XDSL Testing and Loop Qualification
DSL Modem Test
5
5-15
•
Capacity Ch. 0 & Ch. 1 (%), Up & Down: Ratio of the Actual Bit
Rate to the Attainable Bit Rate for both channels.
•
Noise Margin (dB), Up & Down: Margin of safety between the
received signal level and background channel noise.
•
Transmit Power (dBm), Up & Down: Total or aggregate power of
the DSL signal transmitted from the DSLAM (Down) and customer’s
modem (Up).
•
Line Attenuation (dB), Up & Down: Measured difference between
the signal level transmitted from one end and the level received at the
other end, during the initialization process.
•
INP (Impulse Noise Protection), Up & Down: The level of impulse
Noise Protection configured in the DSLAM, expressed as a number of
DMT symbols from 0 to 16.
•
Interleaver Delay (ms), Up & Down: Transmission delay due to the
interleaving process used to implement noise protection.
•
PSD (Power Spectral Density, dBm/Hz), Up & Down: Average
transmit power spectral density over the DSL spectrum.
•
Bits / Bin and SNR / Bin Graphs: Graphical representations of the
number of data bits encoded and the Signal-to-Noise ratio measured
at each DMT carrier frequency.
•
Link Status: The current status of the GM-to-DSLAM or GM-to-CPE
modem communications link (Up or Down).
•
Number of Syncs: The number of times the link has successfully
“trained up” (synchronized) since starting the DSL Modem Test.
•
CRC & ATM HEC Errors, NE & FE: Count of the number of CRC
errors received at the customer modem (NE) and the DSLAM (FE),
indicating the performance of the physical (DSL) layer; and a count
of the number of HEC errors detected, indicating the performance of
the Link (ATM) layer in the ADSLx environment.
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