Rohde & Schwarz 1145.1010.04/05/06, Руководство по эксплуатации

Страница: 291 / 813

R&S
®
ZVA/ZVB/ZVT Channel Menu
1145.1084.12 4.129 E-6
ZVA24,
receiver
ZVA24-B31 ZVA24-B32 ZVA24-B33 ZVA24-B34
•
Refer to the data sheet for detailed ordering information and technical specifications.
Attenuation factors for the received waves and the generated waves serve different purposes:
•
Received wave factors are used to adjust the received signal levels to the input level range of
the analyzer in order to avoid damage to the instrument, e.g. if the DUT is a power amplifier .
The range of attenuation values depends on the analyzer model.
Port-specific attenuation factors can be set in the
Receiver section of the Port Configuration
dialog .
•
Generated wave factors are used to protect a sensitive DUT from excess input levels . The
attenuation values are set automatically. The range of values depends on the analyzer model.
Port-specific attenuation factors can be set in the
Source section of the Port Configuration
dialog .
Automatic generator attenuation
The aim of the automaticattenuatorsetting is to ensure that the analyzer can perform the entire sweep
without switching the generator step attenuators. The output power p
el
at each port depends on the
following settings:
•
The channel power p
ch
(the Power set in the Channel – Power Bandwidth Average menu).
•
The port-specific power offset p
b
(for arbitrary sweeps) and the port and frequency-dependent
power slope factor p
Slope
(for frequency sweeps) defined in the Receiver section of the Port
Configuration dialog.
•
A port and stimulus-dependent correction factor p
corr
introduced by a generator (source) power
calibration.
•
The port-specific generator step attenuator setting a
step
.
If everything is expressed in dB units, the output power p
el
at each port must be equal to the sum of the
channel power and all port and stimulus-dependent correction factors:
p
el
= p
ch
+ p
b
+ p
Slope
+ p
corr
+ a
step
•
The automatic attenuator setting algorithm selects a
step
such that the variation range for p
el
is
sufficient to account for the stimulus-dependent variations of p
b
and p
Slope
, and p
corr
. If this is
not possible in a particular subrange of the sweep (e.g. because the sweep settings are such
that an excess variation range for p
el
or a negative attenuation factor a
step
would be required)
then the analyzer generates an error message.
The position and function of the step attenuators is illustrated in the following figure. The analyzer
measures both the attenuated generated waves and the attenuated waves received from the DUT.