Digital noise cancellation in a metal detector
US4854113A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 29, 1987 |
| Grant date | Aug 8, 1989 |
| Priority date | — |
| Expiry date | Dec 29, 2007 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA01D75/187
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method and apparatus for cancelling cyclically recurring noise induced in a magnetic metal detector by movement of ferrous machine parts in the field of the detector provides for periodically sampling the output of the metal detector, delaying each sample for the duration of one cycle of the cyclically recurring noise, and subtracting the samples taken in one cycle from the output of the metal detector during the following cycle. The delay is accomplished by a delay line or shift register, or by storing the samples under microprocessor control. If the noise has a first component occuring at a first rate and a second component occuring at a second rate cancellation of both components may be accomplished.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.