Speech decoder with DTMF-regenerator and process for regeneration of a DTMF signal

摘要

In accordance with the invention, the distorted DTMF signal is regenerated. For this purpose, a regenerator is used which can be connected to the speech decoding system or can be integrated in this system. The DTMF regenerator corrects the distorted DTMF signals to form a standard DTMF signal shape. So that the device which contains the speech decoding system can be connected to terminals capable of standard DTMF, such as, for example, answering machines and the like, the regenerator contains a detector which detects the DTMF signal. The detector comprises a high-pass and a low-pass filter in order to separate the DTMF frequency groups, and a processing unit in which characteristics of the decoded signal such as autocorrelation and high-and low-band energy are determined and in accordance with these values a DTMF signal occurring is verified and a column and row tone are calculated and verified and from these tones a numerical or character value is formed and verified and transferred to the generator. In this generator, the delay occurring during the detection is corrected and a standard DTMF signal is generated as output signal in accordance with the verified numerical or character value having the correct length. IMAGE