The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 28, 1984
Filed:
May. 06, 1983
Russell D Braunling, Eden Prairie, MN (US);
Dennis L Kurschner, Minnetonka, MN (US);
Honeywell Inc., Minneapolis, MN (US);
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.