US2717374A - Deflection voltage generator - Google Patents

Description

Sept. 6, w55 G. E. WHITE ZWM DEFLECTION VOLTAGE GENERATOR Original Filed April C50, 1942 4 Sheets-Sheet l 2 j U L, J l

.sfRc/e/ TRR/VSM/Tf/e SCAN/VER RECE/ VER VD/C TOR a# z5 Q l GUNS COMPUTER 7 g3 Z j TRRcR/N@ 1 g3 MON/TOR M6 R565/ VER 9 7 Cif/gi INVENTOR. 7 VP/ URD E. l/l/H/ 7.5

TTORNE Y LU-l Sept. 6, 1955 i G, E, WHH-E 2,777,374

DEFLECTION VOLTAGE GENERATOR Original Filed April 30, 1942 4 Sheets-Sheet 2 Sept. 6, 1955 G. E. WHITE 2,717,374

DEFLECTION VOLTAGE GENERATOR Original Filed April 30, 1942 A 4 Sheets-Sheet 3 Ln/ML WUVU Pfg., 7%.

IN VEN TOR. GAL-FORD E. WH/ T5 /4 TTH/VEY Sept. 6, 1955 G. E. WHITE 2,7l7,374

DEFLECTION VOLTAGE GENERATOR 4 Sheets-Sheet 4 Original Filed April 50, 1942 SLI 55 INVENTOR. @Vf-FORD ./5'. WH/ TE ,4 T TOR/VE Y United States Patent 2,717,374 DEFLECTION VOLTAGE GENERAroa Gilford E.l White, Woodland Hills, Calif., assignor to SperryiRand Corporation, a corporation of Delaware Original application April 30, 1942, Serial No. 441,188. Divided and this application March 25, 1948, Seriai No. 17,042 l 12 Claims. (Cl. 340-212) The presentV invention is concerned with radio-directed re control systems especially adapted for use in aircraft and against other fast moving aircraft.

Thepresent application is a divisional of copending application Serial No. 441,188, filed in the United States Patent Ofce on April 30, 19,42, now U. S. Patent No. 2,617,982, granted November 11, 1952.

Forthe protection of large aircraft, such as heavy bombers, itis known to use flexible gun turrets movable independently of the craft in association with a computing gun sight or computer which is manually tracked with the target and thereby derives the proper gun aiming data for controlling the gun turrets. Up to the present time, however, such inter-aircraft re control devices, and also anti-aircraft re control devices, have relied upon visual tracking ofthe target for determining the correct gun aiming angles. Such prior art systems are subject to the well known limitations of visual sighting, such as reliance upon proper weather and visibility conditions,

upon sulicient lighting, and upon the restricted range of optical telescopes. Even under optimum conditions of visibility, the visual detection of the approach of aircraft and visual tracking with aircraft have been diicult and uncertain. For instance, aircraft approaching from the direction of the sun can be seen only with the greatest difficulty. Furthermore, the observer cannot scan the whole zone of danger quickly and carefully with certainty bythe eye alone.

In order to overcome these and other disadvantages of the prior systems, lthe invention of parent application e Serial No. 441,188 provides a system in which the target is detectedjlocated and tracked by a radio beam which etectively replaces the visual line of sight of prior systems. However, before describing the present system, certain essential requirements for such a system will be discussed.

Firstly, the defending aircraft must be apprised of the presence and approximate direction or orientation of all targets in its vicinity in o rder to be able to eectively plan andaccomplish its defense. ln addition, it is desirable that the approximate range of each of these various targets should be indicated simultaneously with its location, for similar reasons. After having been warned of the presence, orientation, and range of these targets, and after having chosen one or more of them as of greater importance for immediate engagement, it is necessary for the particular target selected' to be tracked by the re control system in order to determine the target present position, such as dened .by its elevation, azimuth, and range, in the present case, and to determine the rate of change of position, as defined by target elevation rate and azimuth rate, in order. that the correct gun aiming angles for controlling the guns and vturrets may be derived by the computer.

Y In order to relieve the tire control olcer of as much of the burden of tracking as is reasonably possible, it is desirable` to automatically track with the target, at least inv elevation and azimuth, and possibly also in range, so as to automatically set into the computer mechanism the proper target position and target rate data.

The' system of lsaidparent application Serial No. 441,188 offers an improved type of warning or searching "ice into any one of three different types of trackingsystemsz (1) a system in which the fire control olicer actuates the computer setting in such a manner as to maintain a radio line of sight in track with a'target, (2)` a system in which a radio line of sight is automatically tracked with a target and the iire control oicer actuates a computer to maintain it in synchronism with the radio line of sight,

and (3) a fully automatic system in which a radio line of sight is automatically maintained in synchronism with the target and serves to automatically set into the cornputer the proper target data required by the computer.

By such a system both the warning and tracking may be performed entirely independently of any optical visibility conditions and at a much greater range than was formerly possible, without impairing in any way any of the desirable features of former types of fire control systems.

In addition, the operation of the system is made to agree in substantially all operations to be Vperformed with the operation of prior systems and the natural instinctive reactions of the operator are utilized by the provision of controlling operations which are naturally dictated by the circumstances encountered.

It is the prirnary object of this invention to provide apparatus for producing deflection voltages for a cathode ray tube or the like; and to provide such voltages as will produce a predetermined sweep path of the beam of the cathode ray tube.

More particularly, itis an object of the present invention to provide deection voltage generating apparatus that will provide a sweep of the cathode ray beam in synchronism with a movable element such as a directional antenna. v

It is a still further object to provide dellection voltage generating apparatus that will provide a spiral sweep of the cathode ray beam; apparatus that will selectively produce different sweep configurations such as a spiral sweep and a circular sweep; and apparatus of this character that will produce both of these sweeps in syn,`

chronism with and in simulation of an element such as a directional antenna as it scans a portion of space either spirally or crcularly in what is ordinarily termed a conical scan.

Other objects and advantages of the presenty invention will become apparent from the following specification' and drawings, in which,

Fig. l shows a block or flow diagram of the system of the invention during searching operations.

Fig. 2 shows a corresponding block diagram of the system during manual tracking operations.

Fig. 3 shows a corresponding block diagram of the system during manual automatic operations.

Fig. 4 shows a block diagram of the System during full automatic operations.

Fig. 5 shows a schematic perspective View of one form of scanner useful in the present system.

Fig. 6 shows the radiation pattern of the directive antenna array used with the scanner of Fig. 5.

Fig. 7 shows a longitudinal cross-sectional View of the radiation pattern of the scanner of Fig. 5 during any of the tracking operations.

Fig. 7A is a cross-section of Fig. 7 taken in about the plane 7A-7A thereof.

Fig. 8 shows a schematic block wiring diagram of one form of radio transmitting, receiving and indicator circuit for searching operations.

Fig. 8A shows a representative view of the cathode ray screen of the indicator of Fig. 8.

Fig. 9 shows a schematic circuit diagram of the spiral sweep or reference voltage generating apparatus for the circuit of Fig. 8.

Figs. 10A, 10B, 10C, and 10D are voltage-time graphs useful in explaining the operation of the circuit of Fig. 9.

Fig. 11 shows a modification of a portion of the circuit of Fig. 9 to the right of line A-A thereof.

Fig. 12 shows a further modification of the spiral sweep or reference voltage generating apparatus of Fig. 9.

Fig. 13 illustrates the phase relation of the detlection voltages derivable from the apparatus of Figs. 9, 11 and 12 to produce a circular deflection of the cathode ray beam.

Fig. 14 shows a block circuit diagram of one form of indicator useful during tracking operations.

Fig. 14A shows a representative indication produced by. the. circuit of Fig. 14.

Although I have herein described my invention in connection with a gun control system and particularly in connection with a more comprehensive system, more fully described in parent application Serial No. 41,188, it is to be understood that my present invention is not necessarily limited to. such use but may be employed in other indicating systems involving diierent parameters.

As discussed above, the system with which the present invention is adapted for use, is adapted for two major types of operation, namely, (1) a searching operation for roughly indicating the position and/ or distance of any targets within the field of operations of the device and (2) a tracking operation in which a particular target may be selected and followed by the device for properly directing` a gun thereat. Three alternative types of tracking operation, known as manuaL semiautomatic, and full automatic tracking may be used.

For describing generally these various types of operation, recourse is had to Figs. 1-4, more specic details of the system being described with respect to later figures.

Fig. 1 showsv a. block orow diagram of the present system when` operating during searching. In this system, a scanner 1 projects a sharply directive beam of radiant energy, such as 19 in Fig. 6, obtained as from a suitable transmitter-2 and` directive antenna arrangement 3. This beam comprises a periodic` sequence of short duration pulses of high frequency energy, and during searching is swept in a spiral cone overr a predetermined solid angle, which is preferablyy substantially a hemisphere, in such manner that-the radiant energy is projected at some time duringits cycle intoeverypart of the solid angle. Should any object or target be located in this solid angle, the projected radiant energy-will be reflected therefrom when the beam is directed thereat, and will be received in the same antenna system 3, which acts dually as a transmittingand a receiving system.

This reected series of pulses of high frequency energy is received in a radio receiver 4 whose output actuates a suitable indicator 6. This indicator, as will be described below more in detail, is preferably a cathode ray tube whose electron beam trace is caused to sweep in spirals in synchronism with and instantaneous correspondence with the spiral scanning motion of the scanner. For this purpose the indicator 6 is also controlled from scanner 1. The received reected pulse is caused to momentarily brighten the trace of the beam and thereby produce on the cathode ray screen an indication of the existence and approximate orientation of the reilecting object. The approximate range of the reflecting object may also be( shown.

The orientation of the scanner 1, which may be taken to be the orientation of the polar axis of the spiral conical scanning motion, is placed under the control of a computer 7, whose elevation and azimuth settings may be manually actuated froma suitable manual control 8. Computer 7 is adapted to calculate the proper gun aiming angles for intercepting the target by a projectile when the computer is set in accordance with the present target position data, such as elevation, azimuth and range of the target, and in accordance with the rate of change of the present target position, such as elevation rate andy azimuth rate. A suitable form for such a computer is shown more in detail in copending application Serial No. 411,186, for nter-aircraft Gun Sight and Computer, tiled September 17, 1941, in the names of C. G. Holschuh and D. Fram, now abandoned. This application was reled as application Serial No. 492,838, which matured into U. S. Patent No. 2,399,676 on May 7, 1946. As is shownA in this copending application, the range setting of cornputer 7 may be performed by a suitable foot pedal 10. The orientation control is effected by a handle bar control 8 Whose displacement about two independent axes' represents a combination of the displacement and rate of change of displacement of azimuth and elevation settings of computer 7, providing aided tracking. In operation, the controlling othcer actuates control 8 so as to maintain the present target position setting of the computer 7 in tracking with the target, as evidenced in the prior application) by a suitable optical sighting arrangement. By so doing, the proper target elevation, target azimuth, tar- 9 get elevation rate and target azimuth rate are set into the computing mechanism 7 together with the range data sety in by foot pedal 10, whereby computer 7 may determine the gun aiming angles. In the present system, the same operations are performed, but utilizing a different type of indicator to show the proper tracking conditions, as willv be described.

The scanner 1 is suitably controlled, as will be seen hereinafter, in accordance with the target elevation and' target azimuth setting of computer 7. The gun aiming angles determined by computer 7 are used to'suitably control the orientation of one or more guns or turrets 9, which are thereby rendered effective against the target.

A suitable type of gun control apparatus for orientingV the guns 9 under the control of' the computer 7 is shown in copending application Serial No. 424,612, for Hydraulic Remote Operating Systems, tiled December 27S, 1941, in the names of E. L. Dawson, F. M. Watkins and C. N. Schuh, Jr., and now U. S. Patent No. 2,445,765', issued July 27, 1948. It is to be noted that the present f system is not confined to the use of this particular type of gun control apparatus, but that any other suitable type of remote control system may also bev used., If desired, the guns 9 need not be directly controlled from com puter 7 but may be locally controlled in accordance with suitable indications transmitted from computer 7 inA any well known manner.

The system as shown in Fig. 1 is not intended for use as the actual gun control system but, is merely intended. to search out possible targets and to enable the scanner to properly locate a` target for the purpose of later tracking with it. For this reason, the control from computer 7 to guns 9 is shown dotted in Fig. l. After a target is. observed on the screen of cathode ray indicator 6, the manual control 8 of computer 7 is actuated4 to adjust` the orientation of scanner 1 to the positionwhere this orientation coincides as closely as possible with thevorientation of the desired target, as evidenced by the position. of the bright spot indication on the indicator screen. When this adjustment has been made, the system is ready to change over to the tracking operation.

The system is adapted to use three separate and distinct types of tracking, any one ofwhich may be selected at the option of the fire control oflicer. It is to be noted' that each of these typesV of'l tracking system may be used'- independently ofthe others if, desirable. For all' of these,

sans@ types oftracking operation, scanner 1 is energized from transmitter 2 by the same type of periodic pulse wave as described with respect to the searching operation. However, scanner 1 no longer performs spiral scanning as in Fig. 1 but instead it is converted to perform a. narrow circular conical scanning withfa very small apex angle. Preferably, this angle is of the order of the angular width of the radiation and reception pattern derived from antenna 3, indicated in Figs. 6, 7 and 7A.

Thus, if antenna system 3 is adapted to produce a beam of radiant energy having a directive radiation pattern such as 19 in Fig. 6 with a directivity axis 21 then, during tracking, beam 19 will be rotated by scanner 1 about an axis such as 23 in Fig. 7, whereby directivity axis 21 performs a conical motion about axis 23, which may be termed the tracking directivity axis since it is this axis which Vdefines the radioline of sight, as will be seen. Preferably, radiation patternp1`9 is made to have a small apex angle such as of the order of 4 in angular width between the half-power points. Then, during tracking, the cone described by axis 21 would preferably have an` apex angle also of the order of 4. In this manner, the useful portion of the radiant energy would be projected over a conical solid angle having an `8 apex angle. Energy reilected from an object or target within the field of this radiant energy will be received by antenna arrangement 3 and led thereby to receiver 4 whose output actuates the tracking indicator 6 to indicate the relative displacement between the scanner orientation defined by axis 23 and the orientation of the target.

In the system of Fig. 2, manual actuation of computer control 8 serves to set azimuth and elevation data into computer 7 and at the same time controls the orientation of scanner 1, as determined by axis 23, to assume the same azimuth and elevation as is set into computer 7, in the same manner as described with respect to Fig. 1. In effect, the orientation of scanner 1 is made the same as the orientation of computer 7, the latter term meaning the orientation corresponding to the azimuth and elevation data set into the computer mechanism.

Also actuated from receiver 4 is a range indicator 6". A matching index is provided for indicator 6", as will be described more in detail below, which is placed under the control of range pedal serving also to set range data into computer 7.

In operating the system of Fig. 2, the operator will, by his manual control 8, orient scanner -1 until the, tracking indicator 6 shows that the target orientation coincides with the scanner orientation. At the same time, the operator actuates the range foot pedal,10 to match the range index to the indication produced by range indicator 6". When these-conditions obtain, and are maintained even during the motion of the target, the operator will know that the proper data is set into computer 7 and that the guns 9 controlled fromy the computed output of computer 7 `are directed at the correct aiming angles to intercept the target with aV projectile, and he may therefore, by a suitable firingkey orcontrol, iire at the target. y

This system is known as manual tracking since the operator, through his manual control 8 and foot pedal 10, directly actuates the scanner and computer- 7 to track with the target as evidenced by indicators 6 and 6". The scanner 1, `in effect, voperates to produce a radio line of sight in the same wayas the sighting telescope in a conventional` anti-,aircraft or inter-aircraft system operates to producevanfopticalline of sight, to enable the computer 7 toy track with the present position of thetarget, whereby the proper gun aiming angles are determined. Y l i Y Y n A second type of tracking operation is illustated in Fig. 3 and is termed semiautomatic tracking. Y In this4 case the scanner `1, againrperforming circular conical scanning as describedy with respect to Fig. .2, lis caused to*A automatically'align its orientation with that of the target. This is done by using? thereflected pulsesre-l ceived from the target to.actuate suitable servomto'rs for orienting the scanner, which is` thereby automati-l cally oriented 'toward and tracks with the targetf'The computer 7 is again manually controlled fromv controls 8,- in this instanceto follow and track with the orientation of scanner 1. Thus, tracking indicator l6 in4 Vthis,

type of system serves to indicate thefdisplacement between the orientations of scanner 1 andV computer 7, and computer 7 is actuated to maintain this computer error" at zero. When this conditionobtains, and with the proper computer range adjustment, y'similar to that described in Fig. 2, the output of 'computer 7, ,controlling guns 9, again represents theproper gun aiming angles and effective tire may be obtained from the guns. i

Fig. 4 shows the third or ffull automatic tracking system in which no manual actuation is necessary. VHere, scanner 1 is automatically oriented toward theQtar'get, under the control of the outputof receiver 4,.as in Fig. 3, and in addition the orientation of ,computer 7 is caused to automatically follow ,the position of scanner 1 by a suitable servo mechanism. In this manner, the proper target azimuth and elevation data are set into the computer 7. The range adjustment of computer 7 is also automatically performed by a range control 10' under the control of'receiver 4. This system, however, d oes not obtain the target rates, that is, elevation rate and azimuth rate, in the same manner as in Figs. 2 and 3. In the system of Fig. 4, it is necessary to determine elevation rate and azimuth rate by actually measuring the angular rate of motion of the azimuth and elevation input controls of scanner 1. This may be done in any well known way, such as is shown and described in U. S. Patent No. 2,206,875, for Fire Control Device issued July 9, 1940, in the name of E. W. Chafee et al. In this manner, all the required data may be set into computer 7 and therefore the guns 9 are automatically oriented at the proper gun aiming angles and automatically follow the target with, of course, the computer lead angles.

Indicator 6 in this instance merely serves as a monitor indicator to show how well the scanner 1` is following the target or, alternatively, how well the computer 7 is following and tracking with scanner 1. Indicator 6" serves similarly as a range monitor indicator.

The system is therefore capable of four alternative modes of operation, namely, searching, manual tracking, semi-automatic tracking, and full automatic track` Fig. 5 shows a schematic representation of one suitable type of scanner 1. Thus, the scanner 1 may comprise a directive antenna system 3, shown as comprising a parabolic wave guide reflector, and energized through suitable electromagnetic wave guide connections 11 from transmitter 2. A suitable construction for scanner 1 is shown and described in copending application Serial No. 438,388, for Scanning Devices, led April 10, 1942, in the names of L. A. Maybarduk, W. W. Mieher, S. J. Zand and G. E. White, now U. S. Patent No. 2,410,831, issued November 12, 1946. As therein disclosed, the antenna arrangement 3 in one form may be.

continuously nodded or oscillated at a slow rate about nod axis 12 which is itself rapidly and continuously rotated or spun about spin axis 13 thereby producing a spiral conical scanning pattern by the continuous widening of the conical sweeping about spin axis 13. To convert from the spiral searching scanning to the circular tracking scanning, the nod motion about the nod axis 12 is interrupted, with the orientation of the directive radiation or receptivity pattern axis 21 dis? 7 438,388, and in Copending application Serial No. 447,524 for High Frequency Apparatus, tiled June 18, 1942, in the names. vof W.v W` Mieher and J. Mallet, now U. S. Patent No.1 2,407,318, issued September 10, 1946.

T0 provide thev necessary control of tracking indicator 6 from scanner 1, in the manner to be described, suitable self-synchronous positiony transmitters are provided for producing signals indicative of the instantaneous position of the'radiator in nod and in spin, that is, indicative. of the orientation of axis 21. The nod transmitter is indicated schematically at 17, the spin transmitter `at 18. These transmitters may be of the well known selsyn, Autosynf or Telegon types.

Referring to Fig. 6, there is shown the radiation or receptivity pattern 19, of the antenna array 3. of Fig.. 5,. It ywill be noted, that this, radiation pattern 19 preferably is axially symmetrical about axis 21, and is substantially contained-within a narrow solid cone 22, thereby formingy asharply directive beam of transmitted energy or a sharply directive reception pattern. been exaggerated for purposes of illustration, and preferably is very narrow, such as about 4 between the halfpower points. During searching operations the axis 21 of this beam 19, by virtue of the combined effect of the. nodding and spinning action of scanner 1, is caused to sweep out a spiral cone in space, the solid angle of this sweep being4 suitably chosen and ranging up to a complete hemisphere as desired. Preferably, the angular pitchY of this spiral is chosen to be of theorder of the effective angular width. of the beam 19 whereby, during one complete spiral scanl every portion of the conical solid angle will have had radiant energy projected to it, and radiant energy may be received from every such portion. The rate of nod' and spin of the scanner of Fig. 5 are suitably chosen to provide a sufficiently short time interval for a complete scan, suitable for the purposes at hand.

DuringV tracking operations the nod motion of scanner 1 is stopped' at a position so that the axis 21 of maximum radiation or receptivity is displaced slightly from the spin axis 13 about which the radiation4 pattern 19 is, rot-ated. ln this way, as shown in Figs.V 7 and 7A, energy of constant intensity is radiated or received along an axis 23 co incident with spin axis 13. However,- along some other axis, such as 24, for example,Y maximum radiation and. maximum receptivity is encountered only once during each spin cycle, resulting in a spin frequency modulation of waves received by retlection from4 an object oriented along axis 24'.

The use of the same antennay arrangement for transmitting and receiving increases the sharpness of the resulting determinations since the over-all response pattern is; the product of the radiation and receptivityl patterns. If desired', however, aV non-d`irectional transmitter or receiver could be used with the described scanner acting. respectively as a receiver or transmitter.

Conversion from searching to tracking scanning is` effected as. described in application` Serial No. 438,388, merely by energization of a suitable control sdenoid. Other types of Scanners are also described therein.. re`

quiring different apparatus for converting from searchingv to tracking, but all adapted to be usedr for searching or tracking in the. same manner as the scanner of Fig. 5.

It may also, be desirable `to adjust the axis of this spiral scanning during the searching operation. For this purpose, scanner 1' may be provided with an elevation axis 26 and' an azimuth axis 27 about which it may be suitably adjusted, in the manner described in application Serial No. 4383388', theA control action being as -described below. Also, suitable elevation and` azimuth position transmitter-s 28 andv 29may be used, as will` also be described below.

Fig*l 8 shows one form of'radi'o and indicator system for givingsuitable indications during searching. Thus,

assuming that' the scanner of'Fig. 54 is performing the spiral.

scanning; described above, antenna array 3 is fed with Pattern 19 has Lf radiant energy as over wave guide 11, from a transmitter and modulator u-nit 31. This transmitter 31 is adapted to produce high frequency radiant energy in any well known manner, and to modulate this high frequency energy by means of periodically recurring short duration pulses such as may be derived from a conventional control oscillator and pulse generator 32. There is thus radiated from the radiating arrangement 3 a sequence of short pulses of high frequency radiant energy. The frequency of control QScillator 32 and thereby the repetition frequency of the radiated pulses is chosen to have a suitably high value such that a substantial number of pulses is sent out during each spin rotation of the scanner 1 of Fig. 5. Suitable valuesl for various constants of the circuits during this form of operation have been found to be the following: spin .ro-tation, 1200 revolutions per minute; nod oscillation, 30 complete oscillations `per minute; pulse repetition frequency, 2000 per second. With these values it will be seen that one complete cycle of spiral scanning will be accomplished each two seconds, one second being taken up in a spiral scan from zero nod to full nod, the other second of the cycle comprising the time for spiral scanning from full nod back to zero nod. During each half of the complctc cycle 20 complete spin rotations are performed. Thus, for a full hemisphere of scan the angular advance for each spinv cycle will be approximately 41/2 degrees, which is of the order of magnitude of the width of the radiation pattern 19- shown in Fig. 6. The pulse repetition rate or" 2000. pulses per second gives 1-00 pulses per spin rotation, which thereby produces one pulse for each 3.6 degrees of` motion of the radiation pattern 19 during scanning. Since the radiation pattern 19 is approximately 4v to, S degrees. wide, it will be seen that at least one pulse of radiant energy is transmitted to each point of the hemisphere.

Should a distant object be in the eld of the system during radiation, at least one pulse will be incident thereon, and reected therefrom. This reflected pulse or pulses will be picked up in the antenna arrangement 3 and conducted through wave guide 11 to the receiver unit 4 through a ri`.-R box 33. T-R box 33 is adapted to pass the relatively l'ow intensity received pulses but to block out the relatively high intensity transmitted pulses derived from transmitter 31. A suitable form for such a T-R box 33 is shown in copending application Serial No. 406,494 for Radio Apparatus for the Detection. and Location of Objects, led August 12', 1941 in the name oil'. Lyman et al., and in, continuation applications Serial Nos. 754,420 and 780,160. based on said application Serial No. 406,494, and comprises, as i's therein shown, an ionizable medium containing a spark gap within a resonant cavity which is resonant` to the high frequency of transmission. The spark gap. i's so adjusted' that the. low intensity received waves are insufficient to createI a discharge across the. gap, whereas the high intensity transmitted pulses are suticient to create such a discharge, which thereby ionizes the ionizable medium and" effectively short circuits the wave guide 11 to these transmitted waves. In this manner the receiver unit 4 is effectively isolated from the high intensity transmitted pulses while being free tol receive the pulses reiTectedV from a distant object. Receiver unit 4 includes conventionalvr pre-amplifying, detecting and wide-band amplifying units, all well known in the art, and is adapted to produce, in its output, signal' currents or voltages corresponding to the wave shape of the envelope of the received' reflected' wave;

The, received pulses are applied to the control grid 37 of'the cathode ray tube indicator 6 shown in Fig. 8'. Gnid 37 is provided with a suitable bias, as by way of lead 38,' such that, with no output from receiver 4, the cathode, ray.- beam, produced. by. the usual. means, is preventedfromreachingthe screenof the cathode ray" tube indicator 6,'. Howeven, this. biasY is. also. so adjusted that the. received pulses, 36 derived from the receiver unit 4. are, permitted to momentarily render, the. electron` beam trace visible on the screen of indicator 6. Thus, it will be clear that each time a reflected pulse is received a momentary bright spot occurs on the cathode ray screen.

In order to give an indication of the orientation of the reflected object with respect to the location of the system of the invention it is desirable to produce a spiral scanning of the electron beam in synchronism with and corresponding instantaneously to the spiral scanning of the radiation and reception pattern 19. Suitable devices for obtaining deflecting voltages which will produce such a spiral scanning are shown in Figs..9 through 12. Assuming, for the moment, that such spiral sweep voltages, designated as P1 and P2, have been obtained, these voltages P1 and Pz, to be hereafter described more in. detail, are impressed upon respective pairs of deflecting` plates of the cathode ray indicator 6 and produce a spiral scanning of the electron beam such that at each instant the orientation of the latent trace of the beam on the screen displaced 90? in space with respect to winding 52, will have induced in it a voltage of similar wave shape but displaced 90 in phase at the spin frequency. In efect, spin transmitter 18 serves as a two-phase generator of spin frequency whose output amplitude is controlled by nod transmitter 17.

of the cathode ray indicator,6 with respect to the screen the control of receiver 4 will produce a momentary brightV spot such as 41 shown in Fig. 8A. If a plurality-of objects having different orientations are within the effective field of the searching system further bright spots such as 42 and 43 will also be produced, each having an orientation with respect to pole 39 respectively corresponding to the orientation of `the corresponding reflecting object with respect to the spin axis 13 of the scanner 1.

As described above, the transmitted pulses and hence the reflected pulses are of quite short duration, such as the order of 1 microsecond. In order that the bright spots 41, 42 and 43 may be more clearly shown it is desirable to let the beam impinge upon the screen for a longer interval. For this purpose a signal storer 44 is inserted between receiver 4 and intensity control grid 37. This signal storer 44 may simply comprise a condenserresistor network adapted to be instantaneously charged by a pulse derived from receiver 4 and which will maintain its charge beyond the duration of the pulse. However, the time constant of the signal storer 44 is preferably so chosen that this accumulated charge will be fully dissipated within a time not much longer than one recurrence period of the transmitted pulses in order that erroneous indications shall not be obtained. l In this way the traces 41, 42, 43 are made brighter. In addition, the screen of indicator 6 is preferably made of high retentivity, so as to maintain its indication for asubstantial interval after excitation is removed.

Fig. 9 shows one form of circuit for producing the spiral sweep voltages used with indicator 6 of Fig. 8. In this figure, nod transmitter 17 is indicated as being of a two-phase type having a single-phase energizing winding 46 and a two-phase secondary winding 47, in this instance connected in series to provide a single output. Winding 46 is energized from a suitable source 48 of alternating current. The output voltage appearing across the polyphase winding 47, namely voltage V1 having a wave shape as shown in Fig. 10A, will therefore be an alternating voltage having the frequency of source 48 and an amplitude varying in correspondence with the amount of nod, referred to the orientation of the scanner spin axis as zero nod. This wave is shown in Fig. 10A, being illustrated as having a linear change of amplitude with nod. It is to be noted that ordinarily this change of amplitude will be sinusoidal in character. However, by the use of proper motionconverting devices whereby full nod motion corresponds to a small angular displacement of winding 46 with respect to winding 47, it may be made linear as illustrated. Preferably full nod is made to correspond to less thanl 45 rotation of transmodulated wave.

To each of these voltage Voutputs from windings 52 and 53 there is added a voltage of the frequency of source 48, as Vby way of transformer 54, producing the wave shown in Fig. 10C. It is to be noted thatthe wave of Fig. 10B represents in effect a suppressed-carrier The reinsertion of the carrier as by transformer 54 produces the usual modulated carrier wave shown in Fig. 10C. Theresulting two waves are then rectified or detected in respective rectiiiers 56 and 57 and filtered in lters 53 and 59 to produce the output as shown in Fig. 10A.

voltages appearing on output leads,61 and 62 having the wave shape shown in Fig. 10D, namely, phase-displaced voltages of spin frequency modulated by the nod wave envelope.

These two voltages appearing on lines 61 and 62 will be phase displaced by of the spin frequency. They will be termed the spiral sweep voltages P1 and P2, respectively. As is well known, if two voltages of equal amplitude andfrequency, phase displaced by 90, are impressed on the respective pairs of deecting plates of a cathode ray tube, the resulting traceof the electron beam will be circular. By simultaneously varying the amplitudes of the two voltages the diameter of the circle will be varied.

In the present instance, by using the two waves P1 and P2 as the deilecting voltages, the beam will be caused to produce a circular pattern of constantly changing diameter and will thereby produce a spiral pattern similar to the pattern swept out in space by the scanner 1. It will, therefore, be clear that these voltages P1 and P2 are particularly suited for usein indicator 6.

During any of the three types of tracking, nod transmitter 17 is disconnected from spin transmitter 18 .by switch 49, which then connects winding 51 of spin transmitter 18 to a xed source of alternating voltage, such as source 48, as byA way of lead 5i). In this case, output sweep voltages P1 Vand P2 will have constant amplitude, producing a circular trace on indicator 6, and accordingly will be termed circular sweep voltages.

Fig. ll shows an alternative circuit for inserting the carrier and demodulating the waves produced by spin transmitter 18 to produce the sweep voltages P1 and P2. Thus, here the respective outputs of windings 52 and 53 are impressed upon the grids of respective detector or demodulator tubes 63 and 64 whose plate circuits are energized simultaneously from alternating voltage source 48. By properly phasing the anode voltage with respect to the grid voltages, and by filtering out all carrier fre-V quency components, as in filters 58 and 59, the same type of spiral sweep voltages P1 and P2 will be obtained as in Fig. 9;

Fig. l2 shows a further modification of the spiral sweep voltage generatingcircuits of Figs. 9 and 1l, particularly adapted for using conventional autosyn or selsyn devices. Thus the nod transmitter 17 comprising, as is well known, a three-phase type winding 47 and a single-phase winding 46' relatively rotatable with respect to one another, 'has two of its polyphase eld windings energized in series from the source 48 of alternating voltage the third winding remaining unenergized. In effect, therefore, there is produced in the single-phase winding 46' a varying alternating voltage similar to the voltage V1 shown in Fig. A. It will be apparent. that nod transmitter 17 of Fig. 9 and transmitter 17 of Fig. 12 are completely interchangeable, since, as used, they produce the same voltage output. This voltage derived in winding 46 is fed to the single-phase winding 51 of the selsyn type spin transmitter. There is thereby producedv in the polyphase windings 52', 53 and 55' three voltages of the character shown in Fig. 10B, relatively displaced 120 with respect to one another and thereby forming a three-phase spiral sweep voltage. This three-phase voltage is converted into a two-phase voltage in a conventional Scott T transformer 66, which isv well known in the art. The two-phase voltage output of transformer 66 is combined with a carrier voltage derived from source 48 by way of transformer 54, identical to that in Fig. 9 and the resulting voltages are each demodulated in respective demodulators 67 and 63 of any well known type, to produce the required sweep voltages P1 and P2 as before.

Here again means are provided for converting voltages P1 and P2 from spiral sweep voltages to circular sweep voltages. This means comprises switch 65 which connects winding 51' of spin transmitter 18' to nod transmitter 17 during searching, and to a xed source 48 during tracking.

Fig. 13 represents the sweep voltages P1 and P2 which are derived from the foregoing voltage generating apparatus when no modulation corresponding to the nod motion of the antenna or transmitter is effected. These voltages indicated as 70 and 71 respectively, have substantially equal maximum amplitudes and are of a frequency corresponding to the spin frequency of the antenna, being phase displaced by 90. These voltages are therefore useful under tracking conditions, whenl conical scan is effected, as azimuth, and elevation reference voltages in determining those error components of the angle of error between the directivity axis of the scanner and the direction toward the chosen target. The spiral sweep voltages P1 and Pz will have the appearance of that shown in Fig. 10D, but phase displaced as in Fig. 13.

During manual tracking, in which the scanner 1 and computer 7 are manually actuated together, it is necessary to provide some type of indication whereby the gunner may know when he is accurately tracking with the target; that is, when scanner 1 is oriented toward the target, and the correct target orientation data is being set into computer 7.

Fig. 14 shows one type of such tracking indicator circuit. As described above, during all tracking operations, including manual, semiautomatic and full-automatic tracking, the transmitted beam is rotating about a very narrow cone, as illustrated in Figs. 7 and 7A. If the target is situated exactly along the axis of symmetry 15 (or 23) of this cone, all reflected pulses will be received with constant and equal intensity. This indicates proper z tracking with the target. Should the target, however, deviate from this desired condition, as when its orientation is along axis 24 of Fig. 7, the reected pulses will periodically vary in amplitude at a frequency equal to the spin frequency of the scanning. In effect, this produces a spin frequency modulation upon the received pulses.

Furthermore, it will be clear that the instantaneous maximum of this spin frequency modulation will occur at the instant the axis 21 of the beam is projected closestv to line 24. Hence the phase of this modulation bears a relation to the spinning of the scanner which is indicative of the orientation of the reflecting object. Accordingly, the orientation of the object with respect to spin axis 13 (or 23) may be determined by comparing thephase of the modulation with the spin cycle ofthe scanner, or, which is the same, with the sweep voltage- Pi and P2, which will be of fixed amplitude upon operation of the switch to cut out unit 17 or 17 and havefixed phase relation to the scanner motion.

Thus, referring to Fig. 14, the receiver output 94, nowl comprising the received pulses 36 periodically varying in amplitude at theY spin frequency, is applied to a further detector, such as 107, including a filter adapted to pass waves only of the spin frequency, whose intensity will therefore give a measure of the amount of deviation of the target from the desired orientation, with respect to the tracking system (within a predetermined region), and whosephase with respect to voltages P1 and P2 indicates the relative orientation of the target with respect to the scanner orientation. Preferably, detector 107, also acts to iill in the wave envelope between pulses, whereby a substantially sinusoidal output in phase with the pulse modulation is obtained.

Such phase comparisons are performed in the respective azimuth and elevation phase sensitive ampliers 108 and 109 in Fig. 14. These amplifiers are of any conventional ftype adapted to produce in their outputs a unidirectional voltage corresponding in polarity and magnitude to the sense and magnitude of the component of the output of detector 107 co-phasal or anti-phasal with the reference voltage P1 or P2.

The respective outputs of amplifiers 108 and 109 are connected to the respective deecting plates 99, 101 of indicator 6 and will thereby produce on its screen a bright dot, such as 111, shown in Fig. 14A, whose position relative to the pole 39 of the screen is the same as the position of the reflecting object relative to the axis of Ithe conical. scanning performed by the scanner 1 and hence indicates the displacement or error between scanner and target. It will be clear that the fire control oicer, to performv accurate tracking, must control the settings of the computer in such a manner that spot 111 is maintained at the pole 39, in which case the scanner is oriented toward the target and the proper azimuth and elevation data corresponding to present target position are introduced into computer 7. If, at the same time, the range control 10 of the computer 7 is adjusted, the complete data required by computer 7 is thus set into it, and the output of computer 7 may serve to correctly orient the guns or turrets 9 to effectively engage the target.

As many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

l. Apparatus for producing deflecting potentials adapted to control the sweep of the electron beam of a cathode ray tube, said apparatus including a source of constant amplitude, alternating voltage, a first modulator means connected to said source of voltage for variably modulating said voltage in amplitude in accordance with desired variations in radial displacement of the electron beam from the electrical center of the tube, and a second modulator means connected to receive the output of said rst modulator means comprising two modulating parts for respectively modulating the voltage supplied thereto in like sinusodial manners but in relatively phase displaced relations, whereby to provide two output voltages of like wave formv and amplitude but relatively 90 displaced in time phase.

2. Apparatus for producing spiral detlecting potentials adapted to control the sweep of the electron beam of a cathode rayk tube, said apparatus including means for producing an alternating voltage having a frequency of variation of amplitude corresponding to the desired angular rate of sweep of the electron beam, means for controlling the amplitude of said voltage to vary in accordanceI with desired variations in displacement of the electronv beamradially fromy the electrical center of the tube, and. means for rectifying the output of said last mentioned means.

3.. Apparatus for producing spiral deecting potentials 13 adapted to control fthe sweep of an indicating means, said apparatus comprising means for producing an alternating electrornotive force having the amplitude of its wave envelope varying as the radius of a spiral, a first modulator for modulating said electromotive force by a signal having a frequency corresponding Ito the desired angular rate of sweep of said indicating means, a second modulator for modulating said electromotive force by a signal having a phase quadrature relation to said irst modulating signal, and means for demodulating the outputs of said modulators for producing spiral deecting potentials.

4. Apparatus for producing spiral deflecting potentials adapted to control the sweep of an indicating means, said apparatus comprising means for producing an alternating electromotive force having the amplitude of its wave envelope varying as the radius of a spiral, a rotary transformer having a primary winding connected to said means and two secondary windings arranged in phase quadrature relation, means for relatively rotating said primary and secondary windings according to the desired angular rate of sweep of said indicating means, and means for demodulating the outputs of said two secondary windings for producing spiral deilecting potentials.

5. In combination with a spiral scanning device, apparatus for producing deflecting potentials adapted to spirally scan the beam of a cathode ray tube synchronously with said device, comprising means for varying the amplitude of an alternating electromotive force synchronously with each scanning cycle of said device, a first modulator for modulating said electromotive force by a signal of frequency corresponding to the rate of rotation of said device, a second modulator for modulating said electromotive force by a signal having a phase quadrature relation to said first modulating signal, and means for demodulating the outputs of said modulators to produce spiral deflecting potentials.

6. In combination with a directional scanning device supported to spin about one aXis and oscillate about a second axis to spirally scan a portion of space, apparatus for producing deiiecting potentials adapted to spirally scan the beam of a cathode ray tube synchronously with said device, comprising means controlled by the oscillation of said device for varying the amplitude of an alternating electromotive force according to said oscillations, a iirst modulator connected to said means and controlled by the spinning of said device for modulating said electromotive force by a signal of a frequency corresponding to the spinning rate of said device, a second modulator connected to said means and controlled by the spinning of said device for modulating said electromotive force by a signal having a phase quadrature relation to said first modulating signal, and means connected to each of said modulators for demodulating said modulated electromotive forces to produce spiral scanning potentials.

7. In combination with a directional scanning device supported to spin about one axis and oscillate about a second axis to spirally scan a portion of space, apparatus for producing deecting potentials adapted to spirally scan the beam of a cathode ray tube synchronously with said device, comprising means controlled by the oscillation of said device for varying the amplitude of an alternating electromotive force according to said oscillations, a transformer having a primary winding excited by said means and two secondary windings having a phase quadrature relation, means for producing relative rotation between said primary and secondary windings according to the spinning movements of said device, and means connected to each of said secondary windings for demodulating the electromotive force outputs thereof to produce spiral scanning potentials.

8. Apparatus for producing spiral deflecting voltages for cathode ray tubes comprising a two-phase rotary transformer having a stator and rotor, means for rotating the rotor of said transformer at a rate corresponding to the desired angular rate of rotation of the electron beam of said tube, means for modulating an alternating voltage to provide a wave having a generally triangular envelope, the frequency of the wave envelope being less than the frequency of rotation of said transformer rotor, means for exciting said transformer with said voltage, and means for detecting the two-phase output of said transformer to produce said deilecting voltages.

9. In apparatus for producing deiiecting voltages adapted to control the sweep of the electron beam of a cathode ray tube, a first modulator having a stator and rotor part, one of the parts of said irst modulator being adapted to be connected to a voltage source, means for rotating the rotor of said modulator in accordance with a iirst component of a desired sweep pattern, a second modulator having a stator and Vrotor part, one of the parts of said second modulator being connected to receive the output of said iirst modulator and the other comprising two portions for respectively modulating the voltage supplied thereto in like manner but in relatively phase displaced relation, means for rotating the rotor part of said second modulator in accordance with a second component of the desired sweep pattern whereby to provide two output voltages of like wave form but relatively phase displaced.

10. Apparatus for producing deiiecting potentials adapted to control the sweep of the electron beam of a cathode ray tube, said apparatus including a source of constant amplitude, alternating voltage, a first modulator means connected to said source of voltage for variably modulating said voltage in amplitude in accordance with desired variations in radial displacement of the electron beam from the electrical center of the tube, a second modulator means connected to receive the output of said first modulator means comprising two modulating parts for respectively modulating the voltage supplied thereto in like sinusoidal manners but in relatively phase displaced relations, whereby to provide two output voltages of like wave form and amplitude but relatively 90 displaced in time phase, and means for rectifying the output voltages of said second modulator.

11. In apparatus for producing delecting voltages adapted to control the sweep of an indicator, a iirst modulator means adapted when connected to a source of voltage to variably modulate said voltage in amplitude in accordance with a variable component of the desired sweep pattern of said indicator, and a second modulator means connected to receive the output of said rst modulator means comprising two modulating parts for respectively modulating the voltage supplied thereto in like manner in accordance with a second component of the desired sweep pattern of said indicator but in relatively phase displaced relation, whereby to provide two output voltages of like wave form but relatively phase displaced.

12. Apparatus for producing deflecting voltages adapted to control the sweep of an indicator, said apparatus comprising modulating means energized from an alternating voltage source for providing a substantially linearly varying amplitude modulation of said voltage, a rotary transformer having space displaced stator windings and a rotor winding connected with the output of said modulating means, and means for respectively demodulating the outputs of said stator windings.

References Cited in the le of this patent UNITED STATES PATENTS 1,568,938 Clement Ian. 5, 1926 2,135,171 Chireix Nov. 1, 1938 2,149,292 Hogan Mar. 7, 1939 2,213,874 Wagstatfe Sept. 3, 1940 2,272,068 Pollock Feb. 3, 1942 2,400,791 Tolson May 21, 1946 2,403,967 Busignies July 16, 1946 2,408,414 Donaldson Oct. 1, 1946

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