5.6 Digital Multi-Meter (DMM) - Option for BX100A Models Only
DMM measurements help verify that the copper pair meets specified requirements for DSL service. These tests are normally
conducted during the pre qualification phase or on problematic service loops.
6.0 DSL Measurement Setup
The Setup menu can be reached at anytime during operation by pressing the
Home
key, accessible on the rubber keyboard.
BX100A ADSL Setup Menu
BX100V ADSL Setup Menu - Annex A
6.1 ADSL CPE (ATU-R) Setup:
The following ADSL test functions are available under the
Mode
tab on the BX100A and BX100V models;
ANSI:
Enables ANSI mode.
Defined by the American National Standards Institute (ANSI) Telecommunications Committee, T1.413 was the first standardized
ADSL specification. The underlying modulation is Discrete Multi-Tone (DMT) line code which divides the bandwidth of the standard
two wire copper wire used in the PSTN into 256 separate 4.3125 kHz wide bins called sub-carriers. Even though each of these 254
sub-carriers or tones can support a modulation of up to 15 bits, the maximum achievable downstream data rate is actually 8.128
Mbit/s due to error checking and related overhead data. In the upstream direction, a maximum of 30 sub-carriers is used, each
tone being modulated with up to 15 bits providing a maximum theoretical throughput of just over 1.5 Mbit/s.
DMT:
Enables DMT mode.
Also referred to as ITU G.992.1, the standard expands the usable bandwidth of existing copper telephone lines to rates up to 12
Mbit/s downstream and 1.3 Mbit/s upstream. Discrete Multi-Tone (DMT) mode, divides the ADSL signal into 255 carriers (bins)
spaced in multiples of 4.3125 kHz. The DMT spectrum has 224 downstream frequency bins and up to 31 upstream bins.
In
Annex A
systems where Voice (POTS) is used on the same line, the frequency spectrum can be outlined as follows:
0-4 kHz is allocated to Voice traffic
4-25 kHz is an unused guard band
25-138 kHz is for Upstream data
138-1107 kHz is for Downstream data (ADSL)
BX100A/V e-Manual D07-00-001 Rev E01
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