Precise call progress detector
US4742251A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 12, 1985 |
| Grant date | May 3, 1988 |
| Priority date | — |
| Expiry date | Aug 12, 2005 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04Q1/46
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A circuit for providing a dynamic noise floor level. An analog to digital converter provides one of a plurality of outputs as determined by the level of an input signal. A comparator compares each digital input signal with the signal latched in a storage device. For an increasing digital signal the value is latched in a storage device. If the signal is decreasing, the value stored in the storage device is decremented by 1. The output of the storage device is coupled to a demultiplexor for digital to analog conversion. The outputs of the demultiplexor are coupled to a plurality of capacitors of varying capacitance so that a range of output signals may be achieved. The analog output of the circuit is used as a noise floor level in a precise call progress detector.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.