Wavetek ANT-20, Руководство по эксплуатации

Страница: 47 / 126

ANT-20/ANT-20E Broadband Analyzer/Generator
Operation O-29
5.5 The “ATM Layer QoS (PVC) - Looped” test type
This test type is intended for ATM layer QoS measurements with permanent virtual connections
where the virtual channels are to be looped back in the DUT either in the physical layer or in the
ATM layer.
Loop-back in the physical layer
If you select unidirectional channels in the extended
“Test Setup <...>” dialog, this corresponds to a
loop-back in the DUT in the physical layer.
Tip: Only virtual channels with symmetrical
bandwidth can be used with this method.
Characteristics
•
Measurement of permanent virtual connections
(PVC)
•
Up to two virtual channels possible
•
Cell delay measurements are possible
•
Bi-directional, symmetrical channels can be tested.
From the point of view of the DUT, the channels are
bi-directional and symmetrical; from the test
instrument point of view, the connection is a
unidirectional loop.
Loop-back in the ATM layer
If you select bi-directional channels in the extended
“Test Setup <...>” dialog, this corresponds to a
loop-back in the DUT in the ATM layer.
Characteristics
•
Measurement of permanent virtual connections
(PVC)
•
Up to two virtual channels possible
•
Cell delay measurements are possible
•
Bi-directional, symmetrical or asymmetric
channels can be tested.
Basic instrument settings
•
“Emulate” topology
•
Signaling emulation “off”
The pictogram shown opposite appears in the
workspace of the VI.