Nokia Mobile Phones Limited

Nokia Telecommunications Oy

Nokia Corporation

Antti Vahatalo

Jorma Makinen

Erkki Paajanen

Juha Antero Rasanen

Ville-Veikko Mattila

Jani Ekman

Janne Haikonen

Olli Ali-Yrkko

A negotiation unit for operation in a communication system whereby a first communication unit may transmit data to a second communication unit by means of a protocol including the step of negotiating a parameter for use in the operation of the protocol by the transmission of a first negotiation message to the second communication unit and in response thereto the transmission of a second negotiation message from the second communication unit to the first communication unit, the negotiation messages being configured to be capable of including data defining a value for the parameter, the negotiation unit comprising: storage means for storing information on a criterion on the parameter, interception means for intercepting at least one of the negotiation messages directed towards one of the first and second communication units; and message analysis means for analysing the intercepted negotiation message and if the message includes a value for the parameter f) checking whether the stored criterion on the value is met, g) if the criterion is not met, modifying the message to include a value for the parameter that meets the criterion, and sending the modified message towards the said one recipient.

Negotiation of transmission parameter

An improved method converts a first sampling rate of signal values to a second sampling rate, the second sampling rate being a non-integer multiple of the first sampling rate. The method includes the steps of: interpolating between successive signal values occurring at the first sampling rate to derive further signal values at an integer multiple sampling rate thereof, the integer multiple sampling rate falling within a range that is a greater than 0.5 and less than two times an integer multiple of the second sampling rate; employing a method of weighted average interpolation or decimation to derive from the signal values occurring at an integer multiple sampling rate of the first sampling rate, signal value magnitudes occurring at the integer multiple of the second signal sampling rate; and decimating the signal values at the integer multiple of the second sampling rate by an integer multiple factor to derive second sampling rate.

Method for sampling frequency conversion employing weighted averages

The invention relates to echo cancelling methods used in telephone systems, more specifically to echo cancelling methods based on two filters. The echo cancelling method according to the invention employs two adaptive filters, namely, a main filter (10) and a background filter (50). The purpose of the background filter (50) is to make sure that the main filter (10) model stays correct. The main and background filter coefficients are updated on different conditions, and the residual signals (L.sub.-- RES1, L.sub.-- RES2) produced by the filters are compared to each other. The set of filter coefficients used for generating the echo canceller's output signal (S.sub.-- OUT) is selected on the basis of said comparison of the residual signals. The selection of the set of filter coefficients is carried out either by copying the background filter coefficients to the main filter or by interchanging the background and main filter functions. Operation of the echo canceller in a double talk situation is enhanced by comparing the residual signals produced by the two filters frequency band by frequency band, thus avoiding errors caused by echo-resembling correlations caused by random loud sounds in double talk situations.

System and method for echo cancelling and mobile communications device

The invention concerns a voice activity detection device in which an input speech signal (x(n)) is divided in subsignals (S(s)) representing specific frequency bands and noise (N(s)) is estimated in the subsignals. On basis of the estimated noise in the subsignals, subdecision signals (SNR(s)) are generated and a voice activity decision (V.sub.ind) for the input speech signal is formed on basis of the subdecision signals. Spectrum components of the input speech signal and a noise estimate are calculated and compared. More specifically a signal-to-noise ratio is calculated for each subsignal and each signal-to-noise ratio represents a subdecision signal (SNR(s)). From the signal-to-noise ratios a value proportional to their sum is calculated and compared with a threshold value and a voice activity decision signal (V.sub.ind) for the input speech signal is formed on basis of the comparison.

Method and device for voice activity detection and a communication device

The invention relates to a method of noise suppression, a mobile station and a noise suppressor for suppressing noise in a speech signal. The suppressor comprises means (20, 50) for dividing the speech signal into a first amount of subsignals (X, P), which subsignals represent certain first frequency ranges, and suppression means (30) for suppressing noise in a subsignal (X, P) based upon a determined suppression coefficient (G). The noise suppressor further comprises recombination means (60) for recombining a second amount of subsignals (X, P) into a calculation signal (S), which represents a certain second frequency range, which is wider than the first frequency ranges and determination means (200) for determining a suppression coefficient (G) for the calculation signal (S) based upon the noise contained by it. The suppression means (30) are arranged to suppress the subsignals (X, P) recombined into the calculation signal (S) by said suppression coefficient (G), determined based upon the calculation signal (S).

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Tampere, Finland

Antti Vahatalo