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:
Jul. 28, 1987
Filed:
Dec. 28, 1983
Robert G Nelson, Dallas, TX (US);
Timeback Systems, Inc., Dallas, TX (US);
Abstract
Methods and apparatus are described for generating a digital representation of an analog condition. In one method high-frequency digital signals are generated with the frequency of each signal being constant and the frequencies bearing a harmonic relationship one to the other. A representation of the analog condition is applied to cause a shift in phase in at least one of the digital signals. The digital signals are then compared to obtain a measure of the phase shift which is utilized to adjust the phase of the phase shifted signal toward its original phase condition. As a result of the measure of phase shift, there is generated a single weighed digital function which is representative of the amplitude of the adjustment utilized to return the phase shifted signal toward its original phase shifted condition. The single weighed digital function is applied to a low-pass digital filter to produce a multi-bit digital word representative of the instantaneous value of the analog condition. Apparatus of invention comprises a pair of oscillators whose frequencies are constant, harmonically related to one another and whose outputs are time spaced digital pulses. An analog condition responsive means has applied thereto the aforesaid pulses to effect a relative phase shift between the digital pulses and a phase comparator measures the relative phase shift. Means are provided responsive to the measure of the relative phase shift to return the digital pulses toward an in-phase relationship, and in so doing, there is produced a single weighed digital function representative of the measure of the relative phase shift. A new and improved geophone is described.