Output correction system for analogue sensor

摘要

To correct the output of an analogue sensor 3 to a standard value, the gradient of the sensor response between a condition when the quantity being measured is zero and a pseudo-condition equivalent to the quantity having a reference value is calculated and stored. A scattered-light smoke detector may have a reference source 10 adjusted to supply a light level equivalent to the light scattered from the main source 7 to the detector 8 by a smoke density 5%/m. The detector outputs with no smoke present and the reference source 10 on and off are measured by the c.p.u 5 to determine the gradient of the output/smoke density characteristic, and this gradient is used subsequently to correct the sensor output. ……