## Saturday, January 31, 2009

### higher frequency content

relative polytone generator. excessive use of precision rectification op amp circuits. wont be perfect due to wave shape but should "work". (f, oct, oct+p5, 2nd oct, etc...).

sine wave through 4 folds. dramatization of new "high frequency content".

f(x) = sin(2x)

g(x) = 2|f(x)| - 1

j(x) = 2|g(x)| - 1

k(x) = 2|j(x)| - 1, etc...

|f(x)| implemented through rectification. -1 or -c (a constant) represents a DC offset, without which running stages in series would be ineffective.

it isn't a strict doubling of frequency, but an approximation of. the shape of f(x) will change unless it is a perfect triangle. but that might be the charm of it. ie the harmonics generated will be waveform dependant, although there should be general trends.

using FFT approximation to see spectrum created...

first fold shows strong second harmonic, subsequent folds show a reasonable fourth then a fair distribution of upper even harmonics.

from this point high pass filters could be used with a sort of subtractive synthesis mentality to move the distribution more in favor of the higher ordered harmonics. not sure if 6 stages are really necessary. probably 4 would be interesting enough.

## Friday, January 30, 2009

### beyond 2000, one bit multiplier

block diagram for a more complete implementation of "what we thought the year 2000 would sound like". program selectable lfo and harmonics filter to alleviate "generic" restructuring of any input and other problems.

possibly will be asm three/four etc...

### isd interchange

relaxed implementation of chopping/sampling ideas. burdens and limitations of isd smoothed over by flexible connections with acoustically distracting hardware.

project proposed in conjunction with emilie mouchous.

## Thursday, January 1, 2009

### s/h to the mouchous

random signals...

Zener Type Avalanche Noise Generation:

"Matthew J Bennion, mjb296@soton.ac.uk, pointed out that noise sources are important as random number generators, for situations where you really do need truly random numbers (as opposed to the pseudorandom number generators implemented in software). An example where this is necessary might be encryption and decryption"

"I agree with what you have on Noise Diodes, but I think you overlook the main use: measurement of noise figure. To characterize, for example, a receiver, one adds noise from a noise generator until the observed noise just doubles (or changes by some other convenient factor). Shannon's theorem says that noise always adds (Murphy's law says the same thing). Since the noise generator would typically make a relatively high level of noise that would be attenuated down by precicesly calibrated attenuators, one can know how much noise was required to equal the intrinsic noise of the receiver, and thus infer its performance."

"This white noise generator is based on the avalanche noise generated by a zener breakdown phenomenon. It is created when a PN junction is operated in the reverse breakdown mode. The avalanche noise is very similar to shot noise, but much more intense and has a flat frequency spectrum (white). The magnitude of the noise is difficult to predict due to its dependence on the materials."

Shot Noise Generation:

"Shot noise exists because phenomena such as light and electrical current consist of the movement of discrete, quantized 'packets'. Imagine light coming out of a laser pointer and hitting a wall. That light comes in small packets, or photons. When the spot is bright enough to see, there are many billions of light photons that hit the wall per second. Now, imagine turning down the laser brightness until the laser is almost off. Then, only a few photons hit the wall every second. But the fundamental physical processes that govern light emission say that these photons are emitted from the laser at random times. So if the average number of photons that hit the wall each second is 5, some seconds when you measure you will find 2 photons, and some 10 photons. These fluctuations are shot noise."

The full picture/recent developements and changes in thinking...

http://www.lorentz.leidenuniv.nl/beenakkr/mesoscopics/topics/noise/noise.html

The Poisson Distribution:

http://en.wikipedia.org/wiki/Poisson_distribution

sources:

http://www.maxim-ic.com/appnotes.cfm/an_pk/3469

http://www.avtechpulse.com/faq.html/IV.8/

http://en.wikipedia.org/wiki/Shot_noise

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