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The frequency response of a LTI system is given by     

                                                           b_k= filter  coefficients                                                                                                                                                             h[k]=Impulse response

                    & M corresponds to the order of the filter

DB4 WAVELET

Daubechies 4  wavelet gives the filter coefficients for

lofd: lowpass decomposition filter : -0.0106  0.0329  0.0308  -0.1870  -0.0280  0.6309  0.7148  0.2304

hifd: highpass decomposition filter : -0.2304  0.7148  -0.6309  -0.0280  0.1870 0.0308  -0.0329  -0.0106

lofr: lowpass reconstruction filter : 0.2304  0.7148  0.6309  -0.0280  -0.1870 0.0308  0.0329  -0.0106

hifr: highpass reconstruction filter :  -0.0106  -0.0329  0.0308  0.1870   -0.0280  -0.6309  0.7148  -0.2304            

The normalized frequency response of these 4 filters is shown below

                               Magnitude Response  

The processes of downsampling & upsampling (by a factor of 2 corresponding to the dyadic scale) & the fact that the filters used at each level are half bandpass filters enable the same filter coefficients to be used at each  level of decomposition & reconstruction.

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