| Author |
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saras
Guest
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 Posted:
Wed Nov 30, 2005 3:31 pm Post subject:
symmetric transpose form fir filter |
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hi..
Can anybody tell me the structure of symmetric transpose form fir
filter? Please Help.. |
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Nick Molkov
Guest
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| Posted:
Wed Nov 30, 2005 5:17 pm Post subject:
Re: symmetric transpose form fir filter |
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saras wrote:
| Quote: | hi..
Can anybody tell me the structure of symmetric transpose form fir
filter? Please Help..
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please, tell me in what context do you hear this? |
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saras
Guest
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| Posted:
Thu Dec 01, 2005 9:16 am Post subject:
Re: symmetric transpose form fir filter |
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hi..
I know that by exploiting the symmetry of coeffs , the number of
multipliers can be reduced to half. But what I saw in many books is the
direct form structure(linear phase filters).So I want to know
symmetric transpose form fir filter if such structure exists.
Nick Molkov wrote:
| Quote: | saras wrote:
hi..
Can anybody tell me the structure of symmetric transpose form fir
filter? Please Help..
please, tell me in what context do you hear this? |
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Guest
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| Posted:
Thu Dec 01, 2005 11:39 pm Post subject:
Re: symmetric transpose form fir filter |
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saras wrote:
| Quote: | hi..
I know that by exploiting the symmetry of coeffs , the number of
multipliers can be reduced to half. But what I saw in many books is the
direct form structure(linear phase filters).So I want to know
symmetric transpose form fir filter if such structure exists.
|
On most DSPs, single cycle MACs are standard, ie. you don't save
anything when you cut down the number of multiplications in an FIR.
If you still need it, look at this examle: Filter coefficients h = [h1
h2 h1] (symmetric linear phase FIR with three coefficients).
Typically y(n) = h1 x(n) + h2 x(n-1) + h1 x(n-2).
To save multiplications: y(n) = h1 (x(n) + x(n-2) ) + h2 x(n-1).
You can hopefully generalize that yourself to arbitrary (odd and even)
length symmetric FIRs.
Regards,
Andor |
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Nick Molkov
Guest
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| Posted:
Thu Dec 01, 2005 11:50 pm Post subject:
Re: symmetric transpose form fir filter |
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I can't imagine, how could it be done. When you design FIR filter, you
really get the symmetry coeffs. But the only one way, that i know to
decrease the mathematical operations - is to use the algorithm of fast
convolution, based on fft. |
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Ron N.
Guest
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| Posted:
Fri Dec 02, 2005 1:17 am Post subject:
Re: symmetric transpose form fir filter |
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abariska@student.ethz.ch wrote:
| Quote: | saras wrote:
hi..
I know that by exploiting the symmetry of coeffs , the number of
multipliers can be reduced to half. But what I saw in many books is the
direct form structure(linear phase filters).So I want to know
symmetric transpose form fir filter if such structure exists.
On most DSPs, single cycle MACs are standard, ie. you don't save
anything when you cut down the number of multiplications in an FIR.
|
Although a multiply or MAC takes the same number of cycles as an add
operation on a modern DSP, the multiplier toggles a lot more gates
and wires than the adder; so there still might be a power savings
in using adds over multiplies in FIR intensive operation. And power
is king these days, especially in the design of battery operated
products.
IMHO. YMMV.
--
rhn A.T nicholson d.O.t C-o-M |
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Vladimir Vassilevsky
Guest
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| Posted:
Fri Dec 02, 2005 1:17 am Post subject:
Re: symmetric transpose form fir filter |
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Ron N. wrote:
| Quote: |
Although a multiply or MAC takes the same number of cycles as an add
operation on a modern DSP, the multiplier toggles a lot more gates
and wires than the adder; so there still might be a power savings
in using adds over multiplies in FIR intensive operation. And power
is king these days, especially in the design of battery operated
products.
IMHO. YMMV.
|
Ron, you are quite rignt. During the execution of MAC instructions the
DSP power consumption is several times higher then when executing a
general program flow. This is the fact; I observed it with ADSP-21xx.
Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com |
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Rick Lyons
Guest
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| Posted:
Tue Dec 06, 2005 1:16 am Post subject:
Re: symmetric transpose form fir filter |
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On Thu, 01 Dec 2005 21:15:44 GMT, Vladimir Vassilevsky
<antispam_bogus@hotmail.com> wrote:
| Quote: |
Ron N. wrote:
Although a multiply or MAC takes the same number of cycles as an add
operation on a modern DSP, the multiplier toggles a lot more gates
and wires than the adder; so there still might be a power savings
in using adds over multiplies in FIR intensive operation. And power
is king these days, especially in the design of battery operated
products.
IMHO. YMMV.
Ron, you are quite rignt. During the execution of MAC instructions the
DSP power consumption is several times higher then when executing a
general program flow. This is the fact; I observed it with ADSP-21xx.
Vladimir Vassilevsky
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Hi Vladimir,
Now that is interesting,... very interesting.
Thanks,
[-Rick-] |
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Steve Underwood
Guest
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| Posted:
Tue Dec 06, 2005 7:14 am Post subject:
Re: symmetric transpose form fir filter |
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Rick Lyons wrote:
| Quote: | On Thu, 01 Dec 2005 21:15:44 GMT, Vladimir Vassilevsky
antispam_bogus@hotmail.com> wrote:
Ron N. wrote:
Although a multiply or MAC takes the same number of cycles as an add
operation on a modern DSP, the multiplier toggles a lot more gates
and wires than the adder; so there still might be a power savings
in using adds over multiplies in FIR intensive operation. And power
is king these days, especially in the design of battery operated
products.
IMHO. YMMV.
Ron, you are quite rignt. During the execution of MAC instructions the
DSP power consumption is several times higher then when executing a
general program flow. This is the fact; I observed it with ADSP-21xx.
Vladimir Vassilevsky
Hi Vladimir,
Now that is interesting,... very interesting.
Thanks,
[-Rick-]
Not only interesting. It should be fairly obvious. Its interesting to |
spot the people in this group that never work on portable equipment.
Lines like "MACs are really fast these days, so we can use an FIR
instead of an IIR" are a dead giveaway. :-) The software in portable
devices very much affects their battery life, right down to choosing the
least complex instructions. Designing software for the absolute minimum
power consumption is an interesting art.
Regards,
Steve |
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Peter K.
Guest
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| Posted:
Tue Dec 06, 2005 7:33 am Post subject:
Re: symmetric transpose form fir filter |
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Steve Underwood <steveu@dis.org> writes:
| Quote: | Designing software for the
absolute minimum power consumption is an interesting art.
|
It's also interesting that many IT schools are teaching so abstractly
about software (i.e. divorcing it from the hardware), that the
graduating students won't have a snowball's chance in hell of figuring
out how to do this.
Ciao,
Peter K. |
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Vladimir Vassilevsky
Guest
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| Posted:
Tue Dec 06, 2005 7:52 am Post subject:
Re: symmetric transpose form fir filter |
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Peter K. wrote:
| Quote: | Steve Underwood <steveu@dis.org> writes:
Designing software for the
absolute minimum power consumption is an interesting art.
It's also interesting that many IT schools are teaching so abstractly
about software (i.e. divorcing it from the hardware), that the
graduating students won't have a snowball's chance in hell of figuring
out how to do this.
|
Have you ever heard of any graduate student capable of doing absolutely
anything? The only things they teach at school (fortunately) is how to
learn and where to find the information...
Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com |
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Peter K.
Guest
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| Posted:
Tue Dec 06, 2005 8:02 am Post subject:
Re: symmetric transpose form fir filter |
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Vladimir Vassilevsky <antispam_bogus@hotmail.com> writes:
| Quote: | Have you ever heard of any graduate student capable of doing
absolutely anything?
|
One or two, yes. By that I mean that I know several grad students who
have started companies and made them successful, without previous
commercial experience.
| Quote: | The only things they teach at school
(fortunately) is how to learn and where to find the information...
|
I was referring to undergrad, not graduate work.
Ciao,
Peter K. |
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Guest
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| Posted:
Tue Dec 06, 2005 3:57 pm Post subject:
Re: symmetric transpose form fir filter |
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Steve Underwood wrote:
....
| Quote: | Not only interesting. It should be fairly obvious. Its interesting to
spot the people in this group that never work on portable equipment.
Lines like "MACs are really fast these days, so we can use an FIR
instead of an IIR" are a dead giveaway. :-) The software in portable
devices very much affects their battery life, right down to choosing the
least complex instructions. Designing software for the absolute minimum
power consumption is an interesting art.
|
Steve,
I'm interested in that art. Can you give more examples of where, given
some specification, the program for minimum power consumption actually
differs from the program with minimum number of instructions (ie. the
fastest program that achieves a given spec)?
I'm not talking about chosing IIR over FIR, as this would be part of
the spec. Or perhaps the real art is to bend the specs to achieve
minimum power consumption?
Regards,
Andor |
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Jerry Avins
Guest
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| Posted:
Tue Dec 06, 2005 5:15 pm Post subject:
Re: symmetric transpose form fir filter |
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abariska@student.ethz.ch wrote:
...
| Quote: | I'm not talking about chosing IIR over FIR, as this would be part of
the spec. Or perhaps the real art is to bend the specs to achieve
minimum power consumption?
|
Implementation specs are second-rate at best. The spec should be on
performance.
Jerry
--
Engineering is the art of making what you want from things you can get.
ŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻ |
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Guest
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| Posted:
Tue Dec 06, 2005 5:16 pm Post subject:
Re: symmetric transpose form fir filter |
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Jerry Avins wrote:
| Quote: | abariska@student.ethz.ch wrote:
...
I'm not talking about chosing IIR over FIR, as this would be part of
the spec. Or perhaps the real art is to bend the specs to achieve
minimum power consumption?
Implementation specs are second-rate at best. The spec should be on
performance.
|
I don't want to argue about the definition of "specs", but about power
consumption. Even if you could choose between filter types in an
implemenation, most certainly that type which is faster to compute also
consumes less power.
Regards,
Andor |
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