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13.2.5. Probability Density Function Ch.A or Ch.B
The instantaneous probability histogram is defined as:
where k ( a(n))
= {
O~n~N-1,
O~j~J-1,
~X
~X
1 if
a(j)--~
a(n)
~
a(j)
+ -
2
2
0
N
=
2048
J
=
512,
j
=
amplitude class index
The Probability Histogram gives the relative occurrance of a signal level within a given
amplitude interval
~
x.
The averaged Probability Histogram
q (
a(j)) is the ensemble averaged Probability His-
togram at each amplitude interval across a series of instantaneous Probability Histo-
grams. The displayed function is the averaged Probability Density, this being the nor-
malised average Probability Histogram:
100
p (
a(j))
= -
·
q (
a(j)) in %/V
~X
normalised with respect to the amplitude interval
~
x, or:
100
p (
a(j))
=
lf;- ·
q (
a(j)) in %/RMS
~X
where the mean-square value equals:
J-1
l/;2
= .L.
q (
a(j)
)
. a(j)2
J=O
The Probability Density Function can be displayed in 512, 256, 128, 64 or 32 amplitude
intervals covering the input voltage range.
Similar for Ch.B.
13.2.6. Probability Distribution Ch.A or Ch.B
The probability distribution is defined as:
i
p (
a(i))
=
100 ~
0
q (
a(j))
0
~
i
~
511'
0
~
j
~
511
The Probability Distribution gives the probability in % that the signal level is below a
given amplitude level a(l). It is equal to the sum of the averaged Probability Histogram
values below the given amplitude level.
149
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