Patent · US Expired

System for transmitting coded speech signals

US5912923A · kind A · utility

1Cited by

14References

20Claims

0Family size

Assignee

U.S. Philips Corporation · US

Inventors

Karl Hellwig · Wonfurt, DE
Dietmar Lorenz · Erlangen, DE
Rainer Dietsch · Heroldsberg, DE

Key dates

Filing date	Jul 21, 1995
Grant date	Jun 15, 1999
Priority date	—
Expiry date	Jul 21, 2015

Classification

Technology area (CPC H)Electricity
CPC primaryH04M9/082
WIPO fieldTelecommunications
WIPO sectorElectrical engineering

Abstract

Complex coding of speech signals, as this is used, for example, in the GSM half rate speech coder, requires the use of a signal processor. On the other hand, a hands-free facility requires an arithmetic unit which adaptively calculates filter coefficients. This is only effected during speech pauses in which the speech coder is switched to a mode in which it generates codes for background noise with only little processing circuitry and expense. According to the invention, the signal processor for the coding device is therefore used for calculating the coefficients for the echo cancelling filter during speech pauses. This requires the use of not more than a single signal processor which can thus be used twice.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.