[onerng talk] RNG designs

[Paul Campbell]

On Sat, 01 Feb 2014 22:44:58 ianG wrote:

> >> 1.  Ideally, I would treat the device as two separate Collectors and read
> >> it the diode part separately from the RF stream.
> >> 
> >> 2.  But from an engineering perspective I'd just be annoyed at having to
> >> twice the amount of work, twice the threads, twice the potential for
> >> trouble.  I'd probably just end up reading the interleaved stream and
> >> having one Collector.
> > 
> > actually it's pretty easy (I actually took that bit out, the thing this
> > came from had 3 streams)
> 
> Sorry, which bit was taken out?

this board was derived from another board on the verge of release a combined 
serial/programmer/RF gateway board for my other RF project - it naturally has 
3 streams, something I knocked together a couple of months ago when I was laid 
up  

>That probably suffices for a first cut board.  Looking at John's stuff,
>that comes surprisingly close:
>
>http://www.av8n.com/physics/thermo/entropy.html#sec-quantify-s
>
>The formulas there basically say that 50:50 gives 1 bits per bit.
>although you'd probably want to run something like diehard to get a
>better feeling for whether there are any patterns in there, such as a
>change in probability from a previous bit.

I've been running diehard, a bunch of tests bomb out because of the mismatched 
set of 1s vs 0s which is expected, simple whitening through crc16 gets past 
this and so far I'm passing (I haven't had the patience to run the whole thin 
yet)

> Perhaps standardise and say that the 0 feed is always the mix, and feeds
> 1,2,...n are sources 1,2,3...n.

I like that idea - 3 streams - we'll be careful not to cross them - stream 0 
can be the combined one as well as the command stream

I'm a bit worried though that udev scripts may not be able to be convinced to 
do the right thing - we may be better with 1 stream and a user controlled mux 
(what we have now)

	Paul