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