Aaronia NF-5030S Manual page 60

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19.0 Spectrum analysis basics

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 0Hz to

400Hz (in our metaphor, the 400m range of the giant motorway). It will step by

step measure each frequency range individually. Starting at 0-1Hz, then 1-2Hz

and so on, until it reaches 400Hz. 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]

16.7Hz

50Hz

350-360Hz

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:

0Hz

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:

Application

Traction power

Mains power

Unknown

400Hz

Measurement

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