Pattern recognition system having electronically controllable aperture shape, scan shape, and scan position

Claim 2

A pattern recognition system comprising: a. an image dissector tube including a photocathode and an anode having an aperture therein, an electronic image of a subject pattern optically projected on said photocathode being formed on said anode, and means to deflect said image with respect to said aperture and to multiply the electrons passing through said aperture to produce an output signal, b. scanning means to apply sweep voltages to said deflection means to produce in the output of said tube a signal signature which is a function of the scan of said pattern, c. means to impose a relatively high frequency modulation signal on the basic sweep voltages electronically to enlarge the effective size of said aperture, d. processing means coupled to said tube to integrate the signal signature in the output thereof to yield a signal signature which is effectively indistinguishable from that which would be obtained by using a mechanically driven slit aperture whose width covers a region equivalent to that produced by the electronically enlarged aperture; and e. means coupled to said procesSing means to compare the signal signature produced by scanning said subject pattern with a signal signature produced by scanning a reference pattern to effect pattern recognition.

Claim 3

A pattern recognition system as set forth in claim 1, wherein said scanning means is constituted by a sweep voltage generator for applying basic voltages to said deflection means for producing a circular scan pattern, which basic voltages are modulated to produce an annular scan pattern.

Claim 4

A pattern recognition system as set forth in claim 2, further comprising means to vary the amplitude of said modulating signal to vary the effective size of said aperture.

Claim 5

A pattern recognition system as set forth in claim 1, wherein said comparison means is constituted by a correlator.

Claim 6

A pattern recognition system comprising: a. an image dissector tube including a photocathode and an anode having an aperture therein, an electronic image of the pattern optically projected on said photocathode being formed on said anode, and means to deflect said image with respect to said aperture and to multiply the electrons passing through said aperture to produce an output signal, b. scanning means to apply sweep voltages to said deflection means to effect sequential deflection in an X direction and in a Y direction normal thereto to produce in the output of said tube a signal signature which is a function of the scan of said pattern, said scanning means including means to impose a relatively high frequency modulating signal on the basic sweep voltage electronically to enlarge the effective size of said aperture, c. processing means coupled to said tube to integrate the signal signature in the output thereof to yield a signal signature which is effectively indistinguishable from that which would be obtained by using a mechanically driven slit aperture whose width covers a region equivalent to that produced by the electronically enlarged aperture, and d. means coupled to said processing means to compare the signal signature produced by an initial scan with the signal signature produced in a subsequent scan.

Claim 7

A pattern recognition system comprising: a. an image dissector tube including a photocathode and an anode having an aperture therein, an electronic image of the pattern optically projected on said photocathode being formed on said anode, and means to deflect said image with respect to said aperture and to multiply the electrons passing through said aperture to produce an output signal, b. scanning means to apply sweep voltages to said deflection means to effect sequential deflection in an X direction and in a Y direction normal thereto to produce in the output of said tube a signal signature which is a function of the scan of said pattern, said scanning means including means to impose a relatively high frequency modulating signal on the basic sweep voltage electronically to enlarge the effective size of said aperture, c. processing means coupled to said tube to integrate the signal signature in the output thereof to yield a signal signature which is effectively indistinguishable from that which would be obtained by using a mechanically driven slit aperture whose width covers a region equivalent to that produced by the electronically enlarged aperture, and d. means coupled to said processing means to compare the signal signature produced by an initial scan with the signal signature produced in a subsequent scan.

Claim 8

A system as set forth in claim 5, wherein said comparison means includes: a memory device to store the signal signature produced by an initial scan, and a correlator coupled to said memory device and to said dissector tube to compare the signal signature produced by said initial scan with a signal signature produced in a subsequent scan to produce a composite signal having X and Y error signal components representative of a displacement in said pattern in the period between scans, and means coupled to said correlator to separate said X-error component from said Y-error component to produce X and Y error signals with no cross coupling.

Claim 9

A system as set forth in claim 5, wherein said system is a V/H system and is installed in a moving vehicle flying over terrain, optical means being provided to project an image of the flight terrain onto said photocathode.

Claim 10

A system as set forth in claim 5, wherein said deflection means is constituted by horizontal and vertical electromagnetic deflection coils.

Claim 11

A system as set forth in claim 8, wherein said scanning means includes circuit means producing respective periodic drive voltages for said horizontal and vertical coils, each cycle of which has a sawtooth deflection portion and a square nondeflection portion.

Claim 12

A system as set forth in claim 9, wherein the drive voltages for the horizontal and vertical coils produced by said circuit means are out of phase, whereby horizontal and vertical deflection takes place alternately.

Claim 13

A system as set forth in claim 6, further including an amplifier and signal-processing circuit coupled to the output of said tube for switching the initial signal signature to said memory device and for transferring the subsequent signal signature to said correlator.

Claim 14

A system as set forth in claim 6, wherein saiD means to separate the error signal components is constituted by two sets of gating means responsive to the composite signal, one gating means yielding said X-error signal and the other set said Y-error signal.