LSFR

Hi all,


Could you pls explain what LSFR is ?
or where can I obtain some information on them.

thanks in advance

Dev

Dev

Hello:

I suppose you talk about a LFSR, a linear feedback shift register.
In hardware is primarily used for generate pseudo-random number sequences.

If you look in google LFSR you will find lot of information about them

Regards

Javier Castillo



(Dev) wrote in news:78403711.0408252022.165c5da1
@posting.google.com:

> Hi all,
>
>
> Could you pls explain what LSFR is ?
> or where can I obtain some information on them.
>
> thanks in advance
>
> Dev
>

Javier Castillo

Helle Dev,,

LFSRs are used to create pseudo random sequences.
You can create a random sequence which repeats in 255 cycles with an 8
bits wide LFSR, by feeding certain bits in that register back to the
first bit. Usually done via an XNOR or XOR gate.

You can find the necessary tap-positions in the xapp052.pdf document of
Xilinx. (Google) or:

direct.xilinx.com/bvdocs/appnotes/xapp052.pdf

Good luck!

Niels Bakker

Javier Castillo wrote:
> Hello:
>
> I suppose you talk about a LFSR, a linear feedback shift register.
> In hardware is primarily used for generate pseudo-random number sequences.
>
> If you look in google LFSR you will find lot of information about them
>
> Regards
>
> Javier Castillo
>
>
>
> (Dev) wrote in news:78403711.0408252022.165c5da1
> @posting.google.com:
>
>
>>Hi all,
>>
>>
>>Could you pls explain what LSFR is ?
>>or where can I obtain some information on them.
>>
>>thanks in advance
>>
>>Dev
>>
>
>

Niels Bakker

On Thu, 26 Aug 2004 11:05:18 +0200, Niels Bakker
<> wrote:

>LFSRs are used to create pseudo random sequences.

But be careful...

LFSRs are quite good for creating random streams of
*bits*. They are rubbish for creating random
streams of *numbers*, because the LFSR register
value is highly correlated from one sample to the
next. If you want a new random *number* from an
LFSR, you must clock it as many times as there
are bits in your desired number.

LFSRs are great in hardware, because they map on
to such a simple and fast hardware structure. But
in a test fixture, the various linear-congruential
and other numerical recipes for random numbers are
likely to be more efficient, and will also provide
better-quality random numbers. The UNIFORM
procedure in IEEE.MATH_REAL does the job, and spares
you the very great pain of understanding the maths
--
Jonathan Bromley, Consultant

DOULOS - Developing Design Know-how
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The contents of this message may contain personal views which
are not the views of Doulos Ltd., unless specifically stated.

Jonathan Bromley

HI,

LSFR stands for Linear Feedback Shift Registers

Go to this link
http://www-math.cudenver.edu/~wchero.../m5410fsr.html

Regards,
A.khader

(Dev) wrote in message news:<. com>...
> Hi all,
>
>
> Could you pls explain what LSFR is ?
> or where can I obtain some information on them.
>
> thanks in advance
>
> Dev

M.A.Khader

Hi,

Another link :
http://www.newwaveinstruments.com/re...ister_lfsr.htm

Regards

(M.A.Khader) wrote in message news:<. com>...
> HI,
>
> LSFR stands for Linear Feedback Shift Registers
>
> Go to this link
> http://www-math.cudenver.edu/~wchero.../m5410fsr.html
>
> Regards,
> A.khader
>
> (Dev) wrote in message news:<. com>...
> > Hi all,
> >
> >
> > Could you pls explain what LSFR is ?
> > or where can I obtain some information on them.
> >
> > thanks in advance
> >
> > Dev

Alain

Jonathan Bromley wrote:
> On Thu, 26 Aug 2004 11:05:18 +0200, Niels Bakker
> <> wrote:
>
>
>>LFSRs are used to create pseudo random sequences.
>
>
> But be careful...
>
> LFSRs are quite good for creating random streams of
> *bits*. They are rubbish for creating random
> streams of *numbers*, because the LFSR register
> value is highly correlated from one sample to the
> next. If you want a new random *number* from an
> LFSR, you must clock it as many times as there
> are bits in your desired number.

well... If you search hard enough you'll actually
find a variation on the theme that actually
generates uniform distribution of *numbers*

lukasz

Lukasz Salwinski

My site has an LFSR package in VHDL

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Try this link. A great software utility running on Windows.

http://www.logiccell.com/~jean/LFSR/

Regards,
=================
Kholdoun TORKI
http://cmp.imag.fr
==================

Dev wrote:

> Hi all,
>
>
> Could you pls explain what LSFR is ?
> or where can I obtain some information on them.
>
> thanks in advance
>
> Dev

Kholdoun TORKI