by updating and storing reference thresholds

Full Title

Checking or monitoring of signalling or alarm systems; Prevention or correction of operating errors, e.g. preventing unauthorised operation > Prevention or correction of operating errors (G08B29/02, G08B29/12 take precedence) > Calibration, including self-calibrating arrangements > Self-calibration, e.g. compensating for environmental drift or ageing of components > by updating and storing reference thresholds