Thomas,

Further, the “white” applies in the range of (+/- Fs/2).

Whereas, a true white-noise is flat in [-infinity, infinity].

Regards

arun

-----Original Message-----
From: Thomas Patrick [mailto:t...@yahoo.com]
Sent: Tuesday, January 25, 2005 3:57 PM
To: arun d naik (WT01 - EMBEDDED & PRODUCT ENGINEERING SOLUTIONS)
Cc: m...@yahoogroups.com
Subject: RE: [matlab] LFSR flat frequency

Hi Thomas
As Predrag says, the LFSR sequence(which is also called as pseudorandom
binary sequence) has almost delta-correlation. i.e. its autocorrelation
function is a symmetric, narrow triangular waveform with width equal to
two times the bit-width. Further, the peak of the function is 2^N-1 and
the remaining values of the function lie at (+ or -1). This can be
proved. Though the this function is (almost) like a delta function, it
is indeed not because this function repeats every 2^N-1 samples. That is
why it is called as "pseudo-random".
Because the waveform has an impulse like auto-correlation function, its
spectrum will be flat and hence white.
Ideally white-noise should not be predictable at any time period, (i.e.
ACF is a pure delta function) but since the sequence is predictable also
it is called as pseudo-random.

Hope t his helps.

Regards
arun -----Original Message-----
From: Valozic [mailto:p...@vtszg.hr]
Sent: Monday, January 24, 2005 4:34 PM
To: m...@yahoogroups.com; thomas_lpc
Subject: Re: [matlab] LFSR flat frequency
Hi Tomas!

Try:

FFT(Autocorrelation function(LFSR sequence))

It is important to calculate ACF on the whole sequence L=(2 exp n) -1.

Best wishes,
Predrag

----- Original Message -----
From: "thomas_lpc"
To:
Sent: Friday, January 21, 2005 5:32 PM
Subject: [matlab] LFSR flat frequency >
> Hello,
>
> LFSR (linear feedback shift register) generate flat spectrum
> and I prosssed the output of LFSR for DFT to see flat spectrum and it
> does generate.
>
> Somebody suggests mathamatical model to prove LFSR generate flat
> spectrum. I would appriciate if somebody pass hints.
>
> Regards,
>
> Thomas >
>
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