R&S ZVAX-TRM, User Manual

Page: 10 / 32

Building Blocks and RF Signal Flow
R&S
®
ZVAX-TRM
10 User Manual 1325.1268.02 ─ 04
Reference Signal Access
The block diagram also shows the access points for the reference signal:
●
at the pulse modulator (only if the modulator is looped into the source path)
●
at the combiner (for paths 3 and 4)
●
at the front-end's high-power couplers (for paths 1 and 2)
For paths 3 and 4 the reference signal can also be accessed at the NWA's coupler
(see
Chapter 2.5, "RF Signal Flow (w/o combiners)" , on page 11).
The analyzer fimware ensures that only one of these access points is active at a time.
2.1 Pulse modulators
Pulse modulators can be looped into source paths 1, 2 and 3, enabling bidirectional
pulsed measurements even on a two-port R&S
ZVA. In combination with a
R&S ZVA/ZVT with two or more internal generators, IMD measurements with pulsed
sources can be performed.
Pulsed measurements are configured in the R&S ZVA/ZVT Firmware (pulse profile
measurement requires software option R&S ZVA-K7 at the R&S ZVA/ZVT). To control
the pulse modulators of the R&S ZVAX-TRM the analyzer can provide pulse generator
signals via the CASCADE interface (see Chapter 3.3.4, "CASCADE IN" , on page 17;
requires software option R&S ZVA-K27 at the R&S ZVA/ZVT). If a pulse modulator is
looped into the signal path, its input signal can be used as reference signal, which ena-
bles ALC even in pulsed measurements (depending on the pulse length).
For the related options, see Chapter 4.2.2, "Pulse Modulators" , on page 29.
2.2 Output Amplifiers
Each of the source paths can be equipped with an additional amplifier, intended to
compensate for the losses due to other modules and switches on the respective path.
If the amplifier is looped into the source path, output levels similar to those of a stand-
alone R&S
ZVA/ZVT can be achieved.
For the related options, see Chapter 4.2.3, "Output Amplifiers" , on page 29.
2.3 Broadband Combiners
Source paths 1 and 3 (source paths 2 and 4) can be combined and output to port 1
(port 2) on the R&S
ZVAX-TRM. With CW source signals the resulting two-tone output
signal is suitable for intermodulation measurements. If both combiners are equipped, a
Broadband Combiners