Transmitter with an improved harmonic speech encoder
First Claim
1. A transmitter for transmission of a speech signal, said transmitter including a speech encoder having analysis means for deriving a plurality of linear prediction coefficients from said speech signal;
- said analysis means comprising;
pitch determining means for determining a fundamental frequency of the speech signal;
means for determining the amplitude and frequency of each of a plurality of harmonically related sinusoidal components of said speech signal, said determination being based on said linear prediction coefficients and said fundamental frequency; and
pitch tuning means for tuning a fundamental frequency (pitch) of said plurality of harmonically related signal components so as to minimize the difference between a representation of said speech signal and a representation of said plurality of harmonically related signal components;
said transmitter further comprising means for transmitting a representation of the amplitudes of said plurality of harmonically related signal components and of the fundamental frequency of said speech signal;
and wherein;
(i) determination of the amplitude and frequency of each of said plurality of harmonically related signal components is based on said linear prediction coefficients in substantially unquantized form; and
(ii) the representation of the amplitudes of said plurality of harmonically related signal components comprises said linear prediction coefficients in quantized form and a gain factor based on said quantized linear prediction coefficients and said fundamental frequency of said speech signal.
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Accused Products
Abstract
In a harmonic speech encoder (16) a speech signal to be encoded is represented by a plurality of LPC parameters which are determined by a LPC parameter computer (30), a pitch value and a gain value. The speech encoder comprises a (coarse) pitch estimator (38) for determining a coarse pitch, and a refined pitch computer (32) to determine a refined pitch from the coarse pitch value. The refined pitch value is determined in an analysis by synthesis way, in which a refined pitch value is selected which results in a minimum error measure between a representation of a synthesized speech signal and a representation of the original speech signal.
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Citations
9 Claims
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1. A transmitter for transmission of a speech signal, said transmitter including a speech encoder having analysis means for deriving a plurality of linear prediction coefficients from said speech signal;
- said analysis means comprising;
pitch determining means for determining a fundamental frequency of the speech signal; means for determining the amplitude and frequency of each of a plurality of harmonically related sinusoidal components of said speech signal, said determination being based on said linear prediction coefficients and said fundamental frequency; and pitch tuning means for tuning a fundamental frequency (pitch) of said plurality of harmonically related signal components so as to minimize the difference between a representation of said speech signal and a representation of said plurality of harmonically related signal components; said transmitter further comprising means for transmitting a representation of the amplitudes of said plurality of harmonically related signal components and of the fundamental frequency of said speech signal; and wherein; (i) determination of the amplitude and frequency of each of said plurality of harmonically related signal components is based on said linear prediction coefficients in substantially unquantized form; and (ii) the representation of the amplitudes of said plurality of harmonically related signal components comprises said linear prediction coefficients in quantized form and a gain factor based on said quantized linear prediction coefficients and said fundamental frequency of said speech signal. - View Dependent Claims (2, 3)
- said analysis means comprising;
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4. A speech encoder for encoding a speech signal for transmission by a transmitter over a communication channel, said encoder including analysis means for deriving a plurality of linear prediction coefficients from said speech signal, said an analysis means comprising:
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pitch determining means for determining a fundamental frequency of the speech signal; means for determining the amplitude and frequency of each of a plurality of harmonically related sinusoidal components of said speech signal, said determination being based on said linear prediction coefficients and said fundamental frequency; and pitch tuning means for tuning a fundamental frequency (pitch) of said plurality of harmonically related signal components so as to minimize the difference between a representation of said speech signal and a representation of said plurality of harmonically related signal components; said transmitter further comprising means for transmitting a representation of the amplitudes of said plurality of harmonically related signal components and of the fundamental frequency of said speech signal; and wherein; (i) determination of the amplitude and frequency of each of said plurality of harmonically related signal components is based on said linear prediction coefficients in substantially unquantized form; and (ii) the representation of the amplitudes of said plurality of harmonically related signal components comprises said linear prediction coefficients in quantized form and a gain factor based on said quantized linear prediction coefficients and said fundamental frequency of said speech signal. - View Dependent Claims (5, 6)
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7. A method of encoding a speech signal for transmission by a transmitter over a communication channel, said method including derivation of a plurality of linear prediction coefficients from said speech signal;
- said method comprising the steps of;
determining a fundamental frequency of said speech signal; determining the amplitude and frequency of each of a plurality of harmonically related sinusoidal signal components of said speech signal, said determination being based on said plurality of linear prediction coefficients and said fundamental frequency; and tuning a fundamental frequency (pitch) of said plurality of harmonically related signal components so as to minimize the difference between a representation of said speech signal and a corresponding representation of said plurality of harmonically related signal components; transmission of said speech signal being effected by transmission of a representation of the amplitudes of said plurality of harmonically related sinusoidal components and of the fundamental frequency of said speech signal; and wherein; (i) determination of the amplitude and frequency of each of said plurality of harmonically related signal components is based on said linear prediction coefficients in substantially unquantized form; and (ii) the representation of the amplitudes of said plurality of harmonically related signal components quantized form and a gain factor based on said quantized linear prediction coefficients and said fundamental frequency of said speech signal. - View Dependent Claims (8, 9)
- said method comprising the steps of;
Specification