Патент USA US2404356код для вставки
July 23, 1946. c. E. A'rKlNs 2,404,356 l SECRET SIGNALING SYSTEM Filed June 3, -1944 _ 1_ _ 2 Sheets-Sheet l _ _ _ MW A 25.9@Sb QQ N „w w July 23, 1946. c. E. ATKlNs Y 2,404,356 SECRET SÍGNALING SYSTEM Filled June 5, 1944 2 s.n. nv e t S sh e e t 2 _ @ï@n „EhmSI INVENTOR 642.4 fan/„Ha ÄT/f//vs +60 BY --b ¿wma 2,404,356 Patented July 23, 1946 UNITED STATES PATENT "OFFICE 2,404,356SECRET SIGNALING SYSTEM Carl Edward Atkins, Elgin, Ill., assignor to Tung- . Sol YLamp Works, Inc., Newark, N. lJ., `a corpora- . . tion of Delaware Application June 3, 1944, Serial No. '538,667 10 Claims. (Cl. 179---1.5) 1 v2 My present invention relates to secret station to-station communication-systems, of the general type disclosed in my copending applications Serial No. 443,898, ñled May 21, 1942, and Serial No. either of two sources butY not when activated by 504,679, iiled October 2, 1943, wherein the signal bothsources simultaneously. Thus whenkey Illa is depressed vand if there is vnooutput fromthe detector 4a, transmitting gate 6a will'operate- to pass a signal, .but if the input terminals of gate originating at one station is used to scramble the 6a are Asimultaneously activated .from the signal signal transmitted from the other station. In the system of application Serial No. 504,679, inter source by lthe -key lila and from the detector 4a, no signal is'v passed by the gate. Conversely, if modulation -is effected by simultaneously keying key Iûa is not depressed but a lsignal is impressed the equipment a't the two stations. A monotone 10 upon »gate ßa'from detector 4a, the gate passes of the same frequency Iis yinjected in such phase the signal. The ysame is -true of transmitting gate relationship that there is :no change in amplitude 6b and of receiving gates 2a and 2b. These gaies when the keys at both stations are simultaneously depressed but only a change of phase. The pres ent system differs from the system above briefly >described and from the system of application Serial No. 443,898 in that when the .keys at the are varieties of electronic switches and ywill be more fully described hereinafter .in connection with Fig. 2. The equipment at each stationY will ,include also, of course, the necessary radioV fre quency apparatus for the transmission and radia two stations are simultaneously depressed no sig tion of the signal passed by the transmitting gate nal is transmitted from one lstation to the other. and for reception and demodulation of the energy In the present system the signal »energy from one 20 radiated ¿from the other station before delivery transmitter serves to reverse the background con of the ysignal to the rreceiving gate. These ele ditions for the other. Thus during a period of ments kof the 4system Vhave been omitted from silence a telegraphic symbol may be transmitted Fig. 1 for simplicity .but are ‘included in the circuit drawing of.Fig.,2. ~' while during the subsequent period, which may In’operation of the system of Fig. 1, if key i-Ua be a millisecond, several seconds or even a minute, 25 the appearance of a .signal might mean that no is depressed, transmitting gat-e -Ba is activated and character at all was being sent but that an alter a signal is sent to station B, where, after recep nate type of background was being used. tion and demodulation, receiving gate 2b is acti For an understanding of the present invention Vated and passes the signal on toI detector »4b. reference may be had to theaccompanying 4draw 30 In the »output »of detector 4b the signal is Aavail ings, 'of which ,able fas useful intelligence and is also used to Fig. 1 is a simplified block diagram of equip actuate ytransmitting gate 6b which causesthe ment at two communicating stations for opera signal to be returned to station A for application tion of the new system; >to vone input terminal of receiving gate 2a. At Fig. 2 is a circuit diagram of the complete 35 the same time .that the depression -o-fìkey «lilla equipment suitable for use at 'each station and started the signal onits wayto station B and representing the preferred embodiment of `the back to station A, Vit also :started a similar signal, invention; and , .a pulse of exactly the same time duration, through Y l Fig. 3 is a graph explanatory of therelati‘on .the Ylocal ¿delay system '8a.Y Delay system 8a, yas between charging _potential and gateY output .in -40 `.more fully described in -connection with Fig; l2, the various networks of Fig. .2. isconstructed to simulate @the time characteristics 'I‘he new system and its operation will 'i'lrst be of the equipment at station B and of the inter described by reference to the simple diagram Iof vening space.. .'I‘hus Ythe yreturning signal-‘arrives Fig. 1. As shown .in li‘ig. 1, the essential fequip ment at station vA comprises a .receiving v,gate 2a, ,atione of the input terminals of receiving gate »2a simultaneously with the --arrival at the other ' detector 4a, transmitting gate 6a, a delay system input terminal of asimilar signal locally retained Ba, and `a key 'lila for introduction of the signal, ' >by>an-d` delivered through the >delay system 8a and' the output from those various instrumentalities .hence Jboth input terminals lof the gate 2a beingy being delivered in the directions indicated by the activatedmo signal isjpassed‘to `detector 4a. Y Sim- 'Y respective arrows. vStation >B .is provided with : ilarly, when key vMib -on‘lyis depressed, the signalV ' similar equipment, namely, receiving gate 2b, a detector 4b, a transmitting gate 6b, a delay sys tem ’812, and a .key lûb. Each “gate” Yhas two input terminals and one :output terminal. Its yfunction is to .pass a signal when activated by >is passed by transmitting :gate 6b, radiated from , ' ' station B, received at :stati-on A, 'passed by. receiv ing gate i211, detected’ at station A, -passed by transmitting Igate iifartransmitted back to‘s‘tation, yB 'and L"blocked'atreceivingtgate12b :by the dupli V 2,404,356 3 ich is depressed at the moment when the signal the balance of the “gate” is upset and energy is passed. When the inner grids of both tubes are negative, both tubes are blocked and the “gate” from key Iûa ñrst reaches the portals of trans mitting gate 6b, that is after transmission from three position switch which is “off” when the cate signal retained and delayed by delay system 8b. If key Ita is depressed and subsequently key station A, reception and detection at station B, then transmitting gate 6b will not operate and nothing will be transmitted to station A. How ever the depression of key IDb will be detected at station A because receiving gate 2a, being acti vated only by the delayed signal through system 8a, will pass energy to operate detector 4a. If key Ilia is still depressed, then after detection by de tector 4m, transmitting gate 6a will cease to oper ate. No signal will be radiated to station B but receiving gate 2b will operate because of activa tion through delay system 8b. Thus if both keys passes no energy. The gate 2 is thus a kind of inner grids of both tubes are at ground potential, can be turned “on” by a suitable‘negative voltage on the inner grid of either one‘of the tubes, and can be turned “off” again if' the corresponding grid of the other tube is likewise made negative. In the particular embodiment of the invention illustrated in Fig. 2‘, receiving gate 2, as hereto fore indicated, is excited by radio frequency en ergy applied to the outer grids of tubes I8 and I9. Audio frequency energy could be employed for this purpose but radio frequency energy is pre ferred in order that transmitting gate 6 can be actuated by a rectiñer system containing little or are depressed for a substantial length of time no no time delay. signal is sent from one station to the other but Energy passed by the transformer 24 is rectified the fact of the depression of the key of one sta 20 by rectiñer 26 and appears across load network tion is made apparent by the operation of the 28. As previously indicated network 28 need in detector at the other station. If after both keys troduce little or no time delay and its rectified have been depressed and no signal is being trans potential is almost immediately applied to a grid mitted from one station to the other, as above de of one tube of the transmitting gate 6. The ele scribed, one of the keys is lifted, a signal will be ments 23, 24, 26 and 28 comprise the detector 4 sent from that station and after a suitable delay a signal will follow from the other station. If both keys are worked the keying at the two stations will be superimposed and each signal will be subjected corresponding to the units 4a and 4b of Fig. 1. As indicated in Fig. 1, the output of the detector may yield the useful signal, for example, the volt to a more or less capricious scrambling. Thus if one key is held down for a sustained period of age across network 28 can be directly utilized as a signal or indicator operating means. Prefer time, periods of' depression of the other key corre spond to periods of no signal transmission be tween stations. Thus the holding down of one key has the effect of reversal of background for the operate a separate detector unit 30 as hereinafter described. other, so far as concerns an interceptor of the transmitted radiation. Specific apparatus functioning as above de scribed in connection with the simple block dia gram of Fig. 1 is shown in Fig. 2 to which refer ence‘may now be had. In Fig. 2 a suitable re ceiving mechanism I2 is shown Within the dashed line enclosure as including an antenna, a wave trap tuned to the transmitting frequency of the same station and conventional radio frequency amplifier, demodulator and audio frequency am plifier circuits. The output of the receiving mech ably, however, this Voltage is used indirectly to The transmitting gate 6 is substantially similar to gate 2 except that it is arranged for excita tion by audio frequency rather than radio fre quency energy. As shown, gate 6 includes two tubes 3I and 32 having their cathodes connected by a resistor having a variable center tapped ground connection, their anodes connected in par allel to the primary of a'transformer 34 and their outer control grids connected for excitation across a center tapped secondary of transformer 36 con nected to a source of audio frequency energy. The inner control grid of tube 3l is connected to the network 28 of detector 4 and the inner control grid of tube 32 is connected through a network anism I2 is fed to a rectifier I4 which differs from 40 simulating the characteristics of network 28; the conventional half wave diode rectifier circuit `in the inclusion of a series resistor I6. The func 50 and a resistor 4I with the key I0. The key Il), when closed applies a negative potential to the »tion' of resistor I6 will become apparent herin after. rI’he output from rectifier I4 provides the D. C. voltage needed for activation of the receiv ing gate 2. As shown, gate 2 includes a pair of tubes I8 and I9 such as the 6 SAlGT. The cath odes of the tubes are connected through a resistor 2n having an adjustable center grounded tap. grid of tube 33 suñ'icient to block operation of the tube. The detector unit 30 includes a high y. triode f- 42 the grid of which is excited vby an audio fre quency tone and the cathode of which is con nected to the cathode of tube 3| of gate 6. Nor mally the positive potential on the cathode of The inner grid of tube I8 is connected to the out tube 42, due to the space current of gate tube put circuit of rectifier I4 and the inner grid of tube I9 is connected to delay system 8. The outer 60 3'I so blocks the tube 42 that the audio frequency tone is not heard in the ear phones 44 connected grids of tubes I8 and I9 are excited by radio to the plate of tube 42 through the' blocking con frequency voltages from an oscillator circuit denser 45. When gate tube 3I is blocked, how through a tuned transformer with a center tapped arrangement. The oscillator circuit, here shown as of the Colpitts type, and the transformer are indicated by the reference number 22. The plates of tubes I8 and I9 are parallel connected to a tuned-circuit comprising a variable capacity 23 connected across the primary of a radio frequency transformer 24. The tap on resistorA 20 is so ad ever, by voltages appearing across network 28 of detector 5, tube 42 becomes ’operative and a tone is heard in the head phones 44. This corresponds to the keying action at the cooperative station when the system is operating properly. In the particular embodiment'of rthe invention 70 illustrated in Fig. 2, the output of transmitting gate 6 is used to amplitude modulate a'trans mitter 46. Instead of amplitude modulation, .I9 are at ground potential, substantially no en phase or frequency modulation could bel employed ergy appears in the output circuit of the gate. When a negative potential is applied to the inner one delay or both system stations. '.8 which". `. 21;».comprisesl . ‘ _` aseries . grid of either tube I3 or I9, that tube is blocked, 75 at'I'he justed that when the inner gridsof tubes I8 and 2,404,356 „.6 of gates and ñlters will now be described." The :first gate includes a. .pair of tubes 48 and 49 VAhav ing their anodes connected in parallel through Va load impedance 50 to a source of positive potential and their cathodes connected to ground through adjustable resistors 5I and 452. The networkcondensers become charged at maximum; YIn’ 3 the krelation lbetween `charging potential andA gate output is graphically representedi If the maximum negative charging potential for the inner grid Vof one lof the tubes of a gate is .repre? sented by E1 lon Fig. '3, then from the graph it isapparent that the gate output will reach its maximum prior to complete charging of the >gate grid and that minor variations in the charging outer grids of tubes 48 and -49 are connected ,for excitation to the transformer 36. The vinner grid of tube 48 is connected through network 40 and resistor 4I with key lil while the inner grid of 10 potential will have no eifect upon the gate Áout tube 49 is grounded. Thus 'when key I-ß is up, put. On the other ihandl'with-a maximumcharg both inner grids are at ground potential and the ing potential represented by the lineqEe, .the gate gate comprising tubes 48 and 49 does not pass out-put will not reach-its maximum .value and energy, but when key I'U is depressed, tube '48 is variations in the charging potential result in blocked by the application of negative voltages 15 variations in gate output; In order for the sys to its cathode, the gate becomes unbalanced and tem as a whole to operate ias hereinbe?ore -de' a signal appears across impedance 5U. 'This sig scribed, it is thus necessary to correlate` the mag. nal is îfed through a delay filter ‘54 designed and .nitudes of the resistors and condensers ofthe y»adjusted to simulate the delay occasioned by various networks and the charging potential, such transmission of the signal through the lspace 20 as E1, E2 or Es, so as‘to insure 'equalftime delays »from one station to the other. From the ñlter during charging and discharging of the grids- 'of 54, the ysignal is fed through a rectiiier network the various- gates. ' ' ` having time characteristics simulating lthose of The invention has now beenV described in con nection with one -speciñc embodiment thereof. detector I4 at the other station. Output from rectiñer 56 unbalances a second gate of the delay system 8 comprising the tubes il and 58 causing Obviously the invention as >diagrammatically il. lustrated in Fig. .l -could be embodied in equip ‘the signal to appear across a load impedance ‘6B and to be fed to a second delay ñlter 6'2. Filter ment differing from that specifically illustrated v in Fig. 2, andv various changes inthe circuits of '62, like -ñlter 54, is designed to simulate the delay Fig. 2 will -oc’cur to those skilled in the art.-` .For occasioned by transmission of the signal through 30 example, although the blocking `of a »gatetube space from one station to the other. LFinally, the has been show-n and described asv being’efi'ect‘ed output from filter 6'2 is applied to a rectifier '64 by the application of a negative voltage `to the having time characteristics similar to rectiñer i4 inner grid of the tube, the'tube could be blocked of the same station. The rectified potential by other means, as for example by groundingof across the network 66 in the output o1" rectiñer 35 the outer grid. Although the particular hal'f Y 64 is applied to the inner grid of tube I9 of re wave rectifier `circuits with ltheir accompanying ceiving Igate 2. -time delay element heretofore described are `pref- ' When two stations are each equipped with the erably employed inthe system, full wave recti instrumentalities of Fig. 2 and when the various iiers involving 'substantial ~reduction ‘in time delay networks thereof are properly adjusted, the lsys 40 `could be employed if desired. îOth'er alternatives tem will operate as previously described in con nection with Fig. 1. In order to insure that the concurrent depression of the keys at the two sta tions causes an absence of signalling between the within the -spirit >of `the invention as deñned in ’ theappended claims will 4‘occur -to ‘those skilled in the art. I claim: ’ Y ' ~ ' » c stations, precise timing is essential, that is the 45 1.z A secret station-to-station signaling system charge rates and also the discharge rates >of all comprisingin combination a receiving “gate” and important time delay networks must be identical. ffl-'transmitting gate at each station, each of said This is due to the fact that the depression of a “gates” having two input terminals ‘and teach key while the system is quiescent calls for the vadapted to pass energywhen 'activated at'e'ither charging of all the cascade networks and the one of saidterminals and to block the’p'assjage concurrent and synchronous charging rof similar of energy when activated at neithero‘f the input networks in the delay lsystem 8, while when the terminals or at both simultaneously, key means system is operative due to the depression of one at each station connected to one of said input key, the subsequent depression of the key at the 'terminals of each of said gatesior :activation other station serves to discharge all the signal 55 thereof, means v interposed betweenV >‘said >key channel networks while matching this action means `and the 'terminal o'f said ‘receivingfgat‘e " timewise `>with a charging procedure in the local :for introducing a time delay between operation delay system 8. This requirement explains the .of the .key means Yand `activation of the terminal ‘special form of rectifier units used in the system. ofV theV receiving gate, 'a 'detector connec'te’dfI-bei The series resistors, such as resistor I6 in unit I 4, >tween-said receiving. .gate andthe other' _inëput retards the charging rate for the shunt condenser terminal -of said transmitting gate', 'and .means in the output network of the rectifier so that the at each »station for transmitting energyY passed same amount of time will .be required for charg by :the transmitting gate to the other station Afor ing as for discharging. It should be noted that .actuation of the »other input .terminal of the when the exciting input voltage of a rectiñer unit 65 `receiving gate at that station whereby 'th‘e.rle~ disappears, the rectilinear character of 'the diode tector at each station can be made îtorespon'd of the rectiñer serves to isolate the output net -only to -signals initiated by the key ‘means at work from the rest of the system so that its dis the distant station. . ' _ ii . charge rate is for the most part a function of its Y2. A station-to-st-ation 'secret signaling system own constants. 70 comprising interconnected receiving andfîtrans-A Since the gates are voltage operated devices, any consideration of the time delay involved in operating them must also consider the magnitude of the various negative charging potentials and therefore the absolute value to which any of the 75 mitting means at each station, signal introduc ing means at each station, detecting means at each station interposed between said receiving and transmitting means, means at each station for creating a delayed replica of the locally in 2,404,356 8 7 6. The signaling system according to. claim 2 troduced signal, means for suppressing the trans mission .of a signal when the signal introducing means and the detecting means are simultane wherein said receiving means includes a rectiñer circuit comprising a diode, an input circuit con nected to the cathode of said diode comprising ously operated, and means jointly controlled by said means for creating a delayed replica of the 5 a condenser and resistor connected in series and a resistor having one end connected to said con local signal and by said receiving means for denser and to said first resistor and its other end suppressing operation of the detecting means connected to a source of low positive potential when the energy passed by said receiving means and an output circuit connectedr to the anode results from the retransmission from the other of said diode comprising a resistor anda con station of the signal previously introduced at the denser connected in parallel, the various resistors same station whereby no signal is transmitted and condensers being so proportioned that the from one station to the other during simultane time rate of charging of said output network, ous operation of the signal lintroducing means upon application of energy to the condenser in at lboth stations. the input circuit equals the time rate of dis 3. The secret signaling system according to charge of the output network upon cessation of claim 2 wherein said means for suppressing the the application of energy to the input condenser. transmission of a signal when the signal intro 7. In a secret station-to-station signaling sys ducing means and the detecting means are simul tem equipment at each station comprising re taneously operated comprises a pair of tubes each ceiving means, an electronic switch, a detector, having a cathode, an anode and at least two a second electronic switch and transmitting grids, a center grounded resistor connected be means all connected in a chain in the given order, tween said cathodes, an output circuit connected key operated means connected to both of said to said transmitting means and to which the electronic switches, and a delay circuit interposed anodes of said tubes are parallel connected, a between said key operated means and the first source of energy connected to one grid of each mentioned switch, said ñrst mentioned switch tube for applying alternating voltages thereto in operating to pass energy to said detector only opposite phase, a second grid of one tube being when activated either by said key means through connected to said signal introducing means and said delay circuit or by said receiving means and a second grid of the other tube being connected said second mentioned switch operating to pass to said detecting means whereby the application energy to said transmitting means only when of negative voltage to the second grid of one tube activated either by said key means or by said only resulting either from the operation of the signal introducing means or of the detecting 8. Station equipment in a secret signaling sys means blocks one tube, upsets the balance of .- tem according to claim 7 wherein said delay cir the tubes and permits passage of energy to the cuit of one station includes networks simulating transmitting means, whereas simultaneous ap the time constants of the chain of the other sta plication of negative voltage to the second grids tion, of the intervening space between stations of both tubes blocks both tubes and suppresses and of the receiving means at the same station the passage of energy to the transmitting means. whereby energy passed by said second switch as 4. The secret signaling system according to a result of operation of said key means, trans claim 2 wherein each of said receiving means mitted to the other station, passed through the includes a rectiñer circuit and wherein each of equipment at the other station, retransmitted said means for creating a delayed replica of the back to the first station and received by the re signal includes a circuit simulating the time ceiving means at the ñrst station Iarrives at said detector. constants of the rectifier circuit at the same sta- ' ' tion, a circuit simulating the time constants of Y .. first mentioned switch simultaneously with energy passed by said delay circuit as a result of the same operation of the key means. 9. The method of secret signaling between two the rectiiier circuit at the other station, and cir cuits simulating the time constants of the space intervening between the stations, each of said stations which comprises blocking the transmis circuits having charging periods equal to their sion of a signal between stations during such periods as keys are simultaneously depressed at discharging periods. 5. In a secret station-to-station signaling sys tem, an electronic switch having two input ter minals and one output terminal and arranged to pass energy when a negative voltage is im pressed on either input terminal and to be blocked when negative voltage is impressed on both stations and during such periods detecting at one station the signal at the other station by reference to the signal at the same station. 10. The method of secret signaling between two stations which comprises passing modulating energy to a transmitter at one station for trans neither or both input terminals, a source of mission to the other station upon operation of negative Voltage, a network between said source the key at the same station, detecting the modu and one of said input terminals and key means `-' 6.0 lation at the other station and passing modulat between said source and said network, said net ing energy to the transmitter at the other station work having equal charging and discharging in response to such detection for retransmission periods, a detecting circuit connected to said to the ñrst station, blocking detection of such other input terminal, and transmitting means modulation at the ñrst station by energy con connected to the output terminal of said elec fea trolled by operation of the key and delayed at the tronic switch for transmission of a signal when ñrst station, while blocking transmission of mod said key is operated and the detecting circuit ulating energy to the transmitter of a station is not energized or when said key is in open cir during concurrent detection and key operation of cuit position and the detecting circuit is passing energy. no the same station. CARL EDWARD ATKINS.