VeEX VePAL BX100A Series, Электронное руководство

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A bit swapping history of all affected tones is possible using paging function or zoom function.
BX100A/V Bitstogram Events Mode BX100A/V Bitstogram Events Mode
Note: Discrete Multi-Tone (DMT) and Bit Swapping:
Dividing the available bandwidth into independent, orthogonal sub channels is the key to DMT performance.
By measuring the SNR of each sub channel and assigning bits based on its quality, data will be transmitted
on subcarriers with good SNRs, while regions of the frequency spectrum that are too noisy or severely
attenuated will be avoided. DMT allocates from 2 to 15 bits per channel (bin). As line conditions change, bit
swapping allows the modem to swap bits to different channels without retraining.
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12.0 DR.DSL Loop Diagnostics (future option)
VDSL2 has a loop diagnostic mode and Dual Ended Line Test (DELT) function similar to that defined for ADSL2/+ systems. VDSL2
transceivers can measure line noise, loop attenuation, and signal-to-noise ratio (SNR) at each end of the line. Measurements can
be obtained even when line conditions are so bad that a connection isn't even possible. If a connection isn't possible, the modem
goes through each step of initialization but with improved robustness in order to exchange the test parameters.
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13.0 Digital Multi-Meter (DMM) (Option for BX100A models only)
The following Voltage measurements are supported by the BX100A DMM option;
AC Voltage -
check for unwanted power influence which is generally caused by induction from power lines running in
close proximity to the copper pair or by poor grounding. The power influence test measures the voltage and noise levels
related to either 50Hz or 60 Hz interference.
DC Voltage -
verify the presence of POTS or ISDN voltages. An Annex A (ADSL over POTS) circuit is powered by 48-
VDC while an Annex B (ADSL over ISDN) loop is powered by 90-VDC or higher voltages depending on various regulations.
Running a DCV measurement verifies that the cable pair is connected and properly powered by the POTS switch or ISDN
Line Termination (LT).
DMM - AC Voltage measurement DMM - DC Voltage measurement
BX100A/V e-Manual D07-00-001 Rev E01 Page 48 of 52