Her Majesty the Queen in Right of Canada As Represented by the Minister of Industry Through the Communications Research Centre Canada

Her Majesty in Right of Canada As Represented by the Minister of Industry

Her Majesty the Queen As Represented by the Minister of Industry Through the Communications Research Centre

Louis Thibault

Liang Zhang

Gilbert Arthur Joseph Soulodre

Martin Bouchard

Hossein Najaf-Zadeh

Zhihong Hong

Frederic Mustiere

Hassan Lahdili

William Treurniet

Ramin Pishehvar

William C Treurniet

The invention relates to compressing of sparse data sets contains sequences of data values and position information therefor. The position information may be in the form of position indices defining active positions of the data values in a sparse vector of length N. The position information is encoded into the data values by adjusting one or more of the data values within a pre-defined tolerance range, so that a pre-defined mapping function of the data values and their positions is close to a target value. In one embodiment, the mapping function is defined using a sub-set of N filler values which elements are used to fill empty positions in the input sparse data vector. At the decoder, the correct data positions are identified by searching though possible sub-sets of filler values.

Sparse data compression

The invention relates to receivers and methods for receiving multi-carrier differentially modulated signals utilizing iterative decision-directed differential detection. The receiver includes a decision feedback loop including a channel estimator for estimating inter-symbol channel variations, and a differential equalizer for correcting channel-induced errors in a differentially detected signal based on the estimated inter-symbol channel variations.

Receiver for differentially modulated multicarrier signals

An iterative channel estimation and inter-carrier interference (ICI) cancellation process is provided for OFDM receivers, and more particularly for mobile OFDM receivers. The iterative process uses decision feedback to estimate both the channel gain and the ICI gains, the latter being the multiplicative gain applied to the adjacent sub-carriers. Thus the receiver performs equalization and ICI cancellation in an iterative fashion and is advantageous for estimating fast fading channels.

Channel estimation and ICI cancellation for OFDM

The present invention relates to a method for encoding an audio signal. In a first embodiment a model relating to temporal masking of sound provided to a human ear is provided. A temporal masking index is determined in dependence upon a received audio signal and the model using a forward and a backward masking function. Using a psychoacoustic model a masking threshold is determined in dependence upon the temporal masking index. Finally, the audio signal is encoded in dependence upon the masking threshold. The method has been implemented using the MPEG-1 psychoacoustic model 2. Semiformal listening test showed that using the method for encoding an audio signal according to the present invention the subjective high quality of the decoded compressed sounds has been maintained while the bit rate was reduced by approximately 10%. In a second embodiment, the inharmonic structure of audio signals is modeled and incorporated into the MPEG-1 psychoacoustic model 2. In the model, the relationship between the spectral components of the input audio signal is considered and an inharmonicity index is defined and incorporated into the MPEG-1 psychoacoustic model 2. Informal listening tests have shown that the bit rate required for transparent coding of inharmonic (multi-tonal) audio material can be reduced by 10% if the modified psychoacoustic model 2 is used in the MPEG 1 Layer II encoder.

Bit rate reduction in audio encoders by exploiting inharmonicity effects and auditory temporal masking

A process and system for providing objective quality measurement of a target audio signal. Reference and target signals are processed by a peripheral ear processor, and compared to provide a basilar degradation signal. A cognitive processor employing a neural network then determines an objective quality measure from the basilar degradation signal by calculating certain key cognitive model components.

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Gatineau, Canada

Louis Thibault