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32)
Turning on the LPF 80 kHz
(l9)
or LPF 30 kHz (20)
key decreases the
noise component,
thereby decreasing the distortion factor.
This
state can be visually checked by observing the monitor output with
an oscilloscope.
The monitor output provides the distortion and
noise components excluding the fundamental component.
33} Measure the distortion factor, varying the frequency and amplitude
of the oscillator.
It will be found very easy to use - neither the
frequency nor the meter range need to be set.
The range can also
be selected manually,
in which case the OVER and UNDER annunciators
of the INPUT RANGE OVER/UNDER keys
(is)
warn the operator of
excessive input or too little input.
If either LED comes on,
select the appropriate range to turn it off.
____NOTES-----
(1)
The input signal levels below 1 V will limit the
selectable ranges for distortion measurement.
Detailed information will be described later in
paragraph 4.5.
(2)
The use of the LPF and HPF restricts the frequency
of the measurable fundamental wave as follows:
LPF 80 kHz.
20 kHz
(max.)
LPF 30 kHz.
7.5 kHz
(max.)
HPF 400 kHz ....
500 Hz
(min.)
This is the last step in measuring the distortion.
Turn off all
filters and turn off the RANGING key, placing the analyzer in the
AUTO mode.
Set the oscillator frequency to 1.000 kHz, and the
output amplitude to 4.0 dB.
S/N measurement
34) When the S/N measurement function is enabled with the connection
(Fig.
4-1)
kept as is and the set state unchanged,
the S/N of the
analyzer itself will be indicated.
The S/N in this case implies
the degree of residual noise content.
To measure the S/N ratio, press .the S/N key of the MEASUREMENT keys
(J) with the LED in the key on.
The meter range indicator (J)
shifts,
and after a pause the range will shift again and will be
stable.
The large meter (J) at the right indicates the S/N ratio.
Both the INPUT LEVEL meter (T) and indicator (V) are in the
4-15
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