6 ms·
Sure here's something very simple take [0]. This is for RF, and you probably need less bandwidth. Search on Robert Penfold hobby designs for noise generators f
by nonrandomstring 1y ago
Sure here's something very simple take [0].
This is for RF, and you probably need less bandwidth. Search on Robert
Penfold hobby designs for noise generators for audio too. In practice
you'll need to do a few things to get a good digital noise source with
proper entropy.
1) Shield it! What you want is noise from the bandgap transition
not from your local radio station or ambient "cosmic" noise.
2) Thermally stabilise it.
3) Convert to a digital stream. A Schmitt gate with properly set
hysteresis to get clean edge transitions and a 1-bit sampling circuit.
The whole design should cost you a few bucks and be buildable in
hours. Maybe use a USB audio dongle (minus the DC block capacitors) as
an easy-in for your digital side.
[0] https://www.radiohobbyist.org/blog/?p=1884 https://www.radiohobbyist.org/blog/?p=1884
[1] https://www.geeksforgeeks.org/schmitt-trigger/ https://www.geeksforgeeks.org/schmitt-trigger/
- atoav 1y ago4) add a Von Neumann extractor (or similar/better) in the digital domain for good measure (pseudocode): function von_neumann_extractor(input_bits): output_bits = [] i = 0 while i + 1 < length(input_bits): bit1 = input_bits[i] bit2 = input_bits[i + 1] if bit1 != bit2: output_bits.append(bit1) # else: discard the pair i += 2 return output_bits See: https://en.m.wikipedia.org/wiki/Randomness_extractor https://en.m.wikipedia.org/wiki/Randomness_extractor
- K0balt 1y agoThanks! This will definitely be useful as I anticipate that setting the threshold for the Schmidt trigger will be imperfect.
- K0balt 1y agoThank you! This will be useful!