Re: Noise source processing

[David Honig <honig@sprynet.com>]

At 10:31 AM 8/6/98 -0400, mgraffam@mhv.net wrote:
>On Thu, 6 Aug 1998, David Honig wrote:
>
>> I have digitized FM radio hiss using a $10 transistor radio feeding
>> into the LINE in of my soundcard.  The spectrum looks poisson
>> with prominant, periodically spaced noise spikes.  It does not pass
Diehard.
>
>Yeah, I ran Diehard on it .. and that is why I wanted to find some
>references on removing bias.
>
>> But if you take the PARITY of 8 bits to get one bit, then assemble bytes
>> out of these bits, the results pass Diehard.
>
>This is a neat idea. I smiled when I read this in RFC1750
>
>> 1. There are some nice spectrogramming shareware programs out there.
>
>I haven't been able to find any for UNIX/X .. any recommendations
>for Win31 (I'll try it with Wabi ;) software?
>

You should probably look for native freeware, no?
Otherwise look in various win archives.

I have not yet done systematic experiments looking at, e.g., entropy in
less-than
full-amplitude noise, or intentionally filtering out various pieces
of spectrum.  The tables in RFC 1750 show that 8 bits is reasonable.

Interestingly, the parity of a $10 10year old Radio shack monophonic
FM radio, UNSHIELDED, in a digitally-noisy environment, sampled 
at 44Khz and 16 bits, passed Diehard.  

NB: Consumer computainment devices will include FM/TV receivers very shortly.
Less of a rat's nest in back of the machine.

I always thought listening to static was a suspicious activity.

A CDROM burner is $350.  "Entropy.  Its not just for ambassadors anymore."




honig@alum.mit.edu