Back to our example: the individual vehices are called
applications
and have
handy abbreviations: for instance, the
application
“traction power“ has its own
frequency range
of 16.7Hz.
We will also replace the formerly used expression “speed“ with something else:
field strength
.
So far we are done with all the physical units and wording. Next, spectrum ana-
lysis itself; it works exactly like our motorway:
Say our spectrum analyser should measure all
frequency ranges
from 0
Hz
to
400
Hz
(in our metaphor, the 400m range of the giant motorway). It will step by
step measure each
frequency range
individually. Starting at 0-1
Hz
, then 1-2
Hz
and so on, until it reaches 400
Hz
. It will also exactly record the signal strength
in each
frequency range
, also providing us with the
signal strength
in each of
the
frequency ranges
.
Some practical examples:
Let’s assume we want to accurately study the
frequency range
from 0Hz to
400Hz, and let’s further assume that the following 3
applications
are currently
active in this range, with varying
signal levels
(in practice, you will often find a
far bigger number of applications):
Frequency range [MHz]
Application
Measurement
16.7Hz
Traction power
40
50Hz
Mains power
20
350-360Hz
Unknown
80
How could such a result be displayed optimally on a measurement device? Well,
first of all, we apply the frequency range of 0Hz to 400Hz on the X axis, from left
to right:
OK, now that was simple. Now, we tag each of the 3 applications on the X axis,
according to their frequencies, and their positions in the frequency range beco-
me visible:
0Hz
400Hz
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19.0 Spectrum analysis basics
