Configure ADSL profile parameters in UA5000, what measures can improve line stability?

Question

Options

• ATurn on the grid delete coding switch
• BThe channel mode is selected as fast
• CTurn off the dynamic online adaptation function
• DImprove noise tolerance

• A
  79% (26)
• B
  6% (2)
• C
  15% (5)

Explanation

Enabling trellis (grid delete) coding (A) improves line stability by adding forward error correction, allowing the receiver to reconstruct data corrupted by noise without requiring retransmission, effectively hardening the link against impulse interference. Increasing noise tolerance (D) directly raises the signal-to-noise margin threshold, giving the line more headroom to absorb interference before losing synchronization. Option B is wrong because fast channel mode disables interleaving, which reduces the line's ability to correct burst errors and actually decreases stability in noisy environments. Option C is wrong because the dynamic online adaptation function allows the modem to reduce speed gracefully in response to worsening conditions rather than dropping the connection entirely, so disabling it removes a key stability mechanism.

Memory tip: For stability, think "more protection, more margin" -- trellis coding adds error protection, and noise tolerance adds margin. Fast mode and disabling adaptation both strip away protective mechanisms, so they work against stability.

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