Process for transmitting a signal
First Claim
1. In a method of transmitting an analog signal including the steps of converting said analog signal into a digital signal, subdividing said digital signal into successive blocks using windows and converting said blocks into spectra using transformation, coding said spectra and transmitting said spectra, decoding and reconverting said spectra into signal segments using inverse transformation, and joining together said blocks containing said signal segments, an improvement comprising the steps of:
- a) evaluating said blocks for level changes, and when said level is below a predetermined level;
b) subdividing said signal into blocks and overlapping said blocks by 50%;
c) assessing the signal segments within said blocks using analysis windows;
d) transforming said signal segments using subsampling and time domain aliasing cancellation to compensate for aliasing components;
e) inverse transforming said signal segments;
f) assessing said signal segments using synthesis windows;
g) rejoining said blocks in overlapping fashion; and
when said level change is above said predetermined levelh) subdividing said signal into blocks and overlapping by between 0% and n%, where n<
50%.i) fully scanning said signal segments;
j) compressing said signal segments;
k) transforming said signal segments;
l) inverse transforming said signal segments;
m) expanding said signal segments.
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Accused Products
Abstract
A method of transmitting an analog signal including the steps of converting the analog signal into a digital signal and using windows to subdivide the digital signal into successive blocks. The blocks are evaluated for level changes, and when a level change is below a predetermined level the blocks are overlapped by 50%. The signal segments within the blocks assessed using analysis windows. The signal segments are transformed using subsampling and time domain aliasing cancellation to compensate for aliasing components. The signal segments are inverse transformed and assessed using synthesis windows. The blocks are rejoined in overlapping fashion. When the level change is above the predetermined level the signals are subdivided into blocks and the blocks are overlapped by less than 50%, or not overlapped at all. The signal segments are fully scanned, compressed and transformed. The signal segments are finally inverse transformed and expanded.
30 Citations
12 Claims
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1. In a method of transmitting an analog signal including the steps of converting said analog signal into a digital signal, subdividing said digital signal into successive blocks using windows and converting said blocks into spectra using transformation, coding said spectra and transmitting said spectra, decoding and reconverting said spectra into signal segments using inverse transformation, and joining together said blocks containing said signal segments, an improvement comprising the steps of:
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a) evaluating said blocks for level changes, and when said level is below a predetermined level; b) subdividing said signal into blocks and overlapping said blocks by 50%; c) assessing the signal segments within said blocks using analysis windows; d) transforming said signal segments using subsampling and time domain aliasing cancellation to compensate for aliasing components; e) inverse transforming said signal segments; f) assessing said signal segments using synthesis windows; g) rejoining said blocks in overlapping fashion; and when said level change is above said predetermined level h) subdividing said signal into blocks and overlapping by between 0% and n%, where n<
50%.i) fully scanning said signal segments; j) compressing said signal segments; k) transforming said signal segments; l) inverse transforming said signal segments; m) expanding said signal segments.
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2. In a method of transmitting an analog signal including the steps of converting said analog signal into a digital signal, subdividing said digital signal into successive blocks using windows and converting said blocks into spectra using transformation, coding said spectra and transmitting said spectra, decoding and reconverting said spectra into signal segments using inverse transformation, and joining together said blocks containing said signal segments, an improvement comprising the steps of:
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a) evaluating said blocks for level changes, and when said level is below a predetermined level; b) subdividing said signal into blocks and overlapping said blocks by 50%; c) assessing the signal segments within said blocks using analysis windows; d) transforming said signal segments using subsampling and time domain aliasing cancellation to compensate for aliasing components; e) inverse transforming said signal segments; f) assessing said signal segments using synthesis windows; g) rejoining said blocks in overlapping fashion; and when said level change is above said predetermined level h) subdividing said signal into blocks and overlapping by between 0% and n%, where n<
50%;i) fully scanning said signal segments; j) compressing said signal segments; k) transforming said signal segments; l) inverse transforming said signal segments; and m) expanding said signal segments;
whereinthe window functions of said synthesis windows are determined depending upon the window functions of the corresponding analysis windows in the overlap region according to the equations;
##EQU2## where an (t) is the analysis window function for the block n,sn (t) is the synthesis window function for the block n, an +1(t) is the synthesis window function for the block n+1, sn +1(t) is the synthesis window function for the block n+1, TB is the block time; subdividing the blocks which overlap less than 50% into sub-blocks and, depending on the average signal energies in said sub-blocks, altering said sub-blocks using amplifying or attenuating factors during compression and expanding said sub-blocks whereby aliasing components are complementary and cancel. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification