Exam revision

Hi all

Im currently doing some exam revision for my big DSP exam and i cannot
answer one of the revison quesionts.  Please could you offers me some
advice, on the pros and cons.

I have encluded the question below

Q) compare and contrast how a DSP algorithm can be implemented using
either filter or DFT - what are the pros and cons?

Thanks tuurbo

tuurbo46@yahoo.co.uk wrote:
> Hi all
>
> Im currently doing some exam revision for my big DSP exam and i cannot
> answer one of the revison quesionts.  Please could you offers me some
> advice, on the pros and cons.
>
> I have encluded the question below
>
> Q) compare and contrast how a DSP algorithm can be implemented using
> either filter or DFT - what are the pros and cons?
> 
> Thanks tuurbo

What does DFT stand for?

Leon

tuurbo46@yahoo.co.uk wrote:
> Hi all
>
> Im currently doing some exam revision for my big DSP exam and i cannot
> answer one of the revison quesionts.  Please could you offers me some
> advice, on the pros and cons.
>
> I have encluded the question below
>
> Q) compare and contrast how a DSP algorithm can be implemented using
> either filter or DFT - what are the pros and cons?
>
> Thanks tuurbo

It sounds like you are being asked to describe the pros and cons of
both FIR filters implemented using the DFT and IIR filters.  Review
these two types of filter implementations and you should be able to
answer the question.

tuurbo46@yahoo.co.uk wrote:
> Hi all
>
> Im currently doing some exam revision for my big DSP exam and i cannot
> answer one of the revison quesionts.  Please could you offers me some
> advice, on the pros and cons.
>
> I have encluded the question below
>
> Q) compare and contrast how a DSP algorithm can be implemented using
> either filter or DFT - what are the pros and cons?

Hmmm... I am not sure I understand the question. First, "a DSP
algorithm" can be almost anything; filters, correlators, codecs, you
name it. Second, not all such algorithms can be implemented as a
"filter". However, a "filter" can be implemented in time domain or
as a DFT.

All in all, I would take my chances and assume that the question is
intended as something like this:

Q) What are the pros and cons when implementing a filter in time
domain, as compared to implementing it using the DFT?

It was a poorly phrased question. 

Rune

Leon wrote:
> tuurbo46@yahoo.co.uk wrote:
> > Hi all
> >
> > Im currently doing some exam revision for my big DSP exam and i cannot
> > answer one of the revison quesionts.  Please could you offers me some
> > advice, on the pros and cons.
> >
> > I have encluded the question below
> >
> > Q) compare and contrast how a DSP algorithm can be implemented using
> > either filter or DFT - what are the pros and cons?
> >
> > Thanks tuurbo
>
> What does DFT stand for?

He doesn't even seem to know what a DFT is!

Leon

Leon wrote:
> Leon wrote:
> > tuurbo46@yahoo.co.uk wrote:
> > > Hi all
> > >
> > > Im currently doing some exam revision for my big DSP exam and i cannot
> > > answer one of the revison quesionts.  Please could you offers me some
> > > advice, on the pros and cons.
> > >
> > > I have encluded the question below
> > >
> > > Q) compare and contrast how a DSP algorithm can be implemented using
> > > either filter or DFT - what are the pros and cons?
> > >
> > > Thanks tuurbo
> >
> > What does DFT stand for?
>
> He doesn't even seem to know what a DFT is!

That's probably why he couldn't answer that question. Although I do
agree with Rune that the question is badly posed. The statement "DSP
algorithm can be implemented using either filter or DFT" is plainly
wrong. A closely related but sensible question is:

Q) FIR Filters can be realized either in frequency domain or in time
domain. Describe both algorithms and their merits.

> Leon

Regards,
Andor

Noway2 wrote:

  ...

> It sounds like you are being asked to describe the pros and cons of
> both FIR filters implemented using the DFT and IIR filters.  

  ...

There are few FIRs that can be implemented with an IIR. What do you mean?

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

Jerry Avins wrote:
> Noway2 wrote:
>
>   ...
>
> > It sounds like you are being asked to describe the pros and cons of
> > both FIR filters implemented using the DFT and IIR filters.
>
>   ...
>
> There are few FIRs that can be implemented with an IIR. What do you mean?
>
My appologies on the choice of words, which I now see was unclear.  I
was not trying to imply that one can implement an FIR filter with an
IIR filter.  What I was trying to say is that to me it looked like the
question was trying to ask for a comparison of FIR filters implemented
with the DFT versus IIR filters, presumably implemented through an
appropriate means such as the Bilinear Transform or Impluse Invariance
Method.

My interpreation of the part about using Fourier  (DFT) was that it was
either meant to help clarify the question or restrict it by eliminating
other more sophisticated FIR filter techniques.

Noway2 wrote:
> Jerry Avins wrote:
> 
>>Noway2 wrote:
>>
>>  ...
>>
>>
>>>It sounds like you are being asked to describe the pros and cons of
>>>both FIR filters implemented using the DFT and IIR filters.
>>
>>  ...
>>
>>There are few FIRs that can be implemented with an IIR. What do you mean?
>>
> 
> My appologies on the choice of words, which I now see was unclear.  I
> was not trying to imply that one can implement an FIR filter with an
> IIR filter.  What I was trying to say is that to me it looked like the
> question was trying to ask for a comparison of FIR filters implemented
> with the DFT versus IIR filters, presumably implemented through an
> appropriate means such as the Bilinear Transform or Impluse Invariance
> Method.
> 
> My interpreation of the part about using Fourier  (DFT) was that it was
> either meant to help clarify the question or restrict it by eliminating
> other more sophisticated FIR filter techniques.

It seems pretty evident to me that the intended comparison is between an
FIR filter implemented in the time domain by the typical transversal
structure, and the same FIR filter implemented in the frequency domain
using FFT-multiply-IFFT. Both methods achieve time-domain convolution
and each method has its place.

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

Jerry Avins wrote:
...
> It seems pretty evident to me that the intended comparison is between an
> FIR filter implemented in the time domain by the typical transversal
> structure, and the same FIR filter implemented in the frequency domain
> using FFT-multiply-IFFT. Both methods achieve time-domain convolution
> and each method has its place.

Ok, Jerry, you passed the exam :-).