Abstract: An arrangement is described for measuring performance characteristics of a hands free telephone system. There is a measurement system which is coupleable over a telephone audio interface directly to the hands free telephone system for measuring the performance characteristics.

Abstract: An arrangement is described for measuring performance characteristics of a hands free telephone system. There is a measurement system which is coupleable over a telephone audio interface directly to the hands free telephone system for measuring the performance characteristics.

Abstract: An echo reduction system includes a signal analysis filter that converts an input into sub-band signals. A signal down-sampling circuit down-samples the sub-band signals at a first down-sampling rate. An echo analysis filter converts a loudspeaker signal into echo sub-band signal that are further processed by an echo down-sampling circuit. The circuit down-samples the echo sub-band signals at a second down-sampling rate to generate down-sampled echo sub-band signals. An echo compensation filter folds the down-sampled echo sub-band signals with an estimated impulse response of a loudspeaker-room-input system. A second echo down-sampling circuit down-samples the folded down-sampled echo sub-band signals at a third down-sampling rate to generate estimated echo sub-band signals. The first down-sampling rate is equal to the product of the second and third down-sampling rates.

Abstract: A method for calibrating a hands-free system is provided. The hands-free system comprising a hands-free unit and a mobile phone, the method comprising the following steps of setting up a connection between the hands-free system and a distant terminal via a mobile telephony network of the mobile phone, transmitting a predetermined test signal from one of the hands-free system and the distant terminal to the other of the hands-free system and the distant terminal, the predetermined test signal being provided in both the hands-free system and the distant terminal as reference test signal, comparing the received test signal to the reference test signal stored in the other of the hands-free system and the distant terminal, and determining the calibration parameters of the hands-free system in accordance with the comparison.

Abstract: An echo reduction system includes a signal analysis filter that converts an input into sub-band signals. A signal down-sampling circuit down-samples the sub-band signals at a first down-sampling rate. An echo analysis filter converts a loudspeaker signal into echo sub-band signal that are further processed by an echo down-sampling circuit. The circuit down-samples the echo sub-band signals at a second down-sampling rate to generate down-sampled echo sub-band signals. An echo compensation filter folds the down-sampled echo sub-band signals with an estimated impulse response of a loudspeaker-room-input system. A second echo down-sampling circuit down-samples the folded down-sampled echo sub-band signals at a third down-sampling rate to generate estimated echo sub-band signals. The first down-sampling rate is equal to the product of the second and third down-sampling rates.

Abstract: A method for calibrating a hands-free system is provided. The hands-free system comprising a hands-free unit and a mobile phone, the method comprising the following steps of setting up a connection between the hands-free system and a distant terminal via a mobile telephony network of the mobile phone, transmitting a predetermined test signal from one of the hands-free system and the distant terminal to the other of the hands-free system and the distant terminal, the predetermined test signal being provided in both the hands-free system and the distant terminal as reference test signal, comparing the received test signal to the reference test signal stored in the other of the hands-free system and the distant terminal, and determining the calibration parameters of the hands-free system in accordance with the comparison.