Telephone line status circuit
US4734933A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 4, 1985 |
| Grant date | Mar 29, 1988 |
| Priority date | — |
| Expiry date | Nov 4, 2005 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M3/2272
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A circuit for detecting a first plurality of status signals on a multiplicity of telephone lines and generating a second lesser plurality of control signals, less than the first plurality, in response thereto. Predetermined ones of the control signals are transmitted via a multiplexing circuit to a comparator circuit. A digital-to-analog converter generates analog threshold voltages for application to the comparator circuit in response to receiving command signals from a microprocessor. The comparator circuit generates a third lesser plurality of output signals, less than the second plurality, indicative of the status of a multiplicity of remote trunk circuits connected to the telephone lines. The circuit is inexpensive and occupies little circuit board area.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.