Motorola Corporation

Philip J Smanski

Ira A Gerson

David E Borth

Richard J Vilmur

Brett L Lindsley

Kenneth A Felix

John R Haug

Richard A Kaman

Described herein, is an arrangement and method for processing speech information in a speech recognition system (300). In such a system where the speech information is depicted as words, each word representing a sequence of frames (510) and where the recognition system has means (120) for comparing present input speech to a word template, the word template stored in template memory and derived from one or more previous input word, the present invention is best employed. The invention describes combining contiguous acoustically similar frames (512) derived from the previous input word or words into representative frames to form a corresponding reduced word template, storing the reduced word template in template memory in an efficient manner, and comparing frames of the present input speech to the representative frames of the reduced word template according to the number of frames combined in the representative frames of the reduced word template. In doing so, a measure of similarity between the present input speech and the word template is generated.

Word recognition in a speech recognition system using data reduced word

An automatic gain selector is disclosed for use with a noise suppression system which performs speech quality enhancement upon a noisy speech signal available at the input to generate a noise-suppressed speech signal at the output by spectral gain modification. The channel gain controller (240) of the present invention produces a modification signal (245), comprised of individual channel gain values, for application to a channel gain modifier (250). A particular gain table set is automatically selected from one of a plurality of gain tables (450) by a selector switch (470) and a noise level quantizer (440) in response to a multi-channel noise parameter, such as the overall average background noise level of the input signal. Then the individual channel gain values (455) are obtained from the particular gain table set in response to the individual channel signal-to-noise ratio estimate (235). Hence, each individual channel gain value is selected as a function of (a) the channel number, (b) the current channel SNR estimate, and (c) the overall average background noise level. The automatic gain selector further includes a gain smoothing filter (460) for smoothing these noise suppression gain factors on a per-sample basis thereby improving noise flutter performance caused by step discontinuities in frame-to-frame gain changes.

Automatic gain selector for a noise suppression system

Apparatus is disclosed for enabling a mobile radiotelephone to automatically attempt to seize a radio channel in a multichannel radio communication system. The mobile radiotelephone scans the radio channels for a non-busy radio channel and provides an indication signal when detecting a non-busy radio channel. A counter which is continuously clocked by a clock signal is incremented for each clock cycle interval of the clock signal in response to the presence of the indication signal and is decremented for each clock cycle interval of the clock signal in response to the absence of the indication signal. Thus, the totalized count of the counter is proportional to the degree of radio channel blocking of the radiotelephone system. After an unsuccessful channel seizure attempt by the mobile radiotelephone user, time interval generating circuitry provides a random time interval that has a maximum magnitude that is inversely proportional to the totallized count of the counter. Thus, the maximum random time interval is shortest when the totallized count of the counter is greatest. At the end of the random time interval, circuitry automatically attempts to seize a radio channel and if unsuccessful, additional automatic channel seizure attempts are provided after corresponding random time intervals. Thus, overall radiotelephone system efficiency is enhanced by dynamically optimizing the average random time interval between automatic channel seizure attempts according to the degree of radio channel blocking.

Method and apparatus for automatically attempting to seize a radio

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Palatine, IL, United States of America

Philip J Smanski