Telephone line test and display circuit
US4777645A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 10, 1987 |
| Grant date | Oct 11, 1988 |
| Priority date | — |
| Expiry date | Feb 10, 2007 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M3/30
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A telephone line test and display circuit for enabling a craftsperson to automatically monitor a plurality of communication aspects of a telephone line without impacting any communications that may be taking place over the telephone line being monitored includes a communication capability detection and indicator unit through which the craftsperson may observe the DC operational state (busy/idle, battery polarity, talk battery present) condition of the line by observing a pair of light emitting diodes. The light emitting diodes are color-coded in accordance with operational status conditions being monitored and are illuminated in either a steady state or flashing condition, depending upon the DC state of the line. Also contained with the test and display circuit is a frequency discriminator/display unit, having a set of light emitting diodes separate from those employed for monitoring the DC operational status of the telephone line. The frequency discriminator/indicator unit monitors the line for the presence of communication signals and selectively illuminates an individual one of a set of light emitting diodes, each of which is associated with a prescribed frequency band of signal…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.