Spirent DLS 400E3, Operating Manual

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DLS 400E3 Operating Manual
Spirent Communications - Page 3-9
7104000537 03/04 -2
transmission system can be a failure of the digital transmission link, together with a failure of the span
power feeding (if provided) for the duration of the micro-interruption.
The operating objective is that in the presence of a micro-interruption of specified maximum length, the sys-
tem (e.g. DSLAM and corresponding modem) does not reset, the system automatically reactivate or retrain
with a complete start-up procedure if a reset occurs due to an interruption. These parameters are defined in
the ADSL, HDSL2 and SHDSL standards like the ITU-T G.shdsl / G.991.2.
The following graph from the ITU-T G.shdsl standard illustrates the specified micro interruption.
Figure 3.5 Micro Interruption Test Circuit
The standard specifies two configurations based on the powering of the TU-R. The default values for the
micro interruption variables are as follows:
• Micro interruption duration (t)
• 10 ms when TU-R is powered locally
• 1 ms when TU-R is span powered (remotely powered)
• Signal period (T): 5 s
• Test interval: 60 s (total test duration)
In addition to the standard specified values, all the micro interruption variables are custom configurable to
be applied to any of the loops the DLS 400E3 simulates.
3.5.7.1 Setting the Micro Interruption Feature
The micro interruption feature is controlled in the Micro Interruption control window by setting values in
the following fields.
TU-C TU-R Test Loop
Impulse
Generator
S
t
T