Detecting make-break clicks on a telephone line
US5428662A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 1, 1993 |
| Grant date | Jun 27, 1995 |
| Priority date | — |
| Expiry date | Mar 1, 2013 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04Q1/30
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
Method and apparatus for detecting make-break clicks on a telephone line, i.e., clicks produced by going on-hook or off-hook. A click is detected by analyzing time slices of a telephone signal to detect a sharp positive transition in signal energy followed by a diminishing envelope of short duration. Three signal measures are utilized to determine whether a click has occurred: (a) a magnitude transition, i.e., a change of the magnitude of the amplitude of the signal over a short period of time; (b) a peak magnitude, i.e., a magnitude of the amplitude of the signal corresponding to the first acceptably large magnitude transition (the beginning of the click); and (c) a duration of the signal envelope. In accordance with the present invention: (a) the minimum allowable peak magnitude of a valid click is scaled to the maximum magnitude encountered as the telephone signal is analyzed, i.e., a start-of-click adaptive amplitude measure, and (b) the end of the click is determined by comparing the magnitude of the amplitude of the signal with a maximum allowable magnitude for silence which is scaled to the maximum magnitude encountered since the last click ended, i.e., an end-of-click adapt…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.