mi sono basato su questo:
dai sorgenti dei driver/api del chipset, in particolare dal file drv_dsl_cpe_api_g997.h
Downstream/Upstream Line Attenuation (see chapter 7.5.1.9/7.5.1.10 of G.997.1).
This parameter is an integral ("per direction") value over the complete
spectrum. It is the squared magnitude of the channel characteristics function
H(f) averaged and measured during loop diagnostic mode and initialization.
The exact definition is included in the relevant xDSL ITU-T Recommendation.
The line attenuation ranges from 0 (0) to +127 dB (1270) with 0.1 dB steps.
A special value (1271) indicates the line attenuation is out of range to be
represented.
Downstream/Upstream Signal Attenuation (see chapter 7.5.1.11/7.5.1.12 of G.997.1).
This parameter is an integral ("per direction") value over the complete
spectrum. It is the measured difference between the total power transmitted
by the xTU-C and the total power received by the xTU-R during loop diagnostic
mode, initialization and showtime. The exact definition is included in the
relevant DSL ITU-T Recommendation.
The line attenuation ranges from 0 (0) to +127 dB (1279) with 0.1 dB steps.
A special value (1271) indicates that the line attenuation is out of range to
be represented.
Downstream/Upstream Signal-to-Noise Ratio Margin (see chapter 7.5.1.13/7.5.1.16
of G.997.1).
This parameter is an integral ("per direction") value over the complete
spectrum. The signal-to-noise ratio margin is the maximum increase in dB of
the noise power received at the xTU-R, such that the BER requirements are met
for all bearer channels.
The SNR margin ranges from -64 dB (640) to +63 dB (630) with 0.1 dB steps. A
special value (-641) indicates that the parameter is out of range to be
represented.
segnalo anche il riferimento alle 5+5 bande, dal pdf ITU-T G.993.2