Digital Signal Processing Reference
In-Depth Information
Chapter 9
Digitalisation
Haha, you will probably think, now we are going to have an „Introduction to digital
technology”. Even at the first level of training in the vocational field of electrical engi-
neering this subject is an indispensable element in the program of training.
It is such a appealing subject because it can be approached with no previous knowledge.
There is a great deal of specialist teaching materials, experimental construction kits and
simulation programmes for the PC available.
Digital technology does not always mean the same thing
There is not much point in following these well-trodden paths. There is, however, a much
more important reason to transcend this kind of digital technology. It is very important for
technical control and monitoring problems of all kinds but basically it only does one thing
- it switches lamps or relays
on or off
or occasionally activates a stepper motor.
Let us take a set of traffic lights as an example - certainly an important application. It is
confined - like all the examples dealt with in digital technology as a school subject up to
now - to switching on and switching off processes, i.e. two conditions -
on or off
!
Whether using standard digital components (e.g. TTL series),
freely programmable digital circuits such as GALs (Generic
Array Logic) or FPGAs (Field Programmable Gate Arrays) or
even microcontroller circuits - traditional digital technology in
schools has confined itself up to now to switching on and
switching off processes.
In Chapter 1 we explained in detail why our approach has completely different objectives:
In this topic and in present-day practice the central thing is the
computer-based processing of real signals by means of “virtual
systems” (i.e. programs) which as far as possible should like
DASYLab be generated by graphic programming in the form of
block diagrams.
Digital processing of analog signals
Real signals in measuring, automatic control engineering, audio and video technology are
first of all always analog signals. The trend is away from processing analog signals by
analog systems. As has already been mentioned several times analog technology is now
only of importance where it cannot be avoided.
Analog circuit technology is more and more to be found where it
cannot be avoided - at the analog information source and drain
and at the transition to the physical medium of the transmission
path.
