Double talk detector

A method of estimating the echo path in a telecommunication system, wherein the echo path estimation is deactivated when a received coded speech signal is dominated by a non-echo-signal, the method comprising the steps of:

• if the signal power of a received speech signal exceeds a first threshold value, then extracting the Line Spectral Pairs (LSPs) from a coded speech frame of said received speech signal;
• converting each of said extracted LSPs into a corresponding Line Spectral Frequency (LSF), ωi, and calculating the distance between each two adjacent LSFs;
• for each distance that is smaller than a second threshold value, calculating the frequency of the spectral peak, ωc, surrounded by said LSF, and determining whether said spectral peak is an echo;
• and,
• deactivating the echo path estimation when a predetermined number of spectral non-echo peaks are located.

A double talk detector arranged to be connected to a coded received speech signal and to a coded transmitted first speech signal in a telecommunication system for determining when said received speech signal is dominated by a non-echo signal, the double talk detector comprising:

• a signal power monitor arranged to determine when the signal power of a received speech signal exceeds a first threshold value;
• a spectral peak locator arranged to:
• extract the LSPs from a coded speech frame of the received speech signal and to convert each of said extracted LSPs into a corresponding LSF;
• and,
• calculate the distance between each two adjacent LSFs, and calculate a spectral peak, ωc, surrounded by two LSFs separated by a distance that is smaller than a second threshold value;
• and,
• an echo locator arranged to determine whether a located spectral peak is an echo.

An echo path estimating device for a telecommunication system, arranged to deactivate the estimation of an echo path dominated by a non-echo-signal, the echo path estimating device comprising:

• a double talk detector arranged to be connected to a coded received speech signal and to a coded transmitted first speech signal in said telecommunication system, said double talk detector comprising:
• a signal power monitor arranged to determine when the signal power of a received speech signal exceeds a first threshold value;
• a spectral peak locator arranged to:
• extract Line Spectral Pairs (LSPs) from a coded speech frame of the received speech signal and to convert each of said extracted LSPs into a corresponding Line Spectral Frequency (LSF), ωi;
• calculate the distance between each two adjacent LSFs, and calculate a spectral peak, ωc, surrounded by two LSFs separated by a distance that is smaller than a second threshold value;
• and,
• an echo locator arranged to determine whether a located spectral peak is an echo.