Frequency-selective signal receiver for communication equipments, more particularly telephone equipments
US3932708A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 20, 1973 |
| Grant date | Jan 13, 1976 |
| Priority date | — |
| Expiry date | Sep 20, 1993 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04Q1/457
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
In a frequency-selective signal receiver for receiving at least two multi-frequency group codes and equipped with a voice-frequency trap, a broad-band frequency detector and a narrow-band frequency detector are connected in series parallel relative to the frequency coded input signal whereby the receiver channels of the narrow-band frequency detector provided for each single frequency of interest are activated when a conicidence between signals of two groups occurs. Due to the short transient response time of the broad-band frequency detector, character recognition is possible after a short time. The narrow-band frequency detectors are individually adjustable so that in the signal receiver particularly threatened frequency channels can correspondingly be taken into account.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.