Alpha Technologies DSM3 for XM2 - Technical Manual - Manual (Page 40)

40 745-814-B8-001, Rev. C (03/2014)
4.11.2 QAM Constellation Common Impairments, continued
4.0 Web Interface
Fig. 4-25, Twisted or Skewed (Quadrature Distortion) and Entire Constellation Shape
4.11.3 Microreflections Tool
The Microreflections page provides details about impairments on the DOCSIS network and the
approximate distance(s) of the impairment(s). In order to provide the analysis and a display of possible
impairments, this tool requires the Adaptive Equalization function to be enabled on the CMTS.
Navigate the mouse pointer to the Tools menu item and select “Microreflections” in the drop down
menu to open the Microreflections page.
Fig. 4-26, Microreflections Tool
(data values shown for illustration purposes only)
Click on a particular bar in the graph to display the details of the impairment such as time,
distance (feet & meters) and amplitude in the table below. The selected bar will turn a slightly
different shade of color compared to other bars in the graph.
Entire QAM constellation