Db Measurements (1061/1061 A Only) - Datron 1061A User Handbook Manual

dB
measurements (1061/1 061
A
only)
The
dB mode
is
selected
by
depressing
the 'dB' key.
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COMPUTE.
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Selection of 'dB'
causes
the readings to be
expressed
in
terms of decibels relative to
unity (IV, lkT2
or
1mA).
Selection of 'dB'
and
'Ratio' displays readings of
ratio in
decibels relative
to the reference signal
connected
to
the 'Ratio I/P' plug.
Display
is
20 log
Where
x
=
measured
or
computed value
and
y
=
IV,
IkO
,
1mA
or the ratio
reference input.
In addition, a
dB readout can be displayed of the
input signal
in
relation to
any value,
divided
by
100,
stored
in
the
4-
C
store (see
Computation
Facility).
This
facility
is
accessible
by depressing
both
the
'dB'
and
'4-
C'
keys.
If
the
dB measurement
function
is
combined with
the
(A-B) function,
the
subtraction
A-B
is
performed
before the conversion to
dB
is
made.
De-selection of this
mode
is
made
by re-pressing
the 'dB' key.
dB measurement
example
To
plot the
frequency response
of
an
amplifier.
The
gain of
an amplifier
and
the
phase relationship
between
its
input
and output
signals
is
dependent
upon
the
frequency
of those
signals.
A
convenient
way
of representing the
frequency response of
an
amplifier
is
to plot the
magnitude of
the voltage
gain
of the amplifier
in
dB's against frequency.
V
m
„
Voltage gain
=
20
log
10
-
—
^in
The
ratio
V
ou[
/V
in
may
be
measured
using
'Ratio'
mode
(
V,
n
as rear reference input
and
V
0UI
as rear
input) or
measuring
V
in
,
storing
V
in
/
100
in
store
C
(see
Computation
Facility)
and
then
selecting
4-
C
when measuring
V
out
.
To
express
this
gain
in
decibels, the
dB
key
is
selected.
3-5