R&S ZNB Series User Manual page 269

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R&S ZNB/ZNBT
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Use another device as master: Set the analyzer to "External" frequency reference
and synchronize it (and all other devices) to the master's reference clock signal,
fed in at the Ref In connector on the analyzer's rear panel.
Fast sweep mode and conditions
In list mode the external generator steps through a predefined list of frequencies or sig-
nal powers. This mode can be used to accelerate the measurements involving external
generators. If "Fast Sweep" is activated in the "External Generators" dialog, the ana-
lyzer compiles a list of the stimulus values (frequencies and powers) in all channels
and transfers it to the generator. The list is automatically updated and retransferred
whenever the channel settings are changed.
The analyzer uses a trigger handshake mechanism in order to control the generator's
list mode:
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The generator sends an EXT GEN BLANK signal to pin no. 22 of the User Port
connector on the rear panel of the analyzer to show that it is ready to step to the
next frequency or power value in the list.
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The analyzer transmits an EXT GEN TRG signal at pin no. 21 of the User Port con-
nector in order to switch the generator to the next point in the list. Afterwards the
analyzer waits for the next EXT GEN BLANK signal.
If the User Port connection is interrupted during the measurement, the sweep is halted.
It is continued after a "Restart Sweep".
If the number of sweep points exceeds the maximum number of entries in the list
(depending on the generator type), the analyzer must interrupt the sweep in order to
send a new list and complete the stimulus information. This generally slows down the
measurement.
Measurement process for external generators
The measurement process for external generators "Gen 1", "Gen2" ... differs from the
measurement process for internal source ports:
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An external generator always represents a permanent signal source that is
switched on for all partial measurements.
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The external source is measured in the first partial measurement where an internal
source is active. This means that no separate partial measurement for the external
generator signal is needed. If no internal source is needed at all, the external
source is measured in the first partial measurement.
4.7.29 External switch matrices
4.7.29.1 Overview
From the perspective of the VNA, the purpose of a switch matrix is to extend the num-
ber of test ports. I.e. it converts an N-port network analyzer into an N'-port network
analyzer (N'>N) without modifying the instrument itself. The increased number of test
User Manual 1173.9163.02 ─ 62
Concepts and features
Optional extensions and accessories
269