US2605453A

US2605453A - Antenna sector scanning control

Info

Publication number: US2605453A
Application number: US621127A
Authority: US
Inventors: Miller Edward Ernst
Original assignee: Individual
Current assignee: Individual
Priority date: 1945-10-08
Filing date: 1945-10-08
Publication date: 1952-07-29
Anticipated expiration: 1969-07-29

Description

July 29, 1952 BE. MILLER I ANTENNA SECTOR SCANNING CONTROL Filed boy. a, 1945 Xiuk 2 5m ms;

EEmmIF INVENTOR EDWARD E. MILLER ATTORNEY Patented July 29, 1952 ANTENNA SECTOR SCANNING CONTROL Edward Ernst Miller, Medford, Mass., assignor, by mesne assignments, to the United States of America as represented by the Secretary of the Navy 1 a Application October 8, 1945, Serial No. 621,127

This invention relates to a system for controlling the oscillatory scanning of an antenna through a sector of its possible scanning angle and more particularly to such a system in which the angle of scan and the orientation of the center of the scanned sector may be varied as may be found to be desirable.

In the operation of radio echo detection apparatus it is frequently desirable to cause the antenna of the apparatus to scan back and forth through a relatively small angle. By avoiding the necessity of wasting time in the scanning of areas of no interest, a given group of signals can be scanned more slowly and at the same time more frequently over the particular area of interest. Since successive traces will then overlap in greater number, and less time will be consumed between scans, the sensitization of the screen of the plan position indicator may be built up so that faint and fluctuating signals will be seen on a greater percentage of scans than would be seen if it were necessary to scan through three hundred sixty degrees with each sweep.

An object of this invention is to provide an electrical system for causing the armature of a motor to cyclically scan through an arc.

Another object of this invention is to provide an electrical system for causing an antenna or the like to cyclically scan a sector of the possible scanning angle through which the antenna may be rotated.

Still another object of this invention is to provide in an electrical system of the class described, means for varying the size of the angle through which the antenna is caused to scan.

A further object of this invention is to provide in an electrical system of the class described, means for adjusting the orientation of the midpoint of the angle through which the antenna is caused to scan.

A particular object of this invention is to provide a novel circuit for causin an antenna to cyclically scan through a predetermined sector having a gas tube for controlling the reversal of the direction of rotation of the antenna.

Other objects and advantages of this invention, as well as its construction, arrangement, and operation will be apparent from the following description and claims in connection with the accompanying drawing, in which, the figure is a circuit diagram of a preferred embodiment of the invention.

Referring to the figure, there is shown an antenna 20, the motion of, which it is desired to control. Antenna 2!) is geared to the armature 14 Claims. (01. s1s-2s2) of a suitable drive motor 2| which is capable of rotating antenna 20 in a clockwise or counterclockwise direction under control of an automatic reversing switch 22 actuated by a relay 23, switch 22 being disposed in the armature circuit of motor 2| and adapted to control the direction of current therethrough. Operation of relay 23 is controlled by a second relay 3| having the coil 32 thereof/connected in the plate circuit of a gas tube 40 of the 2050 type. A third relay 24 .is provided to allow suitable ganged

switches

25, 2G and 21 to open the motor armature and field' circuits whenever ganged control switches '28, 29 and 30 are placed in a stop position. .Relay 24, being connected across the power. line will always be energized except when switch. 28 is placed in a.stop position.

It will readily be apparent from the figure that with the placement of'switch 30 in a spin position the plate circuit of tube 40 will be opened, thereby causing relay 3| to be inoperative. and preventing reversing action which normally occurs due to operating the relay through action of tube 40.. Although relay 24 is normally energized irrespective of the action of relay 3|, relay 23 is alternately connectedacross the power line and disconnected therefrom in accordancewith the position of movable contact 33 of relay 3|. In the positionshown in the figure, relay 23 is deenergized so that switch 22 is in the down position. Energization of coil 32 of relay 3| results in a switching action of relay 3|, thereby energizing relay 23 and causing switch '22 to assume a position opposite to that illustrated, with a resultant reversal of the direction of' rotation of antenna 20. t 3 1 As heretofore stated, relay 3| is controlled by gas tube 40, coil 32 of relay 3| beingconnected in the plate circuit of tube 40. An RrG circuit .36 is connected across coil 32 to prevent chatter of relay 3|. When current flows through coil 32, contact 33 will touch contact 35, but when coil 32 is deenergized contact 33 will be connected to contact 34" as illustrated. Energization and deenergization of coil 32 depend upon the firing of tube 40, the coil being energized when tube 40 fires and deenergized when tube 40 is, caused to cease firing. A transformer 31 having

secondaries

38 and 39 supplies A. C. voltage to the oathode 43, plate 42, and heater 44 of tube 40. A balance potentiometer 45 is connected between grid 4| and cathode 43 to impress A. C. voltage on cathode 43. A feed-back circuit connected to member 33 of relay 3 l causes grid 4| to be supplied with a negative A. C. voltage whenever tube 413 does not fire and with a positive voltage when the tube fires by reversing the flow of current through a potentiometer 41 providing for adjusting the angle of scan through which it is desired to cause antenna 20 to oscillate. As shown, potentiometer 41 is connected between arm 33v of relay 3| and a half-voltage point between two'resistances48 and 49 connected across the power line. More specifically, the switching of arm 33 from one position to the opposite position changes the relative phase of the grid feed-back voltage one hundred eighty degrees with respect to its previous phase relationship. This feed-back circuit, therefore, places a nega: tive voltage on grid 4| when plate 42 is positive for one position of arm 33 and a positive voltage on grid 4| for the opposite position (alarm 33 when plate 42 is positive.

In addition to the voltage impressed upon grid 4| by the feed-back circuit, a, selenium disc rectifier 50 and filter capacitor 51' areconnected across secondary winding 39 to. supply a fixed negative I). C; voltage bias upon grid 4|- It is apparent, therefore that two. voltages inseriesmake up the bias upon grid 4!, one being a fixed D. C. voltage making the grid more negative and the, other an A. C. voltage which opposes the D. C. voltage. by making the grid more positive during the halfcycle when the plate of. tube 40 is positive. An error voltage, the amplitude of which, is proportional to the sine of the angle, throu h which antenna 20. is. caused to rotate is supplied by a control transformer 52, preferably of the Selsyn type, and impressed upon grid. througha suitable potentiometer 53. All of the voltages impressed upon grid 4.! pass through potentiometer 63 which is providcd'with a handle 54 for dete'rmining the:particular sector. in azimuth to be sca'niiedl. In operation, thesense of the feedeback voltage: is such. that: if the grid becomesiust post tive. enough to fire the tubeandenergize relay-3| the. resulting change in feed-back voltage.- will make.v the grid still more positive. Antenna 20, and selsyn 52 'which is rotated thereby-must move until a. sufficient negative errorvoltage is gen- 1 erated to cancel the. feed-back, whereupontube *4.0.-ce asesfiring and relay 3! is deenergized and the resulting changeinfeed-back makes thegrid still more negative. Thus, the more feedeback voltage supplied the wider will, be the scan. through which antenna 20 will rotate. By-varyins potentiometer 41 the scan can. be changed from abare minimum to a value approaching one hundred, eighty degrees. By varying the position of thepick-ofi points-of potentiometer 53 the-posh tion of the center of scan may be varied through three hundred sixty degrees, while the setting of potentiometer 41 varies the widthof. scan from approximately-two degrees to one hundred forty degrees. 1

Asthe voltageongrid 4| is raised to the point wheretube 40 fires, the average current in coil 32 suddenly jumps from zero. to asubstantiall constant value and does not increase,v further even though the grid .be drivenmore positive. Lowering of the grid voltage. tocut-oif causes the tube to cease firing thereby suddenly dropping the coil current in relay 3| back to zero.

I A thermal relay 55 is provided to delay the plate voltage in tube ill-until the filament of the.

tube is properly heated in order to prevent de- 55. issufliciently heated to close switch 51. T11 1- mal relay 55 is adjusted to allow sufiicient time for the filament of tube 46 to become properly heated before relay 55 closes.

While a specific embodiment of this invention has been disclosed and described, it is to be understood that various modifications and changes may be made in this invention without departing from the spirit and scope thereof as set forth in the appended claims.

What is claimed is:

1. An electrical system for causing the armature of a motor to oscillate through a given are comprising switching means for reversing the direction of current fiow through said armature, a relay for actuating said switching means having the coil thereof connected in the plate circuit of a gas tube, a. feed-back circuit for impressing a negative A. C. voltage upon the grid of said tube, means for impressinga negative D. C. voltage upon said grid, and means responsive to rotation of said armaturefor impressing an A. C. voltage upon said. grid for counteracting said feed-back ture of'a motor to oscillate through an arc comprising'switching means for reversing the direction of current fiow through said armature, a relay for actuating said switching means having the coil thereof connected in the plate circuit of a gas tube, a feed-back circuit connecting the movable arm of said relay and the grid of said gas tube, means for impressing a negative D. C. voltage upon saidgrid; and means responsive to rotation of said armature for'counteracting th voltage impressed, upon said grid by said'feedback circuit.

3. An. electrical systemfor causing the armature of. a motor to oscillate through. an are comprising switching means for reversing the direction of current flow through said armature, a relay for actuating saidaswitchin means having the coil thereof connected in the plate circuit of a. gas tube, a feed-back circuit connecting the movable. arm of relay and the grid of said tube, means .disposedin said feed-back circuit for. varying the voltage impressed by said circuit on said grid, means for impressi g a negative'D'. C.voltage on said grid, and means responsive to rotationof said armature for impressing a voltage on said grid having an amplitude proportional to said rotation for counteracting said 'feed-back voltage and said D. C. voltage bias,

4. Anelectrical system forcausing the armature of a motor to oscillate through an are comprising switching means for reversing the direction of current flow through said armature, a

. relay for actuating said switching means having the coil thereof connected-in the plate circuit of a gas tube, a feed-back. circuit connecting the movable arm of said relay and the grid of said tube, means disposed in said feed-back: circuit for varying the voltage impressed by said circuit upon said grid, means for impressing a negative D. C. voltageupon said grid having an amplitude proportional to rotation of said armature for counteracting said feed-back voltage and said D. C. voltage thereby causing energization of said relay, said relay being adapted to reverse the polarity of said feed-back voltage energization and deenergization thereof.

5. Anelectrical system for causing the armature of a motor to oscillate through an are comprising switching means for reversing the directionof currentfiow through said armature, a relay for actuating said switching means having said plate, a. feed-back circuit l connecting the movable, arm of said relay .and the control grid of said gas tube, said relay bein adaptedto reverse the p'olarity'of saidffeed-back circuit upon en ergization and. deenergization thereof, means disposed in said iced-back circuit for varying the voltage impressed upon said grid, me'ansfor impressing aD. C. voltage upon said grid, and means responsive to rotation of said armature for impressing an A. C. voltage upon said grid having an amplitude proportional to rotation of said armature for counteracting said feed-back and D. C. voltages thereby causing energization and deenergization of said relay.

6. An electrical system for causing the armature of a motor to oscillate through an are comprising switching means for reversing the direction of current flow through said armature, a relay for actuating said switching means having the coil thereof connected in the plate circuit of a gas tube, means for impressing a voltage on said plate, a feed-back circuit connecting the movable arm of said relay and the control grid of said tube, said relay being adapted to reverse the phase of said feed-back circuit voltage upon energization and deenergization of said relay, means disposed in said feed-back circuit for varying the voltage impressed thereby upon said grid, means for impressing a negative D. C. bias upon said grid, means for varying the centerpoint about which said armature is to be caused to oscillate, and means responsive to rotation of said armature for impressing an A. C. voltage upon said grid having an amplitude proportional to the amount of rotation of said armature for counteracting said feed-back and D. C. voltages, thereby causing alternate energization and deenergization of said relay.

7. An electrical system for causing an antenna to scan cyclically through a given are comprising an electric motor for driving said antenna, switching means for reversing the direction of current flow through the armature of said motor, a relay for actuating said switching means having the coil thereof connected in the plate circuit of a gas tube, means for impressing a voltage on said plate, a feed-back circuit connecting the movable arm of said relay and the control grid of said tube, said relay being adapted to reverse the phase of said feed-back circuit voltage upon energization and deenergization of said relay, means disposed in said feed-back circuit for varying the voltage impressed thereby upon said grid, means for impressing a negative D. C. voltage upon said grid, means for varying the centerpoint about which said armature is caused to oscillate, and means responsive to rotation of said antenna for impressing an A. C. voltage upon said grid having an amplitude proportional to the amount of rotationof said antenna for counteracting said feed-back and D. C. voltages, thereby causing alternate energization and deenergization of said relay with a resultant reversal of the direction of rotation of said antenna.

8. An electrical system for causing the armature of a motor to oscillate through an are comprising switching means for reversing the direction of current flow through said armature, means for actuating said switching means connected in the plate circuit of an electron tube, a feed-back circuit connecting said actuating means and the grid of said electron tube, means for impressing a negative voltage upon said grid,

,and meansiresponsive to rotation of said armature for counteracting the voltage impressed upon said grid by said feed-back circuit.

posite directions froml a reference point, the

combination" comprising [a reversing motor for mparting movement to said-object, a gas filled rectifier for controlling the operation of 'said motor,'said motorbeing operable in one direction whensaid rectifier is conducting and in a reverse direction when said rectifier is cut off, said rectifier havingfa control grid, and circuit means for supplying a' biasing potential to said'grid varying with the position of said object, said biasing potential being operative to render said rectifier conductive when said object moves to one end of said path and to cut ofi said rectifier when said object moves to the other end of said path.

10. A scanning system comprising a source of voltage having a movable element, reversible driving means adapted to displace said element in either of two directions for varying the output voltage of said source in one sense or another, respectively, a relay having contacts adapted to reverse said driving means, an energizing circuit for said relay, an electronic discharge device in said circuit, said device having an input connected across the output of said source, biasing means arranged in the non-conductive condition of said device to render the same conductive when the said output voltage reaches a first predetermined limiting value toward which it is being driven in the non-conductive condition of said device, and bias modifying means arranged in the conductive condition of said device to maintain the same effectively conducting until the said output voltage reaches a second predetermined limiting value toward which it is being driven in the conductive condition of said device.

11. A scanning system comprising a source of variable voltage having a movable element, an electronic discharge device having an input connected across the output of said source, re versible driving means adapted to displace said element in either of two directions for varying the output voltage of said source in one sense or another, respectively, said driving means being responsive to the conductive and the non-conductive condition of said device for displacing said element in a respective direction, first biasing means arranged to be eiTective in the non-conductive condition of said device for maintaining the same substantially non-conductive until said output voltage reaches a first predetermined value, and second biasing means arranged to be efiective in the conductive condition of said device for maintaining the same substantially conductive until said output voltage reaches a second predetermined value.

12; In a reversing drive for moving an object back and forth along a path extending in opposite directions from a reference point, the combination comprising a reversing motor for imparting movement to said object, means for producing an alternating voltage having a potential varying with the distance of said object from said reference point, said alternating voltage when said object is on one side of said reference point having a phase displacement of with respect to the alternating voltage produced when said object is on the other side of said reference point, control means for reversing the operation of said motor to reverse the movement of said object, and means responsive to said alternating voltage for operating said control means each time said object moves to an end. of

said path.

13. A reversing drive as claimed in claim 12 in which theposition of said referencepoint is adjustable to thereby change the position of the path along which said object moves.

14. In a reversing drive for moving an object Ioackv and forth along a path extending in opposite directions from a. reference point, the combination comprising a reversing motor for imparting movementto said object, a gas filled rectifier for controlling the operation of said motor, said motor being operable in one direction 8 when said. rectifier is conducting and in a reverse direction. when said rectifier is cut 011, said rectifier havingv a control grid, means operable when said rectifier is cut off for applying a constant alternating potential to said control grid for preventing condnction by said rectifier, and means responsive to movement of said object, to an end oi said path for reducing said potential to a value at which said rectifier is rendered con- 10 ductive.

. No references cited.