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richloo
Joined: 24 Aug 2004
Posts: 103
Helped: 5
Location: Isolated Island
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 05 Jan 2005 9:56 Linear Phase Filter? |
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Hi there,
What is linear phase filter?
Dose it related to the conventional filter i.e. Butterworth,Bessel,Chebychev... etc?
Thanks in advance!
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terryssw
Joined: 18 Apr 2004
Posts: 176
Helped: 14
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| 06 Jan 2005 16:05 Re: Linear Phase Filter? |
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| Linear phase filter, as the name suggest, have the linear phase characteristics and thus no phase distortion. This usually constructed by discrete-time FIR filters. What you have mentioned is all IIR filters, which do not process linear phase characteristics in wide frequency range.
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flatulent
Joined: 19 Jul 2002
Posts: 4856
Helped: 292
Location: Middle Earth
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| 06 Jan 2005 17:46 Re: Linear Phase Filter? |
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In traditional analog types with poles and zeros, the Bessel and Thompson are this type. One is maximally flat phase derivatives at DC and the other is an approximation of the Gaussian amplitude response which also has flat time delay. The amplitude and phase responses are related by the Hilbert transform.
As stated above, in DSP type filters the FIR with symmetrical tap weights has linear phase and any arbitrary amplitude response.
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richloo
Joined: 24 Aug 2004
Posts: 103
Helped: 5
Location: Isolated Island
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| 06 Jan 2005 18:45 Linear Phase Filter? |
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thanks you guyz... great... i m clear now...
one confusing matter, this type of FIR filter must implement on DSP? if yes, then why there is a paper "JSSC Vol.38,No.2 February 2003" implemented using analog gm-C. Or it is just the analog filter have such linear phase characteristic?
thanks in advance!
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flatulent
Joined: 19 Jul 2002
Posts: 4856
Helped: 292
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| 06 Jan 2005 19:18 Re: Linear Phase Filter? |
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| The FIR filter can also be implemented with an analog delay line, but it is not that economical. It does make a nice thesis topic for academics.
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chinito
Joined: 05 Jul 2004
Posts: 133
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| 06 Jan 2005 23:55 Re: Linear Phase Filter? |
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| filter design, long time back, went into digital domain for the economic reason. Analog designers are integrating more and more functionality into Analog block while digital designers are pulling as much stuff into their digital block as they possibly can. Filter, for the most part, is done in digital (DSP block) because it is more economical.
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borodenkov
Joined: 02 Mar 2004
Posts: 129
Helped: 11
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| 07 Jan 2005 2:25 Linear Phase Filter? |
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| Could you please post a link about Hilbert transform in connection with filter design?
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boeysue
Joined: 23 Dec 2004
Posts: 190
Helped: 3
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| 07 Jan 2005 9:02 Re: Linear Phase Filter? |
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Linear phase means constant delay in time .That is useful for audio.
It is always linear-phase in fir.
iir is not linear-phase,but it can be designed in minimun-phase.butte,cheb is iir filter. non-linear phase design must be keeped in mind that phase delay in design.
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