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 
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 > > 
Hi Thomas As Predrag says, the LFSR sequence(which is also called as pseudorandom binary sequence) has almost deltacorrelation. i.e. its autocorrelation function is a symmetric, narrow triangular waveform with width equal to two times the bitwidth. Further, the peak of the function is 2^N1 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^N1 samples. That is why it is called as "pseudorandom". Because the waveform has an impulse like autocorrelation function, its spectrum will be flat and hence white. Ideally whitenoise 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 pseudorandom. Hope this helps. Regards arun Original Message From: Valozic [mailto:] Sent: Monday, January 24, 2005 4:34 PM To: ; 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 > > 
Hello Arun & Valozic,
Thanks guys, your hints helped me to come up with a mathematical model to prove
LFSR generate flat spectrum.
cheers,
Thomas
a...@wipro.com wrote:

Thomas, Further, the “white” applies in the range of (+/ Fs/2). Whereas, a true whitenoise is flat in [infinity, infinity]. Regards arun Original
Message
Hello Arun & Valozic,
Thanks guys, your hints helped me to come up with a mathematical model to prove LFSR generate flat spectrum.
cheers,
Thomas
