QUICK GUIDE
D2061 ADSL TESTER
2. READING THE ADSL ACCESS STATUS
2.1. Smart Status™
The feature allows to display immediately modem, line and instrument status.
In particular the Smart Status™ allows to display:
►
Number of bits assigned per tone
►
G.826 quality measurement results
►
Count of errors, events, or anomalies on the line.
►
ATM cells statistics
►
Current and history status of any near-end and far-end alarms at
ATM level.
►
Vdc on the line.
2.2. DMT Bits Allocation
The Bits graphic/table feature measures the bits per tone distribution used by the
modem to transmit the provisioned rate and displays the number of bits assigned
per tone either in a graphic or table format.
During modem initialisation, a signal to noise measurement is made for each
tone; bit distribution is then optimised to meet the desired bit rate.
Each tone can support a theoretical maximum of 15 bits. During operation, the bit
distribution may be adjusted to optimise bandwidth.
The modems constantly monitor the signal to noise ratio for each tone. If a tone
degrades in quality, a bit swap command can be sent to adjust the amount of bits
assigned to that particular tone.
These bits may be added to a different tone or taken out completely.
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