On Jul 16, 8:33&#4294967295;am, "sarw...@YouEyeYouSee.edu" <dvsarw...@gmail.com>
wrote:

> Good. &#4294967295;Now tell your boss that the convolutional code
> is going to be better in almost any application and the
> Reed-Solomon code is useless (unless he has a CD or
> DVD (or a concatenated coding scheme) in mind.)
> Reed-Solomon codes are not very good as channel
> codes, but they make great straw men to be knocked
> down while touting the merits of a coding scheme that
> you really ought to be using in the first place.

I  think that is a bit unfair especially when you have enough
bandwidth to afford to use Reed-Solomon codes with orthogonal
waveforms, such as FSK.

jaco.versfeld@gmail.com wrote:

> Are these arguments true for soft-decision Reed-Solomon as well?
> Wouldn't soft-decision Reed-Solomon decoding outperform convolutional
> decoding, especially when the RS block lengths are longer , for
> instance(255,k) RS codes?

The good comparison of the properties of cyclic codes and convolutional 
codes is in this book:

Johannesson, Zigangirov. "Fundamentals of convolutional coding".

According to the results, the moderately complex convolutional codes 
outperform the cyclic codes by their properties.

The optimal decoding of cyclic codes is possible, however it is 
cumbersome and not very practical. The main advantage of RS is the 
efficient algebraic hard decision decoding.


Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com

Are these arguments true for soft-decision Reed-Solomon as well?
Wouldn't soft-decision Reed-Solomon decoding outperform convolutional
decoding, especially when the RS block lengths are longer , for
instance(255,k) RS codes?

Just wondering
Jaco

_______________
Jaco Versfeld

http://dept.ee.wits.ac.za/~versfeld

"It is not the best team that wins, but the team that gets along best
that wins" John C. Maxwell

>On Wed, 16 Jul 2008 08:53:36 -0500, "cpshah99"
><cpshah99@rediffmail.com> wrote:
>
>>>On Jul 16, 2:10 am, "cpshah99" <cpsha...@rediffmail.com> wrote:
>>>> >On Jul 15, 3:03 pm, "cpshah99" <cpsha...@rediffmail.com> wrote:
>>>>
>>>> >> What should I do to make it fair? or is this comparision valid at
>>all?
>>>>
>>>> >Which is better for chiseling wood, a screwdriver
>>>> >or a ball-peen hammer?  Neither is very good for
>>>> >the task, but you could do a little bit, maybe, with
>>>> >the screwdriver and hardly anything with the
>>>> >hammer.  So, "clearly" the screwdriver is the
>>>> >"better" tool.  But, ah, when you have to drive
>>>> >nails, the hammer is far far better than the
>>>> >screwdriver (think of CDs and DVDs), isn't it?
>>>> >And when you need to drive screws, the
>>>> >screwdriver is the best tool, though you might
>>>> >be able to do a little with a chisel if you have a
>>>> >flat-head screw (forget Phillips heads!) and
>>>> >nothing with the hammer.
>>>>
>>>> %%%%%
>>>>
>>>> Hi
>>>>
>>>> Thanks for this carpentry stuff which I already know!!!!
>>>>
>>>> chintan
>>>
>>>Good.  Now tell your boss that the convolutional code
>>>is going to be better in almost any application and the
>>>Reed-Solomon code is useless (unless he has a CD or
>>>DVD (or a concatenated coding scheme) in mind.)
>>>Reed-Solomon codes are not very good as channel
>>>codes, but they make great straw men to be knocked
>>>down while touting the merits of a coding scheme that
>>>you really ought to be using in the first place.
>>>
>>%%%%
>>
>>Hi
>>
>>Thanks again. I had expected convolutional code to do better and it is
>>doing the same.
>>
>>But another advantage of RS code is that it corrects burst error, which
is
>>problem in fading channel, and because of burst errors DFE (Decision
>>Feedback Equaliser) will not work properly. But if you use RS, this
problem
>>is solved. 
>>
>>Now to solve the same problem with convolution encoder, u will have to
use
>>'interleaver', otherwise forget that even BCJR will decode the burst
>>errors.
>>
>>So my system with convolution encoder and interleaver outperforms RS
>>system.
>>
>>Everything is same when I am comparing both the systems, channel,
doppler,
>>noise, adaptive algorithm for DFE.
>>
>>But I was wondering that if I can claim that given the channel
perticular
>>channel conditions, convolution code will outperform RS.
>>
>>BTW, nobody is boss.
>>
>>Chintan
>
>The bottom line is that care has to be taken to match codes to
>channels.   The assumptions about the error distributions in the
>channel can make a big difference in how the code is applied or
>architected into the system.
>
>While on the surface the fact that RS codes can correct "burst errors"
>is true, the nature of the "burst error" can make a big difference.
>Often the length of the error burst can overwhelm the correcting
>capability of the RS code.   The performance curve (in an error
>probability vs SNR sense) of a system with an RS code is pretty steep.
>What often happens is that the region from performing well to
>performing poorly is small, and RS codes exhibit a sometimes
>undesirable characteristic of aliasing codewords when in the "poor"
>region.  i.e., many of the codewords coming out of the decoder will be
>marked as corrected, but they'll be incorrect.   At least with a
>convolution code and a Viterbi decoder you can tell when it's unlocked
>and spewing garbage.
>
>So the nature of the error bursts matters, and the sensitivity of the
>system to output errors matters.   Interleavers are often used to
>reduce the length of error bursts so that the channel code works
>better.  There are all kinds of considerations, and I think Dr.
>Sarwate's initial response hints at the complexities of picking the
>appropriate tool depending on the situation.
>
> 
>Eric Jacobsen
>Minister of Algorithms
>Abineau Communications
>http://www.ericjacobsen.org
>
>Blog: http://www.dsprelated.com/blogs-1/hf/Eric_Jacobsen.php
>

%%%%

Hi Eric

Thanks for your reply.

So it all depends on burst error patterns.

And as Dr. Sarwate said, convolution will do better than RS and I can
confirm (I am nobody to do this, but I am just saying) that from my
results. 

Thanks a lot to everybody.

Chintan

>cpshah99 wrote:
>
>   ...
>
>> Thanks for this carpentry stuff which I already know!!!!
>
>Some of us think that knowledge from one field can carry over to a 
>related one, and go so far as believing that analogy can have a useful 
>place in explanation. Others feel that the only way to deal with a 
>subject is in its own terms, with no reference to parallel disciplines. 
>You apparently belong to the second group. I'll try to keep that in mind

>when answering your future questions.
>
>Jerry
>-- 
>Engineering is the art of making what you want from things you can get.
>�����������������������������������������������������������������������
>

%%%%

Hi Jerry

I am really sorry but you misunderstood me. But I am also from first
group, because when I explain something to some stranger or to my friends
what I am doing (who are not from EE filed) I use real life examples,
because this is what makes it simple isn't it?

But sometimes you are in such a state that you dont know what to do. So I
just replied like that.

I am asking abt this comparision because I dont want to cliam something
which is not true on paper.

And please use these sort of examples when u answer my posts next time.

Sorry for any misunderstanding. :-)


chintan

On Wed, 16 Jul 2008 08:53:36 -0500, "cpshah99"
<cpshah99@rediffmail.com> wrote:

>>On Jul 16, 2:10 am, "cpshah99" <cpsha...@rediffmail.com> wrote:
>>> >On Jul 15, 3:03 pm, "cpshah99" <cpsha...@rediffmail.com> wrote:
>>>
>>> >> What should I do to make it fair? or is this comparision valid at
>all?
>>>
>>> >Which is better for chiseling wood, a screwdriver
>>> >or a ball-peen hammer?  Neither is very good for
>>> >the task, but you could do a little bit, maybe, with
>>> >the screwdriver and hardly anything with the
>>> >hammer.  So, "clearly" the screwdriver is the
>>> >"better" tool.  But, ah, when you have to drive
>>> >nails, the hammer is far far better than the
>>> >screwdriver (think of CDs and DVDs), isn't it?
>>> >And when you need to drive screws, the
>>> >screwdriver is the best tool, though you might
>>> >be able to do a little with a chisel if you have a
>>> >flat-head screw (forget Phillips heads!) and
>>> >nothing with the hammer.
>>>
>>> %%%%%
>>>
>>> Hi
>>>
>>> Thanks for this carpentry stuff which I already know!!!!
>>>
>>> chintan
>>
>>Good.  Now tell your boss that the convolutional code
>>is going to be better in almost any application and the
>>Reed-Solomon code is useless (unless he has a CD or
>>DVD (or a concatenated coding scheme) in mind.)
>>Reed-Solomon codes are not very good as channel
>>codes, but they make great straw men to be knocked
>>down while touting the merits of a coding scheme that
>>you really ought to be using in the first place.
>>
>%%%%
>
>Hi
>
>Thanks again. I had expected convolutional code to do better and it is
>doing the same.
>
>But another advantage of RS code is that it corrects burst error, which is
>problem in fading channel, and because of burst errors DFE (Decision
>Feedback Equaliser) will not work properly. But if you use RS, this problem
>is solved. 
>
>Now to solve the same problem with convolution encoder, u will have to use
>'interleaver', otherwise forget that even BCJR will decode the burst
>errors.
>
>So my system with convolution encoder and interleaver outperforms RS
>system.
>
>Everything is same when I am comparing both the systems, channel, doppler,
>noise, adaptive algorithm for DFE.
>
>But I was wondering that if I can claim that given the channel perticular
>channel conditions, convolution code will outperform RS.
>
>BTW, nobody is boss.
>
>Chintan

The bottom line is that care has to be taken to match codes to
channels.   The assumptions about the error distributions in the
channel can make a big difference in how the code is applied or
architected into the system.

While on the surface the fact that RS codes can correct "burst errors"
is true, the nature of the "burst error" can make a big difference.
Often the length of the error burst can overwhelm the correcting
capability of the RS code.   The performance curve (in an error
probability vs SNR sense) of a system with an RS code is pretty steep.
What often happens is that the region from performing well to
performing poorly is small, and RS codes exhibit a sometimes
undesirable characteristic of aliasing codewords when in the "poor"
region.  i.e., many of the codewords coming out of the decoder will be
marked as corrected, but they'll be incorrect.   At least with a
convolution code and a Viterbi decoder you can tell when it's unlocked
and spewing garbage.

So the nature of the error bursts matters, and the sensitivity of the
system to output errors matters.   Interleavers are often used to
reduce the length of error bursts so that the channel code works
better.  There are all kinds of considerations, and I think Dr.
Sarwate's initial response hints at the complexities of picking the
appropriate tool depending on the situation.

 
Eric Jacobsen
Minister of Algorithms
Abineau Communications
http://www.ericjacobsen.org

Blog: http://www.dsprelated.com/blogs-1/hf/Eric_Jacobsen.php

cpshah99 wrote:

   ...

> Thanks for this carpentry stuff which I already know!!!!

Some of us think that knowledge from one field can carry over to a 
related one, and go so far as believing that analogy can have a useful 
place in explanation. Others feel that the only way to deal with a 
subject is in its own terms, with no reference to parallel disciplines. 
You apparently belong to the second group. I'll try to keep that in mind 
when answering your future questions.

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

>On Jul 16, 2:10 am, "cpshah99" <cpsha...@rediffmail.com> wrote:
>> >On Jul 15, 3:03 pm, "cpshah99" <cpsha...@rediffmail.com> wrote:
>>
>> >> What should I do to make it fair? or is this comparision valid at
all?
>>
>> >Which is better for chiseling wood, a screwdriver
>> >or a ball-peen hammer?  Neither is very good for
>> >the task, but you could do a little bit, maybe, with
>> >the screwdriver and hardly anything with the
>> >hammer.  So, "clearly" the screwdriver is the
>> >"better" tool.  But, ah, when you have to drive
>> >nails, the hammer is far far better than the
>> >screwdriver (think of CDs and DVDs), isn't it?
>> >And when you need to drive screws, the
>> >screwdriver is the best tool, though you might
>> >be able to do a little with a chisel if you have a
>> >flat-head screw (forget Phillips heads!) and
>> >nothing with the hammer.
>>
>> %%%%%
>>
>> Hi
>>
>> Thanks for this carpentry stuff which I already know!!!!
>>
>> chintan
>
>Good.  Now tell your boss that the convolutional code
>is going to be better in almost any application and the
>Reed-Solomon code is useless (unless he has a CD or
>DVD (or a concatenated coding scheme) in mind.)
>Reed-Solomon codes are not very good as channel
>codes, but they make great straw men to be knocked
>down while touting the merits of a coding scheme that
>you really ought to be using in the first place.
>
%%%%

Hi

Thanks again. I had expected convolutional code to do better and it is
doing the same.

But another advantage of RS code is that it corrects burst error, which is
problem in fading channel, and because of burst errors DFE (Decision
Feedback Equaliser) will not work properly. But if you use RS, this problem
is solved. 

Now to solve the same problem with convolution encoder, u will have to use
'interleaver', otherwise forget that even BCJR will decode the burst
errors.

So my system with convolution encoder and interleaver outperforms RS
system.

Everything is same when I am comparing both the systems, channel, doppler,
noise, adaptive algorithm for DFE.

But I was wondering that if I can claim that given the channel perticular
channel conditions, convolution code will outperform RS.

BTW, nobody is boss.

Chintan

On Jul 16, 2:10 am, "cpshah99" <cpsha...@rediffmail.com> wrote:
> >On Jul 15, 3:03 pm, "cpshah99" <cpsha...@rediffmail.com> wrote:
>
> >> What should I do to make it fair? or is this comparision valid at all?
>
> >Which is better for chiseling wood, a screwdriver
> >or a ball-peen hammer?  Neither is very good for
> >the task, but you could do a little bit, maybe, with
> >the screwdriver and hardly anything with the
> >hammer.  So, "clearly" the screwdriver is the
> >"better" tool.  But, ah, when you have to drive
> >nails, the hammer is far far better than the
> >screwdriver (think of CDs and DVDs), isn't it?
> >And when you need to drive screws, the
> >screwdriver is the best tool, though you might
> >be able to do a little with a chisel if you have a
> >flat-head screw (forget Phillips heads!) and
> >nothing with the hammer.
>
> %%%%%
>
> Hi
>
> Thanks for this carpentry stuff which I already know!!!!
>
> chintan

Good.  Now tell your boss that the convolutional code
is going to be better in almost any application and the
Reed-Solomon code is useless (unless he has a CD or
DVD (or a concatenated coding scheme) in mind.)
Reed-Solomon codes are not very good as channel
codes, but they make great straw men to be knocked
down while touting the merits of a coding scheme that
you really ought to be using in the first place.

>On Jul 15, 3:03 pm, "cpshah99" <cpsha...@rediffmail.com> wrote:
>
>> What should I do to make it fair? or is this comparision valid at all?
>
>
>Which is better for chiseling wood, a screwdriver
>or a ball-peen hammer?  Neither is very good for
>the task, but you could do a little bit, maybe, with
>the screwdriver and hardly anything with the
>hammer.  So, "clearly" the screwdriver is the
>"better" tool.  But, ah, when you have to drive
>nails, the hammer is far far better than the
>screwdriver (think of CDs and DVDs), isn't it?
>And when you need to drive screws, the
>screwdriver is the best tool, though you might
>be able to do a little with a chisel if you have a
>flat-head screw (forget Phillips heads!) and
>nothing with the hammer.
>

%%%%%

Hi

Thanks for this carpentry stuff which I already know!!!!

chintan