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From: Clay on 5 Mar 2010 16:21
On Mar 5, 11:33 am, Tim Wescott <t...(a)seemywebsite.now> wrote:
> Jerry Avins wrote:
> > Rune Allnor wrote:
> >> On 5 Mar, 14:45, "gretzteam" <gretzt...(a)yahoo.com> wrote:
> >>> Hi,
> >>> I've been playing with wave lattice filters for a little while and only
> >>> yesterday realized that they were just a structure used to implement the
> >>> same good old transfer function that maps nicely onto the Direct Form I,
> >>> II, transposed etc. For some reason I thought they were a different
> >>> beast.
>
> >>> Now I wonder how do people come up with new structures. The mapping from
> >>> the transfer function to a lattice wave filter is not obvious at all!
> >>> Let's
> >>> say that I couldn't just start from DF1 and come up with a lattice
> >>> structure...
>
> >>> Are there still new structures being found yielding power or area
> >>> advantages?
>
> >>> Are there any book or research on this topic?
>
> >> There are two lines of thought on this topic:
>
> >> 1) There is *always* something new anexciting to be discovered.
> >> 2) Most of the useful stuff has already been discovered.
>
> >> I must admit that I subscribe to view 2) - that most of the
> >> useful DSP stuff is already ot there. This view is based on
> >> the premise that
>
> >> 1) There are only so many ways to compute the same quantity
> >> 2) A lot of ridiculously smart people have reviewed the
> >>    subject in the past, which leave very little to be
> >>    discovered in the future
>
> >> I know some of the regulars here disagree fiercly with me,
> >> but it's up to them, not me, to argue in defence of their
> >> views.
>
> > Of course there are new things to be discovered. The hard question is,
> > are there new *useful* things to be discovered? Sometimes, a slightly
> > inferior solution is useful for circumventing a patent.
>
> > Jerry
>
> Sometimes, an effort to circumvent a patent leads to a superior solution
> (I wish I had an example to hand).
>
> --
> Tim Wescott
> Control system and signal processing consultingwww.wescottdesign.com- Hide quoted text -
>
> - Show quoted text -

And there are some patents that can't be circumvented. For example US
Patent 3,156,523 (issued Nov 10, 1964) where claim 1 is:

1. Element 95


This will be hard to get around!

Clay



From: Clay on 5 Mar 2010 16:24
On Mar 5, 8:45 am, "gretzteam" <gretzt...(a)yahoo.com> wrote:
> Hi,
> I've been playing with wave lattice filters for a little while and only
> yesterday realized that they were just a structure used to implement the
> same good old transfer function that maps nicely onto the Direct Form I,
> II, transposed etc. For some reason I thought they were a different beast..
>
> Now I wonder how do people come up with new structures. The mapping from
> the transfer function to a lattice wave filter is not obvious at all! Let's
> say that I couldn't just start from DF1 and come up with a lattice
> structure...
>
> Are there still new structures being found yielding power or area
> advantages?
>
> Are there any book or research on this topic?
>
> Thanks!
> Diego

I've seen quite a few papers on alternate network forms for
calculating the DCT recursively as saving silicon and reducing power
consumption is very useful for jpeg compression of images in cameras.

Clay
From: Eric Jacobsen on 5 Mar 2010 16:30
On 3/5/2010 2:21 PM, Clay wrote:
> On Mar 5, 11:33 am, Tim Wescott<t...(a)seemywebsite.now> wrote:
>> Jerry Avins wrote:
>>> Rune Allnor wrote:
>>>> On 5 Mar, 14:45, "gretzteam"<gretzt...(a)yahoo.com> wrote:
>>>>> Hi,
>>>>> I've been playing with wave lattice filters for a little while and only
>>>>> yesterday realized that they were just a structure used to implement the
>>>>> same good old transfer function that maps nicely onto the Direct Form I,
>>>>> II, transposed etc. For some reason I thought they were a different
>>>>> beast.
>>
>>>>> Now I wonder how do people come up with new structures. The mapping from
>>>>> the transfer function to a lattice wave filter is not obvious at all!
>>>>> Let's
>>>>> say that I couldn't just start from DF1 and come up with a lattice
>>>>> structure...
>>
>>>>> Are there still new structures being found yielding power or area
>>>>> advantages?
>>
>>>>> Are there any book or research on this topic?
>>
>>>> There are two lines of thought on this topic:
>>
>>>> 1) There is *always* something new anexciting to be discovered.
>>>> 2) Most of the useful stuff has already been discovered.
>>
>>>> I must admit that I subscribe to view 2) - that most of the
>>>> useful DSP stuff is already ot there. This view is based on
>>>> the premise that
>>
>>>> 1) There are only so many ways to compute the same quantity
>>>> 2) A lot of ridiculously smart people have reviewed the
>>>> subject in the past, which leave very little to be
>>>> discovered in the future
>>
>>>> I know some of the regulars here disagree fiercly with me,
>>>> but it's up to them, not me, to argue in defence of their
>>>> views.
>>
>>> Of course there are new things to be discovered. The hard question is,
>>> are there new *useful* things to be discovered? Sometimes, a slightly
>>> inferior solution is useful for circumventing a patent.
>>
>>> Jerry
>>
>> Sometimes, an effort to circumvent a patent leads to a superior solution
>> (I wish I had an example to hand).
>>
>> --
>> Tim Wescott
>> Control system and signal processing consultingwww.wescottdesign.com- Hide quoted text -
>>
>> - Show quoted text -
>
> And there are some patents that can't be circumvented. For example US
> Patent 3,156,523 (issued Nov 10, 1964) where claim 1 is:
>
> 1. Element 95
>
>
> This will be hard to get around!
>
> Clay

Arg...can't view it for some reason.

Good thing it's expired, though! ;)

--
Eric Jacobsen
Minister of Algorithms
Abineau Communications
http://www.abineau.com
From: Clay on 5 Mar 2010 16:34
On Mar 5, 4:30 pm, Eric Jacobsen <eric.jacob...(a)ieee.org> wrote:
> On 3/5/2010 2:21 PM, Clay wrote:
>
>
>
>
>
> > On Mar 5, 11:33 am, Tim Wescott<t...(a)seemywebsite.now>  wrote:
> >> Jerry Avins wrote:
> >>> Rune Allnor wrote:
> >>>> On 5 Mar, 14:45, "gretzteam"<gretzt...(a)yahoo.com>  wrote:
> >>>>> Hi,
> >>>>> I've been playing with wave lattice filters for a little while and only
> >>>>> yesterday realized that they were just a structure used to implement the
> >>>>> same good old transfer function that maps nicely onto the Direct Form I,
> >>>>> II, transposed etc. For some reason I thought they were a different
> >>>>> beast.
>
> >>>>> Now I wonder how do people come up with new structures. The mapping from
> >>>>> the transfer function to a lattice wave filter is not obvious at all!
> >>>>> Let's
> >>>>> say that I couldn't just start from DF1 and come up with a lattice
> >>>>> structure...
>
> >>>>> Are there still new structures being found yielding power or area
> >>>>> advantages?
>
> >>>>> Are there any book or research on this topic?
>
> >>>> There are two lines of thought on this topic:
>
> >>>> 1) There is *always* something new anexciting to be discovered.
> >>>> 2) Most of the useful stuff has already been discovered.
>
> >>>> I must admit that I subscribe to view 2) - that most of the
> >>>> useful DSP stuff is already ot there. This view is based on
> >>>> the premise that
>
> >>>> 1) There are only so many ways to compute the same quantity
> >>>> 2) A lot of ridiculously smart people have reviewed the
> >>>>     subject in the past, which leave very little to be
> >>>>     discovered in the future
>
> >>>> I know some of the regulars here disagree fiercly with me,
> >>>> but it's up to them, not me, to argue in defence of their
> >>>> views.
>
> >>> Of course there are new things to be discovered. The hard question is,
> >>> are there new *useful* things to be discovered? Sometimes, a slightly
> >>> inferior solution is useful for circumventing a patent.
>
> >>> Jerry
>
> >> Sometimes, an effort to circumvent a patent leads to a superior solution
> >> (I wish I had an example to hand).
>
> >> --
> >> Tim Wescott
> >> Control system and signal processing consultingwww.wescottdesign.com-Hide quoted text -
>
> >> - Show quoted text -
>
> > And there are some patents that can't be circumvented. For example US
> > Patent 3,156,523 (issued  Nov 10, 1964) where claim 1 is:
>
> > 1. Element 95
>
> > This will be hard to get around!
>
> > Clay
>
> Arg...can't view it for some reason.
>
> Good thing it's expired, though!  ;)
>
> --
> Eric Jacobsen
> Minister of Algorithms
> Abineau Communicationshttp://www.abineau.com- Hide quoted text -
>
> - Show quoted text -

Check your email.

Yes it is expired and most if not all of today's smoke detectors use
americium.

Clay


From: Steve Pope on 9 Mar 2010 00:37
Tim Wescott <tim(a)seemywebsite.now> wrote:

>Rune Allnor wrote:

>> On 5 Mar, 19:54, "gretzteam" <gretzt...(a)yahoo.com> wrote:

>>> Now does anybody know of a group doing active research on finding new
>>> structures?

>> Why would anyone want to? The lattice / ladder structures
>> date back at least to the '60s / '70s; possibly a lot further.
>> If there is anything at all going on, it would be in the realm
>> of Kalman'ish filters, like uncented KFs, H_inf or particle
>> filters.

>> This stuff on filter structures is *ancient*.

>You still see papers in the IEEE Circuits & Systems transactions, mainly
>having to do with clever ways to implement them in full-custom silicon.

This has nothing to do with filter structures, but recently I've been
looking into ways of synthesizing all-pole bandpass filters that meet
given design constraints. I'm very sure I'm not breaking new
territory here, OTOH I haven't seen the method I'm using written up
anyway either. Basically, apply a window to a sinusoid that is the
weighted sum of a Hamming window, and a rectangular window; then do
linear prediction on the result; then after some diddling, you have
your bandpass filter coefficients.

The relative weight of the Hamming and rectangular components
controls the Q of the resulting filter in a straightforward way,
and being all-pole, it is cheaper than a filter with both
poles and zeros.

But I'm sure there is some textbook way of achieiving the same result,
that I simply haven't bothered to look up...


Steve
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