Telephone test instrument
US5025466A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 13, 1990 |
| Grant date | Jun 18, 1991 |
| Priority date | — |
| Expiry date | Mar 13, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M3/308
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A telephone test instrument permits voice communications with and monitoring of a telephone circuit to be tested. The instrument includes a microprocessor used in controlling various functions of the instrument. The microprocessor and other circuits of the instrument are energized from a connected telephone circuit and/or an internal energy supply which is automatically recharged from the telephone circuit. The microprocessor continually checks the voltage of the internal energy supply and automatically turns off a loudspeaker of the instrument, or prevents it from being turned on, if the voltage is too low. The instrument includes circuitry which, in combination with the microprocessor, measures loop current or line voltage while the instrument is connected for making voice communications with the telephone circuit. When the loudspeaker within the instrument is energized, the earpiece receiver remains active. A belt hook connected to a housing of the instrument can connect an electrical ground through a switch in the instrument to the telephone circuit for providing a ground start. The instrument also includes a "crow-bar" circuit which effectively open-circuits the instrument fro…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.