Velocity Reviews > VHDL > Question about Gaussian Noise Generator?

# Question about Gaussian Noise Generator?

oscarvhdl
Junior Member
Join Date: Nov 2009
Posts: 3

 11-07-2009
Hello all,

I have a problem with this. I need to generate 2bit noise with a gaussian distribution (only 4 possible values, 11,10,00 and 01), for this purpose I'm using a LFSR code with 32 bits that gives 32-bits noise with an uniform distribution. Then, I added ten signals from ten LFSR block, each one of 32 bits.

The result of this operation gives numbers with 36 bits. If a consider all bits and I plot them using matlab, gives a gaussian distribution. But when I extract only the 2 most significant bit and I plot the result lost all sense.

Is any other way to obtain with only 2 bit a gaussian distribution??

Thanks for any possible help

jeppe
Senior Member
Join Date: Mar 2008
Location: Denmark
Posts: 348

 11-07-2009
Well - with only 4 possible values theres couldn't be much left of the gaussian distribution - how about a 3,4,5 bit value (just for the test of algorithm)
Jeppe

oscarvhdl
Junior Member
Join Date: Nov 2009
Posts: 3

 11-07-2009
it has to be with only two bits. I need to obtain (for example, with 1000 samples) a distribution like this:

11: 150 times
10: 350 "
00: 350 "
01: 150 "

Thanks anyway

jeppe
Senior Member
Join Date: Mar 2008
Location: Denmark
Posts: 348

 11-08-2009
Lets say your LFSR block was 8-bits instead of 36-bit (just for the example)
Then: 0..127 and 128..255 should be 50% ranges.
If you compare and detect the range 0..50 could you get 15% (just a quess)
-----------------------------------51..127 ----------- 35% -------------
and so on.

Hopefully it helped you

oscarvhdl
Junior Member
Join Date: Nov 2009
Posts: 3

 11-08-2009
Jeppe:

I was thinking the same, I'm going to do these and I look what hapen.

Thanks for all