User's Manual

Chapter 16 Test Results
DSL Results
SmartClass TPS User’s Guide
126 22035456, Rev 001 May 2014
Tone Graphs
The graphs provide a graphical representation of the following:
– SNR (signal to noise ratio) Per Tone
– Bits Per Tone (BPT)
Figure 19 provides an example of a Bits Per Tone graph.
– QLN (quiet line noise) Per Tone (Broadcom only)
– Hlog Per Tone (Broadcom only). If a bridged tap is found, press the Utility key and then select
Calculate Bridge Tap Length. T
he bottom number on the cursor display changes from frequency
and tone to frequency and length (for example, “2.10 MHz (486)” changes to “2.10 MHz (77
ft)”).
Navigating the graph
To view the cursor
– Press the OK key when viewing the graph.
The cursor appears (the red line in Figure 19).
The number at the bottom indicates the cursor location (tone 557 in Figure 19). The upper number
indicates the numeric value (BPT=9 in Figure 19). Use the left and right arrows to scroll among the
tones.
To zoom
– Press the up arrow to zoom in or the down arrow to zoom out.
Troubleshooting using the graphs
The SNR graph indicates line quality. The BPT graph indicates the total bit rate and is a useful tool
for finding disturbers. Bits per tone is defined as bits assigned per DMT tone.
Examine the portions of the graphs where there are dips or breaks. These dips represent areas
where interference is degrading the DSL signal.
Figure 19 Bits Per Tone graph