On Jul 5, 1:37=A0am, Vladimir Vassilevsky <nos...@nowhere.com> wrote:
> HardySpicer wrote:
> > On Jul 3, 3:17 pm, Vladimir Vassilevsky <nos...@nowhere.com> wrote:
>
> >>HardySpicer wrote:
>
> >>>On Jul 3, 3:24 am, Vladimir Vassilevsky <nos...@nowhere.com> wrote:
>
> >>>>tinkerz wrote:
>
> >>>>>Hi All
>
> >>>>>Where is the best place to hire a programmer for a DSP/Laplace contr=
ol
> >>>>>system
>
> >>>>>Thanks
> >>>>>Tinkerz
>
> >>>>Programmer is a tool. What you are looking for is probably a coder. T=
o
> >>>>get a coder, go to a forest and find some orangutan.
>
> >>>User interface is fulling functional I see Mr Impaler..
>
> >>The orangutan Ph.D. ?
>
> > What? You don't have a Ph.D and you think your are qualified to answer
> > questions on this NG?
> > Shame on you.
>
> You see, Hardy, I do have Ph.D. However I am not orangutan.

not AN orangutan...

I email Tim I hope he has a simple solution, I am sure its simple solution

On 07/03/2011 11:53 PM, robert bristow-johnson wrote:
> On Jul 3, 1:03 pm, Tim Wescott<t...@seemywebsite.com>  wrote:
>> On 07/02/2011 07:28 PM, Randy Yates wrote:
>>
>>> On 07/02/2011 05:02 PM, Tim Wescott wrote:
>>>> [...]
>>>> Randy is probably forgetting that the z transform (which is what is
>>>> used to analyze sampled-time systems) can be derived from the
>>>> Laplace transform.
>>
>>> There may be some convoluted way to do that, but I don't think it's
>>> going to be of any utility. None of Lyons, Proakis, Mitra, or
>>> Oppenheim discuss deriving it from the Laplace transform.
>>
>>> Of course it has the similar function as the Laplace transform in the
>>> digital domain, and as the Laplace transform is derived from the
>>> continuous-time Fourier transform, the z-transform is derived from the
>>> discrete time Fourier transform. However it isn't "derived" from the
>>> Laplace transform in any way I've seen or can imagine to be useful.
>>
>> Houpis&  Lamont, "Digital Control".  Shows how, if you model the
>> sampling process as multiplying by a chain of impulses then the z
>> transform just falls out of the Laplace transform.
>>
>> IIRC, Oppenheim, Wilsky&  Young, "Signals and Systems" models sampling
>> the same way, and derives the Fourier series from the Fourier transform;
>> I'd be surprised if they don't derive the z transform the same way,
>> later in the book.
>
> it's straight forward.  we've done it here in comp.dsp several times
> since the mid 90s.
>
> the Z transform is nothing other than the Laplace transform of a
> sampled signal (with them weighted dirac impulses) and the
> substitution:
>
>     z = e^(s*T)   where  1/T = sampling frequency
>
> it's nothing more than that.

You're right Robert (and Tim), we have done that here, and I did
forget. It does bring out the mapping between the two domains nicely,
too.
-- 
Randy Yates                      % "Watching all the days go by...
Digital Signal Labs              %  Who are you and who am I?"
mailto://yates@ieee.org          % 'Mission (A World Record)',
http://www.digitalsignallabs.com % *A New World Record*, ELO

On Sunday, July 3, 2011 4:57:02 PM UTC-4, tinkerz wrote:

  ...

> I should have said that is a small project
> 
> "Laplace transform is derived from the
> continuous-time Fourier transform"

It is possible, but nit-picky, to disagree.

> I was working with FFT, but the data is continuous.

Once you plug data into an FFT, it isn't continuous any more. Digital computers and the numbers they operate on are inherently discrete.

> Therefore laplace and the continuous-time Fourier transform are the
> combination I am after.

You might do that symbolically with a math package like Maple. I doubt that you want a solution of that sort.

> Still looking and posting on liveperson to find someone to hire for this
> small project is quite tedious.

Seriously, talk to Tim Wescott. If you tell him what you want done rather than how to do it, you'll get along fine.

Jerry
-- 
Engineering is the art of making what you want from things you can get.

>On Jul 3, 12:44=A0am, boB wrote:
>> On Sat, 2 Jul 2011 12:24:56 -0700 (PDT), Jerry Avins <j...@ieee.org>
>> wrote:
>>
>> >On Saturday, July 2, 2011 3:16:19 PM UTC-4, tinkerz wrote:
>> >> I am after a control system based on frequencies, I need to gather
>> >> information on the time and frequency domain.
>>
>> >> The data is fast and noisy, I made an assumption the fourier and
lapla=
>ce
>> >> will be the place to start.
>>
>> >You need to lay aside your preconceptions and find a good consultant.
As=
> a former consultant, I felt it was my duty to give the clients what they
n=
>eeded. That was often at odds with what they wanted. Tact usually won the
d=
>ay.
>>
>> >Jerry
>>
>> Every time we try to hire a DSP programmer or coder or whatever you
>> want to call him/her, they always want to just consult. =A0Hard to find
>> one that wants to come to work every day.
>
>What would you expect? Where are kids expected to learn the
>skills they actually need? The people who *ought* to learn
>how to actually *use* a computer, at best learns some macro
>programming in MSOffice; the really clever ones might get
>to play with matlab. Which business idea is based on selling
>a toolbox for just about every task possible.
>
>Techie recruits these days are as likely to come across actual
>computer work as a McDonalds burger-flipper is as coming
>across 'abattoirian' tasks.
>
>The least bad you can hope for these days, is to get hold of
>somebody who at least have heard rumours or hearsay that this
>or that ought to be possible.
>
>Rune

This is nonsense. You can't keep good people down, no matter how much the
education system in many countries is trying these days. There will always
be smart motivated people who gain the knowledge they need to be valuable.
Are there less than there used to be? Logic would say no, because people
don't change a lot. What is more likely is they are just diluted amongst a
much larger pool of people who go to something laughingly called University
these days.

Steve

HardySpicer wrote:

> On Jul 3, 3:17 pm, Vladimir Vassilevsky <nos...@nowhere.com> wrote:
> 
>>HardySpicer wrote:
>>
>>>On Jul 3, 3:24 am, Vladimir Vassilevsky <nos...@nowhere.com> wrote:
>>
>>>>tinkerz wrote:
>>
>>>>>Hi All
>>
>>>>>Where is the best place to hire a programmer for a DSP/Laplace control
>>>>>system
>>
>>>>>Thanks
>>>>>Tinkerz
>>
>>>>Programmer is a tool. What you are looking for is probably a coder. To
>>>>get a coder, go to a forest and find some orangutan.
>>
>>>User interface is fulling functional I see Mr Impaler..
>>
>>The orangutan Ph.D. ?
> 
> 
> What? You don't have a Ph.D and you think your are qualified to answer
> questions on this NG?
> Shame on you.

You see, Hardy, I do have Ph.D. However I am not orangutan.

On Jul 3, 3:17=A0pm, Vladimir Vassilevsky <nos...@nowhere.com> wrote:
> HardySpicer wrote:
> > On Jul 3, 3:24 am, Vladimir Vassilevsky <nos...@nowhere.com> wrote:
>
> >>tinkerz wrote:
>
> >>>Hi All
>
> >>>Where is the best place to hire a programmer for a DSP/Laplace control
> >>>system
>
> >>>Thanks
> >>>Tinkerz
>
> >>Programmer is a tool. What you are looking for is probably a coder. To
> >>get a coder, go to a forest and find some orangutan.
>
> > User interface is fulling functional I see Mr Impaler..
>
> The orangutan Ph.D. ?

What? You don't have a Ph.D and you think your are qualified to answer
questions on this NG?
Shame on you.


Hardy

On Sun, 03 Jul 2011 18:48:30 -0400, Randy Yates wrote:

> On 07/02/2011 08:22 AM, tinkerz wrote:
>> Hi All
>>
>> Where is the best place to hire a programmer for a DSP/Laplace control
>> system
> 
> tinkerz,
> 
> I think Tim Wescott may be your man. He is a controls guru and I believe
> he lives your part of the country.

Nope, that's me -- at least, I'm only about 150 miles from Seattle, in 
the same time zone.  Compared to a lot of my work, that's exceedingly 
close.

-- 
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

On Jul 3, 12:44=A0am, boB wrote:
> On Sat, 2 Jul 2011 12:24:56 -0700 (PDT), Jerry Avins <j...@ieee.org>
> wrote:
>
> >On Saturday, July 2, 2011 3:16:19 PM UTC-4, tinkerz wrote:
> >> I am after a control system based on frequencies, I need to gather
> >> information on the time and frequency domain.
>
> >> The data is fast and noisy, I made an assumption the fourier and lapla=
ce
> >> will be the place to start.
>
> >You need to lay aside your preconceptions and find a good consultant. As=
 a former consultant, I felt it was my duty to give the clients what they n=
eeded. That was often at odds with what they wanted. Tact usually won the d=
ay.
>
> >Jerry
>
> Every time we try to hire a DSP programmer or coder or whatever you
> want to call him/her, they always want to just consult. =A0Hard to find
> one that wants to come to work every day.

What would you expect? Where are kids expected to learn the
skills they actually need? The people who *ought* to learn
how to actually *use* a computer, at best learns some macro
programming in MSOffice; the really clever ones might get
to play with matlab. Which business idea is based on selling
a toolbox for just about every task possible.

Techie recruits these days are as likely to come across actual
computer work as a McDonalds burger-flipper is as coming
across 'abattoirian' tasks.

The least bad you can hope for these days, is to get hold of
somebody who at least have heard rumours or hearsay that this
or that ought to be possible.

Rune

On Jul 3, 1:03=A0pm, Tim Wescott <t...@seemywebsite.com> wrote:
> On 07/02/2011 07:28 PM, Randy Yates wrote:
>
> > On 07/02/2011 05:02 PM, Tim Wescott wrote:
> >> [...]
> >> Randy is probably forgetting that the z transform (which is what is
> >> used to analyze sampled-time systems) can be derived from the
> >> Laplace transform.
>
> > There may be some convoluted way to do that, but I don't think it's
> > going to be of any utility. None of Lyons, Proakis, Mitra, or
> > Oppenheim discuss deriving it from the Laplace transform.
>
> > Of course it has the similar function as the Laplace transform in the
> > digital domain, and as the Laplace transform is derived from the
> > continuous-time Fourier transform, the z-transform is derived from the
> > discrete time Fourier transform. However it isn't "derived" from the
> > Laplace transform in any way I've seen or can imagine to be useful.
>
> Houpis & Lamont, "Digital Control". =A0Shows how, if you model the
> sampling process as multiplying by a chain of impulses then the z
> transform just falls out of the Laplace transform.
>
> IIRC, Oppenheim, Wilsky & Young, "Signals and Systems" models sampling
> the same way, and derives the Fourier series from the Fourier transform;
> I'd be surprised if they don't derive the z transform the same way,
> later in the book.

it's straight forward.  we've done it here in comp.dsp several times
since the mid 90s.

the Z transform is nothing other than the Laplace transform of a
sampled signal (with them weighted dirac impulses) and the
substitution:

   z =3D e^(s*T)   where  1/T =3D sampling frequency

it's nothing more than that.

r b-j