摘要 |
A method and unit for substracting quantization noise from a pulse code modulated PCM signal being segmented into frames. For achieving this it is proposed to first calculate for each frame of the PCM signal a quantization noise level Bq according to an equation having parameters including n which indicates a specific sample of the PCM signal, S*<SUB>min</SUB>[n] which represents the minimum quantization noise level for a specific sample value s*[n] of the PCM signal, S*<SUB>max</SUB>[n] which represents the maximum quantization noise level for the specific sample value s*[n] of the PCM signal, w[n] which represents a window-function and W which represents the number of samples per window. Subsequently, the quantization noise as represented by the quantization noise level Bq has to be substracted from the PCM signal, preferably with the help of a suitable background noise substracting system. <maths id="MATH-US-00001" num="00001"> <MATH OVERFLOW="SCROLL"> <MTABLE> <MTR> <MTD> <MROW> <MSUB> <MI>B</MI> <MI>q</MI> </MSUB> <MO>=</MO> <MSQRT> <MROW> <MUNDEROVER> <MO>∑</MO> <MROW> <MI>n</MI> <MO>=</MO> <MN>0</MN> </MROW> <MROW> <MI>W</MI> <MO>-</MO> <MN>1</MN> </MROW> </MUNDEROVER> <MO></MO> <MFRAC> <MSUP> <MROW> <MO>{</MO> <MROW> <MROW> <MO>(</MO> <MROW> <MROW> <MSUBSUP> <MI>s</MI> <MI>min</MI> <MO>*</MO> </MSUBSUP> <MO></MO> <MROW> <MO>[</MO> <MI>n</MI> <MO>]</MO> </MROW> </MROW> <MO>-</MO> <MROW> <MSUBSUP> <MI>s</MI> <MI>max</MI> <MO>*</MO> </MSUBSUP> <MO></MO> <MROW> <MO>[</MO> <MI>n</MI> <MO>]</MO> </MROW> </MROW> </MROW> <MO>)</MO> </MROW> <MO>.</MO> <MROW> <MI>w</MI> <MO></MO> <MROW> <MO>[</MO> <MI>n</MI> <MO>]</MO> </MROW> </MROW> </MROW> <MO>}</MO> </MROW> <MN>2</MN> </MSUP> <MN>12</MN> </MFRAC> </MROW> </MSQRT> </MROW> </MTD> <MTD> <MROW> <MO>(</MO> <MI>I</MI> <MO>)</MO> </MROW> </MTD> </MTR> </MTABLE> </MATH> </MATHS> |