 and I4 are disconnected from the phase shifting circuit thereby resulting in a higher net resistance lbetween points 25 and 26 and therefore providing a lower output frequency, it being noted that the new frequency is fed to the same output amplifier 23 through conductor 22 due to closure of switch I9. In the condition shown, the oscillator I is operating at a frequency which is determined by resistors i0, II, I3, and I4, and the oscillations of this frequency will be impressed upon the amplifier 23 upon closure of switch 2I. Hence, depression of push button 20 will impress this control frequency upon the transmitter where it is utilized to modulate the carrier of the transmitter in accordance with well known practice.

It should be noted that resistors I9, II, I3, and I4 are preferably variable resistors so as to permit adjustments. Also, unicontrol means I2 is provided to adjust resistors IU and I I simultaneously, and` unicontrol means I5 is provided to permit simultaneous adjustments of resistors I3 and I4. If-it is desired to transmit the other control frequency, it is only necessary to depress push button lI6 as previously described.

lFor receiving the transmitted energy there may be employed receiving apparatus such as is shown in Figure2, wherein the usual antenna system 39 is. connected to the input of a radio receiver 3l which may be tunable over one or more bands of frequencies if desired, it being noted that the output of 3I comprises the audio output from the detector of the receiver. If `a. superheterodyne type receiver is used then the output is taken preferably from the second detector. The receiver portions 35, 3l, 32 and 42 are, of course, in standby condition in order to detect the control frequencies applied over lead 45 to the relays lcontrolling the connecting means for the loud speaker 49, '19. The audio output of receiver 3I .is fed to a power youtput tube 42 through a network 32 which will be more fully described hereinafter,

,The output terminals 46, 4l of the output tube 42 are connected to a tuned reed unit which includes a pair of tuned reeds 53, 59, one of which reeds is responsive to one of the control frea quencies whereas the other reed is responsive to the other of the control frequencies. The tuned reeds 53 and 59 are provided with driving electromagnets 52 and 58, respectively. Tuned reed 53 is provided with a sliding weight 'I9 which may be adjusted along the reed so as to tune the reed to the desired frequency. Vibration of reed 53 causes the intermittent closure of a switch 54 which acts to connect an energizing winding 51 of a double acting locking relay across the power supply line. Reed 59 is also provided with a. sliding weight 8D for tuning purposes. Vibration of reed 59 causes intermittent closure of switch 60 which in turn connects the other energizing winding 63 of the locking relay across the power supply line. The relay is provided with an armature 8D which is arranged to snap into either of its two positions depending upon which one of windings 5'I and 63 is energized. In the position shown, the relay winding 5'I was energized last thereby causing the armature 89 to assume its upward position in which a pair of switches 64 and 65 are maintained in a closed position. Under these conditions, if relay 63 is energized, the armature Bil will snap into its downward position thereby permitting switches 64 and 65 to open and closing switches 66 and 61.

For translating the signals, there is provided a loudspeaker I9 which is connected across switch 65 by means shown generally as a coil 49 so that closure of switch 65 short circuits the speaker input coil 49. In order to provide energizing potentials for the tuned reed apparatus, a plug 69 may be provided which may be plugged into any suitable socket receptacle of a power supply network. Also, a socket receptacle 63 is provided to which may be connected any device which it is desired to control.

In order to insure that low frequency components of the program will not operate the tuned reeds, there is provided a low pass filter composed of elements 35, 36, 31, and 38. This filter operates to effectively cut off all frequencies above approximately 45 cycles per second. For those applications where it is desirable that a loud` speaker be turned on where the loudspeaker is a part of the controlled receiver, an auxiliary net-A work composed of resistor 34, condenser 39, and resistor 4I is included. By making the capacity of condenser 39 small so that its reactance as compared with resistor 4I is high, this auxiliary network operates to pass program frequencies above say 200 cycles per second. This insures that the grid of the power output tube 42 has applied to it low frequency components from the oscillator at the transmitting station and also program signals, but that a band of frequencies from approximately 45 cycles to 200 cycles is eliminated, thus obviating the chance of low frequency components of program such as organ music actuating the reeds. The resistor 38 is shunted across condenser 38 to provide a direct current return path for the input grid of tube 42.

In the operation of the device shown in Figure 2, ii' the control frequency representative of reproducer operation is impressed upon terminal 46 from tube 42 and the circuit arrangement is in the condition shown in Figure 2, the control energy will be fed to the energizing winding of electromagnet 58 through the following circuit,

' terminal 46, conductor 48, closed switch 65, con- This means that the ductor 59, conductor 11, closed switch 64, conductor 'I 8, winding of magnet 58, to terminal 41.

`control frequency is imi pressed upon` the winding" ofVN` driving magnet` 58: If-L r'ee'd`V 59"*isit'uned to that'particul'ar control frequency, it'willstartto vibrate causingintermittent closurel of switchf; When this happens the relajywinding 53@ will be energized through the following circuit, closedlswitch 60', reed 59,- magnet coreB-, conductor '15, one side of the'power line tonne-'terminal of the-power supply, then from the other terminal of thepo'wer supply to the otherside of the powerline, resistor 14, conductor 133, the winding of relay 63, conductor 12, backto switch 60. This will cause armature 80 to be pulled'4 downwardly te its' other position thereby openingswitches Gland 65 and closing switches 66 a`ndf61.y Closure of switch' 61 shortcircuits the winding of relay 53 so thatthe reed-59 will stop vibrating. Closure of switch 661 will connect socket-receptacle'68A across the power supply line and'will thereby energizeany desiredrcontrolled device. At the same time, the short clrcuitlacross speaker vcoil 45- is removediby the opening of switch E5. Hence,the special broadcast that was the occasion for sending the reproduce control frequency may be reproduced through loudspeaker' '19. The broadcast modulation energy is impressed across the input coil i9 of the speaker 19 throughthe following circuit, terminal 46,conductor 43, voicel coilliconductor 5t, oondenser 5I to terminallll.

When it is desired to render the receiver reproducer ineffective the other frequency is transmitted from the transmitter thereby energizing the relay 52 at the receiver which causesclosure of switch 5d', and energization of relay 51, thereby bringing back the various switches to thev position shown.

While I have disclosed certain preferred embodirn'ents of. my invention, it is to be understood that the same is not limited to the details disclosed and that they may be varied within the scope of the appended claims.

What I claim is:

l. In a signalling system of the type wherein the carrier of a transmitter is modulated by modulation signals representative of a special broadcast and at least two auxiliary modulation signals representative of the beginning and end of the special broadcast, a single receiver including settable means, responsive to said auxiliary signals in the detected output of the receiver, acting upon receipt of one of said auxiliary signals t0 condition the receiver reproduction so as to render the special broadcast signal intelligible, said settable means acting upon receipt of another of said auxiliary signals to condition the receiver reproduction so as to render the special broadcast signals unintelligible.

2. In a signalling system wherein means are provided at the transmitting station for generating a plurality of different auxiliary frequencies which are independent of the program frequencies and lower in frequency than the lowest program frequency to be transmitted, one of said auxiliary frequencies being transmitted to indicate that a special program transmission is about to take place and another of said auxiliary frequencies being transmitted to indicate the end of the special program transmission, a receiver tuned to receive the modulated carrier energy transmitted from said transmitter, said receiver including a detector, a detected signal translating device and relay means, means for coupling the detector output to the relay means comprising a low pass lter circuit adapted to pass only frequencies which are below the lowest program frequency,l an additional-r circuit arranged:l tov pass only frequencies above' the lowest'lpro'gramfree quen'cies, and an operableswitchingvdeyice for connecting the translating device. to:` said addi;- tional circuit, wherebyl the programfrequencies are fed to the translating device.

3. In a receiver'ofvthe type. adapted. tocollect modulatedcarrier waves which have* included in the modulation at' least` one subi-audible control frequency representative'of onedesired condition of the receiver, saidreceiver, including; meansto provide demodulation of the collected waves thereby to provide said control frequency, and means to reproduce demodulated wave energy; the improvement which comprises a. device for controlling the effectiveness of said reproducer means,. means for controllingy the operation of said device, and means selectively operable by said control frequency for actuatingzsaid lastcQn.- trol means, and additional means,` responsive to actuation of said device control means, for ren.- dering effective an electrical circuit.

4; In a receiver ofthe typeadapted to collect modulated carrier waves which have includedin the modulation atleast one sub-audib-le control frequency representative of one desired condition of the receiver, said receiver including means to provide demodulation of the collected waves thereby to provide said control frequency, and means to reproducel demodulated Wave energy; the improvement which comprises a device for controlling the effectiveness of said reproducer means, means forcontrolling the. operationr of said device, and means selectively operableby said control frequency for actuating said last control means, and additional means, responsive to actuation of said control means, for rendering saidv selectively operable means ineffective 5. In a receiver of the type adapted to collect modulated carrier waves which have included in the modulation at least one sub-audible control frequency representative of one desired condition of the receiver, said receiver including means to provide demodulation of the collected waves thereby to provide said control frequency, and means to reproduce demodulated wave energy; the improvement which comprises a device for controlling the effectiveness of said reproducer means, means for controlling the operation of said device, and means selectively operable by said control frequency for actuating said last control means, said selectively operable means consisting of a reed tuned to said control frequency, and electromagnetic means for vibrating said reed in response to energy of said control frequency.

6. In a receiver of the type adapted to collect modulated carrier waves which have included in the modulation at least one sub-audible control frequency representative of one desired condition of the receiver, said receiver including means to provide demodulation of the collected waves thereby to provide said control frequency, and means to reproduce demodulated wave energy; the improvement which comprises a device for controlling the effectiveness of said reproducer means, means for controlling the operation of said device, and means selectively operable by said control frequency for actuating said last control means, a second means selectively operable by a different sub-audible control frequency included in said modulation in place of said first control frequency, a second means, controlling the operation of said reproducer control device, adapted to be actuated by said second selectively operable means. x

. yr1. In a receiver of the type adapted to collect modulated carrier Waves which have included in the modulation at least one sub-audible control frequency representative of one desired condition of the receiver, said receiver including means to provide demodulation ofv the collected Waves thereby to provide said control frequency, and means to reproduce demodulated wave energy; the improvement which comprises a device for lcontrolling the effectivness of said reproducer means, means for controlling the operation of said device, and means selectively operable by said control frequency for actuating said last control means, a second means selectively operable by a diierent sub-audible control frequency included in said modulation in place of said rst control frequency, a second means, controlling the operation of said reproducer control device in a sense opposed to the control of said first device control means, adapted to be actuated by said second selectively operable means.

8. In a radio signalling system including a receiver upon Whose input terminals are applied modulated carrier Waves Whose modulation sig- `nals include at least one control frequency representative of a desired state of eiectiveness of the receiver, said receiver including detection means for deriving energy of said control frequency from the waves, a control device for controlling tlie eiectiveness of the receiver, an electromagnetic device including an energizing circuit for actuating said control device, a selective reed means, tuned to said control frequency, for controlling the said energizing circuit, and means, responsive to said derived control frequency energy, for intermittently controlling said selective means.

9. In a radio signalling system including a receiver ,upon whose input terminals are applied modulated carrier waves whose modulation signals include at least one control frequency representative of a desired state of effectiveness of the receiver, said receiver including detection means for deriving energyof said control fr equency from the Waves, a control device for controlling the effectiveness of the receiver, an electromagnetic device including an energizing circuit for actuating said control device, a selective means, tuned to said control frequency, for controlling the said energizing circuit, and means, responsive to said derived control frequency energy, for controlling said selective means, and additional means, responsive to energization of said electromagnetic device and actuation of the control device, for preventing operation of the means for controlling the selective means.

l0. In a radio signalling system including a receiver upon whose input terminals are applied modulated carrier waves Whose modulation signals include at least one control frequency representative of a desired state of effectiveness of the receiver, said receiver including detection means for deriving energy of said control frequency from the waves, a control device for controlling the effectiveness of the receiver, an electromagnetic device including an energizing cir. cuit for actuating said control device, a selective reed, tuned to said control frequency, for controlling the said energizing circuit, and means, responsive to said derived control frequency energy, for controlling said selective reed, and a lter network following said detection means for prevention of transmission of modulation energy of from approximately to 200 cycles.

HARMON B. DEAL.

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