GUI Reference
R&S
®
ZNC
281
User Manual 1173.9557.02 ─ 13
The spurious signal can be eliminated by dividing the sweep range into two segments
with different LO settings:
●
In the low-frequency segment, ranging up to the center frequency of the bandpass
filter, the frequency of the local oscillator is set to LO < RF. This ensures that the
spurious signal b'
2
is not measured at port 2.
●
In the high-frequency segment, starting at the center frequency of the bandpass filter,
the frequency of the local oscillator is set to LO > RF. If the center frequency is larger
than B
+
– 2*IF, then there is no distortion from b'
2
.
Remote command:
AGC Mode
Configures the Automatic Gain Control (AGC).
In
"Auto"
mode the analyzer automatically adapts its receiver step attenuator settings
to the RF input level (
→
Automatic or Adaptive Gain Control, AGC). The A/D converter is
always operated at optimum input level, selecting one of the following gain settings for
every measurement point:
●
"Low Dist(ortion)"
, corresponding to a lower internal A/D converter input level. This
setting allows for a high RF overdrive reserve and is appropriate for high RF input
levels.
●
"Low Noise"
corresponding to a higher internal A/D converter input level. This setting
increases the dynamic range and is appropriate for low RF input levels.
"Low Dist(ortion)" and "Low Noise" can also be selected
statically
, completely disabling
the adaptive behavior. This is appropriate if the characteristics of the input paths must be
constant, e.g. because
●
interfering signal contributions originating from the receiver (noise, nonlinear contri-
butions) must not change during the measurement.
●
a large interfering signal in the vicinity of the measured signal must not overdrive the
receiver.
"Manual"
mode allows to select the preferred "AGC Mode" per sweep segment, drive
Remote command:
Manual Config...
Opens the "AGC Manual Configuration" dialog that allows to configure the Automatic
Gain Control for the individual sweep segments, drive ports and receivers. This button is
enabled in "Manual"
The manual AGC settings are persisted and reused for subsequent measurement
sweeps, which may increase measurement speed compared to "Auto" mode while not
compromising measurement quality.
●
Range
: If
is enabled, each sweep segment can be configured sep-
arately.
●
Drive Port
,
a
,
b
j
: Selects the AGC mode for the respective drive port and receiver.
●
Auto (column)
: Enables the automatic mode for the corresponding drive port, disa-
bling the manual configuration for the related a- and b-waves.
●
Reset
: restores the default settings ("Auto" for all drive ports)
Channel Settings