Internal telephone intercom system
US5125026A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 28, 1991 |
| Grant date | Jun 23, 1992 |
| Priority date | — |
| Expiry date | Jun 28, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M9/08
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
An internal telephone intercom system including means for connecting to a dedicated telephone communication line, a plurality of telephone sets connected to the line and adapted for telephone communications with locations external to said dedicated line, an audio receiving means at each telephone set for receiving audio signals from a microphone within said telephone set, a radio frequency generator means for generating a carrier frequency and amplitude modulated responsive to said audio signals with said modulated signal being multiplexed on said dedicated line, an audio expander for receiving a modulated signal from the radio frequency generator means and producing an audio signal responsive to audio sounds at a speaker.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.