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Browse Prior Art Database

Adaptive Side Information Channel

IP.com Disclosure Number: IPCOM000050885D
Original Publication Date: 1982-Dec-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 3 page(s) / 37K

Publishing Venue

IBM

Related People

Irvin, DR: AUTHOR

Abstract

This article describes an improved voice transmission scheme. Incoming analog voice signals on line 1 are applied to the input of an analog to digital (A/D) converter 2 which samples the input stream and provides a sequential string of digitized amplitude measurements representative of portions of the input analog waveform. The output is applied on line 3 to a fast Fourier transform circuit 4. A bit allocation algorithm, well known in the art, is applied to the Fourier transformed samples in circuit 5 to determine the allocation of coding bits to represent the content of the spectral band of the Fourier transformed signal. The Fourier transformed signal output on line 6 is quantized in the quantizer 7 using the allocation of bits prescribed by the allocation circuit 5.

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Adaptive Side Information Channel

This article describes an improved voice transmission scheme. Incoming analog voice signals on line 1 are applied to the input of an analog to digital (A/D) converter 2 which samples the input stream and provides a sequential string of digitized amplitude measurements representative of portions of the input analog waveform. The output is applied on line 3 to a fast Fourier transform circuit
4. A bit allocation algorithm, well known in the art, is applied to the Fourier transformed samples in circuit 5 to determine the allocation of coding bits to represent the content of the spectral band of the Fourier transformed signal. The Fourier transformed signal output on line 6 is quantized in the quantizer 7 using the allocation of bits prescribed by the allocation circuit 5. The final output is in the form of an encoded digital signal of the Fourier transformed input samples, with the digital code representing the content of the sub-band according to the Fourier transform. To reconstruct the signal, the distribution of the bits and their representation of the various frequency bands for the Fourier transform must be known. The communications channel 8 does not contain this information so it is necessary to provide a aide information channel 9 on which information can be sent to aid the receiver within the dotted block 10 in recreating an analog output.

The present article describes an improvement in which the foregoing general structure is modified. The general structure is known in the art, but the modification comprises using an auto correlator, also known in the art, to receive the digitized input signal from the A/D converter 2 simultaneously with the receipt of those signals by the Fourier transform circuit 4. The auto correlator 11 supplies another input to the Fourier transform circuit 4 over line 12. The auto correlation signal is Fourier transformed and it is known that the Fourier transformed auto correlation signal i...