digital filters - what are they?

[sajeev_antony]

digital filters

does any one know what are these..

Even-Tap, Even-Symmetric Coefficient Set

Odd-Tap, Even-Symmetric Coefficient Set

Even-Tap, Odd-Symmetric Coefficient Set

 

[eternal_nan]

Re: digital filters

Hi,

These are descriptions for linear-phase FIR filter imulse responses (ie, coefficient sets):

Even-Tap, Even-Symmetric Coefficient Set -> linear phase, non-integer group delay (integer + 0.5), used general for filer

Odd-Tap, Even-Symmetric Coefficient Set -> This is the most heavily used kind, linear phase, integer group delay fir filter.

Even-Tap, Odd-Symmetric Coefficient Set -> linear phase, non-integer group delay, usually used for FIR differentiators.

Hope this helps.

 

[mgpc]

Re: digital filters

There are 4 combinations of these filters and they are often categorized as types:

Type 1: Odd number of taps, impulse response is an even function.
Type 2: Even number of taps, impulse response is an evenfunction.
Type 3: Odd number of taps, impulse response is an odd function.
Type 4: Even number of taps, impulse response is an odd function.

You may want to pay special attention to their symmetry around w=0 and w=pi. Odd symmetry around w=0 imply that the system frequency response is zero at w=0 and therefore this filter cannot be low pass. Odd symmetry around w=pi imply that the system frequency response is zero at w=pi and therefore this filter cannot be high pass.

The following table details the symmetry properties associated with each type of filter:

                 Type 1   Type 2   Type 3   Type 4
N taps            Odd      Even     Odd      Even
Symmetry, w=0     Even     Even     Odd      Odd
Symmetry, w=pi    Even     Odd      Odd      Even

MGPC