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Dee 17, 1946. 2,412,631 Q w_ R|¢E HIGH‘ FREQUENCY APPARATUS Filed April 9, 1936 4 Sheets-Sheet 1 .$ . 3 mm 85%OFEH38 \ u / R l ,an?s KPFEIWZ<¢ _ m . A a A 3 a m ,=R Nu “w w“ n \ ~rm, w“ E E a“ g a \ LA / , v G k E v a a Inventor": ' Chester-W Ric, His ttor'neg. Dec. 17, 1946. . c. w. RICE ‘ 2,412,631 HIGH FREQUENCY APPARATUS Filed April 9, 1936 4 Sheets-Sheet 2 Fig. 2. ma ‘ 70o LATOB 99 souncz OF PosnR/e POTENTIAL . ‘Inventor-z , Chester- W. Rice, Attorneg. Dec. 17, 1946. 2,412,631 'c. w. RICE HIGH FREQUENCY APPARATUS Filed April 9, 1956 4 Sheets-Sheet 3 L-------_-_----%---_--f--J 17, 1946. c. w. RICE ' ' 2,412,631 HIGH FREQUENCY APPARATUS Filed ‘April 9, 1936 1,6" O~~ QLPT/M ‘~1571': L1 d1 5 54 I d: Tlm: ~ ._, d:_ @ a ~ 4 Sheets-Sheet 4 Q &@ 3 § ' A 5/2- 3% \\l , _ l; I; I Figs‘ E 8 _ Fr 7 o 8 7 '95‘ a _ 4’ _; 3 HAL d, - ia a L :1: TIME 2 ;_ d: ‘a,’ 3 - E z .13, _ F538. '0 “ I LI g I bl I L- I I , I 0L1—--—-1_"——‘T— l 0 ’ / 2 . a 4 5 "6 DISTANCE 0!’ 951cm- _ Inventor“: Chester‘ ' Rice, b9 WW ~ m is Attorney: 2,412,631 Patented Dec. 17, PATENT orriea I UNITED s'r 2,412,631 ' HIGH-FREQUENCY APPARATUS Chester W. Rice, Schenectady, N. Y., assignor to General Electric Com pany', a corporation of New York Application April 9, 1936, Serial No. 13,511 as Claims. i . (01. 250-1) ' 2 face upon which the wave impinges which are large relative to the wave length employed, the apparatus and one of its objects is to provide an resulting wave travels in directions dependent improved method and means for obtaining in upon the orientation of the irregularities. formation as to the position and motion of an Waves of very short wave length, such as I object with respect to a .single observation point. contemplate to employ, when impinging upon a It is a further object of my invention to pro distant irregular surface are known to scatter vide an improved method and means for locat in all directions about the point of impingement ing an object by determining its bearing and range in accordance with a cosine law. Accordingly, from a single observation point. It is a further object of my'invention to pro 10 a substantial portion of the scattered energy re turns in the direction from which it came. These ‘vide an improved method and means for deter waves further maybe short relative to any irregu mining the line of sight velocity and direction of larities which exist in objects of the kind to be motion along the line of sight of an object from located or observed thereby increasing the energy a single observation point. It is a further object of my invention to pro [15 likely to return toward the observer. The scat tering of high frequency energy after impinge-' vide a novel method for obtaining an echo from ment upon a distant surface increases rapidly a distant surface. with frequency. Accordingly it is important that In accordance with my invention a high fre extremely short wave lengths be employed. I quency radio wave is employed in ascertaining desired information with reference to the posi 20 have obtained extremely satisfactory results with waves having a length of 4.8 centimeters. tion, motion, etc. of a distant object, the high fre These wavelengths are advantageous in the quency wave being transmitted toward the distant location, and observation of the movement of dis- , object and its echo being received and utilized tant objects, such as moving craft, for example, to produce the desired indication. One of the objects of my invention is to effect certain im 25 since such craft possess surfaces small relative to a wavelength, which are disposed at diverse provements in equipment employed for such pur angles with respect to the direction of propaga poses whereby positive indication of the position tion of such waves, and which, therefore, effec of an object, its motion, velocity, etc. may be tively scatter such radiation. Such surfaces may obtained notwithstanding that the object is of relatively small dimensions and is located at a 30 comprise the rails, lattice work or mesh about the decks of a vessel, pipes, or chairs upon the decks, great distance from the observation point. or portions of the propellers, wheels, chassis, In accordance with my invention radio waves struts, etc. of aircraft. At the same time such of extremely short wave lengths are employed. craft also possess numerous plane, or nearly plane, Important advantages may be secured by the use of such waves,v ?rst because they may conven 35 or curve surfaces of large radius of curvature, having dimensions large relative to a wavelength. iently be directed against the desired object, and My invention relates to high frequency radio effectively received after impingement thereon, and secondly, because their behavior after im pingement upon the desired object lends itself advantageously to securing a resultant echo in the direction from which the waves arrive at the , Any such surface disposed at right angles to the direction of propagation of waves impinging on it reradiates said waves with a directivity pat tern which is bisected by the direction of prop agation of the impinging waves. This reradia tion is highly directive if the surface has effec tive lateral dimensions of from ?ve to ten times the wavelength in the direction from which the surface. That is, for example, in accordance with the laws of re?ection the angle of incidence equals the angle of re?ection. Accordingly, "if it be assumed that the wave employed follows the laws 45 waves are received and thus is very effective in the production of echoes. Of course, this direc of re?ection and the transmitted wave impinges tivity is reduced if the surface be of smaller di upon a plane surface oblique to the direction of mensions, the small surfaces tending as above, to propagation of the wave little or no energy returns scatter the radiation. in the direction from which it came, but instead While I have mentioned wavelengths of 4.8 practically all of the impinging energy travels in 50 centimeters, it will be understood that I am not a direction determined by the angles of incidence to be limited thereto'since these effects may be and .re?ection. Accordingly, no satisfactory in produced by waves of diiferent length in this dication may be obtained at the transmitting order. The 'wave length preferably, however, point. , , Of course, if there be irregularities in the sur 55 should not be less than two centimeters since for 9,412,081 . 3 . shorter waves appreciable undesired scattering may be produced by the surfaces of raindrops that direction after being scattered by adis tant object. Transmitter l and receiver 2 are or hailstones. At the same time I prefer to use waves of not more than eight centimeters in length since with such waves surfaces, on mov supported upon a shaft 4 which is arranged for . motion longitudinally of itself through a bearing ing craft, for example, having dimensions suf? ciently large relative to a wavelength to produce sharply directive reradiation of energy impinging lated in the direction in which waves are propa member [whereby the equipment may be oscil gated and received, for a purpose which will presently be described. ‘ ' - thereon, are more numerous, and hence are more A vertical shaft 8, upon which is mounted the likely to improve the echoes received. Such sur 10 bearing member 5, is rotatably mounted on base faces may be highly important especially in the 3 through a ball thrust and guide bearing ‘I at detection or observation of aircraft. the top and by a guide bearing 8 at the bottom. When employing waves of such wave length, ap Ball thrust and guide bearing 1 comprises a bear paratus may be employed which is small in dimen ing plate 9 which forms the top of base 3, a shoul sions and which at the same time is capable of 15 der III which constitutes the under surface of efficiently directing the wave toward the desired bearing block 5 and a plurality of ball bearings ll object, and of receiving such waves only from a placed therebetween. particular direction as from the desired object. Some suitable means for obtaining rotary mo? Such apparatus may be mounted, for example, on tion of the radio apparatus about the base is pro moving craft without objectionable encumber~ 20 vided such as an electric motor l2 mounted on ment and at the same time be capable of directing the inner wall of base 3. As illustrated, the drive a sharp beam of short radio waves over relatively mechanism therefor comprises a small pinion gear great distances. and obtain a satisfactory indi l3 mounted on drive shaft l2’ of motor l2 which cation therefrom. It is to be understood that the term “radio echo” 25 meshes with a gear l4 mounted on shaft 6. The electric supply and control circuit of motor I2 is as used herein refers not only to a true echo as omitted from the ‘drawing for the purpose of sim may be obtained by propagating a high frequency plicity but it will be understood that shaft 6 may impulse and causing a portion of the impulse to be continuously rotated or it may be moved from be reflected to the transmitting point but also to one angular position to another at the will of the any continuous wave whether modulated or not operator. . ' that may be propagated, scattered by an object Oscillatory motion of the radio echo apparatus and a portion returned to the transmitting point. in the direction of propagation of waves on which Similarly, the term “scattered radiation," when it operates is provided by mounting a motor IS employed herein with reference to the wave which on top of bearing member 5. Motor i5 drives a returns from a distant object to the receiver of crank gear "3 which oscillates shaft 4 by means my equipment, applies to all of the energy return of connecting rod H. For purposes of simplicity ing to the receiver irrespective of the cause of its the electric supply and control circuit of motor return, or whether it be due to scattering from i5 is not illustrated but it will be understood that the surface of the distant object, re?ection, or otherwise. 40 motor l5 may run at the will of the operator. A counterweight I8 is secured to one end of The novel features which I believe to be char shaft 4 to counterbalance the weight of transmit~ acterized of my invention are set forth with par ter l and receiver 2 across the bearing 5. ticuiarity in the appended claims. My invention ‘ itself, however, both as to its arrangement and method of operation together with further ob Jects and advantages thereof may best be under stood by reference to the following description taken in connection with the accompanying draw ings in which Fig. 1 illustrates apparatus embody ing my invention. Figs. 2 and 3 show diagram matically electrical circuits which may be em ployed with the apparatus of Fig. 1. Fig. 4 shows diagrammatically the apparatus mounted on a ship for the purpose of determining the bearing of objects in the vicinity and Fig. 5 shows the bear ing indicator screen. Figs. 6. 7, 8 and 9 are dia grams illustrating the operating characteristics Transmitter l and receiver 2 are mounted in a frame 19 which is pivotally supported in a yoke 20 carried by shaft 4. Clamp 2i maintains the apparatus at the desired angle with respect to the vertical. By loosening clamp 2| and rotating frame!!! about its axis the direction in which radio waves are transmitted and received may be varied in a vertical plane. Transmitter I may be of any suitable design which is capable of propagating a highly direc tional high frequency beam of radio waves and 55 preferably a beam of radio waves having a wave length of only a few centimeters. One form of transmitting apparatus which has been found ‘ to give highly satisfactory results is described in my copending application, Serial No. 61,377, ?led mounted on two vessels and arranged so that each 60 January 29, 1936, and assigned to the same as ‘signee as the present application. For purposes apparatus may distinguish between direct and of simplicity the detailed construction of the scattered radiation. transmitting apparatus is not illustrated but it Referring to Fig. 1 of the drawings, I have will be understood that the high frequency gen shown therein a radio echo apparatus which com erating apparatus is housed in compartment 22 prises a high frequency transmitter I of the type which is supported on frame l9 below the radio .which is adapted to transmit a beam of extremely beacon 23. Radio beacon 23 comprises a para short radio waves in the direction indicated by bolic metal reflector 24 and a cylindrical metal the arrow, and a receiver 2 which is adapted to sleeve 25. The radiating member of transmit receive such waves after they have been scattered of the timing apparatus illustrated in Fig. 1. Fig. 10 diagrammatically illustrates apparatus or re?ected from a distant object. The trans 70 ter I (not shown in Fig. 1) is located at the mitter and receiver are mounted upon a base 3 focus of parabolic reflector 24 to give the ap and arranged for rotation around this base. In paratus the desired directive properties. .A small monitor receiver 26, whose function short wave impulses may be transmitted in any will hereinafter be described, is mounted in front direction from the equipment and received from 75 of beacon 23. The control apparatus for moni consequence thereof, a beam of short waves or 2,419,681 tor receiver 26 is housed in compartment 21 lo cated at the rear of beacon 23. ’ 2 ‘may be e?ected by any suitable system ca pable of transmitting angular movements such ceiving a high frequency radio wave from a sin- . as by a transmitting device 58 and a reproduc ing device 59 which are similar in construc tion and are each provided with a polycircuit gle direction. One form of receiver which has been found to give highly satisfactory results is armature winding and a single circuit ?eld wind ing. When the polycircuit armature winding of Receiver 2 of the radio echo apparatus may be of any suitable design which is capable of re each device is physically similar to a three-phase Y or A connected armature winding, transmitting the same assignee as the present application. 10 device 58 and reproducing‘ device\5ii, are con nected together by three conductors 60, 6| and . For purposes of simplicity the structural details 62 to like points on ‘their respective ‘armature of receiver 2 are not illustrated but it will be _ windings. The ?eld windings are connected to understood that the required high frequency ap a suitable source of alternating current supply. paratus is located within radio beacon 28. Beacon 28 comprises a parabolic metal re?ector 29 and 15 The field windings induce alternating electro motive forces in their respective armature wind a cylindrical metal sleeve 30. ' The antenna mem ings the relative value of these electromotive ber of the receiving apparatus (not shown in - described in my copending application, Serial No. 61,378, ?led January 29, 1936, and assigned to Fig. 1) is located at the focus of parabolic re?ec- ‘ forces depending upon the angular relation be- ‘ tween the ?eld and armature windings. When tor 29 in order to give the apparatus the de sired directive properties. The control appara 20 the rotors of the transmitting device and the re producing device are in angular agreement, the tus of receiver 2 is housed within compartment electrotive forces induced in the two armature 3| located at the rear of beacon 28. windings are nearly opposite and hence no cur A pair of small metal re?ectors 32 and 33 are mounted in front of transmitter I and receiver 2 on an adjustable rod 34. Re?ectors 32 and 33 are disposed at a 45° angle with respect to the rent is produced in the armature circuit. How ever, when the transmitting device is turned and direction of propagation and reception whereby longer exists so that currents are caused to ?ow in the armature circuit and a torque is thereby a small portion of the propagated wave is di rectly passed to receiver 2 from transmitter I. The phase, of course, of this transferred portion 30 of the propagated wave depends upon the length of path traveled. Hence, the phase of this por tion may be regulated by adjusting rod 36. In" order that intensity may also be controlled some suitable intensity control means, such as a metal\\ iris diaphragm 35 is disposed in the path of the ‘ directly re?ected wave between re?ector 32 and _ re?ector 33. Since the radio echo apparatus is designed to held in a new position, this voltage balance no exerted upon the rotor of the reproducing device, which torque turns it to a position in which the voltages are again balanced when the rotors are again in angular agreement. Defiecting coils 56 and 51 are mounted upon a yoke 63 which is disposed about cathode ray tube 54 and is carried by the rotor of reproduc ing device 59. Coils 56 and 5? are electrically connected to the apparatus associated with receiver 2 which is housed in compartment 3i" through cable 66, slip be rotated about the vertical axis of shaft 6, 40 rings 36 and 31, conductors 65 and 66, switch 61, and slip rings 68 and 69. As will presently be the various power supply circuits for transmit explained, the apparatus in compartment 3! ter 1 and receiver .‘ and the output circuits of ampli?es the detected radio wave a sumcient receiver 2 and monitor receiver 26 are brought amount to cause coils 56 and 51 to affect the de out through a plurality‘of slip rings 36, 3?, 38, sired change in the electron path in cathode ray 39, 40, 4|, 62,143, 66 and 45. tube 5%. When water cooling is necessary for the high After an object has been detected and its bear frequency generating apparatus housed in com ing determined by the radio echo apparatus, it is partment 22, it may be supplied from a supply often desirable to determine accurately its range. pipe 46 to a channel ring Ill in the base of the _ One method of determining the range of an ob apparatus and thence through a passage 48 in ject is to‘transmit a sharp high frequency radio shaft 6 and ?nally through a ?exible conduit 69 to the high frequency generating apparatus. The impulse and measure the time it takes the im pulse to travel to the object and return. cooling water is conveyed away from the generat One form of timing circuit for effecting this ing apparatus through a ?exible conduit 58, a passage 5| in shaft 6, a collecting basin 52 in > measurement is indicated in the drawings and base 3 and out through conduit 53. comprises two electron discharge devices ‘i0 and The bearing or angular position of any object ‘H. The anode of discharge device '10 is con- ' nected through a potentiometer ‘i2, and a cur detected by the radio echo apparatus is obtained by providing an instantaneous indication of the rent indicating device ‘I3 to a suitable source of direction of propagation and reception of the ap 60 positive potential. The anode of discharge device paratus, whenever scattered radiation is detected ‘H is similarly connected through a resistor ‘I4 by receiver 2._ Any suitable indicating means may be used, such for example, as a cathode ray tube 54 of the type which normally provides and a current indicating device 15 to the same ' source of positive potential. The cathodes of dis- . charge devices 10 and ‘H are connected together a continuous circular trace on its ?uorescent for 65 and to the negative side of the above potential phosphorescent screen 55. A pair of coils 56 and 51 are mounted for rotation about the elongated portion of cathode ray tube 54 and are adapted to superimpose a magnetic de?ecting force upon the stream of electrons as the electrons pass through the length of the tube. Coils 56 and 57 are caused to rotate around cathode ray tube 54 synchronously with the rotational motion of receiver 2 around base 3. The desired synchro nization of motion of coils 56 and 51 with receiver 75 The grid of discharge device 10 is con nected-through battery 16 to the plate of dis-. charge device ‘H. The grid of discharge de vice ‘H is connected to the plate of discharge source. device 10, through potentiometer ‘l2, movable contact ‘H of potentiometer 1!, battery 18 and resistor 19. The grids and cathodes of dis-' charge devices 10 and 1i are connected to the apparatus associated with receiver 2 and trans mitter I, respectively. 9,412,031 I 7 i It a negative impulse be impressed on the grid charge device 82 comprising a long cylindrical ‘of discharge device ‘II each time a sharp high metal anode 88 and a relatively short axial ?la frequency impulse is propagated from transmitter ment 84. Dischargedevice 82 is housed almost I and if a negative impulse be impressed on the entirely within axial apertures of two truncated grid of discharge device 18 each time the re?ected 5 conical pole pieces 88 and 88 which are secured impulse is detected by receiver 2, the average plate to the ends of permanent magnet 8|, thereby current flowing through either discharge device causing an intense axial magnetic field to be pro will be‘a function of the range of the object which duced about the discharge device. ‘ causes scattering or re?ection of the transmitted Filament 84 is maintained at the desired tem impulse. The negative impulse derived from the 10 perature for electron emission by a source of po propagated high frequency wave is obtained from tential 81 and a variable resistor 88. a small monitor receiver 28 and its associated ap Anode 88 is maintained at ground potential for paratus housed in compartment 21 through cable high frequency oscillations and is energized with 88, slip rings 88 and 88, conductors 8I and 82- and positive operating potential through a switch 88 ' switch 83 as will hereinafter be more fully de 15 from a suitable source I88. Filament 84 in con ; scribed in connection with Fig. 2. The negative sequence thereof oscillates at an extremely high impulse derived from the received re?ected im frequency and the oscillations produced thereon pulse is similarly obtained from the apparatus housed in compartment 8i through cable 84, slip are supplied to a suitable radiating member I8I. rings 38 and 31, conductors 85 and 88, and switch 20 Means for modulating the high frequency oscil lations is indicated conventionally by rectangle 88. I82, and is adapted to be placed in operation by In my copending ‘application, Serial No. 73,512, connecting it in the high potential supply line ?led April 9, 1936, and assigned to the same as by moving switch I88 to its lower position. For signee as the present application, a method is de scribed and claimed for determining the relative 25 reasons of simplicity the details of my oscilla tion generator are not shown in the drawings. velocities of two bodies. In that application a When the oscillation generator is being used as highly directional high frequency continuous part of a radio echo apparatus for the accurate radio wave is propagated from one body toward determination of the range of a distant object, the other and the difference in frequency between theoscillation generator must be arranged to the transmitted wave and received wave which 30 generate periodic high frequency impulses having comes back to the ?rst body after being scattered a duration preferably of the order of one micro, by the second body is determined. The fact that second. Any suitable means for obtaining im there is a difference in frequency between the pulses from the oscillation generator of Fig. 2 outgoing and returning wave is due to the relative motion between the two bodies. According to 35 may be used. By way of example, I have illustrated a relaxa DOppler’s principle the difference in frequency be tion oscillator, which periodically supplies a tween the transmitted and received wave is a sharp high potential impulse to anode 83 of the function of the relative velocity of the two bodies. oscillation generator. The oscillating-circuit in The method of determining the difference in fre quency between the transmitted and received 40 cludes an electron discharge device I84 of the type which has an ionizable medium thereini. wave as described in the above referred to co The anode I85 of discharge device I84 is connect-v pending application comprises beating the re ed to the positive side of a suitable high potential ceived wave with a portion of the transmitted wave. direct current source through a resistor I88 and In Fig. 1 of the drawings I have indicated at 84 a beat frequency responsive device, mounted on bearing member 5. This device is connected to the receiver 2 through a switch 85,’ cable 86, and cable 84. A portion of the high frequency wave propa gated from transmitter I and re?ected into re ceiver 2 by re?ectors 32 and 33 is caused to beat with the detected scattered radiation. It will be understood that beat frequency responsive device the primary winding I81 of the load transformer I88. Cathode I89 of discharge device I84 is con nected to the negative side of the potential source through a variable charging resistor II8. A po tentiometer III is connected across the potential source and the movable contact III’ of poten tiometer II I is connected to grid I I2 of discharge device I84 through a resistor H8. The energy storing condenser N4 of the impulse generator is connected between the positive side of the po tential source and cathode I88. , 84 may be calibrated directly in miles per hour. The upper side of secondary winding H5 is Although the velocity of a moving object along ‘ the line of sight from the object to the receiving connected to anode 83 of the oscillation generat ing while the lower side of winding I I5 is ground equipment may be determined from the beat fre- > quency responsive device 84, it is impossible by ed. A damping resistor I I6 is connected in shunt this method alone to determine whether the ob 60 across secondary winding H5. The inductance value of winding H5 is so chosen that the inher ject is moving away from the observer or coming towards him. By providing a pointer 81 on the ent capacity of the magnetron (as indicated by .\portion of the apparatus which is adapted to be » the dotted lines) together with winding II5 have oscillated by motor I5 and by securing a scale a period substantially the same as the period of 88 on bearing member 5, a means for determining the primary circuit. the direction of motion along the line of sight is Since the value of the average plate current provided. which ?ows in thedirect current back-coupled In Fig. 2 of the drawings, I have illustrated dia circuit shown in Fig‘. 1 varies inversely as the time grammatically the electrical circuits associated between impulses, it is desirable to have the pe with transmitter I. The oscillation generator riod of the relaxation oscillator (i. e., the time be shown therein is described in detailv and claimed tween impulses) as low as possible. This period, in my copending application, Serial No. 61,377, of course, varies as a function of the value of re ?ied January 29, 1936, and assigned to the same sistance in resistor H8 and the capacitance of assignee as the present application and includes condenser II4. The lower limit is governed. a permanent magnet 8I and an electron dis 75 largely by- the deionization time of electron dis 9,419,681 . one no is given a negative bias with respect to charge. device I06. The time between impulses cathode I68 through battery I12 and resistor I13. is generally 4 or 5 times this deionization time. Anode "I is connected to a suitable source of Since it is also desirable to render the impulse . potential through resistor I16. The output of ble (preferably of the order of 1 micro second), 5‘ amplifier I66 is taken from across resistor I14 propagated from transmitter I as short as possi through blocking condensers I15 and I16. The number of stages of ampli?cation is chosen such that a negative impulse derived in the output cir cuit of the amplifier for the timing circuit of the the discharge of condenser II6 should have a steep wave front and be highly damped. 7 With-" this type of discharge only the ?rst wave is of suf ?cient intensity to raiseanode 83 of the mag netron to its operating potential. - 10 range indicator. ‘ Serial No. 61,378, ?led January 29, 1936, and as- ' The lower portion of Fig. 3 shows the timing circuit for the range indicator, the de?ecting coils 58 and 51 of the bearing indicator, and the beat frequency responsive device 84 of the velocity indicator. This portion of the circuit of Fig. 3 has already been described in connection with signed to the same assignee as the present appli Fig. 1. In Fig. 3 of the drawings. I have illustrated dia grammatically the electrical circuits associated with receiver 2 and monitor receiver 26. The re ceivers illustrated therein are of the type de scribed and claimed in my cope'nding application; / The e?ect of the above described apparatus cation. Receiver 2 as shown comprises an elec when being used as a means for determining tron discharge device I2I having a U-shaped ?l ament I22. a linear grid electrode I23 and a plate electrode I25. Along side tube I25 with a getter bulb 926 at the bottom is provided to take care of the occluded gases of the device in the conven tional manner. The ?lament, grid, and plate leads I21, I28, and I29 are each provided with the bearing of an object with respect to an obser vation point is emphasized in Figs. 4 and 5 of the drawings. Fig. 4 illustrates a ship I8I upon which the apparatus has been mounted. Two objects I82 and I86 are shown as being within the horizon and hence cause scattered radiation when the radio beam from transmitter I impinges on them. Object I82 is illustrated as another ship while object I83 is illustrated as an island. Fig. 5 is a plan view of the screen 55 of cathode ray tube 56. The circle I84 normally traced on screen 55 by the electron beam within the tube is an electrical tuning means such as metal disks I30, I3I and I32, respectively. Grid electrode I23 is given a positive bias with respect to ?la ment I22 by 1a suitable source of potential I83 through potentiometer I36 and resistor~l35. A second source of potential I36 supplies the ?la bent in at I85 due to the presenceof ship I82. The bearing of ship I82 indicated by the angle x is clearly indicated On screen 55 by the depression I85. The normal circle I86 is also bent in at ment current necessary to heat ?lament I22 to its desired electron emission point through variable resistor I31. Plate electrode I26 may either be ' maintained at ?lament potential or given a nega tive bias by battery I38 through potentiometer I86 as a result of the scattered radiation caused I39. .' Receiver 26 is similar to receiver 2 and in by island I88 and its bearing is indicated by angle B. Since the structure of ship I8I to the rear of its own radio echo apparatus also causes scat cludes an electron discharge device I66 whose ?lament, grid, and plate leads IAI, I82, and I63 40 tered radiation, circle I86 is bent at a bearing corresponding‘ to the ‘position of the structure as and are provided with suitable electrical tuning at I 81. It should be noted that the farther away means use, I55, and I66 respectively. Suitable objects of a given size are from the observation potential sources M1, I68, and I69 are provided point, the narrower will be the marking trace for the ?lament grid and plate electrodes (not shown) of discharge device I40, A variable re on screen 55. - The operation of my echo apparatus when used for the purpose of obtaining useful information as to the position and motion of an object from a single observation point will now be described. sistor 150 connected in the ?lament supply cir cuit controls the ?ow of ?lament current while potentiometers I5I and I52 regulate the poten tial bias on the grid and plate electrodes. respec tively. A resistor I53 is also connected in the 50 Let us assume that the apparatus is mounted on board ship I8I. Switch 98 (Fig. 2) is thrown grid circuit. . ' Receiver 2 is resistance coupled by resistor I85 ' to its upper position thusv connecting the high voltage source I08 to anode 93 of electron dis ‘and capacitor I56 to an ampli?er I55 which in charge device 92 and switch I08 is closed in its cludes one or more stages. For purposes of sim plicity, only one stage of ampli?cation is illus 55 lower position, thereby connecting'modulating trated and it includes an electron'discharge de means I02 to the high voltage supply source I00. vice I56 having a cathode I51, a grid I58, and an anode I59. Grid I58 is given a negative bias with respect to cathode I51 through battery I68 As a result, a high frequency modulated radio beam is propagated from transmitter I. Cathode ray tube 55 and its associated apparatus is con and resistor I6I. Anode I59 is connected to a 60 nected to receiver 2 upon closure of switch 61 (Fig. 3). Motor I2 is energized and as a result suitable source of high potential through a re-_ transmitter I and receiver 2 are rotated in a sistor I62. The output of'the ampli?er I55 is horizontal plane, thereby causing the echo appa taken from across resistor I62 through blocking ratus to scan the horizon for the presence of condensers I63 and I66. Since the polarity of the . output depends upon whether there is an odd 65 objects. If, for example, a ship I82 and an island I83 or even number of stages of ampli?cation, the I be within the operating range of the echo ap proper number is selected to obtain a negative paratus, scattered radiation occurs each time the impulse when receiver 2 is connected to the tim high frequency radio beam impinges on the ship ing circuit of the range indicator. Receiver 26 is similarly coupled to an ampli?er 70 and on the island. A portion of the scattered radiation is detected by receiver 2 and the de I66 by resistor I53 and capacitor I61. Ampli?er I56 may contain any number of stages ‘for pur poses of simplicity, only one stage is shown which includes an electron discharge device I68 hav modulated wave, ampli?ed by amplifier I55, ener gizes de?ecting coils 56' and 51, thereby causing depressions I85 and I86 in the normally circular ing a cathode I69, a grid I10 and an anode HI. 75 trace made on screen 55 of cathode ray tube 54. 2,412,681 ' 11 It will of course be understood that if there is no detector action in the last stage of ampli?er I55, the deflections will extend in both directions from the normal trace (as is indicated by the dotted lines in Fig. 5) since the polarity of coils 56 and 51 would then be reversing at modulating fre quency. Since de?ecting coils 56 and 51 follow the angular motion of transmitter I and receiver 2 due to the‘angle transmitting devices 58 and - 12 cathode I09 is more positive than anode I05 (i. e., the anode is negative with respect to the cath ode). Since current cannot pass from the cath ode to the anode of the discharge device due to its rectifying property, this condition exists until ' the condenser H4 ‘is recharged in its original di rection through resistance I I0. It should be noted that in this type of impulse generator which uses a potentiometer across the 59, the bearing of ship I02 and the bearing of 10 high potential source in order to supply the de island I03 are given by the angularposition at sired grid bias that ?uctuations of the potential which the de?ections I85 and I86 respectively source cause very little error in the impulsing occur on screen 55. Since the intensity of scat time of the generator. ' tered radiation as detected by receiver 2 is rough The sharp impulses generated by the relaxa ly proportional to the distance at which the ob 15 tion oscillator are supplied through secondary ject is from the observation point, the approxi winding I I5 of the load transformer I08 to anode mate range of ship I02 and island I83 may be 03 of the oscillation generator of transmitter I. vobtained by noting the amplitude of the respec In consequence thereof, a series of high frequency tive de?ections on screen 55. sharp impulses are propagated from transmit If the distant object is in motion, the bearing 20 ter I. indicator may also be operated by placing switch At the instant when a high frequency impulse I03 in its upper position so that an unmodulated is sent out from transmitter I electron discharge continuous wave is transmitted from transmitter device ‘II is biased substantially to cut-oil’ and I and by adjusting diaphragm 35 (Fig. 1) so that a portion of the transmitted wave beats with the received wave. The resulting beat frequency is then used in the same manner as the demodu lated wave previously described to energize the de?ecting coils 56 and 57. Let us now assume that it is desired to deter mine accurately the range of ship I02. Motor I2 is deenergized and the echo apparatus is directed toward ship I 82. Switch 67 is opened and switch 83 is closed, thereby connecting the timing cir electron discharge device ‘I0 is biased to pass its maximum value of plate vcurrent. During the time the impulseis traveling to the object and returning, discharge devices ‘I0 and "II remain in this condition. The instant scattered radiation is detected by receiver 2, the bias on discharge device ‘I0 is changed due to the negative im pulse impressed on the grid of that device from receiver 2. As a result, the current ?ow in the plate circuit of discharge device ‘I0 drops sub ’ stantially to zero. same instant the bias cuit to receiver 2 and monitor receiver 26. Switch 35 on discharge deviceAtIIthe is changed through its ' 99 is thrown to its lower position thereby con necting the-relaxation oscillator to anode 93 of electron discharge device 92. grid coupling circuit due to the fact that there ' is no longer a potential drop across resistor ‘I2. Hence, the maximum current now ?ows in the The operation of the relaxation oscillator or plate circuit of this device. impulse generator will be described ?rst. Let us 40 The operation of the timing circuit will be assume that the oscillator has Just been con more readily understood by referring to Figs. 6, nected to its source of potential. The cathode 7, and 8 of the drawings. Curve a of the ?gure I09 of discharge device I04 is practically at the indicates the flow of plate current in discharge potential of anode I05 since the charge of con device ‘II and curve b the plate current in dis denser I I4 is zero and grid I I2 is negative by the 45 charge device ‘I0 when no echo is being picked amount of drop between the positive side of po up by the apparatus. The dots d1, dz, d3 indi tentiometer III and movable contact III’. cate' a succession of impulses sent out from trans‘ Therefore, discharge device I04 remains non~con mitter I at intervals determined by the constants ducting while condenser II 4 charges up through . of the relaxation oscillator circuit. resistance I_I0 until the cathode potential of the 50 Let us now assume that an object intercepts discharge device has fallen to such a value that the high frequency impulses being propagated the grid to cathode potential is equal to the from transmitter I at a distance which causes critical grid voltage of the discharge device. At the returning scattered radiation to reach re this moment, the gas within the discharge device ceiver 2 at a time t after each impulse is sent becomes ionized and the condenser discharges out. Such a condition is shown in .Fig. 7 of the through primary winding I01, resistor I06 and drawings. t ‘seconds after impulse d1 is sent discharge device I04. The discharge current out, the returning detected wave triggers the two which passes through discharge device I04 does discharge devices, causing device 1| to draw its not cease at the instant when the'condenser II4 maximum current and causing device ‘I0 to draw becomes discharged due to the inductance of pri 60 its minimum current. This is shown by curves mary winding I01 which causes the condenser to a and b respectively in Fig. 7. ’ ' be charged with the opposite polarity. A cer Discharge device ‘II continues to pass current tain amount of energy is stored up in winding until a succeeding high frequency impulse is sent I01 and as the current diminishes the collapsing out from transmitter I. As the succeeding im ?ux induces an electromotive force which causes 65 pulse is transmitted, monitor receiver 26 detects the current to charge the lower plate of con a portion of the outgoing wave and impresses a denser II4 to a potential greater than that of negative impulse on the grid of discharge device the line. In other words the polarity of the con ‘II. The negative impulse thus impressed on the denser is reversed from its original state. If grid of discharge device ‘II changes the bias to there were no damping in the circuit, the poten 70 cut-o? and current ceases to ?ow in the plate tial on the lower plate of the condenser would ap circuit thereof. As discharge device ‘II stops con proach twice the line voltage minus the drop ducting the grid of discharge device ‘I0 is again across the discharge device when the current given a su?iciently positive bias to cause current' ?nally falls to zero. In consequence thereof, at to ?ow again in the plate circuit of this device. the moment when the current ceases to flow, 75 This condition is clearly illustrated by the curves 9,412,681» i3 - 14 in Fig. '7. As previously explained, the average motion of ship I82 along the line of sight is de plate current ?owing through either discharge - termined. device ‘II and discharge device ‘I0 may be used to determine the elapsed time of the impulse and hence the distance of the object. Assuming that indicating device ‘I5 has been calibrated to read directly in units of distance the range of ship I82 will be indicated thereon. ' It will be understood that once the line of sight velocity, the direction of motion along the line of sight, and the range has been determined, it is a simple matter to determine the actual ve locity and true direction of motion by comput ing the component of motion perpendicular to the line of sight from the angular speed of the ap If it should happen that two echoes are sent» back from a single outgoing impulse, an inspec 10 paratus which is needed to maintain an echo. Knowing the line of sight velocity of the object tion of Fig. 8 will show that only the arrival of and the velocity normal to the line of sight, it the ?rst echo, if su?icie'ntly intense to carry the is a simple matter to compute the true velocity grid of discharge device 18 negativais effective. and direction of the distant object. If the ob-‘ The arrival of the second negative impulse from the more distant echo merely impresses a second 15 servation point is also in motion it is necessary to take into account the velocity and direction of negative impulse on the grid of discharge device 18 which is already negative. Since discharge motion of the observation point. 7 When high frequency echo apparatus is mount device ‘II is already drawing maximum plate cur ed on a number of vessels navigating in the same rent and since discharge device ‘III is already draw ing minimum plate current, the arrival of the 20 vicinity and are operating on the same wave ' .length, it is desirable that apparatus mounted “second echo has no effect on the timing circuit. Fig. 9 is a chart which illustrates the relation on one vessel be able to distinguish between scat- . tered radiation resulting from its own propagated of average plate current in discharge device ‘II wave and the direct radiation coming from ap with respect to the distance of the object. The range and bearing of ship I82 having been 25 paratus mounted on another vessel but pointed toward the first. It has been found that such a determined, the relative velocity of the ship along result may be obtained if each apparatus propa the line of sight may next be determined. By gates a wave po1arized\ at some predetermined opening switch 83 and closing switch 85 in the angle from the vertical. -The nearer this angle receiver circuit and by moving switch 99 to its upper position and moving switch I03 to its up 30 is to 45° the greater will be the discriminating properties of the apparatus, as will presently be ' per position in the transmitter circuit, a high explained. ' frequency continuous wave is propagated from In Fig. 10, I have illustrated diagrammatically transmitter I and a_ portion of the scattered ra two radio echo equipments I and II, which are diation caused by the impingement of the high frequency wave on ship I82 will be detected by 35 mounted, for example, on two ships facing each other and have indicated by suitable vectors their receiver 2. A small portion of the propagated respective planes of polarization. For reasons wave is passed directly‘from transmitter I to re of simplicity, only the transmitter and receiver ceiver 2 by re?ectors 32 and 33. Iris diaphragm of each equipment together with an auxiliary re 35 is opened a sufficient amount to pass a wave ceiver whose function will presently be explained, of the desired intensity. This portion of the transmitted wave is caused to beat with the re ceived detected scattered radiation in discharge are shown in this ?gure. Transmitters T1 and T11 are each adapted topropagate a high frequency radio beam whose 'plane of polarization is at 45° device I2I. The resulting beat oscillation is am to the right of the vertical in the direction of pli?ed by ampli?er I55 and is then passed to frequency responsive device 84.v The difference 45 propagation. This may be. done, for example, by arranging the radiating member of the transmit in frequency between the outgoing and the re ter so that it lies in the plane of the desired ceived Wave depends upon the relative velocity polarization. The plane of polarization of trans of ship I82 along the line of sight and hence the mitter Tr (i. e., the electric field of the radiated velocity may be read directly by properly cali brating beat frequency responsive device 85. Of 50 _ wave) is indicated by vector I89 and that of TH by vector I90. Receiver R1 of apparatus I is‘ course, if the object be standing still no beat fre; polarized by suitably positioning the antenna quency is detected. The direction'of motion of ship I82 along the _ member or members in the same plane as its asso ciated transmitter, as is indicated by vector I9I. line of sight is next determined by energizing mo tor I5. The oscillatory motion of transmitter 55 Receiver R11 is similarly polarized as is indicated by vector I92. Let us now assume that a high i and receiver 2 along the line of sight causes an frequency radio beam is being propagated from oscillation of the pointer on beat frequency re each transmitter. The wave propagated from sponsive device 84 due to the fact that the point transmitter TI ‘is scattered by the vessel on which with reference to which the velocity of the dis tant object is to be determined is no longer sta 60 apparatus II is mounted and a portion of the scat tered radiation will be detected by receiver R1. tionary. If the object, whose direction of motion Since very- short waves are used, the plane of is to be determined, be moving away from the polarization is not changed by the scattering and apparatus a minimum of frequency occurs during hence, the detected scattered radiation will have the forward motion of the apparatus. If the ob ject be moving toward the observer, 2. maximum 65 the‘ same plane of polarization as. that of the of frequency occurs during the forward motion transmitted Wave. Furthermore, since receiver of the apparatus. If the object be standing still R: is a polarized receiver it will not be able to the frequency is the same during each direction detect direct radiation from transmitter Tn since of motion of the apparatus. The presence of the this radiation is polarized at 90° from the plane beat note, in any case, of course, indicates the 70 of polarization of=._receiver R1 due to the fact presence of the object in the path of the radiated that transmitter II and receiver I face each‘other. waves. Thus, by watching pointer 81 which in It will be observed that when transmitter T11 and dicates the oscillatory motion of transmitter I and receiver- R1 are both pointing in the same direc receiver 2 and by watching the pointer on beat tion their respective planes of polarization coin frequency responsive device 84’ the direction of 75 cide. Similarly, receiver Rn will be able to detect 2,412,081 - 16 15 scatteredi radiation resulting from the impinge ment of the wave propagated from transmitter While I have shown a particular embodiment of my invention, it will of course be understood that I do not wish to be limited thereto since Tu which is scattered from the vessel on which apparatus I is mounted but it will not be able to many modi?cations may be made both in the detect direct radiation from transmitter Tr. If 5 circuit arrangement and in the instrumentalities the planes of ‘polarization of the apparatus are so chosen that they are, for example, at 30°vfrom the vertical, direct radiation from one transmit ter appears only 60" out of coincidence with the plane of polarization‘ of the other receivers. It is thus apparent that by simply polarizing the apparatus on all vessels at some predetermined angle from the vertical, (preferably 45° since this angle is obviously the only angle which will give complete discrimination), each apparatus will be able to distinguish between scattered radiation employed. and I therefore contemplate by the appended claims to cover all such modi?cations as fall within the true spirit and scope of my in vention. ' What I claim as new and desire to secure by Letters Patent 01' the United States is: 1. In an apparatus for determining the direc tion of an object from an observation point, the combination comprising a radio echo scanning apparatus, means to rotate said apparatus there by to scan a distant object whereby an echo is received in said apparatus when said apparatus resulting from its own propogated wave and di rect radiation resulting from the propagated wave during said rotation is directed toward said dis of a second apparatus which is facing the ?rst. tant object, a cathode ray oscillograph of the It, is sometimes desirable to provide an addi type having a stream of electrons which nor tional receiver with each apparatus which is mally traces a predetermined path on the oscil polarized at the angle with respect to the ver lograph screen, and means operable synchro tical equal and opposite to the angle of the asso nously with the movement of said scanning ap ciated echo apparatus in order that direct radia paratus for de?ecting said stream of electrons tion from a second apparatus which is facing the 25 from its normal path at a point thereon corre ?rst may be detected with maximum ei?cienec'y. sponding to the direction in which said scanning I have indicated such a receiver with apparatus apparatus is directed when said echo is received. I as Pr and such a receiver with apparatus II as 2. The combination in a radio echo scanning Prr. Their planes of polarization are indicated apparatus, of means to rotate said apparatus by vectors I93 and I94 respectively. 30 thereby to scan a distant surface by a beam of While I have described a preferred embodiment waves rotated about a predetermined position of my invention many modifications will, of from which said beam is projected and to receive course. suggest themselves to those skilled in the said waves when re?ected from said distant sur art. For example, when the echo apparatus is ' face, an indicating device, means responsive to being used to determine the presence of a distant said re?ected waves received in said scanning object, or the direction of motion of an object apparatus to control said indicating device, and along the line of sight, a re?ector (not shown) means movable synchronously with the move mounted at an angle in front of transmitter I ment of said scanning apparatus to control said and receiver 2 may be oscillated or vibrated in last-named means in accordance with the direc order to provide the desired rate of change of path 40 tion in which said scanning apparatus is directed length of the high frequency wave rather than when said re?ected waves are received. oscillating transmitter l and receiver 2 them 3. The combination, in a radio echo apparatus, selves. I ' of means to radiate periodic high frequency im It will also occur to those skilled in the art that pulses toward a distant surface and to receive echo apparatus of the type described may be used 45 said impulses after impingement on said surface, for harbor protection in the place of a beam of means to measure the time interval between light and a light responsive cell by simply mount transmission and reception of the respective im ing the apparatus on one shore and pointing it pulses, said means comprising an electron dis across the harbor. Whenever a vessel intercepts charge device, means to change the current in the beam of the echo apparatus, a depression of 50 said discharge device from one of two predeter greater depth than that caused by the opposite mined values to_ the other when any impulse is shore appears on screen 55 of the cathode ray transmitted and to return said current from tube 54, or its presence and distance may be de . said other predetermined value to said one pre terminated by the range indicator. ' Although I have described as the preferred em- . determined value when the respective impulse is received, and means to measure the average bodiment of my invention, the use of high fre value of said current, whereby the average value quency apparatus which includes not only a of ‘said current is dependent upon the distance highly directive transmitting unit but also a to said object. highly directive receiving unit, it will be under 4. In an apparatus for ‘determining the dis stood that only one of the units need have highly 60 tance of an object, the combination, comprising directive properties; If a highly directive trans means for periodically propagating a. high fre mitter is used in conjunction with a non-direc quency radio impulse toward said object, means tive receiver, the radiated waves impinge upon for receiving scattered radiation resulting from only a small area of the distant object and hence the impingement of said impulse on said object, scattering and re?ection occurs only from that 65 means for measuring the elapsed time between small area, and the apparatus‘ as a whole main transmission and reception of said impulse, said tains its ‘requisite directional properties. If a timing means including an electron discharge highly directive receiver be used in conjunction device normally biased substantially to cut-oil. with a non-directional transmitter, scattering a second electron ‘discharge device normally and re?ection occurs over a large area of the ref 70 biased to pass current, means responsive to said erence body but since the receiver is only respon received scattered radiation for rendering said sive to the scattering and re?ection which occurs ?rst discharge device substantially non-conduct at a small spot on the surface of the reference ing, means responsive to a transmitted impulse body, the apparatus as a whole maintains its for changing the bias on said discharge devices requisite directional properties. 75 to their original state, and means for indicat aerator - i? ing the average current flowing through one of said discharge devices. i die waves toward a distant moving surface, means to receive said waves after re?ection thereof from said surface, and means responsive to the fre > 5. In apparatus for determining from an ob servation point the direction of motionv of a mov quency of the received wave to indicate the ac ing object along the line of sight, the combina-. tual velocity at a given. instant of the distant tion of means for transmitting a high frequency wave toward said object, means for receiving said wave after impingement on said object, means for increasing and decreasing the length of path traveled by said wave, and means for 10 indicating whether the greatest difference in fre quency between the transmitted and received object. 13. In combination, means to project short ra dio waves toward a distant moving surface, means to receive said waves after re?ection thereof from said surface, means to move at least one of said ?rst-named and last-named means along the line of sight between the said one means and said sur face, and means responsive to the frequency of the wave received by said receiving means during wave occurs on an increasing or decreasing path length. 6. In'radio echo apparatus, the combination 35 motion of said one means, to indicate the ve comprising means for obtaining a radio echo ‘ locity of the distant surface. from a moving object, means for determining 14. In combination, a radio echo scanning ap the actualpvelocity at a given instant of said paratus, means to rotate said apparatus‘thereby object along the line of sight between said ap to scan a distant area for surfaces producing paratus and said object, and means utilizing said 20 echoes in said apparatus, an‘ indicating device, last means for determining the direction of mo-,= means responsive to an echo received in said tion of said object along said line of sight. scanning apparatus to control said indicating de '7. In apparatus for ascertaining information vice, and means operable synchronously with the about an object, the combination comprising movement of said scanning apparatus to control means for obtaining a radio echo from said 25 said last means thereby to vary the indication object, means responsive to said echo to indicate produced by said indicating device in accordance the direction of said object from said apparatus with the direction in which said scanning device and its actual velocity at a given instant in said is directed when said echo is received. I direction. 15. In combination, a radio echo scanning ap 8. In'radio echo apparatus, the combination 30 paratus, means to rotate said apparatus thereby of means for transmitting a high frequency wave to scan a distant area for surfaces producing to an object to be located, means for obtaining echoes in said apparatus, a cathode ray 0scillo~ a radio echo of said wave from said object, means graph, means responsive to an echo received in responsive to said echo for determining the an said scanning apparatus from'a distant surface gular position of said object with respect to said 35 to in?uence the cathode ray of said oscillograph, apparatus, and means responsive to a beat fre and means operable synchronously with the move quency of said'wave and said echo for deter ments of said scanning apparatus to control said mining the direction ‘of motion of said object along the line between said apparatus and said object. _ ' last means thereby to control said oscillograph 40 in accordance with the direction in which said scanning apparatus is directedwhen said echo 9. In radio echo apparatus, the combination of means for obtaining a radio echo from a dis tant object, means responsive to said echo for is received. to an observation point the direction and line of indicating the angular position of said object, means responsive to said echo for determining sight velocity of a distant surface which in the actual line of sight velocity at a given instant of said object, and means=responsive to said echo for determining the direction of motion of said object along the line of sight. 10. The combination comprising radio echo ap 50 paratus mounted on one body, a second radio , 16. The method of determining with reference cludes scanning said surface with an electromag~ netic wave radiated from said point having di. mensions such that component surfaces of said surface normal to the direction of propaga tion of said electromagnet waves reradiate said wave with high directivity in the direction from which they arrive at said surfaces and such that echo apparatus mounted on a second body, said apparatus being capable of orientation toward _» said waves are effectively scattered by other com- -> ponents of said surface thereby producing ad each other, said ?rst-named apparatus, being po larized at a predetermined angle from the vertical 65 ditional reradiation in said direction, receiving a ' portion of said reradiation at said point, utilizing and said second-named apparatus being polarized at said point said portion to indicate directly said at substantially an angle from the vertical equal direction of said surface from said observation and opposite to said predetermined angle when point, and beating at said point said radiated said two apparatus are oriented toward each other whereby each of said apparatus receives radia 60 wave and said reradiation to indicate said line of sight velocity of said surface. ' tion resulting from its own propagated wave after 1'7. The method of determining with reference impingement upon a distant surface and rejects to an observation point the direction and line of direct radiation coming from the other of said sight velocity of a distant surface which includes apparatus, and additional means positioned near said ?rst apparatus for detecting only said direct 65 scanning said surface with electromagnetic waves radiated from’ said point having dimensions such radiation from the transmitter of said second ap that component surfaces of said surface normal to the direction of propagation of said electro 11. In combination, means to project short magnetic waves have effective lateral dimensions radio waves toward a‘ distant moving surface, means to receive said waves after re?ection there 70 several times the wavelength of said waves and paratus. of from said surface, and local means respon sive to a beat frequency of a portion of said pro jected waves and said received waves to indicate ' hence reradiate said waves with high directivity in the direction from which they arrive at said surface, utilizing at said point a portion of said ,reradiated waves to indicate directly said direc the direction of motion of the distant surface. 12. In combination, means to project short ra 75 tion, and heating at said point a portion‘ of said 2,412,631 19 20 ' indicate said line of sight velocity. 18. The method of determining with reference waves to the receiver through a local path of controllable length, combining waves received through said local path with waves received from " to an observation point the direction and line of the distant surface, and varying the length of sight velocity of a distant surface which includes one of said paths. 25. In combination, a short wave directive radiated waves and of said reradiated waves to scanning said surface with electromagetic waves radiated from said point having a wave length transmitter, a short wave directive interceptor, said transmitter and interceptor being positioned su?iciently short that any component portion dis posed at right angles to the direction of impinge together, and oriented at a distant object so that ment of said electromagnetic waves on said sur waves radiated from the transmitter are inter face reradiates said waves by reason of its large dimensions with respect to said wavelength with a sharply directive radiation pattern, said pat tern being substantially bisected by said direc tion, the sharpness of directivity of said pattern being dependent upon the dimensions of said component portion relative to said wavelength, utilizing at said point a portion of said reradiated waves to indicate directly said direction, and beating at said point a portion of said radiated 20 cepted by said interceptor after re?ection from the distant object, said transmitter and inter ceptor being shielded from each other, re?ecting waves and of said reradiated waves to indicate means located in close proximity to said trans mitter and interceptor and positioned to re?ect energy radiated from the transmitter to the in terceptor to combine therein with energy received from the distant object. 26. In combination, a short wave directive transmitter, a short wave directive interceptor, said transmitter and interceptor being positioned , together and oriented at a distant object, so that waves radiated from the transmitter are inter said line of sight velocity. 19. The method of determining with reference cepted by said interceptor after re?ection from to an observation point the direction and line of sight velocity of a distant surface which includes 25 the distant object, said transmitter and inter ceptor being shielded from each other, re?ecting scanning said surface with a radio wave having means located in close proximity to said, trans a wavelength of the order of ?ve centimeters, re mitter and interceptor and positioned to re?ect ceiving at said point a portion of said wave re energy radiated from the transmitter into the ?ected from said surface, utilizing at said point a portion of said re?ected wave to indicate directly 30 interceptor to combine therein with energy re ceived from the distant object, and a shield var said direction, and beating at said point a por iably positioned in the path of waves received on tion of said radiated wave and of said re?ected said interceptor through re?ection from said re - wave to indicate said line of sight velocity. 20. The method of determining with reference ?ector to vary the amount of said waves so re to an observation point the direction and line ceived from said transmitter. 27. The method of reception of waves radiated of sight velocity of a distant surface. which in by a transmitter and received by a receiver after cludes scanning said surface with a radio wave having a wavelength not greater than eight cen traversing a path to a distant re?ecting surface, which comprises transmitting a part of the ra timeters nor less than two centimeters, receiving at said point a portion of said wave re?ected from 40 diated waves to the receiver through a local path of controllable length, combining waves received said surface, utilizing at said point a portion of through said local path with waves received from said re?ected wave to indicate directly said di rection, and beating at said point a portion of said the distant surface, and producing a beat note radiated wave and of said re?ected wave to indi in said receiver between the waves received over cate said line of sight velocity. ‘ said two paths by variation of the length of one 21. The method of reception of waves radiated of said paths. 28. The method of determining the relative by a transmitter and received by a receiver after velocity of two bodies which includes radiating re?ection from a distant surface, which com high frequency electromagnetic waves from one prises producing a beat note between the radi ated and received waves by- locally re?ecting a body toward the other, receiving said waves on said one body after re?ection from said other part of the radiated waves into the receiver and 35 varying the length of the path traveled by said body, and determining said relative velocity from , locally re?ected Waves to vary the frequency of the frequency of the received waves. 29. The method of determining the relative ve locity of two bodies which includes radiating such wavesas received in the receiver. 22. In combination, a transmitter, a receiver, said receiver being arranged to receive waves from the transmitter after re?ection from a distant high frequency electromagnetic waves of substan tially constant frequency from one body toward the other, receiving said waves on said one body surface, a re?ector mounted locally with respect after re?ection from said other body, causing to said transmitter and receiver to re?ect waves from the transmitter to the receiver, and means 60 said received waves to beat with the radiated waves to produce a beat note having a frequency to move the re?ector to vary the frequency of the dependent upon said relative velocity, and deter re?ected waves as received in the receiver. mining said relative velocity from the frequency 23. In combination, a short wave radiator, a short wave interceptor, shielding means to pre of the beat note. 30. Apparatus for determining the relative vent waves radiated by said radiator from being 65 intercepted by said interceptor except when prop velocity of two bodies including means mounted agated over a predetermined path disposed wholly on one of said bodies for propagating an elec tromagnetic high frequency radio wave of sub in proximity to said radiator and interceptor, and means to vary the length of said path thereby stantially constant frequency toward the other to vary the phase with which energy propagated 70 of said bodies, and means on said ?rst body re thereover arrives at said interceptor. sponsive to the frequency or the scattered radia 24. The method of reception of waves radiated tion resulting from the impingement of said wave on said second body for indicating the relative by a transmitter and received by a receiver after velocity of said bodies. traversing a path to a distant re?ecting surface which comprises re?ecting a part of the radiated 75 31. Apparatus for determining the relative I 2,412,681 21 22 velocity of two bodies comprising means mounted on one of said bodies for propagating a wave means to supply said received echo from said scanning apparatus to said cathode ray oscillo of substantially constant radio frequency toward the other of said bodies, means responsive to scattered radiation resulting from the impinge graph to cause a de?ection of the electron beam thereof, and means to control said cathode ray oscillograph in accordance with the movement of ment of said wave on 'said second body, and means said scanning apparatus to cause. said de?ection ' for determining the difference in frequency. be to correspond with the direction from which said tween said transmitted wave and said received echo is received. wave thereby to determine the relative velocity 36. In an apparatus for determining the direc of said bodies. 10 tion of an object from an observation point, the 32. The method of determining the relative combination of a radio echo scanning apparatus, velocity of two bodies which includes radiating means to rotate said apparatus thereby to scan a high frequency electromagnetic wave from one a distant object whereby an echo is received in of said bodies toward the other, receiving on one - said apparatus when said apparatus during its of said bodies that portion of said wave which 15 rotation is directed toward said distant object, is re?ected from substantially a single point on a cathode ray oscillograph, means to produce said other body and determining said relative an indication on said oscillograph of the direc velocity from the frequency of the received wave. tion from which said echo is received, said last 33. The combination in a system for deter means including means to control said oscillo mining the relative velocity of two bodies, of 20 graph in accordance with the movement of said scanning apparatus, and means to control said means for radiating electromagnetic oscillations of substantially constant frequency from one of said bodies toward the other and for receiving oscillograph by the echo received in‘ said scan ning apparatus. 37. In combination, a radio echo scanning ap tion from the other body, said means having 25 paratus, means to rotate said‘apparatus thereby ._ said oscillations on said one body after re?ec such directive properties that only waves re to scan a distant area for surfaces producing ?ected from substantially a single point on ‘said echoes in said apparatus, an indicating device, other body are received on said one body, and means responsive to the frequency of said re means responsive to an echo received in said relative velocity. the movement of said scanning apparatus to scanning apparatus to control said indicatingv ceivedwaves to operate in accordance with said 80 device, and means operable synchronously with - s 34. Radio apparatus comprising in combina tion, a pair of focussed beam antennae, means for continuously varying the orientation of the ‘directional axes of said antennae while main 85 taining substantial parallelism between said axes, means for emitting ultra short wave energy vary the indication produced by said indicating device in accordance with the direction in which said scanning device is directed when said echo is received. - . 38. The combination, in a radio echo scanning apparatus, of means to rotate said apparatus thereby to scan a distant area by a beam of from one of said antennae, a receiver connected waves rotated about a predetermined position to the other of said antennae and responsive to such of said energy as may be re?ected by a dis 40 from which said beam is projected and to receive tant object, means connected to said receiver said waves when re?ected from surfaces in said for producing a graphic indication of its re area, a cathode ray device having a viewing sponse to the re?ected energy, and means for screen, a rotatable de?ection coil‘ structure about correlating said graphic indication with an in said cathode ray device, means to rotate said 48 rotatable de?ection coil structure synchronously dicated axis of reference. 35. In an apparatus for determining the di with said scanning apparatus thereby to rotate rection of an object from an observation point, the ray of said device over said screen, and means responsive to waves received from distant sur the combination of a radio echo scanning ap faces to control said ray to produce an indi paratus, means to rotate said apparatus there by to scan a distant object whereby an'echo 50 cation on said viewing screen at a position cor is received in said apparatus when said ap- . responding to the direction from which said paratus during its rotation is directed toward said distant object, a cathode ray‘ oscillograph, waves are received. » CHESTER W. RICE.