2.) You would like to measure the exposure caused by
each of the radio appli-
cations
separately, e.g. for evaluating exceeding of exposure limits.
Regarding 1):
Let’s reconsider our ‘giant motorway’ example:
Remember that every lane was only intended for use by a single kind of vehicle.
Now imagine that a huge bridge crossed this motorway, with you standing on the
bridge and looking down on the motorway. Wow, what a mess!
Now, for example, you would like to know exactly what is happening on the
motorway, and this for every single lane. However, the motorway is incredibly
wide, so you would need rather good binoculars to be able to even look a few
km far. Let’s just imagine that your binoculars have a range of 6km (6000m).
Now you would like to know how much traffic there is on a specific lane and how
fast it is travelling. So, you’ll take a piece of paper and write down the number of
the lane and the data you evaluated. Starting at lane 1, you see: nothing! OK,
let’s go on with lane 2: nothing either! Now lane 3: OK, there is some traffic going
at 18km/h. Continuing with lane 4: Nothing! etc. until you have reached the last
lane. What have you accomplished now? You’ve performed an
ANALYSIS
of
the entire
range
of lanes from 0-6km. Or, in other words: You performed a
RANGE
ANALYSIS. As you know, to analyze something means breaking it down
into smaller parts which can be evaluated. In this case, the 6km wide motorway
was that big “something” and the smaller parts were the individual lanes. The
word “range” can now be replaced by the word “
SPECTRUM
” and there we are:
You have performed a
SPECTRUM ANALYSIS
! Who would have thought that
you are a
Spectrum analyser
!
Jokes aside: If you now in addition have a lanes plan telling you which lane is
assigned to which kind of vehicle, you can exactly determine what kinds of
vehicles have just been travelling.
Spectrum analysis
in high frequency technology works exactly like that:
There are “lanes” here as well. Though, these lanes are called
frequency ran-
ges
. The width of these
frequency ranges
is measured in the unit
Hz
(Hertz).
However, as the
frequency ranges
are mostly found in high
Hz
ranges, writing
them in plain
Hz
would require huge numbers. Thus, the unit
Hz
is often exten-
ded to
MHz
(1.000.000
Hz
) and
GHz
(1.000.000.000
Hz
). Like this, the whole
thing becomes much clearer. So, 1.000.000.000
Hz
can also be written as
1.000
MHz
or 1
GHz
.
14.0 Spectrum analysis basics
47
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Summary of Contents for SPECTRAN HF-2025
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