Amber 5500 - Page 26

Programmable
Audio Measurement
System
Section 2
_
Amber model
5500
Owner’s Manual
Version
07
(14.4
SPCL)
described
above,
any change
in
FUNCTION
always
reselects the default
in-
ternal
sine wave
source
(unless
IMD
is
selected. See
below.)
This
feature
allows
selection of a
special
source
in an abnormal
mode. For
example,
when
the IMD
function is
selected,
the
ap-
propriate
IMD
composite
test
signal
source is
automatically
selected. This
also means that
the IMD test
signal
can
only
be
selected
in
the
IMD
measurement
mode.
However,
the IMD
signal
source can be
selected in the
WIDE
BAND
LEVEL mode
by
entering
14.2
SPCL.
This allows
measurement
of the rrns level of
the
composite
IMD test
signal,
for
eXample.
It is of course
possible
to
enter
illegal
modes.
Selecting
an IMD
twin-tone source
in the
THD
mode will
usually yield
errors and at
best a
meaningless
value. As
the source is not
explicitly
indicated on the
front
panel
and
an
unaware user
could have
difficulty
sorting
out an
invalid
state,
the
5500
always
clears
the
signal
soUrce to its default
state at
every
function
change.
The default state in
the
LEVEL and
THD modes is a
single
fixed
frequency
sine wave.
In IMD it is
a two
frequency
composite
waveform. In the
SWEEP
mode,
it is the
swept
sine wave
source for
LEVEL or THD
and
a
swept
com-
posite
source for
IMD.
2-24
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