Amber 5500 - Page 6

Programmable
Audio
Measurement
System
Section 2
Amber model
5500
Owner’s Manual
Version
07
the unbalanced
high impedance input
of the
5500.
f)
5500
Input Impedance
-
This is the load
placed
by
the
5500
on the
output
of the
extemal
device under test. It is chosen
by
the
user from
3
possibilities.
See Section
2.1.9.
9)
5500
dBm
Measuring Impedance
-
As
dBm is
in fact a
power
measurement,
both
the
voltage
level and
impedance
are used
to
calculate
dBm.
This
is set either
by
the
user-
chosen
input
impedance
or the
user-chosen
dBm
reference
impedance (Special
func-
tion
26).
It is
not the same reference used
for
output
dBm
calculations. See Section 2.4.2.
h)
Watts
Impedance
Reference
-
Like
dBm,
Watts is a
power
measurement. It is indicated
on the
5500
by measuring Voltage
and cal-
culating power using
a
user
specified
load
impedance
value. This value is
only
the cal-
culation
value,
the actual load must be
sup-
plied by
the user
externally.
See
Section
2.4.1.
Careful
attention to each of the above factors
will
avoid
errors,
ambiguities
and other
problems.
2.1.2
FUNCTION
The row
of buttons in the FUNCTION
group
chooses the
basic function of the instrument.
Two
subgroups
are
possible
-
LEVEL and
DISTORTION. LEVEL
may
be wide band or
narrow
bandand DISTORTION
may
be total
harmonic or intermodulation
(if
the IMD
op-
tion
002
is
provided).
2.1.3 WIDE BAND LEVEL
This function is the AC
voltmeter or dB meter
mode. The
5500 will
automatically
measure and
display
the level of a
signal
in
the
range
of
+40
dBm
(100
V)
to
ap-
proximately
-100
dBm
(10
,uV) (lower
read-
ings may
be
possible
with
band
limiting).
The
reading
can be
expressed
in
Volts,
mV or
”V;
in
Watts,
mW
or
”W
or in dBm or dBV.
The
frequency range
of measurement is
10 Hz to
over
500
kHz.
This mode
always internally
measures the AC
Voltage
on the
input
even
when the
measured result is
displayed
in
Watts or dBm.
These
“power” readings
are
derived
by
cal-
culation
from the
Voltage
measurement
by
assuming
an
(internal
or
external)
load
im-
pedance.
In the case of
Watts,
the
default
impedance
is
8
ohms,
in
the case of dBm the
default
impedance
is 600 ohms. Both im—
pedances
can be
user modified. See Refer-
ence
Impedance
in Section 2.4.
2.1.4
NARROW BAND LEVEL
This mode
is similar to Wide Band
Level
except
a
programmable
filter is inserted into
the measurement
path. Dynamic
range,
overall bandwidth and available
display units
are all the same as the wide
band level mode.
The filter
type may
be selected from a choice
of three
available
configurations:
Band
Pass,
Low
Pass or
High
Pass. In the Band Pass
mode,
four bandwidths
(or
filter
Q’s)
are
available:
very
narrow, narrow, medium,
and
broad
(Section
4
describes the
shape
factors
of these filters
in
detail).
The
High
Pass and
Low Pass
modes are each
2-pole
Butterworth
2-4