Process for transmitting and receiving a signal
First Claim
1. A communication method for use in a communications system having a transmitter and receiver, comprising:
- dividing a signal using windows into successive blocks that overlap by at least 50%, signal sections contained in the blocks being evaluated with analysis windows;
subjecting the signal sections contained in the blocks to a transformation which permits sub-sampling with compensation of aliasing components, said transformation performing time domain aliasing cancellation;
wherein spectra resulting from the transformation are subsequently transmitted from the transmitter to a receiver and are changed back to blocks having signal sections by retransformation;
wherein the retransformed blocks having the signal sections are evaluated with synthesis windows and are joined together in an overlapping fashion; and
wherein window functions of the synthesis windows are determined in dependence on window functions of corresponding analysis windows in the overlap region, according to the following equations;
##EQU5## where an (t) is the analysis window function for block n;
sn (t) is the synthesis window function for block n;
an+1 (t) is the analysis window function for block n+1;
sn+1 (t) is the synthesis window function for block n+1; and
TB is the block time.
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Accused Products
Abstract
A signal is divided by windows into successive blocks that overlap at least by 50% and signal sections contained in the blocks are evaluated by analysis windows. The signal sections contained in the blocks are subjected to a transformation which permits sub-sampling with compensation of the aliasing components such as, for example, the "time domain aliasing cancellation" method. The spectra resulting from the transformation are subsequently coded, transmitted, decoded after transmission and changed back to signal sections by re-transformation. The blocks including the signal sections are evaluated by synthesis windows and are joined together in an overlapping fashion. The window functions of the synthesis windows are determined in dependence on the window functions of the corresponding analysis windows in the overlap region.
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Citations
11 Claims
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1. A communication method for use in a communications system having a transmitter and receiver, comprising:
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dividing a signal using windows into successive blocks that overlap by at least 50%, signal sections contained in the blocks being evaluated with analysis windows; subjecting the signal sections contained in the blocks to a transformation which permits sub-sampling with compensation of aliasing components, said transformation performing time domain aliasing cancellation; wherein spectra resulting from the transformation are subsequently transmitted from the transmitter to a receiver and are changed back to blocks having signal sections by retransformation; wherein the retransformed blocks having the signal sections are evaluated with synthesis windows and are joined together in an overlapping fashion; and wherein window functions of the synthesis windows are determined in dependence on window functions of corresponding analysis windows in the overlap region, according to the following equations;
##EQU5## where an (t) is the analysis window function for block n;sn (t) is the synthesis window function for block n; an+1 (t) is the analysis window function for block n+1; sn+1 (t) is the synthesis window function for block n+1; and
TB is the block time. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A communication method for use in a communications system having a transmitter and receiver, comprising:
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performing analog to digital conversion on an analog signal to form digital samples; selecting a series of successive sampling values from the digital samples; forming blocks that overlap in time by fifty percent from the selected sampling values, wherein adjacent blocks partially contain the same sampling values but at different locations, the sampling values in a first half of a respective block corresponding to sampling values in a second half of a preceding block; evaluating the formed blocks using analysis windows, wherein at borders of the formed blocks, a soft signal start and decay is produced; transforming the formed blocks from the time to the frequency domain to thereby produce spectral values; converting the spectral values into a form containing pseudo magnitudes and pseudo phases, and simultaneously sub-sampling, to produce a result in which a doubling of data caused by the fifty percent overlapping of the formed blocks is cancelled out; transmitting the result of the converting and sub-sampling step from the transmitter to a receiver; inverse transforming the spectral values in the transmitted result from the frequency domain to the time domain to produce blocks, wherein the produced blocks contain only one-half of the sampling values of the originally formed blocks; evaluating the produced blocks using synthesis windows to compensate for the evaluation performed by the analysis windows, wherein window functions of the synthesis windows, in a region of overlap with a corresponding analysis window, supplement each other to equal one, and the analysis window mirrored in the middle of the overlap region multiplied by a synthesis window for block n, minus the analysis window mirrored in the middle of the overlap region multiplied by a synthesis window for block n+1 in the overlap region, equals zero; adding fifty percent overlapping blocks, aliasing components in two blocks to be added occurring in each case with the opposite sign so that the aliasing components are compensated to zero during the addition; joining the blocks resulting from the addition to form continuous sampling values; and performing digital to analog conversion on the continuous sampling values to form an analog signal. - View Dependent Claims (9, 10, 11)
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Specification