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sajeev_antony
Joined: 12 Sep 2002
Posts: 21
Location: India
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 29 Sep 2003 13:42 digital filters |
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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
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eternal_nan
Joined: 10 Mar 2003
Posts: 158
Helped: 15
Location: eternity
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| 29 Sep 2003 18:53 Re: digital filters |
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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.
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mgpc
Joined: 07 Jul 2003
Posts: 12
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| 29 Sep 2003 20:27 Re: digital filters |
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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:
| Code: |
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
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MGPC
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