Double-sided rapid drift correction
First Claim
1. A method of compensating for sensor drift in an environmental gas sensor, the method comprising:
- maintaining in a computer memory a representation of a background gas concentration range for a gas sensor, the background gas concentration range existing between a minimum sensor reading low value and a minimum sensor reading high value, the minimum sensor reading low value corresponding to a first gas concentration value and the minimum sensor reading high value corresponding to a second gas concentration value, higher than the first gas concentration value;
maintaining in the computer memory criteria for declaring patterns in background gas concentration readings based on the background gas concentration range;
accepting recurring gas concentration readings from the gas sensor;
analyzing the recurring gas concentration readings against the maintained criteria with a processor coupled to the computer memory, wherein analyzing comprises determining whether the concentration readings indicate the presence of a pattern of background gas concentration readings either lower than the minimum sensor low value or greater than the minimum sensor reading high value;
when analysis of the recurring gas concentration readings indicates the presence of a pattern of background gas concentration readings lower than the minimum sensor reading low value, adjusting an indicated gas concentration upwards; and
when analysis of the recurring gas concentration readings indicate the presence of a pattern of background gas concentration readings greater than the minimum sensor reading high value, adjusting the indicated gas concentration downwards.
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Accused Products
Abstract
A method and system for gas sensor drift correction is disclosed, appropriate for use in a system placed in an environment that with some regularity reaches a background gas concentration. A background gas concentration range is defined. When the gas sensor readings drop below the background gas concentration range for at least a defined short dwell time, an upwards calibration adjustment is effected. When the gas sensor readings stay above the background gas concentration range for a defined long dwell time (longer than the maximum expected interval between excursions to the background gas concentration), a downwards calibration adjustment is effected.
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Citations
20 Claims
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1. A method of compensating for sensor drift in an environmental gas sensor, the method comprising:
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maintaining in a computer memory a representation of a background gas concentration range for a gas sensor, the background gas concentration range existing between a minimum sensor reading low value and a minimum sensor reading high value, the minimum sensor reading low value corresponding to a first gas concentration value and the minimum sensor reading high value corresponding to a second gas concentration value, higher than the first gas concentration value; maintaining in the computer memory criteria for declaring patterns in background gas concentration readings based on the background gas concentration range; accepting recurring gas concentration readings from the gas sensor; analyzing the recurring gas concentration readings against the maintained criteria with a processor coupled to the computer memory, wherein analyzing comprises determining whether the concentration readings indicate the presence of a pattern of background gas concentration readings either lower than the minimum sensor low value or greater than the minimum sensor reading high value; when analysis of the recurring gas concentration readings indicates the presence of a pattern of background gas concentration readings lower than the minimum sensor reading low value, adjusting an indicated gas concentration upwards; and when analysis of the recurring gas concentration readings indicate the presence of a pattern of background gas concentration readings greater than the minimum sensor reading high value, adjusting the indicated gas concentration downwards. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A data processing system comprising:
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a processor; an input port for receiving recurring gas concentration readings from a gas sensor; a memory system storing executable code for the processor, the processor executing the executable code to perform drift compensation on the recurring gas concentration readings by analyzing the recurring gas concentration readings, wherein analyzing comprises determining whether the concentration readings indicate the presence of a pattern of background gas concentration readings either lower than a minimum sensor low value or greater than a minimum sensor reading high value, and when analysis of the recurring gas concentration readings indicates the presence of a pattern of background gas concentration readings lower than the minimum sensor reading low value, adjusting an indicated gas concentration upwards, and when analysis of the recurring gas concentration readings indicate the presence of a pattern of background gas concentration readings greater than the minimum sensor reading high value, adjusting the indicated gas concentration downwards. - View Dependent Claims (17, 18, 19, 20)
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Specification