EXFO CableSHARK P3 VF/DSL Cable Qualifier User Manual
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CableSHARK P3 User Guide
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8.3 ADSL Data Rate Prediction (ADSL, ADSL2, ADSL2+) Measurements
The DMT test or ADSL, ADSL2 or ADSL2+ Data Rate Prediction tests are unique in that they are
independent of any modem or line coding being carried on the line. This makes the EXFO CableSHARK
ideally suited for use in qualifying any twisted copper pair lines in the local loop to carry DSL technologies.
DMT is based on Frequency Division Multiplexing (FDM). Each frequency division is also known as a “bin” or
“tone” and occupies 4.3125 kHz of bandwidth. ADSL, ADSL2, and ADSL2+ use the DMT line code.
For ADSL, there are 256 bins for a maximum bandwidth of 1.104 MHz in which to encode information. This
permits a downstream rate of approximately 8 Mbps. ADSL is defined by ANSI T1.413 Issue 2 and G.992.1
(G.DMT)
For ADSL2, there are 256 bins for a maximum bandwidth of 1.104 MHz. ADSL2 allows data rates up to
approximately 15 Mbps. ADSL2 is defined by G.992.3.
ADSL2+ uses 512 bins for a maximum bandwidth of 2.208 MHz. ADSL2+ allows data rates of up to 24
Mbps. ADSL2+ is defined by G.992.5
8.3.1 Setting up a DMT Test
From the Main Menu, pressing function button F1 (CABLE TESTS) will bring the user to the CABLE TESTS
pop-up Menu. Choosing DMT TEST will invoke the DMT TEST SETUP Menu. The sections that follow will
explain the operation as each of the control keys is pressed and their respective screens appear. Figure
8.3.1A below shows the DMT Test Setup Menu.