Tektronix WCA200A, User Manual

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Setting Amplitude
WCA230A & WCA280A User Manual
3- 131
Over-Voltage Input
Set the reference level (Ref Level) according to the input signal level. The
default setting is 0 dBm. If the signal level gets too high or the reference level is
set too low, over-voltage input may occur. If an over-voltage input occurs, the
status indicator “A/D OVERFLOW” is displayed in the red box (see
Figure 3--89).
CAUTION.
If a signal exc30 dBm (1 W) is applied, it can damage the
analyzer. Be sure to limit input signals to +30 dBm or below.
When the input signal level is too high, A/D OVERFLOW is indicated in the red box.
Figure 3- 89: A/D overflow indicator
NOTE
. If “A/D OVERFLOW” is displayed, it indicates that the A/D converter in
the subsequent part of the downconverter inside this instrument is overloaded. In
this case, data display is distorted and the measurement is not accurate.
If a signal larger than the reference level set value by 20 dB or more is applied
continuously, however, the limiter of the IF amplifier in the downconverter is
automatically activated to prevent large level signals from passing through the
A/D converter. Even if a signal exceeding the reference level is applied,
therefore, “A/D OVERFLOW” may not be displayed. Auto Leveling the signal
can usually eliminate all overload conditions.
Take sufficient care about the input signal level.
The overflow indicator is updated at every physical frame acquisition. When a
high level signal is applied under a setting that uses multiple physical frames for
one scan, “A/D OVERFLOW” may be displayed for a moment and then turned
off immediately. When a single high-level signal is applied under a setting using
one physical frame in one scan, the same phenomenon may be observed.