Speech encoding and decoding system which modifies encoding and decoding characteristics based on an audio signal
First Claim
1. An encoding apparatus of a telecommunications transceiver for converting an analog signal to a composite digital signal for transmission over a wireless communication channel, the encoding apparatus comprising:
- an analog signal characterization circuit which concurrently measures a plurality of characteristics of the analog signal to concurrently provide a plurality of characterization values;
a sampling circuit which samples the analog signal to form a digital signal;
a parameter generator circuit, providing a plurality of sets of encoding parameters;
processor that sequentially (1) selects at least one characterization value of the plurality of the characterization values, (2) then selects a set of encoding parameters of the plurality of sets of encoding parameters, and (3) then provides the selected one set to the digital encoding circuit and provides a corresponding coding value;
a digital encoding circuit which encodes the digital signal according to the selected set of encoding parameters; and
a combining circuit which combines the encoded digital signal and the coding value to form the composite digital signal, whereinthe analog signal characterization circuit includes a plurality of voice characteristic measurement circuits, each voice characteristic circuit including a filter which bandpass filters the analog signal and an integrator which integrates the bandpass filtered analog signal to measure as one characterization value a signal power of the analog signal within a respective frequency band, andeach set of the plurality of sets of encoding parameters provided by the parameter generator circuit is optimized for a corresponding one characterization value.
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Accused Products
Abstract
The present invention relates to a speech encoder/decoder system employing digital transmission in which the encoding and decoding operations are complimentary, and these operations make use of sets of parameters which may be optimized for a speaker and for a particular digital radio link. A number of sets of parameters are determined experimentally, for example, by employing human sample groups in which perceived audio and transmission quality are tested. The encoder/decoder system then employs a group, or number, of sets of parameters serving all speakers rather than employing one fixed set of parameters. The particular set of parameters for a speaker in the encoder of a first transceiver is determined by a processor which receives values based on an analysis of the input audio signal, and then a parameter set identifier is sent within the digital signal for use by a decoder of a second transceiver. In addition, the processor of the first transceiver which receives a signal from the second transceiver may include circuitry which monitors the signal to noise ratio and bit error rate of the channel to provide a second criteria in addition to the received values based on the analysis of the input audio signal for choosing a particular set of parameters for the encoder.
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Citations
14 Claims
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1. An encoding apparatus of a telecommunications transceiver for converting an analog signal to a composite digital signal for transmission over a wireless communication channel, the encoding apparatus comprising:
an analog signal characterization circuit which concurrently measures a plurality of characteristics of the analog signal to concurrently provide a plurality of characterization values; a sampling circuit which samples the analog signal to form a digital signal; a parameter generator circuit, providing a plurality of sets of encoding parameters; processor that sequentially (1) selects at least one characterization value of the plurality of the characterization values, (2) then selects a set of encoding parameters of the plurality of sets of encoding parameters, and (3) then provides the selected one set to the digital encoding circuit and provides a corresponding coding value; a digital encoding circuit which encodes the digital signal according to the selected set of encoding parameters; and a combining circuit which combines the encoded digital signal and the coding value to form the composite digital signal, wherein the analog signal characterization circuit includes a plurality of voice characteristic measurement circuits, each voice characteristic circuit including a filter which bandpass filters the analog signal and an integrator which integrates the bandpass filtered analog signal to measure as one characterization value a signal power of the analog signal within a respective frequency band, and each set of the plurality of sets of encoding parameters provided by the parameter generator circuit is optimized for a corresponding one characterization value. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A telecommunications system which encodes an analog signal as a digital signal, transmits the encoded analog signal as a portion of a composite digital signal over a wireless communication channel, and decodes the transmitted composite digital signal to provide an analog output signal, the system comprising:
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a first transceiver which encodes the analog signal comprising; an analog signal characterization circuit which concurrently measures a plurality of characteristics of the analog signal to concurrently provide a plurality of respective characterization values; a sampling circuit which samples the analog signal to form a digital signal; first parameter generator circuit providing a plurality of sets of encoding parameters; a first processor that sequentially (1) selects at least one characterization value of the plurality of the characterization values, (2) then selects a set of encoding parameters of the plurality of sets of encoding parameters, and (3) then provides the selected one set to the digital encoding circuit and provides a corresponding coding value; a digital encoding circuit which encodes the digital signal according to the selected set of encoding parameters; a combining circuit which combines the encoded digital signal and the coding value to form the composite digital signal; and a transmitter which modulates the composite digital signal onto a carrier for transmission through the wireless communication channel; and a second transceiver which decodes the transmitted composite digital signal comprising; a receiver which demodulates the composite digital signal from the modulated carrier received from the wireless communication channel; a signal separation circuit which provides the coding value and the encoded digital signal from the transmitted composite digital signal; a second parameter generator circuit providing a plurality of sets of decoding parameters; a second processor that communicates a selection of one set of the plurality of sets of decoding parameters of the second parameter generator circuit according to the coding value; a digital decoding circuit which decodes the encoded digital signal according to the selected set of decoding parameters; and a digital to analog converter which converts the decoded digital signal to the analog output signal, wherein the analog signal characterization circuit of the first transceiver includes a plurality of voice characteristic measurement circuits, each voice characteristic circuit including a filter which bandpass filters the analog signal and an integrator which integrates the bandpass filtered analog signal to measure as one characterization value a signal power of the analog signal within a respective frequency band, and each set of encoding parameters and each set of decoding parameters are optimized for a corresponding one characterization value. - View Dependent Claims (9, 10, 11, 12)
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13. A method of encoding an analog signal by a transceiver for transmission as a composite digital signal through a wireless communication channel comprising the steps of:
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a) concurrently measuring a plurality of characteristic values of the analog signal; b) sample the analog signal to form a digital signal; c) providing a plurality of sets of encoding parameters, each set corresponding to one of the plurality of characteristic values and; d) ranking each characteristic value and then selecting one set of the plurality of sets of encoding parameters according to the ranking; e) associating a corresponding coding value with the selected one set of the plurality of sets of encoding parameters; f) encoding the digital signal after selecting the selected set of encoding parameters to provide an encoded digital signal; and g) combining the encoded digital signal and the coding value to form the composite digital signal. - View Dependent Claims (14)
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Specification