Multi-rate digital voice coder apparatus
First Claim
1. Apparatus for converting analog speech into a digital signal for transmission of said digital signal over a conventional communications channel, comprising:
- pre-emphasis means responsive to said analog speech at an input for providing at an output an array of pre-emphasized speech samples,memory means coupled to said pre-emphasis means for storing said array of samples in contiguous storage locations,linear predictive coder means coupled to the output of said memory means and responsive to said stored samples for providing a first array of reflection coefficients at a first output and a second array of filter coefficients at a second output,pole broadening means coupled to said linear predictive coder means and responsive to said filter coefficient array for providing an array of filter coefficients having a broadened bandwidth including means for multiplying each of said filter coefficients in said array by a given factor,a pre-emphasis correction means coupled to said pole broadening means for receiving at an input said array of broadened bandwidth filter coefficients for providing at an output an array of corrected filter coefficients,pulse processing means coupled to said pre-emphasis means and said pre-emphasis correction means and responsive to said pre-emphasis speech samples and said corrected filter coefficients for providing at a first output a first series of pulses indicative of pulse amplitude and at a second output a second series of pulses indicative of pulse location,encoder means coupled to said first and second outputs of said pulse processing means for providing a stream of pulses indicative of a product code of said first and second series of pulses, andoutput buffer means having a first input coupled to said first output of said linear predictive coding means for receiving said reflection coefficients and a second input coupled to said encoder means for receiving said stream of pulses for providing at an output a digital signal of a given length bit stream having a bit rate determined according to said communications channel.
2 Assignments
0 Petitions
Accused Products
Abstract
An analog to digital converter for a speech signal is implemented in modules to allow for changes in bit rate and changes in bit stream length according to requirements of the digital transmission system. A pre-emphasis circuit provides an array of pre-emphasized speech samples which are stored in memory. A linear predictive coder provides an array of reflection coefficients and an array of filter coefficients. A pulse processor receives the speech samples and filter coefficients and generates speech amplitude and location signals. These signals are multiplied to generate quantized speech samples. The quantized speech samples and reflection coefficients are provided to a buffer which provides an output signal of a proper bit stream length and bit rate for the digital transmission system.
48 Citations
15 Claims
-
1. Apparatus for converting analog speech into a digital signal for transmission of said digital signal over a conventional communications channel, comprising:
-
pre-emphasis means responsive to said analog speech at an input for providing at an output an array of pre-emphasized speech samples, memory means coupled to said pre-emphasis means for storing said array of samples in contiguous storage locations, linear predictive coder means coupled to the output of said memory means and responsive to said stored samples for providing a first array of reflection coefficients at a first output and a second array of filter coefficients at a second output, pole broadening means coupled to said linear predictive coder means and responsive to said filter coefficient array for providing an array of filter coefficients having a broadened bandwidth including means for multiplying each of said filter coefficients in said array by a given factor, a pre-emphasis correction means coupled to said pole broadening means for receiving at an input said array of broadened bandwidth filter coefficients for providing at an output an array of corrected filter coefficients, pulse processing means coupled to said pre-emphasis means and said pre-emphasis correction means and responsive to said pre-emphasis speech samples and said corrected filter coefficients for providing at a first output a first series of pulses indicative of pulse amplitude and at a second output a second series of pulses indicative of pulse location, encoder means coupled to said first and second outputs of said pulse processing means for providing a stream of pulses indicative of a product code of said first and second series of pulses, and output buffer means having a first input coupled to said first output of said linear predictive coding means for receiving said reflection coefficients and a second input coupled to said encoder means for receiving said stream of pulses for providing at an output a digital signal of a given length bit stream having a bit rate determined according to said communications channel. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
-
-
12. Apparatus for converting analog speech into a digital signal for transmission of said digital signal over a conventional communications channel, comprising:
-
an analog to digital converter for converting said analog speech into digitized speech, pre-emphasis means responsive to said digitized speech for providing an array of pre-emphasized speech samples, memory means coupled to said pre-emphasis means for storing said array of samples, linear predictive coder means coupled to said memory means and responsive to said stored samples for providing a first array of reflection coefficients and a second array of filter coefficients, pole broadening means coupled to said linear predictive coder means and responsive to said second array of filter coefficients for providing an array of filter coefficients having a broadened bandwidth, said pole broadeneing means including means for multiplying each of said filter coefficients in said second array of filter coefficients by a given factor, and a pre-emphasis correction means coupled to said pole broadening means for receiving said array of broadened bandwidth filter coefficients for providing an array of corrected filter coefficients, pulse processing means coupled to said pre-emphasis means and said pre-emphasis correction means and responsive to said array of pre-emphasized speech samples and said corrected filter coefficients for providing a first series of pulses indicative of pulse amplitude and a second series of pulses indicative of pulse location, encoder means coupled to said pulse processing means for receiving said first and second series of pulses and for providing a stream of pulses indicative of a product code of said first and second series of pulses, output buffer means coupled to said linear predictive coding means for receiving said reflection coefficients and coupled to said encoder means for receiving said stream of pulses for providing at an output a digital signal of a given length bit stream having a bit rate determined according to said communications channel. - View Dependent Claims (13, 14)
-
-
15. Apparatus for converting an analog speech signal into a digital signal, comprising:
-
a pre-emphasizer to an analog speech input, said pre-emphasizer providing a digital speech sample array; a linear predictive coder for receiving said digital speech sample array and providing a reflection coefficient digital signal and a filter coefficient digital signal; a pole broadener for receiving said filter coefficient digital signal and providing a pole broadened filter coefficient signal; a pre-emphasis corrector for receiving said pole broadened filter coefficient signal and providing a corrected filter coefficient signal; a pulse processor for receiving said corrected filter coefficient signal and said digital speech sample array, said pulse processor generating a first pulse array of amplitude indicating pulses and a second pulse array of position indicting pulses and providing a digital product code indicative of the product of said first pulse array of amplitude indicating pulses and said second pulse array of position indicating pulses; an output means for receiving said digital product code and said reflection coefficient digital signal, said output means providing a digital output signal of a given length bit stream and having a predetermined bit rate and representative of said analog speech signal.
-
Specification