Abstract: A method for reducing power consumption in a cellular telephone that receives multiple copies of a message comprises the steps of receiving a copy of a message block having a plurality of data bits; generating soft output signals representative of all data bits in the message block; computing a block quality metric indicative of the reliability of the message block; comparing the block quality metric with a first threshold; if the block quality metric bears a predetermined relation to the first threshold, combining the copy of the message block with a previously accepted message block to obtain a combined message block; determining the number of erasures in the combined message block; comparing the number of erasures with a second threshold; if the number of erasures is below the second threshold, decoding the combined message block to determine the number of errors in the combined message block; comparing the number of errors with a third threshold and, if the number of errors is below the third threshold, a

Abstract: A digital demodulator and method for demodulating digital data representing a phase shift keyed (PSK) signal are provided. The demodulator comprises a phase detector, automatic frequency controller, automatic timing recovery controller, data decoder, and unique word detector. According to the method of the present invention, a PSK signal is received and digitized to substantially remove the signal's amplitude characteristics. The phase detector receives an input of the digital data and based upon transitions in the data from a high state to low state and from a low state to a high state, provides phase estimates. The phase estimates are converted by the data decoder into binary data representing the symbols transmitted to form the PSK signal. A number of overlapping windows of digital data are used to determine phase estimates.

Abstract: Apparatus and method for reconstructing non-quantized adaptively transformed voice signals are shown to include noise shaping wherein the spectral envelope is scaled prior to generating bit allocation and energy substitution which is achieved after dequantization by generating the spectral envelope information for each block of transform coefficients based upon side information, generating transform coefficients which correspond to transform coefficients which were not de-quantized and for substituting the generated transform coefficients into said blocks; and transforming said blocks of de-quantized transform coefficients and generated transform coefficients from said transform domain into said time domain.

Abstract: A method and apparatus for removing the periodicity from a speech signal in a transform coder prior to the quantization of the speech signal, which speech signal is a sampled time domain speech signal composed of information samples, the transform coder sequenctially segregating the speech signal into blocks of information samples, is shown to include apparatus and method for determining the pitch in each of the sample blocks, determininig a long term predetermined parameter (LTP) for each of the blocks based on the pitch determined for each block, calculating a periodicity value for each sample in the block wherein the calculation of the periodicity value is based upon the pitch and the long term predictor parameter, generating a revised block of difference samples by subtracting the periodically value from the corresponding sample, and performing adaptive transform coding on each of the difference blocks.

Abstract: A transform coder operates on a sampled speech signal transformed from the time domain to a frequency domain to develop pitch information in relation to a given speech signal. The coder segregates groups of information samples into blocks, transforms each block of samples, and generates an auto-correlation function of the transformed signal for each block. Next, the coder determines the pitch period and pitch gain from the auto-correlation function, and determines the striation magnitude and energy from the pitch period and pitch gain. Then a reference pitch model including a number of data points is retrieved from data memory. A striation scaling factor is generated in response to the striation magnitude and energy, and is multiplied by each of the retrieved data points to adaptively generate a pitch model. Finally, the adaptively determined model is sampled to establish the pitch information.

Abstract: Adaptive transform coding of a speech signal by a single digital signal processing chip is performed at low bit rates with reduced quantization noise and distortion. A windowed speech signal is transformed and quantized. New processes are shown for generating envelope information as well as bit allocation which control quantization. The quantized signal and necessary side information are formatted for transmission and subsequent decoding.