# Question about Gaussian Noise Generator?

Discussion in 'VHDL' started by oscarvhdl, Nov 7, 2009.

1. ### oscarvhdl

Joined:
Nov 7, 2009
Messages:
3
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

oscarvhdl, Nov 7, 2009

2. ### jeppe

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Mar 10, 2008
Messages:
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Location:
Denmark
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

jeppe, Nov 7, 2009

3. ### oscarvhdl

Joined:
Nov 7, 2009
Messages:
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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

oscarvhdl, Nov 7, 2009
4. ### jeppe

Joined:
Mar 10, 2008
Messages:
348
Location:
Denmark
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

jeppe, Nov 8, 2009
5. ### oscarvhdl

Joined:
Nov 7, 2009
Messages:
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Jeppe:

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

Thanks for all

oscarvhdl, Nov 8, 2009