Apparatus and method for detecting and discriminating various signal types in the presence of impulse distortions
US5809085A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 28, 1995 |
| Grant date | Sep 15, 1998 |
| Priority date | — |
| Expiry date | Jun 28, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03D1/06
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An apparatus and method are provided for a data communications device, such as a modem (100, 101) or facsimile machine, to detect and discriminate various amplitude modulated signals, such as an ANS signal of the ITU V.25 protocol and an ANSam signal of the ITU V.8 protocol, which may be subject to impulse distortions (FIG. 5B). The apparatus and method embodiments band pass filter (204) an incoming signal at a first frequency, and dynamically limit (208) any impulse distortions of the incoming signal to a limit threshold (211). The limit thresholds may be dynamically determined by rectifying (209) and low pass filtering (210) the band pass filtered signal to determine a low frequency average magnitude level of the incoming signal, with the limit thresholds set as a predetermined variance from this low frequency average magnitude level. The various frequency components of the amplitude modulated signal may then be discriminated by rectifying (215) and band pass filtering (217) at a second frequency, such as the frequency of the amplitude modulating component. Various detectors (205, 206) then determine the type of information present in the incoming signal, such as whether the sign…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.