The concept: methods – content – objectives - Signals, Processes, and Systems - page 10

Illustration 13: Real picture of a signal system and H block diagram
This picture of a PC multi-function board with a signal processor (DSP) illustrates the dominance of
digital technology. The only analog ICs are the programmable amplifier (PGA) and the multiplexer. But
even here the setting is purely digital. This multi-function board can read and output both digital and
analog signals, as it were linking the PC with the outside world. The signal can be processed extremely
rapidly on the board by means of the signal processor. This reduces the workload of the actual PC. This
real picture of the multi-function board only gives an impression of the structure of the hardware.
The hardware block diagram (H block diagram) below provides more information. At least it clearly shows
the structure of the hardware components and the way they work together to receive or send out signals.
Multi-function boards of this kind are structured in such a way that they have universal application within
the framework of measuring and automatic control engineering.
The disadvantage of H block diagrams is that the hardware structure is visible but not the signal processes
which are carried out by the signal processor. In actual fact, these are all-important since the program
decides the signal processing.