SNR Margin & Interleaving
BT's MaxDSL sets out with a 6 dB target SNR margin and the modem takes the speed as high as it can within that constraint. If the line is detected as being unstable the DLM (Dynamic Line Management) can turn on interleaving and ratchet up the SNR margin target to 9, 12 and 15 dB.
In the survey, 22% of respondents had interleaving on their line, 40% were still on Fast Path and 38% didn't know. If the "don't knows" were split along the same lines as those that do know then perhaps 35% of lines have been unstable enough to warrant application of interleaving.
45% of respondents had an SNR margin in the 6-10 dB range, 11% were below that and 16% didn't know.
24% fell into the 11-15 dB bracket and 5% were over 15 dB. 75% of the >15 dB group had speeds of 6M or higher, suggesting that these are the very short lines iwth margin to spare at high sync speeds.
In the survey, 22% of respondents had interleaving on their line, 40% were still on Fast Path and 38% didn't know. If the "don't knows" were split along the same lines as those that do know then perhaps 35% of lines have been unstable enough to warrant application of interleaving.
45% of respondents had an SNR margin in the 6-10 dB range, 11% were below that and 16% didn't know.
24% fell into the 11-15 dB bracket and 5% were over 15 dB. 75% of the >15 dB group had speeds of 6M or higher, suggesting that these are the very short lines iwth margin to spare at high sync speeds.
posted by PhilT at 3:53 PM
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