US3786183A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Contrast detector for video tracking system
Assignee: Northrop Grumman Systems Corp
•
Filing: 1972-06-21
•
Granted: 1974-01-15
•
Expires: 1992-06-21
Abstract
Abstract The video output of a television camera which is being utilized to acquire and track a target is fed through an appropriate clamp and filter to positive and negative peak detectors, which detect the maximum and minimum values of this video appearing within an area defined by a tracking gate or ''''window.'''' The time constants of the peak detectors are adjusted in accordance with the expected area of the target to provide an optimum signal to noise ratio. Peak positive and negative excursions of the video are held in hold circuits, the time constants of these circuits being governed by an appropriate control signal which provides different time constants for the acquisition mode and for the tracking mode. The outputs of the hold circuits are subtracted from each other, the difference signal thus obtained indicating the spread between the peak positive and negative excursions of the sampled video. This difference signal is multiplied by separate predetermined factors to provide separate signals, each of which is a different fraction of the spread signal. These signals are each separately algebraically summed with the signal representing the peak positive excursion and the signal representing the peak positive excursion and fed to separate voltage comparators for comparison with the clamped and filtered camera output. The output signals thus generated, which represent the width of the video signal at the various amplitudes represented by the multiplying factors, are fed to tracking logical control for utilization in controlling the slewing of the TV camera.
Inventors
- 👤 R Satterfield
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 15:44
CPC Classifications
G; G01; G01S; G01S3/00; G01S3/78; G01S3/782; G01S3/785; G01S3/786; G01S3/7864
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
216 words
In a contrast detector for a video tracking system, said system including a TV camera for providing a video signal representing a target to be tracked and means for providing a window for framing said video signal, means for generating a signal in accordance with the peak positive going amplitude of the video signal framed by said window, means for generating a signal in accordance with the peak negative going amplitude of the video signal framed by said window, differencing circuit means for generating a signal in accordance with the spread between said signals in accordance with peak positive and negative going amplitudes, means for separately multiplying said spread signal by first and second predetermined factors, means for algebraically separately summing each of said multiplied signals with the signals in accordance with the peak positive and negative going amplitudes to provide threshold signals, and comparator means for comparing the amplitude of the video signals framed by said window with each of said threshold signals and generating output pulses having widths and times of occurrence corresponding to the periods during which the amplitudes of said video signals exceed that of the associated threshold signals, said output pulses representing logic analogs defining the characteristics of the video signal for use in controlling the tracking operation of said system.
Claim 2
Dependent Claim
216 words
In a contrast detector for a video tracking system, said system including a TV camera for providing a video signal representing a target to be tracked and means for providing a window for framing said video signal, means for generating a signal in accordance with the peak positive going amplitude of the video signal framed by said window, means for generating a signal in accordance with the peak negative going amplitude of the video signal framed by said window, differencing circuit means for generating a signal in accordance with the spread between said signals in accordance with peak positive and negative going amplitudes, means for separately multiplying said spread signal by first and second predetermined factors, means for algebraically separately summing each of said multiplied signals with the signals in accordance with the peak positive and negative going amplitudes to provide threshold signals, and comparator means for comparing the amplitude of the video signals framed by said window with each of said threshold signals and generating output pulses having widths and times of occurrence corresponding to the periods during which the amplitudes of said video signals exceed that of the associated threshold signals, said output pulses representing logic analogs defining the characteristics of the video signal for use in controlling the tracking operation of said system.
Claim 3
Dependent Claim
33 words
The contrast detector of claim 1 and further including means for automatically hard clamping said video signal during the blanking periods of said camera and soft clamping said video signal during target tracking.
Claim 4
Dependent Claim
16 words
The contrast detector of claim 1 wherein said first and second predetermined multiplying factors are fractional.
Claim 5
Dependent Claim
23 words
The contrast detector of claim 1 and further including means for limiting the amplitude of said spread signal to a predetermined maximum value.
Claim 6
Dependent Claim
68 words
The contrast detector of claim 1 wherein said means for generating signals in accordance with peak positive and negative going video signal amplitudes comprise positive and negative peak detectors for detecting the peak values of the current field of the camera signal and hold circuits for each of said detectors for holding the peak values of previous fields while a current field is being scanned by the camera.
Claim 7
Dependent Claim
30 words
The contrast detector of claim 5 and further including means for automatically adjusting the time constant response of said peak detectors in accordance with the expected area of said target.
Claim 8
Independent Claim
167 words
A method for generating pulse signals indicative of the characteristics of a video output signal of a TV camera representing a target comprising the steps of: generating a signal in accordance with the peak positive going excursion of said video output signal, generating a signal in accordance with the peak negative going excursion of said video output signal, generating a signal in accordance with the spread between said peak positive and negative going excursions, multiplying said spread signal by a first predetermined factor, multiplying said spread signal by a second predetermined factor, separately algebraically summing each of said multiplied signals with the signals in accordance with the peak pOsitive and negative going excursions to derive threshold signals, and comparing each of said threshold signals with the video output signal to generate a separate one of said pulse signals for each, the width and time of occurrence of said pulse signals being defined by the periods during which said video output signal is above each compared threshold signal.
Claim 9
Independent Claim
167 words
A method for generating pulse signals indicative of the characteristics of a video output signal of a TV camera representing a target comprising the steps of: generating a signal in accordance with the peak positive going excursion of said video output signal, generating a signal in accordance with the peak negative going excursion of said video output signal, generating a signal in accordance with the spread between said peak positive and negative going excursions, multiplying said spread signal by a first predetermined factor, multiplying said spread signal by a second predetermined factor, separately algebraically summing each of said multiplied signals with the signals in accordance with the peak pOsitive and negative going excursions to derive threshold signals, and comparing each of said threshold signals with the video output signal to generate a separate one of said pulse signals for each, the width and time of occurrence of said pulse signals being defined by the periods during which said video output signal is above each compared threshold signal.
Claim 10
Dependent Claim
23 words
The method of claim 7 and additionally including the step of limiting the amplitude of said spread signal to a predetermined maximum value.
Claim 11
Dependent Claim
13 words
The method of claim 7 wherein said predetermined factors have different fractional values.
Claim 12
Dependent Claim
34 words
The method of claim 7 and additionally including the step of generating a window signal for framing the target, the video output signal comprising the output of said camera framed by said window signal.
References Cited (Backward Citations)
US3257505A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-01-14 | 1977-07-16 | 1978-01-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-14 | 1981-07-16 | 1982-01-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-14 | 1985-07-16 | 1986-01-15 | $7700.00 | Window Closed / Lapsed |