Digital Signal Processing Reference
In-Depth Information
Illustration 102:
Function generator and oscilloscope
These two instruments are never lacking in a traditional laboratory. The function generator produces the
(periodic) test signal u
in
. The following are available as standard signals: sine, triangle and rectangle. In
addition, more sophisticated instruments make it possible to generate “sweep” signals, burst signals and
“one-shot” signals (caused by a trigger process only a period of the signal set is produced). The
“analog” oscilloscope can only make periodic “standing” signals visible on the screen. Digital storage
oscilloscopes are required for one-off signals. (see above).
The days of these two traditional analog measuring instruments are numbered. Computers with an appro-
priate periphery (PC multi-function cards for the input and output of analog and digital signals) can be
used for a specific application by means of graphic interfaces for any tasks in measuring and automatic
control engineering or any form of signal processing (e.g FT)
By means of a function generator and oscilloscope it is possible - using time-consuming
measurement procedures, recording the measurement values, and calculation by means of
a pocket calculator - to determine the representation of the frequency response according
to amplitude (
Û
out
/
Û
in
)
and phase (
Δϕ
) between u
out
and u
in
.
The determination of frequency-selective properties - frequency response and transfer
function - of a (linear) system is limited in principle to two different questions or
measurements:
