US4468763A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Seismic intruder detection using pressure waves
Assignee: Honeywell Inc
•
Filing: 1983-05-06
•
Granted: 1984-08-28
•
Expires: 2003-05-06
Abstract
Abstract In combination: a geophone having a resonant frequency in the pressure wave band and a response that decreases with frequency below the resonant frequency; an amplifier connected to the geophone and having a gain which is substantially constant for frequencies above the resonant frequency, and which varies inversely with frequency for frequencies below the resonant frequency; a band-pass filter connected to the amplifier; a single channel rectifier connected to the band-pass filter; apparatus connected to the rectifier for obtaining short term and long term averages of the rectifier output; and apparatus including a comparator connectied to the last named apparatus for giving an output when the short term average exceeds the long term average by more than a predetermined amount.
Inventors
- 👤 Russell D. Braunling
- 👤 Dennis L. Kurschner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 13:15
CPC Classifications
G; G01; G01V; G01V1/00; G01V1/28; G01V1/288; G01V1/24; G01V1/245; G08; G08B; G08B13/00; G08B13/16; G08B13/1654; G08B13/1663
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
141 words
In combination: a geophone responsive to pressure waves and having a resonant frequency and a response that decreases with frequency below said resonant frequency; amplifying means connected to said geophone and having a gain which is substantially constant for frequencies above the resonant frequency, and which varies inversely with frequency, for frequencies below the resonant frequency, at about 12 decibels per octave; a band-pass filter connected to said amplifying means and having cut-off frequencies of about 5 Hertz and 12 Hertz; single channel rectifying means connected to said band-pass filter; means connected to the rectifying means for obtaining short term and long term averages of the output of said rectifier; and means including a comparator connected to the last named means for giving an output when the short term average exceeds the long term average by more than a predetermined amount.
Claim 2
Dependent Claim
141 words
In combination: a geophone responsive to pressure waves and having a resonant frequency and a response that decreases with frequency below said resonant frequency; amplifying means connected to said geophone and having a gain which is substantially constant for frequencies above the resonant frequency, and which varies inversely with frequency, for frequencies below the resonant frequency, at about 12 decibels per octave; a band-pass filter connected to said amplifying means and having cut-off frequencies of about 5 Hertz and 12 Hertz; single channel rectifying means connected to said band-pass filter; means connected to the rectifying means for obtaining short term and long term averages of the output of said rectifier; and means including a comparator connected to the last named means for giving an output when the short term average exceeds the long term average by more than a predetermined amount.
Claim 3
Dependent Claim
31 words
The combination of claim 1 in which the means connected to said rectifying means includes first and second low-pass filters having time constants of about 12 seconds and about 4 seconds.
Claim 4
Dependent Claim
56 words
Means supplying a unidirectional signal representative of the instantaneous value of a non propagating seismic pressure wave in the frequency band of 5 to 12 Hertz; means determining long term and short term averages of said signal; and means giving an output when one of said averages exceeds the other by more than a predetermined amount.
Claim 5
Dependent Claim
56 words
Means supplying a unidirectional signal representative of the instantaneous value of a non propagating seismic pressure wave in the frequency band of 5 to 12 Hertz; means determining long term and short term averages of said signal; and means giving an output when one of said averages exceeds the other by more than a predetermined amount.
References Cited (Backward Citations)
US3696369A
Cited
US4223304A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-08-28 | 1988-02-27 | 1988-08-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-08-28 | 1992-02-27 | 1992-08-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-08-28 | 1996-02-27 | 1996-08-28 | $7700.00 | Window Closed / Lapsed |