Time-domain equalizer and signal processing method thereof
A time-domain equalizer includes a delay circuit, a weighting circuit, a controller and a summation circuit. The delay circuit receives an equalized signal and accordingly generates M delayed signals for an equalized signal. The weighting circuit applies an m th weighting of M weightings to an m th delayed signal of the M delayed signals to generate an m th weighted signal. The summation circuit sums up the M weighted signals, according to which the equalized signal is updated. The controller iteratively updates the M weightings according to a vector {right arrow over (e)} n,p =[e n,p,1 . . . e n,p,M ], where the symbol e n,p,j is defined as e n,p,j =Σ k (z[k]*z[k−D p,j ]*), the symbol n is an iteration index, k is a sample index, z[k] is a k th sample of the equalized signal, j is an integer index between 1 and M, and D p,j represents a time delay amount corresponding to a j th delayed signal of the M delayed signals.
1. A time-domain equalizer, comprising:
a delay circuit, receiving an equalized signal, and accordingly generating M delayed signals, where M is a positive integer greater than 1;
a weighting circuit, adopting M weightings, and applying an m th weighting of the M weightings on an m th delayed signal of the M delay signals to generate an m th weighted signal, where m is an integer index between 1 and M, wherein M weighted signals are generated accordingly;
a controller, iteratively updating the M weightings according to a vector {right arrow over (e)} n,p =[e n,p,1 . . . e n,p,M ], where e n,p,j is defined as e n,p,j =Σ k (z[k]*z[k−D p,j ]*), n represents an iteration index, k represents a sample index, z[k] is a k th sample of the equalized signal, p corresponds to a p th echo signal, j is an integer index between 1 and M, D p,j represents a j th time delay amount corresponding to a j th delayed signal of the M delayed signals, and z[k−D p,j ]* represents z[k] delayed by delay D p,j ; and
summation circuit, summing up the M weighted signals, according to which the equalized signal is updated.
2. The time-domain equalizer according to claim 1 , wherein the controller updates the M weightings adopted by the weighting circuit according to an equation:
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where μ represents an adjustable parameter in a least mean square (LMS) algorithm; and
the vector {right arrow over (z)} n,p,m is:
[Σ k z[k−D p,m ]*z[k−D p,1 ]* . . . Σ k z[k−D p,m ]*z[k−D p,M ]*],
where D p,m represents an m th delay amount.
3. The time-domain equalizer according to claim 1 , wherein:
the controller further comprises an adaptive adjusting circuit that determines M parameters [k n,p,1 . . . k n,p,M ] according to the M weightings [w n,p,1 . . . w n,p,M ]; and
the controller updates the M weightings according to an equation:
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where μ is an adjustable parameter in a least mean square (LMS) algorithm, and the vector {right arrow over (z)} n,p,m is:
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where D p,m represents an m th delay amount.
4. A signal processing method, comprising:
receiving an equalized signal, and accordingly generating M delayed signals, where M is a positive integer;
adopting M weightings, and applying an m th weighting of the M weightings to an m th delayed signal of the M delay signals to generate an m th weighted signal, where m is an integer index between 1 and M;
iteratively updating the M weightings according to a vector {right arrow over (e)} n,p =[e n,p,1 . . . e n,p,M ]. where e n,p,j is defined as e n,p,j =Σ k (z[k]*z[k−D p,j ]*), n represents an iteration index, k represents a sample index, z[k] is a k th sample of the equalized signal, p corresponds to a p th echo signal, j is an integer index between 1 and M, D p,j represents a j th time delay amount corresponding to a j th delayed signal of the M delayed signals, and z[k−D p,j ]* represents z[k] delayed by delay D p,j ; and
summing up the M weighted signals to update the equalized signal.
5. The signal processing method according to claim 4 , wherein the step of iteratively updating the M weightings comprising updating the M weightings according to an equation:
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where μ represents an adjustable parameter in a least mean square (LMS) algorithm; and
the vector {right arrow over (z)} n,p,m is:
[Σ k z[k−D p,m ]*z[k−D p,1 ]* . . . Σ k z[k−D p,m ]*z[k−D p,M ]*],
where D p,m represents an m th delay amount.
6. The signal processing method according to claim 4 , further comprising:
determining the M parameters [k n,p,1 . . . k n,p,M ] according to the M weightings [w n,p,1 . . . w n,p,M ];
and the step of iteratively updating the M weightings comprises updating the M weightings according to an equation:
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where μ is an adjustable parameter in a least mean square (LMS) algorithm, and the vector {right arrow over (z)} n,p,m is:
[Σ k z[k−D p,m ]*z[k−D p,1 ]* . . . Σ k z[k−D p,m ]*z[k−D p,M ]*],
where D p,m represents an m th delay amount.