Патент USA US2406637код для вставки
Aung. 27, 1946. F'.l c. sANDRl-:TTO ET AL 2,406,637 RADIO DIRECTION FINDER -Filed Jän. 12, 1942 _ NN-I %\ SQ SÜ 1 3 Sheets-Sheet 1 I Aug. 27, 1946. P. c. sANpRETTo ET A1. 2,406,637 RADIO' DIRECTION FINDER Filed Jan. 12, 1942 3 Sheets-Sheet 2 Aug. 27, 1946. P. c. sANDRETTo ET Ax. 2,406,637 RADIO DIRECTION FINDER Filed Jan; l2, 1942 3 Sheets-Sheet 3 Mxm, s fîyagß y Patented Aug. 27, 1946 at UNITED STATES PATENT ÜFFÍCE 2,406,637 RADÍO DIRECTION FINDER Peter C. Sandretto, Chicago, and Elmer P. Buck thai, Brookfield, lill., assignors to United Air Lines, Inc., a corporation of Delaware Application raneaiy 12, 1942, 'serial No. 426,372 9 Claims. The present application is a continuation in part of our copending application Serial No. 403,802, ñled July 24, 1941, and entitled Radio (Cl. Z50-«11) 2 ous output circuits from the radio frequency re ceivers and the source of low frequency signaling energy are arranged to be impressed on a single transmission line which leads to the control sta direction finder. The invention relates to control systems for tion. At the control station suitable selective radio direction finders, more particularly to di iter means are provided for separating the vari rection finders of the type disclosed in our said ous frequencies transmitted from the ñeld station copending application and control means there and conducting these separated frequencies to for, and the invention has for an object the pro~ corresponding recording and indicating means. Vision of reliable and accurately controlled di~ 10 In addition, the control station is provided with rection finders cf this character. a plurality of signal transmitting means for se In various types of direction finders, and par lectively imposing on the transmission line, signal ticularly those having relatively large rotating frequency currents of either continuous or in antenna means such as are disclosed in cur said termittent character for selectively controlling prior application, it is necessary or desirable that at the antenna site the operating motor, the an the antenna structure and the receiver unit be tenna connections, and the respective radio fre located in a relatively open area of large size quency receivers so as to effect the desired op which is free from power lines, metal fences, and eration of the direction finder system. similar structures which might iniluence the ac For a more complete understanding of the in curacy of the bearings received. It is also desir 20 vention, reference should now be had tothe draw-able that the necessity for an attendant at the ings in which: , site of the antenna structure be eliminated7 and Figs. 1 and 2 are respectively the left- and that the operator of the direction ñnder equip right-hand sides ofl a single circuit diagram illus ment be stationed in a readily accessible cfñce or trating a remote control system and direction control station remote from the antenna site. 25 finder embodying the present invention; In receiving and recording the bearing records Figs. 3 and 4 are, respectively, circuit diagrams obtained through proper manipulation of the an illustrating the detailed circuit connections of tenna structure and in controlling these manipu the selector control and cardioid control means lations, it is of course necessary to transmit be illustrated generally in Fig. l; and tween the antenna structure and the remote con 30 Fig. 5 is a diagrammatic illustration of one of trol station not only the incoming signals for the radio frequency receivers. producing the bearing record, but also a plurality Referring now to the drawings, Fig. 1 illustrates of outgoing signals, and it is of course undesir somewhat diagrammatically the antenna struc able to utilize separate control wires for each ture and related equipment which comprise the control or bearing signal. Accordingly, it is a ñeld station located at the antenna site. The further object of this invention to provide an antenna structure is shown as comprising a pair automatically controlled radio direction finder of spaced apart shielded loop antennas il) and and a remote control system therefor, wherein Il, which are preferably, as described in our a single transmission line is employed to carry above referred to copending application, mounted the various control signals between the antenna 40 in face-to-face relation on the opposite ends of site and the remote control station. a horizontally extending support or beam l2 which In carrying out the invention in one form, we provide at the antenna site or ñeld station an antenna structure adapted to be selectively con nected in a plurality of circuit arrangements to provide bearing signals of different character, means for controlling the circuit connections of the antenna structure, and a plurality of radio frequency receivers adapted selectively to be oon nected to the antenna structure. In addition, there is provided at the ñeld station a source of relatively low signal frequency controlled by in is carried on the upper end of a rotatable post i3 mounted on a suitable base l5 containing a driving motor and suitable gearing (not> shown) ' for rotating the post and the antenna structure at a predetermined constant speed. Intermedi ate the loop antennas IE! and H is a vertical an tenna I4 mounted on substantially the laxis of rotation of the post I3. As is more fully explained in our copending application, the loops l0 and Il are intended se lectively to be connected in opposed parallel rela dexing means associated with the antenna struc tion with each other, so that either two or four ture, and a motor for suitably rotating the an hulls will be produced in the signal output of the tenna structure at the desired speed. The varie. 5,5 receiver to which the loops are connected, de 2,406,637 3 4 generated equal respectively to the difference `be pending upon the characteristics of the propagat tween the carrier frequency and the frequency of oscillator 35, and to the difference between the carrier frequency and the frequency of oscillator ing medium and the received radio wave, or one or both of the loops may be connected in circuit with the Vertical antenna I4 so that the output signal of the receiver will follow the usual cardi oid pattern for the purpose of indicating which 36. These two beat frequencies pass through the intermediate frequency amplifier 3l which pref erably is of the type having a Wide response curve, and in the »second detector contained in the de tector and audio amplifier 38 these two interme diate frequencies beat together to form a beat of the previously referred to nulls represents the . true bearing of the transmitting station. In order to provide for such selective connec tion of the loops I0 and II and the antenna I4, I6, is provided having a plurality of stationary note having a frequency equal to the difference between the ñxed frequencies of the two oscil contacts I1, I8, I9, 20, and 2|, and co-operating lators. a switching means, which is illustrated as a relay Y It will of course be understood that similar movable contacts 22, 23, and 24. . It will'be ob oscillators having an identical frequency separa tion are associated with each of the radio fre quency receivers 23, 29, and 30, as shown in Fig. 1. The arrangement i-s such that a constant beat note equal to the frequency separation of the two oscillators, which may be, for example, a fre I1, 22, I9, and 23. Upon energization of the 20 quency of 1020 cycles, will be produced at the out relay I6, these contacts will open and the two put of the audio amplifier regardless of the re loops I0 and II will be connected in additive spective frequencies of the carriers to which the parallel relation with each other to the conduc served that when the relay I6 is in the deener gized position shown in the drawings, the loops I0 and II will be connected in opposed parallel circuit relation with each other to a pair of con ductors or bus bars 25 through the relay contacts various radio frequency receivers are tuned. tors 25 through relay contacts I8, 22, 20, and 23, 25 the vertical antenna at the same time being con nected to a third bus bar 26 through the relay contacts 24 and 2|. The manner in which the cardioid relay I6 is selectively energized, so as to produce a cardioid pattern during one revolu to control the `signal frequency supplied by a suit able'oscillator 42. For purposes of illustration, the oscillator is indicated as being capable of gen erating a 120 cycle signaling frequency. As tion of the antenna structure and thereafter to connect the loops I0 and II in opposed parallel relation during subsequent revolutions, will be Y more fully described hereinafter. Also associated with the antenna structure at the field station >is aV suitable indexing means which, as shown in Fig. 1, comprises a cam oper . ated switch 4I] and an indexing relay 4I arranged shown, the cam operated switch 40 includes a pair of contacts 43 arranged to control the energizing v Associated with the antenna structure and winding of the indexing relay 4I and an operating adapted selectively to be connected to the bus cam 44 which is carried by the post I3 so as to bars 25 and 25, are a plurality of radio frequency close the contacts 43 at a predetermined point receivers 2'! to 30, inclusive. each of which is during each revolution of the antenna structure. tuned to one of the various frequencies on which The indexing relay 4I is provided with two pairs the direction finder is to be used.` suitable multi ple pole switches 3| to 34V being provided for ef 40 of contacts 45 and 45, the contacts 45 being con nected to control the oscillator 42 and the con fecting the desired connection of the receivers to tacts 46 forming a part of suitable cardioid .con the bus bars. While four radio receivers are trol means, indicated by the reference numeral shown, it rwill of course be understood that any 41,' which will be more fully described hereinafter. desired number may be provided, within the limits In addition to the above referred to elements, of the selector switch and the signaling means to the field Istation equipment shown in Fig. 1 in be hereinafter described for selectively operating switches 3| to 34, inclusive. . - While the radio frequency receivers may beof any desired type, they are preferably of the type described with particularity in our above referred to copending application, wherein a pair of beat oscillators are arranged to beat with the carrier of the signal frequency to provide a c-o-nstant audio output beatnote regardlessV of variations in the carrier frequency. In Fig. 5 the receiver 2'! is shown somewhat diagrammatically as includ ing a converter tube IBI having a plurality of control electrodes |02, |03 and |04, the control electrode |04 being supplied withthe carrier fre quency through the radio frequency stage (not shown) of the receiver, and the control electrodes |03 and |02 being respectively connected as shown to suitable crystal oscillators 35 and 35. 'I'he oscillators 35 and 35 are arranged to produce ñxed frequencies having a frequency difference equal to the frequency which the band pass filter 54 (Fig. 2) is designed to pass. For example, if the band pass filter is designed to pass a frequency of 1020 cycles plus or minus 30, the frequencies of the oscillators 35 and 35 will be so selected as to have a frequency dif ference equal to 1020 cycles. When the frequen cies of the two crystal oscillators and the carrier are impressed on the control electrodes of the converter tube IOI, two beat frequencies will be cludes a suitable selector switch 48 for selectively controlling the switches 3| to 34,1inclusive, a lock out relay 48a, and suitable selector control means 49, which control means 49 is illustrated in detail in Fig. 3 and will be more fully described herein after. As Isho-wn, the selector switch 48, the lock out relay 48a, and the output side of the detector and audio amplifier 33 are directly connected to one end of the transmission line 39, While the selector control means 49 and the E25 cycle oscil lator are connected to the transmission line through the contacts of the lockout relay. While the single transmission line 39 may, of course, 60 comprise two conductors, one conductor is all that is necessary, the return circuits being effected through the usual ground connections as indi cated in the drawings. At the control station, which is shown in Fig. 2, es the transmission line 39 i-s connected to a second audio amplifier 5I, and the output of this audio ampliñer is connected to a plurality of suitable filter units 52, 53, 54, and 55. The filter unit 52 is a high pass filter unit, preferably capable of 70 passing frequencies of 300 cycles and above, and is provided in order to insure the removal from this branch of the incoming circuits of all of the relatively low signaling and control frequencies. As shown, the filter units 53 and 54 are connected 75 to the output of the ñlter unit 52, the iilter unit 2,406,637 5 53 being adapted to reject the constant beat note frequency supplied to the transmission line by the audio amplifier 33. Thus the output or this filter 53 contains all of the audio components above 399 cycles except a small spectrum around 1G20 cycles, and accordingly any voice frequencies present in a modulated carrier picked up by the antenna structure are transmitted through this filter unit 53 to a suitable loud speaker 55 which comprises a monitor channel. By means of this monitor channel the operator is able to identify the various signals received and may listen for direc tional bearing requests. The band pass filter 5d is a highly selective nlter adapted to pass frequencies having only a plus orv minus variation of approximately 30 cycles f fromY the beat note VVfrequency suppiied- by Vthe 6 ing switch 59 to control the energization of the recorder motor 58. In addition to the above de scribed equipment, the control station shown in Fig. 2 includes a plurality of signal transmitting means 6l, 68, and S9 adapted to be energized from a suitable source of 60 cycle energy, the trans mitting means 68 and S9 being connected, as shown, to a suitable voltage divider` 'l0 whereby the signal energy imposed on the transmission line by the devices 68 and` 69 is at a reduced volt age comprising only a fraction of the signal energy voltage impressed by the device 61. All of the devices 6l, E8v and E9 are connected by means of a conductor ’il to the transmission line 39. The transmitting means S1 is of the type adapt to impress on a signaling circuit a's'elected radio receivers to thetransmission line. The high number of short impulses for controlling the se order of selectivity employed in this filter, which lector switch d~8, the number of impulses deter is preferably a 1020 cycle unit, enables the re 20 mining tlie operation of the selector switch, and moval of substantially all static interference side this transmitting means may constitute an ordi bands. It has been found that even under severe nary telephone dial. The transmitting device -68 static conditions, the beat note present at the constitutes a push~button controlled pulsing re output terminal of the filter 5i is substantially lay arrangement adapted, when the push button pure, and of course` this beat note is present only is operated, to transmit a single pulse of prede when a carrier frequency is being received at the termined duration. Such devices are of course antenna station. Well known in the art, and accordingly the details The band pass filter 55, which is connected in of the pulsing relay means have not been illus parallel with the filter unit 52, is adapted to pass trated. The third transmitting device comprises the 120 cycle signal frequency placed on the 30 merely a manually operable double-pole single transmission line by the oscillator 4Z, and it Will throw switch adapted to be opened and closed, as thus be seen that the frequencies passing over desired, to impose on the signaling circuit a con the transmission line from the antenna site are tinuous 60 cycle signaling current and also to separated into three distinct channels, one of effect energization of the starting switch 59 for which constitutes a 120 cycle indexing channel, 35 the record-er motor 58. the second of which constitutes a 1020 cycle direc With the above description of the component tional signal channel, and the third of Which con parte of the apparatus constituting the field sta stitutes an audio monitor channel. tion of Fig, l and the control station of Fig. 2, In order that a continuous record of the signal it is thought that a complete understanding of intensity received at the antenna station and 40 our invention may now be had from a description transmitted over the transmission line 3S may be of the operation required to obtain a bearing on produced at the control station of Fig. 2, re any selected transmitting station. as, for example, cording means of the type disclosed in our above a transmitter carried by an airplane in flight, referred to copending application are provided at the bearing of which, with reference to the iield the control station. In Fig. 2 the recording means station, it is desired to determine. is shown as comprising a rotatable drum or re The first control operation, in order to put the cording surface 5i adapted to be driven through direction finder in condition for recording a bear suitable reduction gearing (not shown) by a rnc ing, is to start the loop rotating motor at the tor 58, the energization of which is controlled. by field station This may be accomplished simply a suitable motor starting switch 5d. The motor 50 by pressing the push button of the transmitting for the` recording means and the motor for the device B8 so as to impress on the transmission antenna structure are preferably of the synchro line 39, through the conductor 1i. a measured nous type, and are energized from suitable 60 pulse of 60 cycle energy at the previously referred cycle sources of energy so that the recording drum to reduced voltage Which is preferably less than 51 will be rotated in synchronism with the rotat- i - one~half the full line voltage of the 60 cycle» ing antenna structure. source and may be as low as two volts. The device Associated with the recording drum is a trac 68 is so arranged that the pulse will be of a dura ing element or pen 5B adapted to be energized tion on the order of magnitude of one-tenth of through a suitable rectifier 6l from the 1020 cycle a second, regardless of the length of time that channel containing the band pass iilter 54, the ` the push button is held in its depressed position. recording pen 5S being preferably of the D’Arson At the field station end of the transmission line val type shown in our copending application, so 39, this pulse of low voltage 60 cycle energy is that the pen, when energized, will trace on the transmitted through conductors ‘l2 and 13, the recording surface '5'1 a continuous record of the contacts of the lockout relay 48a, and a con signal intensity. ï ductor 13a to the selector control means 49, the Also associated with the recording surface or details of which are illustrated diagrammatically drum 51 is an indexing pen or tracing element in Fig. 3. Because of its low voltage this pulse 62 adapted to be actuated by an energizing mag will not eifect operation of either the selector net E3 connected for energization through a suit~ switch 43 or the lockout relay 43d. able rectifier 6d from the 120 cycle signaling 5' As shown in Fig. 3, this> selector control means 49» comprises a control relay 'ld responsive to low channel containing the band pass ñlter 55. Also energized from this 120 cycle channel is a suitable voltage signal energy, which relay is connected signal light E5 for indicating when the loops of for energization from the conductor 13a and in cludes a pair of normally closed contacts ’l5 and the antenna structure are rotating, and a suitable control relay 66 which co-operates with the start- ' a pair of normally open contacts 76. In addi 9 2,406,637 8| of the relay 00 after this latter relay has operated. 10 as. to eiïect operation of the relay H9. Upon closure of the contacts |52 of the relay H9, a The above-described application of power to condenser |33 will be discharged to effect ener the cardioid control means 41 conditions this gization of the relay H5, the condenser having control means 41 for operation by the contacts previously been charged through a circuit which 49 of the indexing relay 4| under the control may be traced from the positive one of the con of the cam switch 50 carried by the rotating ductors 90, through the conducto-1' |25, a resistor antenna structure. The details of the cardioid |34, a conductor |35, and the condenser |33 to control means, which are fully described and the negative one ofthe conductors 50 by Way of claimed in our above-identified copending appli 10 a conductor |35. The energizing circuit for the cation, are shown in Fig. 4 and it will be seen relay H8, established by closure of the contacts that closure of the contacts 45 completes an |32, may bev traced from one side of the con energizing circuit for a control relay |06 having denser |33, through> the conductor |35, the con an energizing winding |51, two pairs of normally tacts |32, a conductor |31, the winding |38 of open contacts |08 and |09, respectively, and a 15 the relay H9, a conductor |39, the contacts |08 pair of normally closed contacts H0. This cir on the relay |55 which, as previously described, cuit may be traced from the positive side of the has been operated- by closure of the contacts 49 source of energy represented by the conductors on the indexing relay and by Way of the con 90, through the conductors |H, H2, H3, and H4, ductor H6 to the negative one of the conductors the relay contacts 46, the conductor H5, the 20 90 to which the opposite side of the condenser relay winding |01, and by Way of a conductor |33 isV also` connected by way of the conductor H9 to the negative side of the source of energy. |36. In order to simplify the drawings, the return con Following initial energization thereof, the relay nection to the negative side of the source of H8 is-held in its operated position by a holding energy represented by the conductors 90 is not circuit which may be traced from the positive shown in full, but is indicated merely by a con one of the conductors 90, through the conductors ventional minus sign. IH, H2, and |40, contacts |09, conductor |4|, .in addition to the control relay |05, the contacts |42 on the relay H 8, conductor |43, the cardioid control means 41 includes a plurality Winiding |38 0f the relay H8, conductor |39, of control relays H1, H8, and H9, the energizing contacts |08 and by Way of the conductor H6 winding |20 of the relay H9 being connected in to the negative one of the conductors 90. the output circuit of a full Wave rectifier |2| Closure of the contacts |44 of the relay H8 having a pair of plates or anodes |22, a pair of establishes an energizing circuit for the Winding cathodes |23, and a pair of control elements or |45 of the relay H1, which circuit may be traced grids |24. As shown, the grids or control ele ~ from the positive one of the conductors 90, ments |24 are adapted to be energized from a through the conductors |H and |45, the con secondary Winding |25 of a suitable coupling tacts |44, conductors |41 and |43, and by Way transformer', the primary Winding |25 of which of the winding |45 and a conductor |49 to the is connected by the conductors |00 to a suitable negative one of the conductors 90. The relay antenna for energization by the carriers of the 40 H1 is thus operated and the energizing cir transmitting stations to which the radio receivers cuits thus far traced continue to exist until the are tuned. The primary winding |26 is prefer circuit is broken at the contacts 46 of the index ably connected to the system of Fig. l at any ing relay, at which time the relay |05 is deener suitable point so that it will be energized re gized allowing contacts |08 and |09 to open and gardless of the one of the receivers 21 to 30, in contacts H0 to close. Opening of the contacts clusive, which is selected and in operation, or |09 interrupts the previously traced holding cir the primary Winding may, if desired, be con cuit for the relay H8, and the consequent open nected to an entirely separate antenna and re ing of the contacts |44 on this relay in turn in ceiver. Inorder to provide a constant negative terrupts the energizing circuit for the relay H1. bias on the control elements |24 of the reCti- f Simultaneously, however, closure of the contacts ñer tube |2|, the midpoint of the secondary H0 o-n the relay |05 provides a self-holding cir Winding |25 is connected to the negative side of cuit for the relay | |1 which may be traced from the source of energy, as shown, and the cathodes the positive one of the conductors 90 through the I 29 are connected to a suitable potentiometer conductors IH, H2, and |49, contacts H0, a con represented as comprising resistance elements ‘ ductor |50, contacts |5| on the relay H1, con |21 connected across the direct current source ductors |52 and |48, and by Way of the Winding of energy represented by the conductors 90. |45 and the conductor |49 to the negative one Whenever carrier energy is being supplied to of the conductors `90. This transfer of the hold the rectiñer tube through the transformer, cur ing circuit for the relay H1 is accomplished rent will flow through the winding |20 of the GO Without affecting the operated condition of the control relay H19 by Way of a circuit which eX relay because this relay is of the sloW-to-release tends from the positive one of the conductors type, as indicated diagrammatically in Fig. 4 by 90, through a conductor |28, the Winding |20, the the usual copper slug |53a. conductor |29, the anodes |22, the cathodesV |23, Operation of the relay H1 of course causes and by Way of a conductor |30 to the movable closure of the relay contacts |53, thereby com contact I3! on the potentiometer comprising the pleting an energizing circuit for the cardioid resistance elements |21. relay i5 which may beY traced from the positive As previously described, the operating motors one of the conductors 90, through the conductors of the antenna arrangement having been ener HI, H2; H3, and |54, the contacts |53 and by giaed, the cam switch 40 operates to energize the Way of a conductor |55 to the operating Winding indexing relay 4| and eil’ect intermittent opening of the relay IB, the opposite side of which is and closing of the contacts 46, and in describing connected to the negative side of the sotu'ce of the operation of the cardioid control means 41 it will be assumed that a carrier is being sup plied to the Winding |26 of the transformer so energy as indicated by the ground connection shown in Fig. 1. As previously described, ener gization of the relay I6 is eiîective to connect '2,406,637 the loops l0 and II in additive parallel relation with each >other to the conductors 2'5, and to connect the vertical antenna I4 to the conductor orbus bar 2%. Thus during the ñrst revolution of the lantenna structure, the loop antennas and thevertical antenna will be connected in circuit so as to produce a directional or cardioid pattern which, as will beV hereinafter described, is re corded on the recording surface 5T by the trac ing element Gü. _ The previously described connections exist until the contacts 4B of the indexing relay 4| are again closed upon completion of one revolution of the antenna structure, whereupon the relay |03 -will again be energized through the previously traced energizing circ-uit, causing the contacts lIU to open and interrupt the previously traced self-holding Vcircuit for theY relay II'I. The capacity of the condenser |33 and the ohmic to operate as soon as a 120 cycle pulse is received over the transmissionline. As shown in Fig. 2, this energizing circuit extends from the source of 60 cycle energy and the voltage divider 10, through the lower pole of the switch 69 andthe conductor 3| 'to Ythe energizing Winding of. the » motor starting switch 59, and from thisenergizing winding the circuit is completed by the conductor 92 and the contacts of the relay 65B to the Vground connection 93. Thus, as` soonas the relay 66 closes, the motor starting switch 53 will be ener >- gized to close its contacts gland 95 and connect the motor §38 to its source of energy. Closure of the motor starting ' switch ,59 also is effective through the contacts Bü thereof to establish a self-sealingcircuit,v so that the motor starting switch 59 remains energized after the relay 66 has opened and the motor 58 will therefore continue to operate until the switch 69 is manually opened after the bearing reading has been taken. resistance of the resistor |34 are so chosen that between successive closures of the contacts 46 of the indexing relay 4| there will elapse an in sufñcient time to permit the accumulation yon the Acondenser |33 of a charge of su?licient mag nitude to eñect operation of the relay H8. Therefore, even though the initial energizing circuit Vfor the relay H8 is completed through the contacts of the relay ISS when this relay is again operated, the relay I|8 will not operate and accordingly the relay |Il opens, thereby interrupting at contacts |53 the energizing cir cuit for the cardioid relay I6. Thus the relay It Ywill now be clearr that, through the above « described cycle of control operations, the particu lar station on which a bearing is to be taken has been selected, the antenna structure >has been started to rotate, and the recorder motor has been energized to drive the recording surfacein syn-V chronism with the rotating antenna structure. Therefore, there will’be imposed on the ñeld Vstation end of the transmission line 39 a 1020 Y I5 will return to the deenergized position shown in Fig. 1 and the loops I@ and II are connected in opposed parallel relation to the conductors or bus bars 25,V as heretofore described. Due to the-fact that the capacity and resistance values ‘of ,the condenser |33 and the resistor |34 are chosenl as indicated above, the operating cycle cannot be repeated until a sufficient time has elapsed to permit the condenser |33 torattain a new charge of sufficient magnitude to operate therelay |32. ‘l2V -39 is also effective through the lower pole thereof to prepare an energizing circuit for thejrecorder motor 53, so that the recorder motor willsbegin _ After the desired record has been made in a manner toV be further described hereinafter and the system has been allowed to rest for a cycle note which varies in intensity in accordance with the directional characteristics of the radio wave picked up by the antenna structure. This 1020 cycle note passes through the ampliñer 5|, the filter units 52 and V54, and the rectiñer 6I to the tracing element 60 which records on the recording surface 51 a traceof the signal intensi ty. At the same time, there is transmitted over the transmission line 39 a 120 cycle pulse of signal energy whichl causes the indexing pen or tracing element 62 ~to record on the chart a reference mark each time that the antenna structure passes through a predetermined compass position. During the ñrst revolution of the recorder, the conventional cardioidl pattern will be traced thereon by the tracing element 60 in order to relatively short time, operating voltage will build up across the condenser |33 and the above de indicate the general sense or direction of the scribed cycle of operations may be repeated. Such an operating voltage, however, will not build 60 transmitting station, and on each succeeding revolution of the recording surface the tracing up across the condenser until the system is thus element 6€) will impart to the recording surface a allowed to rest because of the fact that the con continuous trace of the 1020 cycle signal received denser is discharged each time that the contacts the ñrst closure of the cam switch 40 and re with the loops Iû and II connected in opposed parallel circuit relation. The pen will of course retrace this path during successive revolutions if there hasV been no change in the signal intensity for identical positions of the antenna system. mains> closed until the next revolution of the Variations in the propagating medium or in the |08 of the relay |06 close. " It -will now be apparent that as soon as energy is applied to the cardioid control, as'heretof’ore described, the cardioid relay IB is operated by antenna structure causes the energizing circuit 60 signal energy received due to other disturbances will ofcourse appear in the trace made by the for the relay i6 to be broken. The relay I6, therefore, returns to its deenergized position so as to connect the loops l0 and I| in opposed parallel circuit relation and disconnect the ver tical antenna Ill, and the relay I6 will remain 65 pen 66, except in so far as they are eliminated by the antenna structure and its associated appara tus, and accordingly an average trace may readily be determined from the record produced. in this position during subsequent revolutions of Y The recording paper, or similar recording sur the antenna structure. Furthermore, the car rier controlled interlock relay |93 which is ener face which is wrapped around the drum 58, may be graduated in degrees and, accordingly,vthe compass position of any maximum or minimum gized through the conductors |09 insures that the above-described cycle of operations will take 70 point in the continuous trace of the signal energy may readily be located by reference to the index place -only when a carrier is being received by ing mark formed on the recording paper or sur the antenna structure. Y ' face by the indexing pen or tracing element 62. \ Closure of the transmitting means or ‘switch 69 The direction finder is preferably allowed to op to .impose the above referred to continuous low voltage signaling current on the transmission line 75 erate for a period of thirty secondsto one minute, 2,406,637 13 14 so that from seven to fifteen. bearings will be to produce a record trace reflecting the intensity obtained, the antenna structure preferably being rotated at a speed-of approximately fifteen revolu tions per minute, and the direction ñnder malf of the energizing signal, and filter means between said recording means and said transmission line for rendering said recording means responsive then be shut down. To stop the recorder motor 5i! only to signals of said constant beat frequency, in order to enable removal of the record paper from the recording surface 5l, it is necessary only whereby a bearing trace of the received signal energy may be produced from any of said dif to open the switch 69 so as to interrupt the pre ferently tuned receiver channels. viously traced holding circuit for the motor start ing switch 5S. rIîhe operator may then remove thevrecord paper and measure the distance from 2. In a radio direction finder system having an antenna station and a remotely located control station connected by a transmission line, the com bination of rotatable directional antenna means at said antenna station, radio receiver means at said antenna station including a plurality of chan 15 nels respectively tuned to‘receive signals of dif the index mark to the bearing null which is nearest tothe cardioid bearing. rllhis distance indicates in degrees the bearing of the transmit »ting-station- on which the bearing'. has been taken. Upon opening of the switch S8, the relay 1li ferent preselected frequencies picked up by said of theselector control means immediately returns antenna means, means at said control station for toits deenergised position and opens. the energiz selectively imposing on said transmission line con ing circuit to the slow-to-release relay 17. The trol signals of a predetermined frequency having relay 'Il then opens and deenergizes the relay 8d 20 preselected characteristics, means at said antenna which is also slow-to-release and therefore will station responsive to said control signals for se not effect closurev of the contacts äl for a short lectively connecting between said transmission interval after opening of the contacts 1B on the relay- 'il has occurred. The slow-to-release char acteristics ofthe relay EQ insure that all of the relaysfhl, l1, and dil willreturn to their respec tive deenergized positions without completing an energizing circuit for the ratchet relay 83 through the contacts 75„ 73, and 3l. , line and said antenna means a selected one of said channels of said receiver means corresponding to the selected signal characteristic, heterodyning means associated with said receiver means for im posing on said transmission line an output beat note of substantially constant frequency regard In,` order to stop the rotation of the antenna structure, it is necessary only to actuate the push less of the selected receiver channel tuning, i11 dexing means at said antenna station for impos ing on said transmission line indexing signals dif button of the pulsing relay means 53 so as to transmit a short 60 cycle pulse of low voltage to fering in frequency from said control signal fre the selector control means t9 so as to cause the ing signals reñecting the compass position of said quency and said beat note frequency, said index relays 14, Tl, and Sii to operate as hereinbefore 35 antenna means, recording means at Said control described to energize ratchet relay S3. This station having a plurality of energizable tracing energization causes the ratchet relay to move for elements, and filter means between said recording ward one step, whereupon the contacts of the means and said transmission line for rendering ratchet relay open and interrupt the circuit to one element of said recording means responsive the antenna motor in the base I5. All of the 40 only to said constant beat note frequency and an parts having now returned to their initial posi other element thereof responsive only t0 said tions, another bearing reading may be taken on indexing signal frequency, whereby bearing traces any desired transmittingstation merely by follow of the signal energy received from said antenna ing again the above described procedure. means may be produced at said control station re While we have shown particular embodiments 45 gardless of the frequency of the received signal of our invention, it will be understood, of course, and oriented with the compass position of said that we do not wish to be limited thereto since antenna means. many modifications may be made, and we, there 3. In a radio direction finder system having an fore, contemplate by the appended claims to cover antenna station and a remotely located control any such modiiications as fall within the true 50 station connected by a transmission line, the com spirit and scope of our invention. bination of rotatable directional antenna means Having thus described our invention, what we at said antenna station, radio receiver means at claim and desire to secure b-y Letters Patent is: said antenna station including a plurality of 1. In a radio direction finder system having an channels respectively tuned to receive voice modu antenna station and a> remotely located control 55 lated signals of different preselected carrier fre station connected by a transmission line, the com quencies picked up by said antenna means, means bination of rotatable directional antenna means at said control station for selectively imposing at said antenna station, radio receiver means at on said transmission line control signals of a pre Said antenna station including a plurality of determined frequency having preselected char channels respectively tuned to receive signals of 60 acteristics, means at said antenna station re diiîerent preselected frequencies picked up by said sponsive to said control signals for selectively antenna means, means at said control station for connecting between said transmission line and selectively imposing on said transmission line con said antenna means a selected one of said chan trol signals of a predetermined frequency having nels of said receiver means corresponding to the preselected characteristics, means at said antenna 65 selected signal characteristic, heterodyning means station responsive to said control signals for se associated with said receiving means for impos ing on said transmission line the voice frequencies lectively connecting between said transmission of said signals and a beat note of substantially line and said antenna means a selected one of said constant frequency regardless of the selected re channels of said receiver means corresponding to the selected signal characteristic, heterodyning 70 ceiver channel tuning, loud-speaker means at said means associated with said receiver means for im control station, recording means at said control posing` on said transmission line an output beat station energizable to produce a record trace re note of substantially constant frequency regard fleeting the .intensity of the energizing signal, and less of the selected receiver channel tuning, re ñlter means connected to the control station end of said transmission line for rejecting from said Cording means Vat said control station energizable 2,406,637 15 16 loud-speaker said control signal and said beat note frequencies and for rendering said recording means at said control station for imposing on said transmission line a second signal of the same control frequency but of different character than means responsive only to signals of said beat note frequency, whereby a monitor channel is provided and a bearing trace of the received signal energy may be produced from any of said differently said signals of preselected characteristics,.means at said antenna station responsive to said second control signal for energizing said motor means, indexing means for imposing on the antenna sta ' tion end of said transmission line indexing sig 4. In a radio direction finder system having an als differing in frequency from said control signal antenna station and a remotely located control station connected by a transmission line, the com 10 frequency and said beat note frequency and re fleeting the compass position of said antenna bination o-f rotatable directional antenna means means, recording means at said control station at said antenna station, radio receiver meansrat having a movable recording surface and a plu said antenna station including a plurality of rality of tracing elements, filter means at said channels respectively tuned to receive voice modu control station for rendering one tracing element lated signals of Ydifferent preselected carrierY fre responsive only to said constant beat note fre quencies picked up lby ksaid antenna means, means quency and another tracing element responsive at said control station for selectively imposing on only to said indexing signals, and means initially said transmission line control signals of a prede rendered effective by an indexing signal for driv termined frequency having Apreselected charac teristics, means at said antenna station responsive 20 ing said recording surface in synchronism with to said control signals for selectively connecting the rotation of said antenna means to produce at said control station a bearing trace of the between s_aid transmission line and said antenna signal energy received from said antenna means means a selected one of said channels of said re ceiver means corresponding to the selected signal oriented with the compass position thereof` re characteristic, heterodyning means associated 25 gardless of the frequency of the received signal. 6. In a radio direction finder system having an’ with said receiver means for imposing on said transmission line the voice frequencies of said sig- y antenna station and a remotely located control nals and a beat note 0f substantially constant fre station connectedby a transmission line, the com quency regardless of the selected receiver chan bination of rotatable directional antenna means nel tuning, indexing means at said antenna sta 30 at said antenna station including a plurality of tion for imposing on said transmission line index-' antenna elements adapted to be selectively con ing signals differing in frequency from said con nected in different circuit relations with eachv trol signal frequency and said beat note fre other, receiver means at said antenna station quency, said indexing signals reflecting the com having an output circuit connected to said trans pass position of said antenna means, recording 35 mission line, indexing signal means controlled means at‘said control station having a plurality'of by rotation of said antenna for imposing on the energizable tracing elements, monitor means at antenna end of said transmission line signals of said control station responsive to voice frequen predetermined signal frequency, motor means for cies, and filter means connected to the control rotating said antenna, a plurality of control station end of said transmission line for rejecting 40 means at said antenna station for controlling from said monitor means said indexing, signal and said antenna circuit connections, for connecting beat note frequencies, for rendering one element said receiver means to said antenna means and of said recording means responsive only to said for controlling said motor means, a source of beat note frequency and for rendering another signal frequency at said control station, signal element thereof responsive only to said indexing means at said control station for selectively con signal frequency, whereby signals picked up by necting said source to said transmission line to said antenna means may be monitored and bear impose thereon signals of different characteristics ' ing traces of the signal energy received from said separately to effect operation of said antenna antenna means may be produced at said control control means, said receiver control means and station regardless of the frequency of the received 50 said motor control means at said antenna station, tuned receiver channels. signal and oriented with the compass position of ' said antenna means. 5. In a radio direction finder system having and means at said control station jointly con trolled by said indexing means and said Yreceiver means at said antenna station and by said signal means at said control station for determining the trol station connected by a transmission line, the 55 compass bearing of radio frequency signals picked combination of rotatable directional antenna up by said antenna meansV during rotation means at said antenna station, radio receiver thereof. means at said antenna station including a plu 7. In a radio direction finder system having an rality of channels respectively tuned to receive antenna station and a remotely located control signals of different preselected frequencies picked 60 station connected by a transmission line, the com up by said antenna means, means ’at said control bination of rotatable directional antenna means station for selectively imposing on said trans at said antenna station including a plurality of mission line control signals of a predetermined antenna elements adapted to be selectively con frequency having preselected characteristics, nected in different circuit relations with each means at said antenna station responsive to said other, receiver means at said antenna station control signals for selectively connecting between having an output circuit connected to said trans said transmission line and said antenna meansmission line, indexing signal means controlled a selected one of said channels of said receiver by rotation of said antenna for imposing on the means corresponding to the selected signal char antenna end of said transmission line signals of acteristic, heterodyning means associated with predetermined signal frequency, motor means for said receiver means for imposing on said trans rotating said antenna, a plurality of control mission line an output beat note of substantially , means at said antenna station for controlling said an antenna station and a remotely located con constant frequency'regardless of the selected re- Y ceiver channel tuning, motor means at said an antenna circuit connections, for connecting saidÍ receivermeans to said antenna means and for tenna station for rotating said antenna means, 75 controlling said motor means, a source of signal 2,406,637 17 frequency at said control station, signal means 18 of said source at said control station, monitor at said control station for selectively connecting means connected to one of said channels for re said source to said transmission line to impose thereon signals of different characteristics sep arately to effect operation of said antenna con trol means, said receiver control means and said motor control means at said antenna station, filter means at said control station for dividing into separate channels said indexing signal fre quency and the output signal frequency of said ceiving said voice frequencies, and means :at said control station energizable from said output beat receiver means transmitted over said transmis sion line and for rejecting from said channels the signal frequency of said source at said control station, and means at said control station ener gizable by said output signal frequency and said indexing signal frequency for recording a bearing trace of said output signal frequency during rota not@ frequency channel and said indexing signal frequency channel for recording a bearing trace of said output signal frequency during rotation of said antenna means and orienting said trace relative to the compass position of said antenna means. 9. In a radio direction ñnder system having an antenna station and a remotely located control station connected by a transmission line, the combination of rotatable directional antenna means at said antenna station including a plu rality of antenna elements adapted to be selec tively connected in different circuit relations With each other, receiver means at said antenna sta tion having an output circuit connected to said antenna means. 20 transmission line, indexing signal means con trolled by rotation of said antenna for imposing 8. In a radio direction finder system having an on the antenna end of said transmission line sig antenna station and a remotely located control nals of predetermined signal frequency, motor station connected by a transmission line, the corn means for rotating said antenna, a plurality of bination of rotatable directional antenna means at said antenna station including -a plurality of NJ on control means at said antenna station for con antenna elements adapted to be selectively con trolling said antenna circuit connections, for con necting said receiver means to said antenna means nected in diiîerent circuit relations with each other, receiver means at said antenna station and for controlling said motor means, a source having an output circuit connected to said trans of signal frequency at said control station, signal mission line for imposing thereon voice frequen- f means at said control station for selectively con cies including a substantially constant beat note necting said source to said transmission line to tion of said antenna means and orienting said trace relative to the compass position of said frequency, indexing signal means controlled by impose thereon signals of different characteristics rotation of said antenna for imposing on the at said antenna station for controlling said an separately to eiTect operation of said antenna con trol means, said receiver control means and said motor control means at said antenna station, recording means at said control station having a, movable recording surface and a plurality of tenna circuit connections, for connecting said tracing elements, ñlter means at said control sta antenna end of said transmission line signals of predetermined frequency, motor means for rotating said antenna, a plurality of control means receiver means to said antenna means and for tion for rendering one tracing element responsive controlling said motor means, a source of signal 40 only to the output signal frequency of said re frequency at said control station, signal means at said control station for selectively connecting said source to said transmission line to impose thereon signals of different characteristics sep arately to eñ‘ect operation of said antenna con ceiver and another tracing element responsive only to said indexing signal frequency, and means initially rendered effective by a signal of said in dexing frequency for driving said recording sur trol means, said receiver control means and said face in synchronism with the rotation of said antenna means to produce at said control sta motor control means at said antenna station, filter means at said control station for dividing tion a bearing trace of said receiver output fre into separate channels said indexing signal fre quency, the output beat note frequency of said receiver means and the voice frequencies trans mitted over said transmission line and for re jecting from said channels the signal frequency quency during rotation of said antenna means and to orient said trace with the compass posi tion of said antenna means. PETER C. SANDRETTO. ELMER. P. BUCKTHAL.