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ap/xxxxx

Waves paper notes august 26 2006 riga:

Life coding: (Noise ()()))) and quotation

Two texts modulate each other, or make use of multiplexing capabilities

Description of the vocoder:

The synthesis component is in the lower signal path, the analysis component in the upper signal path. The latter's low- and high-pass filters limit the input, e.g. of "speech", while its band-pass filters break down the audible range into several component frequency channels. Following their coordination as envelope curves, the analysis output, using a switching matrix with arbitrarily chosen correspondences between the signal paths, controls the voltage-controlled amplifiers [VCAs], whose band-pass filters have also broken down the "input" or carrier into several component frequency channels. The sum signal at the exit [of the vocoder] appears as an instrumental sound encoded by a voice [vox].

(Friedrich Kittler. Gramaphone)

Modulation already specifies a doubling in its very description:

Modulation is the process of varying a carrier signal in order to use that signal to convey information. The three key parameters of a sinusoid are its amplitude, its phase and its frequency, all of which can be modified in accordance with an information signal to obtain the modulated signal. A device that performs modulation is known as a modulator and a device that performs the inverse operation of demodulation is known as a demodulator. A device that can do both operations is a modem (a contraction of the two terms).

the base electronics, a series of questions:

1) what is zero crossing point?

In alternating current, the zero crossing is the instantaneous point at which there is no voltage present (from positive to negative). In a sine wave or other simple waveform, this normally occurs twice during each cycle.

a zero crossing detector circuit: http://www.dainst.com/info/circuits/zero_crossing.html

further: zero crossing and the diode:

A detector is a device that recovers information of interest contained in a modulated wave. The term dates from the early days of radio when all transmissions were in Morse Code, and it was only necessary to "Detect" the presence (or absence) of a radio wave; not necessarily making it audible.

see also:

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

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

the diode in radio:

The first use for the diode was the demodulation of amplitude modulated (AM) radio broadcasts. The history of this discovery is treated in depth in the radio article. In summary, an AM signal consists of alternating positive and negative peaks of voltage, whose amplitude or 'envelope' is proportional to the original audio signal, but whose average value is zero. The diode (originally a crystal diode) rectifies the AM signal, leaving a signal whose average amplitude is the desired audio signal. The average value is extracted using a simple filter and fed into an audio transducer, which generates sound.

The poorly titled detector picks the audio frequencies out from radio wave by rectifying the waveform. The waveform carries two (the dual) signals of equal positive and negative value, cancelling each other out in mechanical terms for an electromagnetic loudspeaker.

What is amplitude modulation:

Amplitude modulation (AM) is a form of modulation in which the amplitude of a carrier wave is varied in direct proportion to that of a modulating signal.

enter the mirror image or double divided by the alice diode:

In its basic form, amplitude modulation produces a signal with power concentrated at the carrier frequency and in two adjacent sidebands. Each sideband is equal in bandwidth to that of the modulating signal and is a mirror image of the other.

the above and the below

The Alice diode, a looking glass reversibility memento, (that one way street, supposedly, though less than perfect and presenting leakage in an opposing direction) erases the symmetry, the above and below of the wave to present a series of rainbows.

Such Alice through the Looking Glass capabilities, better visualised in terms of a corkscrewed murder weapon instead of a razor, also enter the digital domain. In the case of the diode, a voltage drop across the diode itself causes 'degeneration' of the signal. We cross the threshold back into the denoted realm of the analogue as: "This can ultimately cause a 1 to be interpreted as a 0". [Digital Electronics. William H. Gothmann. New Jersey. 1982. p. 106]

and:

A simple form of AM often used for digital communications is on-off keying, a type of amplitude-shift keying by which binary data is represented as the presence or absence of a carrier wave. This is commonly used at radio frequencies to transmit Morse code, referred to as continuous wave (CW) operation.

what is frequency modulation:

Frequency modulation (FM) is a form of modulation which represents information as variations in the instantaneous frequency of a carrier wave. (Contrast this with amplitude modulation, in which the amplitude of the carrier is varied while its frequency remains constant.) In analog applications, the carrier frequency is varied in direct proportion to changes in the amplitude of an input signal.

amplitude modulation works on the vertical axis

frequency on the horizontal axis

of a wave. a wave in time.

The information thence as orphaned from its carrier in diode-induced demodulation, rectification or detection - only one partner can walk that one way street - a discarding which may as well refer to noise - noise (a la Turing - the one time pad which encodes (voice codes) discretised speech - in the case of Turing in 1941, 11 signals (amplitude information) - one time and not more than one time)

The vocoder encodes the voice (in the interests of an economy, discarding a twinned redundancy already of a carrier in favour of reducing (the expense of) bandwidth during a love telephone call.

quotation:

A vocoder aims to replace the carrier of your voice with another carrier from another source. Thus, it changes the sound of the voice but not the message when you speak. It takes formant and carrier from external sources and splits them up in bands (a band is a region of frequencies, same thing an equalizer does). Then, the envelope (the modulation) is extraced from each formant band. This part is done by an envelope follower, an extreme low pass filter. Next, formant bands are modulated onto the carrier bands and the resulting bands are mixed together to the output signal.

Vocoder theory:

The vocoder examines speech by finding this basic carrier wave, which is at the fundamental frequency, and measuring how its spectral characteristics are changed over time by recording someone speaking. This results in a series of numbers representing these modified frequencies at any particular time as the user speaks. In doing so, the vocoder dramatically reduces the amount of information needed to store speech, from a complete recording to a series of numbers. To recreate speech, the vocoder simply reverses the process, creating the fundamental frequency in an oscillator, then passing it through a stage that filters the frequency content based on the originally recorded series of numbers.

Thanks to Turing's modifications the expression could be encrypted - according to the Vernam principle applied to discretised speech:

So Vernam's system was a very simple, in principle, system where you had plain language add obscuring characters and at the other end add back exactly the same obscuring characters and the they cancel out and leave you with the plain language.

(all in modulo 2 - the cancelling action)

Speech signals at 11 bandwidths sampled 50 times a second and added in modular fashion to the random 9 (reproducible) sequence. the doubling in modulo six this time

What is life coding - as expressed by the design of a CPU, the design of a simulations machinery after Daniel Galouye (Simulacron 3 - reworked by Rainer Werner Fassbinder as a pure filmic description of Rossler's endophysics, head, eye and camera in electronic transition - zero domain crossing is your reference).

Our model for the CPU, and the question that the idea of the CPU renders is precisely where we draw the line, where we mark a division or passage between hardware and software, a false and delirious division which could be imagined as between the analogue and the digital - the digital and/as a reining in of the analogue - not so much in terms of discretisation but of a forbidden zone far from zero crossing - a forbidden zone which precisely the Schmitt trigger is designed to out-sketch, to eliminate, drawing that wave as squared, as regular noise. A different time-frame for a digitised sine wave which can also stand as a modulation. what carrier?

So there is this drawing of the line which is a question of instructions also, of microcodes which express the most basic operations which can be achieved in terms of raw hardware, of gates opening and closing around a machinery. on the bus. a drawing of the line which is a question of virtual machines - of how that instruction is understood by an underlying machinery. an old tale of abstractions which fits language. the same line-drawing which articulates a progression into high-level code by way of the (termed by computer scientists as incestuous - within a bachelor realm) interpreter (we will meet again under the terms of evaluation) or the compiler.

Such allows us to choose as a model for the CPU, the design of a LISP-based processor undertaken by Guy Steele and Gerald Sussman in the 70s at MIT AI labs. the idea here of a layering down to hardware which mimes the same principles or ideas, an equivalence of data and code which marks the incestuous role-play of the interpreter (code into action, into electricity reflexively) and allows for the entry of quotation; quotation implying a system of notation which can equally well be the brackets of the so-called Lisp S-expressions, or ones and zeroes.

Brackets as a form of encoding; binary or otherwise to encode the description of a machine:

In a similar way, we can regard the evaluator as a very special machine that takes as input a description of a machine. Given this input, the evaluator configures itself to emulate the machine described. For example, if we feed our evaluator the definition of factorial, as shown in figure x, the evaluator will be able to compute factorials.

Encoding, vocoding, how is the machine (of quotation) encoded:

To encode the description of a machine...

Circuit diagram translation of the CPU design - switches, multiplexing, gates describe a reconfigurable circuit made active by electricity, by clock speeds (the crystal which can equally well provide us with a carrier).

The classic register machine:

CPU composed of data paths (registers and operations) and the controller:

* registers - storage * operations - active circuits

* controller - state machine - transitions - modulation/clock

Quotation, as in writing, to differentiate between active code and passive data. To mark a transition of cut and pastage - passage

Splicing in...

http://repository.readscheme.org/ftp/papers/ai-lab-pubs/AIM-514.pdf

(Lisp typified as high-level machine language)

How we can proceed from the specification of a high-level programming language - conceived as a means of active process description and symbolic manipulation - the latter as key to the electric process described here - rather than as, say, a spreadsheet - proceed from this specification to the description in a (software generated) circuit diagram for that which will run or mime this language.

How does quotation take place in hardware?

Firstly quotation in software:

(quote bear)

(defun bear (x y) (cons x y))

'(bear cat mouse)

And in hardware -

The evaluation of type 7 (quote) returns the cdr of the object.

And how is an instruction set modulated (hidden opcodes in relation to simulations machinery)?

the question of a carrier.