The
time
constan
t
of
the
meter
mov
emen
t
following
the
detector
smo
oths
the
output,
to
obtain
a
single-v
alued
reading.
The
quasi-p eak
v
alue
alwa
ys
will
b e
less
than
or
equal
to
the
p eak
v
alue
of
the
signal.
See
Figure
4-8 .
Figure
4-8.
Quasi-P
eak
Detector
Output
There
should
b e
no
dierence
b et
w
een
p eak
and
quasi-p eak
readings
for
CW
signals.
Ho
w
ev
er,
for
broadband,
pulsed
t
yp e
signals
with
low
rep etition
rates,
the
dierence
can
b e
signicant.
When
making
quasi-p eak
measuremen
ts,
remem
b er
that
substan
tially
slow
er
sw
eep
rates
are
required
for
quasi-p eak
detection
than
for
p eak
detection,
b ecause
of
the
long
time
constan
ts
in
the
quasi-p eak
circuitry
.
Measurement
Examples
These
examples
sho
w
ho
w
to
use
the
EMI
receiv
er
in
man
ual
mo
de,
to
p erform
an
a
v
erage
measuremen
t,
and
ho
w
to
make
p eak
and
quasi-p eak
measuremen
ts,
on
b oth
CW
and
broadband
signals.
Example:
P
eak
Measuremen
t
(CW
Signal)
In
this
example,
a
100
MHz
signal
will
b e
used
as
the
CW
signal.
1.
Connect
the
signal
source
to
the
correct
receiv
er
input
(INPUT
2
for
this
example).
2.
Adjust
the
reference
lev
el
to
bring
the
signal
amplitude
near
the
top
of
the
display
.
3.
Set
the
correct
quasi-p eak
bandwidth
according
to
the
frequency
range
b eing
tested.
Because
the
signal
of
in
terest
in
this
example
HP
8572A
EMI
Receiv
er
User's
Guide
Making
Typical
Measurements
4-9