On Wed, 24 Apr 2002, Tim May wrote: > I'll probably regret proposing such things, but here goes.
It's all in fun, so why not! > For the sake of this argument, let's assume the goal is worth pursuing. Right, sometimes academics pays off :-) > Second, some approaches: > > 1. Radioactive decay. Don't count on it at these rates. A billion events > per second is a very, very high dose rate, even if spread out over > millions of FETs or diodes. > > 2. Johnson noise, avalanche-breakdown, etc. Much more plausible, as the > leakage current in, say, N cells could be measured M times per second > s.t. N * M = 10^9 bits per second, suitably MUXed and dumped out in a > stream. > > 3. Monitor a WiFi source that is "very noisy." 2.4 GHz implies a bit > rate in the right range. Noise shaping and standard Von Neumann methods > to remove skews (more 1 than 0, or vice versa) would of course be done. > > 4. Monitor a t.v. channel or satellite broadcast that is noisy. Data > rates should approximate the usual video rates. [....] The assumption in all this is that you get 1 bit of output per measurement. That's silly. Assume you can get n bits of data per measurement. Then the actual sample rate you need is (output rate)/n You can get 8 bit A/D's that run at 1 GHz, so even if you smash 4 raw samples to get 8 bits, that's 2 Gb/s of random noise. Time muxing a whole bunch of slower devices is also an obvious way to increase the total data rate, and has been done since the 1950's in real implementations. Putting 100 10MHz devices into one hub wouldn't be all that hard to do either. So as an academic excercise, building Gb/s random bit generators is definitly possible with today's technology. Don't know why you'd want to tho, so on that I agree with Tim. Patience, persistence, truth, Dr. mike
