Motorola Corporation

Jian-Cheng Huang

Floyd D Simpson

Kenneth D Finlon

Lu Chang

Xiaojun Li

Robert J Schwendeman

Sunil Satyamurti

Surendra J Perera

Oleg Andric

Walter L Davis

Michael D Sasuta

Clinton C Powell, Ii

Leon Jasinski

David R Petreye

James Michael Keba

Chun-Ye Susan Chang

Arthur Gerald Herkert

Lorenzo Ponce De Leon

A system controller ( ) is for transferring a low bit rate digital voice message. The system controller generates from an analog voice signal representing the voice message a set of speech model parameters, and generates a first derived set of speech model parameters from a first subset of the set of speech model parameters, the first derived set encoding the voice signal at a second voice quality and second vocoder rate that are less, respectively, than a first voice quality and vocoder rate. The system controller transmits ( ) the low bit rate-digital voice message comprising the first derived set of speech model parameters to a communication receiver ( ). The communication receiver requests ( ) an incremental message when the quality of the voice message is unsatisfactory. The system controller generates and transmits ( ) an incremental message-and the communication receiver uses ( ) the incremental message to generate a higher quality voice message.

Method and apparatus for transferring low bit rate digital voice messages using incremental messages

A digital signal processor for processing data including voice messaging data that may have both voiced and unvoiced speech components utilizes computer routines stored in a memory used by the digital signal processor. The computer routines programmed provide for control of at least a portion of a selective call receiver; receiving and decoding data received at the selective call receiver; comparing the addresses received at the selective call receiver with addresses stored in a memory location coupled to the digital signal processor; controlling voicing including both voiced and unvoiced speech components; and generating a pitch wave using an inverse discrete Fourier Transform and resample the pitch wave to provide a time domain voiced speech component.

Digital signal processor for processing voice messages

A system controller ( ) includes a speech encoder ( ) that encodes a low bit rate digital voice message. The speech encoder sets values of words of a header of the encoded message. The values of the words define a quantity of frames in the voice message, N, and define a vocoder rate used for the encoded message. The speech encoder sets a state of each indicator in each frame status field of N frame status fields that are transmitted after the header of the encoded message. The speech encoder assembles N frame data fields, wherein each of the frame data fields comprises a set of data words. The N frame data fields follow the N frame status fields. Each set of data words conforms to at least one of the vocoder rate and the states of the indicators. A decoder ( ) decodes the encoded low bit rate digital message.

Method and apparatus for encoding and decoding frames of voice model parameters into a low bit rate digital voice message

A system controller ( ) includes a speech encoder ( ) that dynamically segments frames of a low bit rate digital voice message. Speech model parameters have been generated in a sequence of frames. The speech model parameters include quantized speech spectral parameter vectors. The speech encoder selects ( ) a first quantized speech spectral parameter vector as a current anchor vector, selects ( ) a second quantized speech spectral parameter vector located a predetermined number of frames (L ) from the current anchor vector as a target speech parameter vector, and perturbs ( ) the target speech parameter vector to derive a plurality (K) of perturbed speech parameter vectors.

Method and apparatus for dynamic segmentation of a low bit rate digital voice message

A pitch determiner ( ) of a system controller ( ) that generates a smoothed pitch value for a current frame of a low bit rate voice message includes a pitch function generator ( ) that generates a pitch detection function (PDF) for each frame of digital samples of a voice signal, a pitch candidate selector ( ) that selects a future frame pitch candidate from a pitch detection function (PDF), and a pitch adjuster ( ) that generates the smoothed pitch value. The pitch adjuster includes a subharmonic pitch corrector ( ) that determines a future frame pitch value by performing pitch subharmonic correction of a future frame pitch candidate using a roughness factor of the frequency transformed window.

Method and apparatus for pitch determination of a low bit rate digital voice message

A technique is used in a speech encoder ( ) that reduces non-speech activity of a low bit rate digital voice message. Speech model parameters that include quantized speech spectral parameter vectors are generated in a sequence of frames. A determination is made as to which frames of the sequence of frames are voiced frames and which frames are unvoiced frames. A consecutive sequence of frames of unvoiced frames is identified ( ) as an unvoiced burst when a length, N , of the consecutive sequence of frames exceeds a predetermined length, N . A non-speech activity portion of the unvoiced burst is identified ( ) and removed.

Method and apparatus for non-speech activity reduction of a low bit rate digital voice message

A radio communication system includes a voice recognition system (221) for converting (400) a caller's voice message to a textual speech message. The textual speech message is then transmitted to an intended selective call radio (122). To perform these functions, the radio communication system includes a caller interface circuit (218), a transmitter (116), and a processor (222). To perform voice-to-text conversion, the processor is adapted to cause the caller interface circuit to sample a voice signal generated by the caller during a plurality of frame intervals, and to apply a Fourier transform thereto, thereby generating spectral data. The spectral data is subdivided into a plurality of bands. The spectral envelope of the spectral data is then filtered out to generate filtered spectral data. A Fourier transform is applied thereto to generate an autocorrelation function for each band. From the autocorrelation function of each band, a magnitude is determined, which is representative of the degree of voiceness of each band. The degree of voiceness for each band is then applied to a corresponding plurality of phoneme models, which are used to derive a textual equivalent of speech from the voice signal. The textual equivalent of speech is then transmitted to the selective call radio by way of the transmitter.

Subband normalization, transformation, and voiceness to recognize

An interactive method for composing an alphanumeric message by a caller using a telephone keypad includes storing (215) a lexical database (135) from which unigram probabilities, forward conditional probabilities, and backward conditional probabilities for a plurality of words can be recovered; storing a received sequence of key codes (405) representing a sequence in which keys on a telephone style keypad are keyed; generating a word trellis including candidate words (415) derived from the sequence and the lexical database; determining a most likely phrase (420) from the candidate words, the unigram probabilities, forward conditional probabilities, and backward conditional probabilities; generating a most likely message (425) from the most likely phrase and presenting the most likely message to the caller; and confirming that the most likely message is the alphanumeric message (430).

Alphanumeric message composing method using telephone keypad

A communication system includes a transmitter for transmitting messages to a plurality of receiving devices of the communication system, and a processing system. The processing system is adapted to convert a caller's voice message to a sequence of phonemes whereby the caller's voice message is intended for a receiving device. To accomplish the conversion, steps of Fourier transform, spectral subdivision, envelope filtering autocorrelation function determination of each subdivision, and voiceness determination for each subdivision are performed. The processing system is further adapted to generate a sequence of phoneme indexes and voice features corresponding to the sequence of phonemes, and to cause the transmitter to transmit the sequence of phoneme indexes to the receiving device for generating a voice signal representative of the caller's voice message. The voice features can include spectral features, average energy, duration, and pitch to improve the quality of the voice signal. The receiving device can be a selective call radio.

Voice compression by phoneme recognition and communication of phoneme

A MBE synthesizer (2200) for generating speech from information received by a receiver (114) includes a voiced signal generator (2280) for generating voiced signal components in the time domain using an IDFT in a pitch wave generator (2210) and and a pitch wave resampler (2232) and an unvoiced signal generator (2290) for generating unvoiced signal components in the time domain. The MBE synthesizer also includes a voicing processor (2218) responsive to band voicing flags within the excitation information for controlling selection of a voiced spectral component or an unvoiced spectral component from a harmonic amplitude spectrum.

Low complexity MBE synthesizer for very low bit rate voice messaging

A pitch determiner (414) for use with a speech analyzer includes a pitch function generator (414) which generates a plurality of pitch components representing a pitch function for one or more sequential segments of speech. which are represented by a predetermined number of digitized speech samples. A pitch enhancer (1116) enhances the pitch function of a current segment of speech utilizing the pitch function of one or more sequential segments of speech to generate a plurality of enhanced pitch components. A pitch detector (1118) detects the pitch of the current segment of speech by determining the pitch of an enhanced pitch component having a largest amplitude of the plurality of enhanced pitch components.

Pitch determiner for a speech analyzer

A MBE (Multi-Band Excitation) synthesizer (116) generates excitation components from information received by a receiver (2004). The information received includes spectral information representing a segment of speech. The MBE synthesizer (116) includes an excitation generator (2241) and a nonlinear voicing processor (2211). The excitation generator (2241) generates voiced excitation components and unvoiced excitation components. The nonlinear voicing processor (2211) is responsive to the spectral information and controls a selection of the excitation components from the voiced excitation components and the unvoiced excitation components.

MBE synthesizer utilizing a nonlinear voicing processor for very low bit

An apparatus and method for processing a voice message to provide low bit rate speech transmission processes the voice message to generate speech parameters which are arranged into a two dimensional parameter matrix (502) including a sequence of parameter frames. The two dimensional parameter matrix (502) is transformed using a predetermined two dimensional matrix transformation function (414) to obtain a two dimensional transform matrix (506). Distance values representing distances between templates of a set of predetermined templates and the two dimensional transform matrix (506) are then derived. The distance values derived are identified by indexes identifying the templates of the set of predetermined templates. The distance values derived are compared, and an index corresponding to a template of the set of predetermined templates having a shortest distance is selected and then transmitted.

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Lake Worth, FL, United States of America

Jian-Cheng Huang