Digitalization

Principle

Primarily, digitalization is the Projection in a discrete Espace selected of real sizes Analogiques. Digitalization consists in carrying out one or more measurement S of the sizes which one wants to represent while being interested in one or more axes:

the space axis , where one discretizes according to a Length for example all the Millimètre S of a surface; one speaks then about space sampling;
the temporal axis or frequential, or one will discretize the same size during time; one will speak about temporal sampling;
the axis of intensity or one will discretize according to a unit of intensity like the Candela for the Luminous intensity: it is the quantification.

The result of this digitalization is a Nombre or a Suite of numbers representing the size measured along the selected axes. The wise choice of discrete space is crucial so that the digitized object is representative of the initial object.

Constraints

There exist constraints to respect to obtain a faithful digitalization of reality:

a sufficiently fine sampling to follow the evolutions of the object to be digitized: the Théorème of Shannon imposes a Résolution of minimum sampling;
a sufficiently precise quantification not to degrade the representation; the Bruit of quantification (uniform white vibration of variance 1/12) must remain negligible in front of the noise before digitalization.

Processes of digitalization

Digitalization is one in the manners of creating data to be treated. The processes of digitalization are multiple:

direct digitalization of Image:

Camera CCC, numerical camera
scanner (pilot of type TWAIN)

digitalization of a variable analog model during time (its, Video):

sampling ( sampling )

The continuation of numbers obtained is in general stored in a file.

Digitalization poses the problem of the representation of the data in the form of number, therefore Format of the data.

In electronics

The digitalization is defined as the analogical data conversion in a numerical system. The analogical data are collected by various Capteur S (photosensitive cell, thermometer…).

analog-to-digital Converter (digitalization)

In electronics, a chain of conversion A/N (analogical worms numerical) contains the following elements:

one or more analogical sources,
a Filter antialiasing ( anti-aliasing ) by source,
a Multiplexer (MuX), which could be used for to select a source among several (multiple entries but only one exit),
a sampler blocker ( Sample and Hold or S/H), which keeps the stable tension the time of coding,
the analog-to-digital Converter itself ( Analog/DIGITAL Converter or ADC),
a Codeur (or modulator).

Conversion thus follows the following way:

Analogical source - > Filter antialiasing - > Mux - > S/H - > EDGE - > Coder - > Numeric signal (transmission or treatment)

Digital-to-analog converter

Contrary, a chain of passage of a numeric signal towards an analogical signal will contain the following elements:

a decoder (or demodulator),
a Digital-to-analog converter (CNA),
a Demultiplexer (Demux),
a filter of smoothing, which will try to recreate the intermediate values,
an analogical exit.

Conversion follows the following way:

Numerical source - > Decoder - > CNA - > Demux - > Filter of smoothing - > Signal analogical

The choice of the terms (die) coder and (die) modulating gave their name to codec S (coders/decoders) and to the Modem S (modulators, demodulators).

See too

Encoding
Sampling
Noise of quantification

External bonds

digital-analog Conversion
Animation

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