On Tue, 28 Apr 2015 21:38:58 -0700, John Larkin
wrote:

On Wed, 01 Apr 2015 11:00:25 -0700, Jim Thompson
wrote:

For a simulation situation I need a random number generator with a
twist...

What I need to simulate is a "random" selection of one-of-16 outputs.

Clock "speed" is 12.5kHz ;-)

Built of 74HCxx parts is preferred... I have a full ensemble of those
device in my PSpice library.

Thanks in advance.

...Jim Thompson

Only vaguely on-topic, here is a noise generator experiment. The mess
on the left makes 1-bit digital noise clocked at 1 MHz, like a linear
shift register, just easier to draw. The issue at hand is what kind of
lowpass filter to use to get approximately Gaussian noise.

The 200 KHz filter is right out of AoE3 p 559. It looks fine in the
audio frequency domain, but it's nothing like Gaussian.

The 3-pole filter is a lot nicer.

We're actually going to use a LFSR in an FPGA and do the serious
filtering digitally, and drive a DAC with a little analog filtering
afterwards.

I have a Daqarta "mini-app" for converting a uniform to an
arbitrary distribution. I use Gaussian as the example. The
Help page is at
http://www.daqarta.com/dw_0oaa.htm. It includes a
"Theory" section, plus the complete macro script (it's in
Daqarta's own macro language, but I've added lots of
comments).

The basic method uses the inverse Cumulative Distribution
Function (iCDF) with a lookup table. The trick is to create
the proper table.

Best regards,


Bob Masta

DAQARTA v7.60
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