US4489319A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Detector with variance sensitivity
Assignee: Raytheon Co
•
Filing: 1983-04-08
•
Granted: 1984-12-18
•
Expires: 2003-04-08
Abstract
Abstract In a radar or sonar system wherein the detection of a target is to be accomplished with a constant false alarm rate (CFAR), a circuit is provided for adjusting the input to a comparator which compares the received echo signals against the value of a threshold in order to detect targets of interest. The mean value of the background noise is subtracted from the signal, and the resulting difference is divided by the square root of the variance of background noise. The use of the variance compensates for sweep-to-sweep correlation and non-stationarity (in the statistical sense) as is found in clutter so that the clutter, upon the customary sweep-to-sweep integration of the signal, does not tend to introduce a false echo.
Inventors
- 👤 V. Gregers Hansen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 13:00
CPC Classifications
G; G01; G01S; G01S7/00; G01S7/02; G01S7/28; G01S7/285; G01S7/292; G01S7/2923; G01S7/2927; G06; G06V; G06V10/00; G06V10/20; G06V10/255
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
135 words
An echo ranging system having means for adjusting the level of an input signal relative to a threshold level to compensate for a clutter component of said input signal comprising: means for generating a signal having a value which is representative of a standard deviation of said input signal; means for altering the ratio of said input signal relative to said threshold level by the value of said generated signals. said signal generating means comprising: (a) means for determining a plurality of difference between a sample of said input signal and a subsequent sample of said input signal; (b) means coupled to said differences determining means for taking a magnitude of each of said differences; and (c) means for averaging a plurality of said magnitudes to provide said generated signal to said ratio altering means.
Claim 2
Dependent Claim
135 words
An echo ranging system having means for adjusting the level of an input signal relative to a threshold level to compensate for a clutter component of said input signal comprising: means for generating a signal having a value which is representative of a standard deviation of said input signal; means for altering the ratio of said input signal relative to said threshold level by the value of said generated signals. said signal generating means comprising: (a) means for determining a plurality of difference between a sample of said input signal and a subsequent sample of said input signal; (b) means coupled to said differences determining means for taking a magnitude of each of said differences; and (c) means for averaging a plurality of said magnitudes to provide said generated signal to said ratio altering means.
Claim 3
Dependent Claim
148 words
An echo ranging system having means for adjusting the level of an input signal relative to a threshold level to compensate for a clutter component of said input signal comprising: means for determining a difference between said input signal and an estimate of a mean of said input signal; means for generating a signal having a value which is representative of a standard deviation of said input signal; means for altering the ratio of said signal relative said threshold level by the value of said generated signal; and said signal generating means comprising: (a) means coupled to said difference determining means for taking a magnitude of said difference; and (b) means coumpling to said magnitude means for averaging a plurality of said difference magnitudes to provide to said ratio altering means said generated signal having a value which is representative of a standard deviation of said input signal.
Claim 4
Dependent Claim
148 words
An echo ranging system having means for adjusting the level of an input signal relative to a threshold level to compensate for a clutter component of said input signal comprising: means for determining a difference between said input signal and an estimate of a mean of said input signal; means for generating a signal having a value which is representative of a standard deviation of said input signal; means for altering the ratio of said signal relative said threshold level by the value of said generated signal; and said signal generating means comprising: (a) means coupled to said difference determining means for taking a magnitude of said difference; and (b) means coumpling to said magnitude means for averaging a plurality of said difference magnitudes to provide to said ratio altering means said generated signal having a value which is representative of a standard deviation of said input signal.
References Cited (Backward Citations)
US2842761A
Cited
US3946382A
Cited
US4047172A
Cited
US3968490A
Cited
US3995270A
Cited
US4031364A
Cited
US4074264A
Cited
US4148025A
Cited
US4213127A
Cited
US4249177A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-12-18 | 1988-06-18 | 1988-12-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-12-18 | 1992-06-18 | 1992-12-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-12-18 | 1996-06-18 | 1996-12-18 | $7700.00 | Window Closed / Lapsed |