Line monitor for two wire data transmission
US5670937A · kind A · utility
22Cited by
11References
5Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | May 16, 1995 |
| Grant date | Sep 23, 1997 |
| Priority date | — |
| Expiry date | May 16, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08B29/06
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A line monitor uses two wire data transmission in a fire alarm and detection system. A line voltage monitoring mechanism is within each wiring/contact monitoring circuit such that the exact value at any time of varying source voltage is known. The monitoring current resultant from the monitoring arrangement is strictly a function of impedance and not a function of source voltage because a line-monitoring scaling factor is incorporated into the final calculation. The monitoring scheme also results in the alarm and trouble voltage thresholds being suitably altered to take account of changed line voltage conditions.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.