Communications device responsive to spoken commands and methods of using same

A communications device, comprising:

• a pre-processor for transforming an audio signal into a sequence of data vectors;
• extraction means for extracting a plurality of feature frames from the sequence of data vectors;
• a plurality of classifiers for generating a plurality of discriminant signals, each of the plurality of classifiers designating a different spoken command and generating a discriminant signal according to a polynomial expansion having a form ##EQU6## wherein x.sub.j represents a feature frame, y represents the discriminant signal, w.sub.i represents a coefficient, g.sub.ji represents an exponent, and i, j, m and n are integers;
• an accumulator for generating a plurality of accumulated discriminant signals, the accumulator generating each of the plurality of accumulated discriminant signals by summing ones of the plurality of discriminant signals produced by a respective one of the plurality of classifiers;
• a selector for selecting a largest accumulated discriminant signal from the plurality of accumulated discriminant signals;
• and
• a two-way audio interface for transmitting and receiving data across a communications channel according a control signal, the control signal being a function of the largest accumulated discriminant signal.

A two-way handheld communications device, comprising:

• a microphone for generating an audio signal;
• an A/D converter for digitizing the audio signal to produce a digitized audio signal;
• a pre-processor for transforming the digitized audio signal into a sequence of data vectors;
• a speech activity detector for producing a vector sub-sequence representing a spoken command, the speech activity detector continuously receiving the sequence of data vectors and including in the vector sub-sequence those of the sequence of data vectors having an energy-level that exceeds a background noise threshold;
• a feature extractor for extracting a sequence of feature frames from the vector sub-sequence;
• a plurality of classifiers for generating a plurality of discriminant signals, each of the plurality of classifiers designating a different spoken command and generating a discriminant signal according to a polynomial expansion having a form ##EQU8## wherein x.sub.j represents a feature frame, y represents the discriminant signal, w.sub.i represents a coefficient, g.sub.ji represents an exponent, and i, j, m and n are integers;
• a plurality of accumulators for generating a plurality of accumulated discriminant signals, each of the accumulators summing ones of the plurality of discriminant signals produced by a respective one of the plurality of classifiers;
• a selector for selecting a largest accumulated discriminant signal from the plurality of accumulated discriminant signals;
• and
• a two-way audio interface for transmitting and receiving data across a radio channel according a control signal, the control signal being a function of the largest accumulated discriminant signal.

A method for controlling access to a communications channel, comprising the following steps:

• receiving a spoken command;
• extracting a plurality of features from the spoken command;
• generating a discriminant signal based on a polynomial expansion having a form ##EQU10## wherein x.sub.j represents the plurality of features, y represents the discriminant signal, w.sub.i represents a coefficient, g.sub.ji represents an exponent, and i, j, m and n are integers;
• and
• accessing the communications channel according the discriminant signal.