Single-wire loop alarm system

摘要: A single-wire loop alarm system in which the status of each switch can be determined and is relatively immune to effects noise. False alarms are avoided by incorporating an integrator potential test circuit; during polling, however, switched out. Low-frequency noise discriminated against verifying existence condition; current doubled and, if condition being caused impedance-introducing open switch, voltage change should double. Polling made more reliable relying on a "window" test, rather than simple threshold test.