Qualcomm Incorporated

Andrew P DeJaco

Khaled Helmi El-Maleh

Arasanipalai K Ananthapadmanabhan

Nikolai K N Leung

Pengjun Huang

Johnny Kallacheril John

Eddie-Lun Tik Choy

Wideband speech signals must be converted to narrowband speech signals if the transmission medium or the destination terminal is constructed with narrowband constraints. A typical wideband-to-narrowband conversion method is the elimination of frequencies above 3400 Hz using a low pass filter and a down sampler. However, this method produces a muffled speech sound since the resulting narrowband signal has a flat frequency response. Methods and apparatus are presented herein to enhance the acoustic quality of a wideband-to-narrowband converted signal. A bandwidth switching filter is used to emphasize a mid-range frequency portion of the wideband signal so that the resulting narrowband signal has a non-flat frequency spectrum.

Enhanced conversion of wideband signals to narrowband signals

A system and method for detection of rate determination algorithm errors in variable rate communications system receivers. The disclosed embodiments prevent rate determination algorithm errors from causing audible artifacts such as screeches or beeps. The disclosed system and method detects frames with incorrectly determined data rates and performs frame erasure processing and/or memory state clean up to prevent propagation of distortion across multiple frames. Frames with incorrectly determined data rates are detected by checking illegal rate transitions, reserved bits, validating unused filter type bit combinations and analyzing relationships between fixed code-book gains and linear prediction coefficient gains.

Method and apparatus for improved detection of rate errors in variable rate receivers

A method and apparatus to facilitate service negotiation by a digital telecommunications system that allows a low activity communication to be transmitted by the system over vocoded channels. In one embodiment, once the telecommunication system is noticed that a low activity signal needs to be transmitted, each telecommunication system vocoder involved in the transmission automatically locks into full rate, and where applicable, adjusts the transmission power to reduce frame error rate. Further, the telecommunications system may include any number of wireless links. The invention includes a noticing apparatus coupled to a sensor that receives a low activity communication device attachment and notices the digital telecommunications system that a low activity communication is being initiated or discontinued.

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Dublin, OH, United States of America

Andrew P DeJaco