Instrument zeroing circuit
US4374362A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 17, 1981 |
| Grant date | Feb 15, 1983 |
| Priority date | — |
| Expiry date | Feb 17, 2001 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R17/02
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An electronic interface circuit for coupling a source of analog signals to a measuring and/or recording device whereby the time varying component of the analog signal can be separated from any steady-state component, such as a DC bias, which may be present, allowing further signal processing on the time varying component only. The interface circuit comprises a servo control device having both a digital feedback loop and an analog feedback loop. Upon closure of a manually operable switch, a timer is initiated which first actuates the digital feedback loop wherein a digital number is generated which is proportional to the deviation of the signal output from a summing amplifier from a zero volt level. This digital number is applied through a digital-to-analog converter to the summing amplifier along with a second feedback signal obtained by sampling the output from the summing amplifier at a time subsequent to the digital correction operation. As a result, the deviation of the steady-state signal from zero occasioned by the inherent granularity in the analog-to-digital conversion process is eliminated.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.