US3609672A
Expired / Lapsed
US
⏱️ 0.0 years remaining
False alarm inhibit circuit in echo ranging systems
Assignee: United States Department of the Navy
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Filing: 1969-07-28
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Granted: 1971-09-28
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Expires: 1989-07-28
Abstract
Abstract Two or more filters with narrow side-by-side passbands will each pass broadband noise voltages but only one filter can pass a useful narrowband signal. An exclusive OR gate will pass a single filter output but will block simultaneous noise outputs thus effectively distinguishing between useful signals and false alarms.
Inventors
- 👤 Lewis H Bossert
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 14:48
CPC Classifications
G; G01; G01S; G01S7/00; G01S7/02; G01S7/28; G01S7/285; G01S7/292; Y; Y10; Y10S; Y10S367/00; Y10S367/901
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
115 words
A false alarm inhibit circuit in an echo ranging system, said circuit comprising: a plurality of narrow passband filters connected in parallel to the output of an echo receiver, and being responsive, respectively, to frequencies equal to and slightly removed from the transmitted frequency, fo, of said system so that one only of said filters will pass said transmitted frequency but all filters can pass broadband noise, a logical exclusive OR gate circuit coupled to the outputs of said filters, means responsive to all said outputs for disabling said gate when signal voltages occur simultaneously on all said outputs and for enabling said gate when a signal voltage occurs on one only of said outputs.
Claim 2
Dependent Claim
115 words
A false alarm inhibit circuit in an echo ranging system, said circuit comprising: a plurality of narrow passband filters connected in parallel to the output of an echo receiver, and being responsive, respectively, to frequencies equal to and slightly removed from the transmitted frequency, fo, of said system so that one only of said filters will pass said transmitted frequency but all filters can pass broadband noise, a logical exclusive OR gate circuit coupled to the outputs of said filters, means responsive to all said outputs for disabling said gate when signal voltages occur simultaneously on all said outputs and for enabling said gate when a signal voltage occurs on one only of said outputs.
Claim 3
Dependent Claim
30 words
In the false alarm inhibit circuit defined in claim 1, said filters comprising matched filters resonant, respectively, to fo, fo+fd, and fo-fd, wherein fd comprises a doppler shift frequency component.
Claim 4
Dependent Claim
49 words
In the false alarm inhibit circuit defined in claim 1; said means comprising an AND gate with plural inputs connected and responsive to the outputs of all of said filters and a single output connected to said OR gate to produce an inhibiting pulse which disables said OR gate.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-09-27 | 1975-03-29 | 1975-09-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-09-27 | 1979-03-29 | 1979-09-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-09-27 | 1983-03-29 | 1983-09-28 | $7700.00 | Window Closed / Lapsed |