Cisco Headend System Release 2.5 Guía Del Usuario
1-46
DHCT Status Reporting Utility
78-738186-01 Rev B
DHCT Delay Value Saturation Report,
Continued
Understanding the DHCT Delay Value Saturation Report
There are two parts to the DHCT Delay Value Saturation Report:
•
•
A graphical representation of the distribution of the various delay values of
DHCTs assigned to each QPSK modulator on the system
Note: Read Graphical Distribution of DHCT Delay Values, next in this section,
Note: Read Graphical Distribution of DHCT Delay Values, next in this section,
for help in interpreting the graphical representation.
•
A numerical analysis of the graphical representation of the various delay values of
DHCTs assigned to each QPSK modulator on the system
Note: Read Delay Value Analysis, later in this section, for help in interpreting the
Note: Read Delay Value Analysis, later in this section, for help in interpreting the
graphical representation.
Graphical Distribution of DHCT Delay Values
The first part of the DHCT Delay Value Saturation Report contains a graph that
The first part of the DHCT Delay Value Saturation Report contains a graph that
shows the distribution of the various delay values of DHCTs assigned to a specific
QPSK modulator. In the following example, the modulator is QPSKMOD1. The
horizontal axis of the graph plots units of time in microseconds (ms); the vertical axis
(not marked on the report) plots the relative number of DHCTs with each delay
value.
DHCT Delay Value Saturation Report - QPSKMOD1
|------------------------------------------------------------------------------------------------------------------------------|
| T |
| | |
| | |
| T TT |
| | || |
| |T |T T |
| || T|T| |
| |T T|||| |
| T T|| ||||T |
| | T||T T|||T| |
| T TTTT||| T|||T| |
| TTT T| T TTT|||||T|||||TT |
| TTTTTTTTTTT TT TTT||||||TT|||||T|T |
| TTTT TTTTT||||TTT|T|TTTTTTTTTTTTT TTTTTTTT|||||||||||||||TT |
|+------+-----+---------+--------------+---------------+--------------+--------------+---------------+--------+-----+---+---+--|
50 100 134 200 300 400 500 600 700 761 800 825 850 8
=============>|<======================>|<====================================================================>|<===============
^ ^ ^ ^
| | | |
TOO Far from Headend CORE POPULATION (300-761ms) Close to Headend Next to QPSK
Distant but Within Range
The data in this graph shows that the QPSK called QPSKMOD1 supports two
distinct clusters of DHCTs. The first cluster of DHCTs is located close to the
headend, as confirmed by the Close to Headend label along the x-axis. These
DHCTs have a delay value centered around 700 ms.
The second cluster of DHCTs is located farther from the headend, as confirmed by
The second cluster of DHCTs is located farther from the headend, as confirmed by
the Far from Headend but Within Range label along the x-axis. These DHCTs have
a delay value centered around 400 ms.
Having multiple clusters of DHCTs, as illustrated in this example, is normally not a
Having multiple clusters of DHCTs, as illustrated in this example, is normally not a
problem. Non-responding DHCTs begin to appear only when delay values fall
below the 134 microsecond range, as designated by the Too Distant label along the
x-axis.