Digital memory area correlation tracker

• US 3,943,277 A
• Filed: 02/20/1969
• Issued: 03/09/1976
• Est. Priority Date: 02/20/1969
• Status: Expired due to Term

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Todd, Barry S., Everly, John W.
• Primary Examiner(s): Wilbur, Maynard R.
• Assistant Examiner(s): Buczinski, S. C.
• Application Number:
  US04/802,328
• Time in Patent Office: 2,574 Days
• Field of Search: 244/3.17, 178/6.8, 178/DIG. 21, 250/203 CT
• US Class Current: 348/169
• CPC Class Codes: G01S 3/7865 using correlation of the live video image with a stored image

Abstract

A digital tracker which provides a continuous display of the area tracked mprising a delay line coupled in circuit with a comparator, a video digitizer and a sensor. The digital tracker further comprises circuit means connected between the delay line and the sensor for deriving an error correction signal in response to any mismatch between the present, delayed video scene and the reference scene, stored in the delay line. A staircase raster generator which can be positively synchronized with the delay line through the use of a common master clock is used as the sensor and the delay line is a shift register which enables any desired bit of the stored signal to be available for use at any time.

Claims

1. A digital memory, area correlation tracking device with continuous television display of the tracked area comprising:

a. a sensor,

b. a video digitizer coupled to the sensor,

c. a delay circuit connected to the video digitizer,

d. a comparator connected in circuit with the delay circuit,

e. a video selector connected to the delay circuit,

f. a memory update control connected to the video selector,

g. a shift register coupled to the video selector and also connected in circuit with the comparator,

h. scanning means for generating a normal scan of the sensor in circuit with the sensor,

i. a master clock connected in circuit with both the shift register and the scanning means whereby the shift register and the scanning means are positively syhchronized together, and

j. integratinig means for modifying the normal scan of the sensor in response to the output of the comparator, connected between the comparator and the sensor.

2. A tracking device as claimed in claim 1 wherein the sensor is an image dissector.

3. A tracking device as claimed in claim 1 further comprising a video amplifier containing automatic gain control means connected in circuit between the sensor and the video digitizer, said video amplifier being operable to strengthen the output from said sensor, and the automatic gain control means therein being operable to hold the output amplitude of said sensor at a predetermined level over a given range of illumination levels for the tracked area.

4. A tracking device as claimed in claim 1 wherein said comparator consists of a multiplicity of coincidence circuits each of which comprises a pair of "and" logic circuits coupled in circuit with an "or" logic circuit.

5. A tracking device as claimed in claim 1 wherein said shift register comprises a raster of elements equal in number to the number of elements scanned in the sensor.

6. A tracking device as claimed in claim 1 wherein said scanning means comprise:

a. an element counter,

b. a line counter connected in circuit with the element counter so as to be responsive thereto,

c. a first digital-to-analog converter the input side of which is coupled to the element counter and the output side of which is coupled to the sensor, and

d. a second digital-to-analog converter the input side of which is coupled to the line counter and the output side of which is coupled to the sensor.