Telephone line monitoring system
US4742537A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 4, 1986 |
| Grant date | May 3, 1988 |
| Priority date | — |
| Expiry date | Jun 4, 2006 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M1/82
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A device for detecting voice signals in the presence of supervisory signals on a number of telephone lines so as to determine when machine-placed telephone calls have been answered. The device comprises a zero crossing detector for each telephone line monitored to determine the zero voltage crossings in the voltage of an incoming telephone signal, a latch associated with each detector for storing the occurrences of each zero voltage crossing detected and a microcomputer for processing the frequency-related information of the incoming telephone signals according to a voice detection algorithm. The voice detection algorithm comprises timer interrupt and analysis routines that direct the microcomputer to count the number of occurrences of different wavelengths of the waveforms composing an incoming telephone signal in determining the condition of response on a respective telephone line.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.