
86-1
86.1 Introduction
Most sensors and instruments described in the previous chapters of this handbook can produce con-
tinuous measurements in time or sequential measurements at xed or variable time intervals, as repre-
sented in Figure 86.1. e temporal patterns resulting from such measurements are usually referred to
as si
gnals
. Si
gnals
ca
n
ei
ther
be co
ntinuous
or di
screte in time
. e ma
in
ob
jective
of sp
ectral analysis
is
to pr
ovide
an es
timate
of th
e
di
stribution
of sig
nal
po
wer
at di
erent
fr
equencies
. Spe
ctral
an
alysis
an
d
co
rrelation
te
chniques
ar
e
an ai
d
to th
e
in
terpretation
of sig
nals
an
d
to th
e
sy
stems
th
at
ge
nerate
th
em
.
e
se
me ...