US2743439A - Radar method for target acquisition - Google Patents

Radar method for target acquisition Download PDF

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Publication number
US2743439A
US2743439A US291437A US29143752A US2743439A US 2743439 A US2743439 A US 2743439A US 291437 A US291437 A US 291437A US 29143752 A US29143752 A US 29143752A US 2743439 A US2743439 A US 2743439A
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Prior art keywords
target
antenna
oscilloscope
indication
screen
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US291437A
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Elmo E Crump
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AT&T Corp
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Bell Telephone Laboratories Inc
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Priority to NL79497D priority Critical patent/NL79497C/xx
Priority claimed from US705024A external-priority patent/US2656532A/en
Priority to FR948577D priority patent/FR948577A/fr
Priority to GB28262/47A priority patent/GB658745A/en
Application filed by Bell Telephone Laboratories Inc filed Critical Bell Telephone Laboratories Inc
Priority to US291437A priority patent/US2743439A/en
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/66—Radar-tracking systems; Analogous systems
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F41—WEAPONS
    • F41G—WEAPON SIGHTS; AIMING
    • F41G5/00—Elevating or traversing control systems for guns
    • F41G5/08—Ground-based tracking-systems for aerial targets
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/06—Systems determining position data of a target
    • G01S13/42—Simultaneous measurement of distance and other co-ordinates
    • G01S13/422—Simultaneous measurement of distance and other co-ordinates sequential lobing, e.g. conical scan
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/66—Radar-tracking systems; Analogous systems
    • G01S13/68—Radar-tracking systems; Analogous systems for angle tracking only

Definitions

  • This invention relates to a radar system, and particularly to a system and method adapted to simplify and speed up the processV of acquiring and utilizing all of the positional data necessary for the purpose of getting on-target quickly and systematically.
  • This application is a division of application Serial No. 705,024, led October 23, 1946, which was issued on October 20,1953, as Patent No. 2,656,532.
  • the positional data needed as to a target in gun pointing include the range of the target and its position in bearing and in elevation.
  • this positional data in order to be elective, must be obtained and utilized in a very brief interval of time, ordinarily in the order of a few seconds.
  • the system of the present invention is so designed and organized that this may be accomplished with a high degree of regularity and certainty.
  • One of the primary objects of the present invention is to secure the presentation of all significant target data at a' single position, and preferably upon an ,indicating device before a single operator, so that that operator may exercise complete control over the pointing of the gun and of the associated antenna throughout the entire preliminary or search period and up to the time when the gun director or re control operator takes over for final tracking.
  • the present invention provides for the presentation at a single operators position and upon a single oscilloscope screen of the target indications resulting from the impulse transmitting and echo receiving action of a narrow angle directive scanning beam of approximately circular vcross-section that is caused continuously to rotate rapidly about an axis, the antenna axis being eccentric to the beam axis and lying within the beam area, and the beam being caused continuously to nod or oscillate through a controllable angle about 2,743,439 Patented Apr. 2d, 1956 a mean nodding axis in one of the dimensions of bearing and elevation and at the same time progressively advance in the other dimension.
  • the oscillation or nod of the directive beam is in elevation and the progressive advance is in azimuth or bearing.
  • the transmitted impulses and received echoes are subjected to a lobe-switching action that causes all of the echoes received from impulses transmitted during corresponding half rotations of the beam to produce oscilloscope indications that are slightly displaced laterally from the indications resulting from echoes received from the same target produced by irnpulses transmitted during the corresponding opposite halt ⁇ rotations of the beam.
  • the position of these paired indications along one dimension of the oscilloscope screen indicates the range of the target producing the indications, and equality of magnitude and brilliancy of the two indications of the pair indicate coincidence in bearing of the target With the antenna axis.
  • the position of the paired indications in the other dimension ofthe screen preferably the vertical dimension, indicates the position'of the target in elevation.
  • the target acquisition operator at Whose station the oscilloscope screen is located, is provided with means for continuously translating the acquired positional data into a signal at the position of the gun tire director operator, under whose control, guided by the signal, the mean scanning axis is moved in bearing and elevation and centered upon the target, a condition the attainment of which is indicated to the acquisition operator by the centering in the vertical dimension of the equalized paired indication of the selected target.
  • the angle of nod is then reduced to facilitate the determination of the range of the selected target, indicated by the movement of the range lines to coincide with the paired target indication.
  • the nodding is stopped with the antenna axis in its mean position, the target having been spotted with a degree of accuracy sufiicient to bring it within the range of the precision operations thereafter under the control of the gun fire director operator.
  • a target Prior to the time when, in the search operation, a target is presented on the acquisition operators oscilloscope screen as paired signal indications, it may appear as a single indication. inasmuch as a paired, rather than a single, indication is required for precise determination of a target in bearing, the presentation of a target indication as a single line is ambiguous as to the direction in which the antenna axis must be moved in bearing to establish the exact position of the target. rfhe present invention provides means whereby such ambiguity is avoided by affording visual differentiation between signals resulting from left lobe echoes and right lobe echoes over the continuously rotating directive scanning beam.
  • such visual diiferentiation is a color differentiation secured by the interposition between the eye and the oscilloscope screen of means, such as a sector disc, synchronized in its movement or rotation with the right and left lobe switching of the rotating directive beam.
  • This causes single indication right lobe signals to appear to the eye as of one color and left lobe single indications to appear as of another color.
  • the target acquisition operator is thus provided with information immediately upon the appearance of the single indication as to which direction the antenna axis must be moved to cause it to produce paired indications and coincide with the corresponding target.
  • the length of time necessary to acquire a target after it has been designated may be further reduced.
  • the preferred form of radar system embodying the various features of the present invention may be more .3,743,439 A Y e' Y, i
  • Figs. l and 2 taken together, with ⁇ Fig. l arranged above Fig. 2 in position Vto inatch the functional connectins lines, .constitute a schematic illustration of .the entire system' and N Eig. 3 is a schematic illustrationof the manner in which .the target ⁇ signal indications .formedfbyand .related to the lobe-switching patterns of the rotatinsdirective tbe r1.1, and also the relation' between the ytratterlris and therr'resultantsignal .indi tions and the rotating sector disc that produces visual erentiation between right lobe and left lobe target signals!A
  • a preferred form of the :S5/Sitting' ofthe present invention is .disclosed in lthe functional bleek schematic diagram of Figs...1 rid 2- As indicated, the'opparatus of the organization-is centered generally in three operation Vcforlirol Position
  • .radar antenna 1.1i' at the sun ydirector position is the pedestal type one-man director 12,; and at the target acnuisitioo and rodar position are located the target acquisiti9l1 .oud radar oseilloseopes 13 and 1,4 together with the various leontrols provided for manipulation by the op- @rotor or operators at this Position in respouse'to. the target indications presented upon the Oscilloscopes.
  • Ythe operational relationship between these three positions is one Vin which the pointing of the gunsV at the gun position is under the complete control of the fire control operator at the gun director position, which operator in turn performs his functions, as to radar idenn tified targets, under the guidance and'control of a signal electrically communicated to the gun director position from the controls at the target acquisition and lradar position.
  • the radar antenna 11 is directly mounted upon the twin gunsV and partakes of their movement.v It ,is also Ycapable of independent movement with lrespect to its gun carried support, asV vwill hereinafter be described. As'indicated,l the structure upon which the guns 10 are mounted is capable of beingV swung in azimuth or bea-ring about a vertical axis, and *in elevationr about a horizontal axis.
  • the antenna 11 mounted upon the gun support is preferably of the front feed paraboloid reflector type disclosed in the application of'Cassius C. Cutler, Serial No. 518,377, tiled January d5, 1944, now Patent No. 2,422,184 granted June 51,6, 1947, the vfront feed or primary antenna portion being rotated about the focus of the paraboloid reflectorto generateY a conical scanning field as -disclosedin the application of Edward Kar- No. 2,457,562 granted December 28, 194,8.
  • the wavelength of the radiated wave and the effective reilec- Y tor dimensions are so chosen asrto generate a directive scanning beam approximately circular in cross-section and three degrees in width at the half power point; and theradius vot rotation of the kfeed about the reilector focus is such as to cause a rotation o f the three-degree scanning beam on a three-qnart'erldeg'ree Vradius about the antennaaxis, .to produceV a lobe-switching beam shifter approximately 1.5 degrees.
  • the rotating beam has an ,over-all width or coverage of about 4.5 degrees.
  • the vsupport of .the antenna 11 upon the gun mount is through Athe medium of a gimbal frame 16.V
  • the horizontal axis of the frame gives the antenna freedom of movementin a vertical plane, and associated mechanism c (not shown) causes the antenna during the search operation ⁇ contnuously to oscillate or nod uniformly in the vertical plane through a ,controllable angle about a mean position and at the end of the search Operation to be broughtto ⁇ rest at the center of the nod with the antenna axis in alignmnet with the g-un axis.
  • the search operation therefore the'antenna automatically con-V Throughout the the ⁇ noddingV center ofV the antenna.
  • the 'center of the automatically scanned sector in ⁇ bearing and elevation during-'search is determined by the position in bearing and elevation of the gun mount as controlled by the gun director 12.
  • the rotation of the directive scanning beam is effected by a motor which in the present embodimentV of the invention rotates and drives the rotating antenna front feed at the rate of 30 cycles per second; and this motor drives Y.
  • a two-phase 30Y cycles per second generator schematically indicated 21117, fOr Supplying controlling kvoltages to other elements of the organization.
  • the above-mentioned motor and generator form part of the antenna Vhousing structure mechanically supported by the gimbal frame 16.
  • Another element, schematically indicated at 1 8 as a potentiometer, is controlled by the nodding movement of the antenna to furnish voltages in proportion to the nodding angle to the vertical sweep circuit of the acquisition operators oscilloscope 13.
  • the gundirectormV is represented as being arranged. to be swung vertically upon a horizontal axis and horizon-y tally upon a vertical axis through. the medium of handle bars grasped by the gun director operator. As has been stated; these vertical: and horizontal angular movements of the gun director aretranslated ⁇ Vinto exactly corresponding angular movements'of the mounting of the guns 10.
  • the manuallyv operated-,director 12 is provided-with means ⁇ for effecting both optical4 andA radar tracking of the target.
  • the optical elements of the system are .suggested by the bari-e129 offa telescope projecting from fthe front of the director, and the radar elements by the oscilloscope 15 which, for clarity of representation, is indicated as merely associated' with rather Sthanmounted inside the directork housing.
  • rfhe director 12. is also provided with a computer and gun sight control19, indicated as.
  • the-,director housing which functions in respouse to variou data Communicated to it to control the angular alignment of the radar antenna 11 in such a way that the radar beam, as well as the optical line of sight of the director, remains directed at the present target position While the guns are being aimed at the future target position.
  • the two Oscilloscopes 13 and 14 together with the elements 21, 22 and 23 through the medium of which the bearing, elevation and range, respectively, of a target are ascertained and this positional target information employed to direct the pointing of the guns through the medium of the director 12 and associated computer 19.
  • a switch 24 for controlling the angular amount of automatic nod of the antenna 11 and a switch 25 for shifting the operation of the system from search to track.
  • a sector disc 26 driven by a motor 27 for enabling the operator to ascertain by visual differentiation the direction in bearing of a target that appears on the oscilloscope screen as a single rather than a paired indication.
  • the radio pulse energy transmitting portion of the system includes the oscillator 28, pulse generator 29, pulse amplifier 30 and transmitter 31, from the latter of which the pulses of radio frequency energy are transmitted over the path 32 to the rotating front feed of the antenna 11 and, after reflection by the parabolic reflector of the antenna, are projected as a narrow conical beam.
  • the echo from a target in the path of the beam is reflected back over the directive beam to the antenna and thence passes over the path 32 to the receiving elements which are schematically represented as including the TR or transmit-receive box 33, converter 34, intermediate frequency amplifier 35, and detector and video frequency amplifier 36 to the echo or reflected pulse control elements of the Oscilloscopes 13 and 14 at the position where the target acquisition operator is stationed.
  • Certain of the received pulse energy also passes by way of the search-track switch 25 when the switch is in its lower position to the elements of the oscilloscope 15 associated with the director 12.
  • the function of the pulse generator 29 is to establish, under the control of the oscillator 2S, the pulse repetition rate of the system, and to supply the necessary synchronizing and keying pulses to the other units.
  • the transmitter 31 is keyed by pulses from the pulse generator 29, amplified by the pulse amplifier 3G, which in turn produces pulses of radio frequency energy of very short duration.
  • the pulse repetition rate in the present system may conveniently by nominally 1,800 per second, and the pulse duration may be a fraction of a microsecond.
  • Those pulses from the transmitter 31, which may include a magnetron, are supplied over the path 32 to the antenna 11.
  • the TR box 33 operates to protect the receiving equipment while each pulse is being delivered to the antenna by the transmitter 31 and is restored immediately after the pulse so as to permit the returning echoes from the pulse to flow into the receiving circuit.
  • the returning echoes of ultra-high frequency are demodulated to an intermediate frequency by the converter 34, which preferably employes a crystal detector and a beating oscillator, and the intermdiate frequency, after amplification in the intermediate frequency amplifier 35, passes to the detector and video frequency amplifier 36 where the final demodulation and amplification of the target signal takes place.
  • the target signal is transmitted over path 37 to the radar oscilloscope 14, over path 38 to the target acquisition oscilloscope 13, and over path 39 to the pointing demodulator 87.
  • the horizontal or range sweeps of the Oscilloscopes 13 and 14 are keyed by the pulse generator 29.
  • the keying pulse for the acquisition oscilloscope 13 controls the Uil range sweep generator 49 to produce an appropriately shaped voltage wave which is amplified in the range sweep amplifier 41 and applied to the horizontal sweep plates of the oscilloscope 13.
  • the keying pulse for the radar oscilloscope 14 controls the range sweep generator 42 to produce an appropriately shaped voltage wave which is amplified by the range sweep amplifier 43 and applied to the horizontal deflection plates of the oscilloscope 14.
  • the vertical deflection plates of the acquisition oscilloscope 13 are under the control of voltages supplied from the potentiometer 18 associated with the antenna 11, which as previously mentioned vary proportionately with the angle of the antenna nod.
  • the vertical deflection plates of the radar oscilloscope 14 serve, under control of the signals received over path 37, to produce the target indicating pips or vertical deflections along the horizontal trace of the cathode ray beam, and also, under the control of the range mark generator 44, to produce a vertical deflection along the horizontal trace, the position of which deflection is controlled by the range unit 23 to identify the position in range of an acquired target.
  • each pulse from the range mark generator increases the brilliancy of each horizontal trace of oscilloscope 13 at a point along the horizontal or range trace that corresponds to the setting of the range unit 23 and thus appearsas a vertical line on the screen.
  • the horizontal or range trace of the acquisition oscilloscope 13 is, further, under lthe controlof the two-phase 30-cycle generator 17 forming a part of the antenna unit through the medium of the square wave generator 45 connected with the generator 17 over path 46.
  • the square Wave generator applies through the range sweep amplifier 41 a voltage to the horizontal defiection pla-tes of acquisition oscilloscope 13 that slightly displaces the origin of the horizontal or range sweep. The purpose of this is to cause each target when it is close to the axis of rotation of the directive beam to produce a paired rather than a single indication on the oscilloscope screen.
  • the two-phase generator 17 of the antenna has functional connection over path 47 with the driving motor 27 of the color differentiating sector disc 26, which disc is thereby driven in synchronistn and phase wi-th the rotating antenna feed.
  • Another functional connection of the generator 17 extends by way of path 48 to the pointing demodulator 87 to which the target signal is also applied by way of path 39.
  • the signal and the wave from generator 17 are here intermodulated to produce pointing voltages that are conveyed over paths S8 and 89 to the director oscilloscope 15 by Way of the search track switch 25 when the switch is moved to its lower or track position.
  • the target data obtained through observation of the Oscilloscopes 13 and 14 is utilized to bring about the pointing of the guns 10 lthrough the medium of controls associated with the bearing unit 2.1, theA elevation unit Z2, the range unit 23 and the associated switches 24 and 25.
  • the acquisition operators control of the gun pointing is through the medium of the operator of the director 12, constantly guided by the wandering spot 74 on the direc-tor oscilloscope 15 as determined by controls manipulated by the acquisition operator.
  • the control exercised by the director operator over the poin-ting of the guns continues to be under the guidance of the position of the spot 74 in oscilloscope 15,
  • the acquisition of they target is effected by the operator under the guidance of the target patterns presented upon the screens of the Oscilloscopes 13 and 14.
  • the pattern presented on the screen of oscilloscope 14 is a conventionalso-called A presentation in which the trace of Ythe cathode ray is a single horizontal trace diametrical'ly across the screen, the origin of the trace being identified by the vertical dellection of the trace at its extreme left-hand end, and the target signals being identied las vertical deflection lying along the'trace between th'e'two ends.
  • the distance along the trace from its origin to the target deflection or pip 83 is proportional to the radiall distance in -space .between vthe antenna and the corresponding target.
  • the abrupt, depression-82 in the trace just short of the target indication is the so-called stepY movable lalong Vthe trace underV the control of the range unit 2.3, which'through Ythe counter 49 on the range unit indicates the distance, usually in yards, to this target or any other target to which the step isV advanced.
  • the A presentation ofthe oscilloscope 14 presents merely range data, and gives no information asV to the position Y of the target in elevation or in bearing.
  • the double-B or paired presentation of target signals on the oscilloscope 13 presents upon the same screen all of the positional dataV necessary for the determination of the elevation ⁇ and bearing of a target as well as its range.VV
  • the B type of presentation is one in which the reflected signal orlecho from thetarg'etrproduces an increase in luminous intensity rather than a deflection of the trace.
  • VThe range or distance to any given target is represented by the dis-Y tancealong the trace to the point of greater luminosity.
  • the vertical deection plates of an oscilloscope such as 13, giving a B type of presentation, are employed to dis-V tribute lthe luminous range Yindications of the targets vertically over the face of the screen, in the present case in accordance with the elevation angle of the directive beam'V at the instant the target echo is received.
  • tive target indications 50,51', 52, 53 and 54 are represented.
  • 50, V51 and'52 are paired indications, showing that the corresponding objects or targets lie vsufficiently close to the antenna-axis to fall within the conical'area'- defined by Ithe rotation beam during all phases of its rotation about the antenna axis.
  • In-V dications S3 ⁇ and 54 are single or unpaired, showing thatr the objects or targets they represent are far enough'off the axis of rotation of the directive beam so that they is secured by .choosing Ya screen having an effective phos phor persistence related to the length of :the vertical scanning cycle, and preferably somewhat greater than the v brightness, 'eachl dot representing an individual echo yrep lec'ted from the target as'th'e directive 'beam sweeps over I it, ythe vertical V,arrangement l,of these dots with respect -to each other vbeing due to the continuous vertical disreceive and reect-"pulses during only one-half or the other of the cycle of rotation of the beam. ⁇
  • These signals are all produced by the brightening of the horiz'onta range trace ofthe cathode rayat a point along the trace with reference to its origin corresponding with the time interval between the transmitted pulse and the return of the echo.
  • This distancealong the trace constitutes ameasure of the 'Y Y distance of the object from the antenna in space.
  • the target represented by the paired indications 50 is the closest, followed'in order by the more remote targetsrepresented by the indications 53, 54, 51 and 52.
  • AstheA range sweep or trace s'c'aused to move vertically up and down over the oscilloscope screen in proportion to the angular nod of the antenna about itsV nodding center the vertical .positions of the indications 'show that in elevation the target represented by' the indication 50 is at theangular center of the nod, and that the targets represented by the other indications are above or below the nodding ⁇ center by amounts in elevation corresponding to the-verticaly distances of the associated indications from the center of the screen.
  • the scanning beam during the Search stage in the operation of the system is'simultaneously executing three sorts of movementgnamely, a rapid continuous rotation of the, narrow Vcircular cross-section beam about the antenna axis, a uniform nodding ⁇ movement of theirotating beam over a relatively large angle in elevation, and
  • the Vrate of the progressive advance in bearing ofthe nodding rotating beam is 'made such, if automatic, as to cause an overlap in bearing of the areas covered by the Vbeam in its successive nodsV in elevation so thatnoportion of the search area will be skipped.
  • Target retlections are received from this area only when the beam is inthe half cycleV of its rotation in which the area lies. These are the areas lying between the full, and broken lines designated 59 in the upper pattern representing Vthe right lobe halfvcycle rotation 66 ofthe scanning beam and 60 in the. lower pattern representing the left lobe half-cycle ro-r ⁇ tation 67 of the scanning beam. Targets lying at all other pointsV within the scanning beam pattern are within the effective Vareas of both-lobes. are returned from them in both lobe positions, and thus throughout the complete cycle of rotation of the beam.
  • ⁇ Ail of the echoes whether right lobe or left lobe, produce luminous. indications on the oscilloscope screen.
  • lobe indications are displaced laterallyV on the screen with. respect to each other, and thus may be utilizedto irnlorm the acquisition operator which direction in bear-v I vvhe relationV between the position ofY ⁇ a ta'rgetfwithY ⁇ V respect vto the phase of yrotation of the scanning beam Therefore echoes 9 Aing the antenna axis must be moved to cause it to approach and coincide with the target from which the echoes are being reflected. The manner in which this is done is schematically illustrated in Fig. 3.
  • the beam is rotating about the antenna axis at the assumed rate of ⁇ 30 cycles per second, half of each cycle of rotation constituting the right lobe pattern of the beam, and the other half cycle constituting the left lobe pattern.
  • a device 62, 63 schematically shown as a commutator, but actually the elements of the system that are shown in Figs. l and 2 as the twophase, 30-cycle generator 17 at the antenna and the connection of this generator through the square wave generator 45 and the range sweep amplifier 41 to the horizontal deflection plates of acquisition operators oscilloscope 13.
  • the varying kinds of indication produced on the oscilloscope screen by the advance of target 61 through the scanning beam are represented at 64 in Fig. 3, and the control of the lateral displacement of the target indications on the screen in accordance with whether the rotating beam is in its right lobe or left lobe position is represented as functional connecting lines 68-and 69 extending from the commutator 62 and 63, respectively, and terminating in vertically extending stubs, each of which is in Vertical alignmentfwith the position of the indication produced on the screen when the beam is in the corresponding right lobe or left lobe phase of its rotation.
  • all left lobe indications areV slightly displaced on the-screen to the right with respect to the indications from the same target produced when the beam is in its rightlobe position.
  • the target When the target has advanced to one and one-half degrees left it is still within the inactive area 59 of the beam in its right lobe position, but is within the active area of the beam in its left lobe position and therefore still appears upon the screen as a single or unpaired indication. But the single line indication has become longer and brighter, as the target in this position is intersected by a greater length of the active area of the left lobe pattern of the beam, and has advanced deeper into the power area of the beam.
  • the target When the target has advanced to one degree left of the antenna axis it has reached a point where it is in the active area of the beam in both the right lobe and left lobe positions. Therefore the corresponding indication becomes a paired indication on the screen.
  • the target has just entered the active area of the right lobe pattern of the beam, but has advanced well within the active area in the left lobe pattern, the right lobe line at the left of the pair is shorter and fainter than the left lobe line at the right of the paired indication.
  • the right lobe line at the left of the pair increases in length and brightness
  • the left lobe line at the right of the pair after reaching a maximum length and brightness at a point at one-half degree right where the target is intercepted by the most effective area of the beam in its left lobe position, diminishes in length and brightness until it finally disappears when the target has moved to a point one and one-half degrees right of the antenna axis and therefore is within the ineffective area 60 of the beam in its left lobe position.
  • the target is still within the effete area of the beam in its right lobe position and therefore appears as a single line indication on the screen.
  • the single right lobe indication of the target has become shorter and fainter, and has disappeared entirely when the target has moved to two and one-half degrees right of the antenna axis.
  • the target indications are either single line indications or paired indications with the lines of unequal length and brilliancy at all positions of the targetexcept that at which it coincides with the antenna axis. At this zero position the target is past the maximum power position with respect to the eltective left lobe area of the beam and is approaching the maximum power position in the right lobe effective area of the beam. When the diminishing left lobe indication and the increasing right lobe indication become equal in length and brilliancy, the target lies in bearing at the antenna axis.
  • the showing of the target indications 64 of Fig. 3 as disposed at different points horizontally is merely for convenience in description. lt will be understood that the location of the target indication along the horizontal dimansion of the oscilloscope screen is determined by the position of the target in range, and as long as the range remains the same the target indication remains at exactly the same range or horizontal position on the screen.
  • the appearance upon the oscilloscope screen would be that of a gradually changing pattern at a single point on the screen as the direction of relation of the rotating antenna beam with the target changes in bearing. At this point there would first be a faint single line gradually increasing in length and brightness, then becoming an unequal paired indication, and then becoming an equal paired indication as the antenna axis coincided with the target, but all at the same point on the oscilloscope screen.
  • the lateral displacement of the two portions of the paired target indication with respect to each other is effected by laterally displacing the origins of the oscilloscope range sweeps occur either during all of the right lobe positions or all of the left lobe positions of the scanning beam.
  • the sweep regions are shown as being displaced toward the right during all left lobe positions of the beam. This results in positioning the left lobe indications at the right of each pair and the right lobe indications at the left of each pair.
  • Fig. 3 also illustrates schematically the manner in which visual differentiation is employed in identifying the direction in bearing from the antenna axis of a target indicated on the osclloscope screen merely as a single line, and thus informing the acquisition operator the direction to move the antenna in order quickly to acquire the target.
  • the position of a sector disc 26 with reference to the screen 65 of the acquisition oscilloscope 13 is shown for each of the two lobe positions of the scanning beam illustrated in the left-hand portion of Fig. 3.
  • Two ambiguous single line indications 53 and 54 are shown on the screen 65.
  • the sector disc may *assume a variety of forms vwith respect to construction, dimensions, material employed,
  • vof the rotating scanning-beam indicate that in rate of rotation and phase the disc corresponds with
  • thev sectorrdisc In the upper representation thev sectorrdisc is shown in Y the position it occupies as the scanning beam starts the right lobe half or its rotation, and in the lower representation the sector disc 26 is shown in the position it occupies at the start of the left lobe hal-f of the rotation of the scanning beam.
  • the relationship therefore is such that as the scanning beam swings through its rig-ht ⁇ V lobe position the amber sector is interposed between the oscilloscope screen and the eye, and as the beam Vswings through its left lobe position the clear or cut-away por-.
  • Vthe disc is interposed between the oscilloscope screen and the eye.
  • target indication 54 which Vis Van indication produced Vonly while the scanning beam is in its'right lobe position, would at all times during its production have the amber portion of the sector disc interposed, and would therefore appear to the eye as an amber-colored indication.
  • target indication 53 be-ing produced only during the left lobe position of the scanning beam, would not be seen through an inter-V posed color screen and therefore would impress the eye as ja white indication.
  • all left lobe indications would appear Awhite and all right lobe indications would appear amber to the eye. In this way the operator would immediately know in which direction to move the antenna axis bearing to cause Yit to coincide with, Vthe Atarget producing the singleline indication.
  • the phosphor characteristics of the screen are such that the target indication consists of an instantaneous blue-White" ash followed by an amber phosphorescence of relatively long persistence. Such characteristics, however, do not prevent the method of color differentiation described from being, effective.
  • the phosphor causes the light of Vall target indications, whether right lobe or left lobe, or whether viewed directly or through the interposed amber ycolor sector screen, to appear amber to the eye.
  • the instantaneous bluewhite flash characteristic reaches the eye only in-theY case of the left lobe signals, the instantaneous flash of 'which always occurs when the color screen is not interposed.
  • V'Ihisdescripti'on will 'be directed merely to the' particular operations that have a bearing upon the novel'features that constitute or form .a basis for the present invention. It will -be understood Y that the entire system Vas schematically shown in the drawings-'embodies many features ⁇ other than those toward which the'claims of the present ⁇ application are directed. v
  • switch V25 When switch V25 is thrown to its, upper or search -position, it alsov functionally connectedV the bearing unit 21 with the horizontal deection plates of the director oscilloscope 1'5 by way of Ypath 72,. and the elevation unit 22 with the'verti'cal deflection plates of oscilloscope 15 byk way of path V73a.
  • the spot -74 of the director oscilloscope Y 15 is now under the control, through the medium of 'synchro devices, of the bearing control knob 75 of unit 21 with r'es'p'ectto the horizontal position of the'spotV on the screen, an'd under the Ycontrol of elevation knob Y 7'6 of'unit 22 with Vrespect to the vertical position of which the director 12, and therefor the ⁇ guns l10 andY antenna 11, points andthe angles at which 'the bearing v unit 21 and elevation unit 22.a"re set by the acquisition Yoperator'. Assurnngrhat the spor 74 of oscilloscope lis The movement of switch 24 into .its
  • the acquisition operator has complete control of the pointing of the antenna and the guns through the medium of the director operator, acting as a human servo, to keep the spot 74 centered on the cross-hairs of oscilloscope 15.
  • the angle in elevation at which the pointer 78 of unit 22 is set by turning the elevation knob 76 establishes the angle of the center of nod of the antenna 11, and the nodding antenna is moved in bearing in accordance with the setting of pointer 79 of unit 21 by turning knob 75 of that unit.
  • the antenna nods projects pulses and receives echoes from any object lying in the sector determined by the vertical nodding angle and the breadth of coverage of the rapidly rotating narrow angle beam.
  • the energy of the pulse echoes from any target in the scanned sector is applied, as has been described, to the grid of the acquisition oscilloscope 13 to control the intensity of the horizontal or range sweep at a point corresponding to the range of the target; and at the same time the range trace is being moved vertically over the screen of the oscilloscope proportionately to the angle of antenna nod under the control of voltages delivered by the potentiometer 18 associated with the antenna.
  • the knob 75 of the bearing unit 21 to bring about, through the medium of the director operator a movement of the antenna axis toward the left in bearing, the directive beam is moved so that the. target now lies within both left and right lobes in the rotation of the beam, and therefore appears on the screen of oscilloscope 13 as a paired indication.
  • the turning of the knob 75 has, in the meanwhile, caused the pointer 79 to indicate the bearing angle.
  • the vertical position of the target indication on the screen shows that the target in elevation lies above the present center of the antenna nod.
  • the means supplied to the acquisition operator for bringing the center nod of the antenna in alignment with the target is disclosed in the patent of C. W. Norwood, No. 2,407,019 issued September 9, 1947. Briefly, this comprises a horizontal cross-hair that can be moved vertically to any desired position on the screen from its normally centered diametrical position by pressing inwardly and turning the elevation knob 76.
  • the acquisition operator observes the indication 53 of the designated target he presses in and turns the knob 75 until the cross-hair 77 bisects the indication 53.
  • the turning of knob 76 at the same time causes the pointer 7S to move in elevation the same nimber of degrees that the target 53 is above the nodding 14 center of the antenna as represented by the normal position of the cross-hair 77.
  • the cross-hair 77 Upon releasing the knob 76 the cross-hair 77 immediately returns to its normal position. But the turning of the pointer 78 to the new position in elevation moves the spot 74 of director oscilloscope 15 oli center in elevation, and in recentering the spot the director operator moves the director, and therefore the guns l@ and the nodding center of the antenna 11, in elevation by an amount that is just suiiicient to bring the center of the antenna nod in alignment with the target.
  • These operations are usually performed in such a short interval that by the time the cross-hair 77 has returned to its normal diametrical position, the indication of the designated target has centered on the cross-hair.
  • the indication on the screen now consists of a paired indication.
  • the acquisition operator brings about equalization by causing the antenna to move slightly in bearing in the direction of the weaker signal of the pair.
  • target indication 53 now paired, centered and equalized, has become the signal designated 50.
  • the spot 74 of oscilloscope 15 is centered, Vthe director 12, the guns 1i? and the antenna 11 are aligned with the target in bearing and elevation, and the bearing angie and elevation angle are indicated by the pointers 79 and 78.
  • the range detennination of the target is also indicated on the acquisition operators oscilloscope 13 when the paired range lines 80 coincide with the paired indication 5G, as will be described.
  • the determination of the range of the acquired target is under control of the lrange unit 23.
  • the operator When the operator has acquired the target and caused the equalized indication to center on the hair line '77, he throws the nodding control switch 24 into its low nodding position. This causes the amplitude of the nod to be reduced to a lesser angle, such as represented by the inner pair of arrows of the four-arrowed line 71, and causes the directive beam to vsweep over the target more frequently.
  • the target echo had also beenv received as a so-called A or deflection pattern on the oscilloscope 14 located in close proximity to the oscilloscope 13.
  • Both Oscilloscopes fare within the range of observation of one operator; ⁇ but 'it is customary to assign the acquisition oscilloscope 13 and its ⁇ associated controls to the acquisition operator and the oscilloscope 14 and its associated controls to the radar operator, the two operators working as a team.
  • that operator keeps the target centered in bearing and elevation while the radar operator, guided by the A pattern on the radar yoscilloscope 14, proceeds to gate andy determine the range of the target.
  • ⁇ this consists merely in turning the range crank S1 of range unit 23 until the lower extremity of the range step 82 coincides with the lower left-hand edge of the target indication 83 appearing on the horizontal trace of oscilloscope 14.
  • the range crank S1 is geared with the counter 49 'of unit 23 in such a way that when the range step S2 contacts the target indication 83 the range in yards of t-he target may be read on 'the counter.
  • the turning of the crank S1 operates over the functional path S4 to cause range mark generator 44 to produce a pulse that -is fed over path 85 to the vertical deflection plates of radar oscilloscope 1d and over path S6 ⁇ to the intensity control grid of the acquisition oscilloscope 13.
  • This pulse produced by range mark generator 44 is delayed with respect to 'the ori-gin of the range sweep in each oscilloscope by an amount proportionate to the angular rotation of the range crank 81. ln each case this delayed pulse from the range mark generator 44 produces 1-5 a range indication along the horizontal vsweep of .the oscilloscope trace.
  • the acquisition operator ortlre radar operator may throw .the switch 25 fi'o'm 'its Search 'toV its track position.
  • VThe mrowing 'of 'the switch from Search to track effects several changes.
  • One of these is to stop the nodding of the antenna and immediately center it atits nodding center 'and 'thus with the mean scanning axisof the beam in alignment withthe pointing position of the ⁇ guns V1i) and the director 12'.
  • the antenna nodding ceases, but the axis of therbeam 57 continues to rotate'about the antenna axis S8.
  • theV target when switch 25, is thrown over to track would be outside the narrow ⁇ coverage of the centered, rotatingVA beam, and no target signal would be received upon the Vdirector oscilloscope i5 for the guidance of the director operator dur# ing the nal precision tracking of the target.
  • the radar positional data including ⁇ bearing and elevation of the target, range and rate of change in range, as well aslvarious corrections such as wind, drit, and initial velocity loss the projectile speed, are fed into the computer'YV and gun sight control shown as'the box 19 on the director 12, and that these data so modify the control relationships between the various elements that while the radar and optical line of sight remains on the target, the guns are so pointed as to cause the projectile to intersect the line of .flight at a predetermined future position of the target. As suggested by the broken lines within. the
  • the radar image of the target as produced by oscilloscope 15 is superposed upon the optical-'image of the target as viewed through the tel'ev.
  • Thev control 'of the device 19 over the pointing of the antenna 11 in elevation and bearing, exercisedover the functional control paths '90 and 91, is such that although the antenna is supported on the guns that are pointed at the future 1e Y Y position of the'targcathe antenna 11 continues to point at the .present position of the target. It may be added that the range of the target as indicated on counter 49 of unit 23 and the rate of change in range as indicated on the indicator 92 of that unit areconveyed to theV com- Yputer 19 over the functional paths 93 and 94.VV
  • the method of target acquisition and utilization according to radar technique and utilizing the conventional oscilloscope screen thereof which consists in nodding, rapidly rotating about an axis lying within the beam area and transversely lobe-switching a scanning beam while advancing the same in a direction transverse to the direction of nod, transmitting energy impulses by said beam and receiving corresponding energy echoes from the targets upon which the impulses impinge, translating the echoes received from a selected target into indications on said oscilloscope screen of the position of the target 18 in bearing, elevation and range, translating said indication into a visual signal at another station to indicate the position of the selected target with reference to the beam mean axis, and aligning at said other station, as in -accordance with the position of said visual signal, the beam mean axis with the selected target.

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  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • General Engineering & Computer Science (AREA)
  • Radar Systems Or Details Thereof (AREA)
US291437A 1946-10-23 1952-06-03 Radar method for target acquisition Expired - Lifetime US2743439A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
NL79497D NL79497C (fr) 1946-10-23
FR948577D FR948577A (fr) 1946-10-23 1947-06-27 Repérage de but par radar
GB28262/47A GB658745A (en) 1946-10-23 1947-10-22 Radar systems
US291437A US2743439A (en) 1946-10-23 1952-06-03 Radar method for target acquisition

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US705024A US2656532A (en) 1946-10-23 1946-10-23 Radar system
US291437A US2743439A (en) 1946-10-23 1952-06-03 Radar method for target acquisition

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US2743439A true US2743439A (en) 1956-04-24

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2946051A (en) * 1955-03-23 1960-07-19 Sperry Rand Corp Angle sensing indicator for nutating beam radar system
US3085239A (en) * 1957-03-18 1963-04-09 Rca Corp Radio-frequency switching
US3135955A (en) * 1960-02-15 1964-06-02 North American Aviation Inc Search controller
US4579035A (en) * 1982-12-06 1986-04-01 Hollandse Signaalapparaten B.V. Integrated weapon control system

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BR8707523A (pt) * 1986-11-03 1989-02-21 Contraves Ag Dispositivo para o alinhamento de um corpo de visor para um alvo

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2522880A (en) * 1946-12-14 1950-09-19 Rca Corp Indicating system for radar direction finders
US2589965A (en) * 1940-01-10 1952-03-18 Rost Helge Fabian System for locating, indicating, and/or following objects in space
US2617982A (en) * 1942-04-30 1952-11-11 Sperry Corp Radio gun control system
US2656532A (en) * 1946-10-23 1953-10-20 Bell Telephone Labor Inc Radar system

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2589965A (en) * 1940-01-10 1952-03-18 Rost Helge Fabian System for locating, indicating, and/or following objects in space
US2617982A (en) * 1942-04-30 1952-11-11 Sperry Corp Radio gun control system
US2656532A (en) * 1946-10-23 1953-10-20 Bell Telephone Labor Inc Radar system
US2522880A (en) * 1946-12-14 1950-09-19 Rca Corp Indicating system for radar direction finders

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2946051A (en) * 1955-03-23 1960-07-19 Sperry Rand Corp Angle sensing indicator for nutating beam radar system
US3085239A (en) * 1957-03-18 1963-04-09 Rca Corp Radio-frequency switching
US3135955A (en) * 1960-02-15 1964-06-02 North American Aviation Inc Search controller
US4579035A (en) * 1982-12-06 1986-04-01 Hollandse Signaalapparaten B.V. Integrated weapon control system

Also Published As

Publication number Publication date
FR948577A (fr) 1949-08-04
GB658745A (en) 1951-10-10
NL79497C (fr)

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