Recent Downstream Band Plan Changes

[Bald_Eagle1]

I noticed that my downstream band plan changed 24th May from a max of 3939 DS available tone to 3959 available tone.

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# xdslcmd info --pbParams
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 2
Max: Upstream rate = 4828 Kbps, Downstream rate = 33676 Kbps
Path: 0, Upstream rate = 4785 Kbps, Downstream rate = 28568 Kbps

Discovery Phase (Initial) Band Plan
US: (0,95) (868,1207) (1972,2783)
DS: (32,859) (1216,1963) (2792,3959)
Medley Phase (Final) Band Plan
US: (0,95) (868,1207)
DS: (32,859) (1216,1963)
       VDSL Port Details       Upstream        Downstream
Attainable Net Data Rate:       4828 kbps         33676 kbps
Actual Aggregate Tx Power:        6.3 dBm          12.5 dBm
============================================================================
  VDSL Band Status        U0      U1      U2      U3      D1      D2      D3
  Line Attenuation(dB): 8.4 55.1 80.9   N/A 21.9 64.8 0.1
Signal Attenuation(dB): 9.6 54.3   N/A   N/A 21.9 64.8   N/A
        SNR Margin(dB): 6.3 6.1   N/A   N/A 6.3 6.4   N/A
         TX Power(dBm): -4.2 5.8   N/A   N/A 11.4 6.0   N/A





Some users noticed this change in early April, so it seems to be yet another unannounced phased change by BT.

As my bit-loading cuts off at around tone 1750 anyway (on a good day), these additional tones are no use to me as their frequencies are too high for my connection to use due to attenuation levels.

I also notice that my Upstream Line Attenuation (U2) increased by around 20dB at exactly the same time.
It had been around 60dB since I started logging my stats last October/November.

Again these tones are unuseable for me due to their higher frequencies.

The net effect though is that both my DS & US sync rates have taken a hit since the changes.

Has anyone else noticed this, especially increased attenuation?


EDIT: My connection was "fixed" 26th May by an engineer replacing the VDSL2 faceplate (cured dropping connections while the phone was used) & repaired the underground cable to DP connection (a bit of wire fell off in his hand when he went up the pole to check it. This appears to have also cured the frequent general disconnections).

The band plans mentioned above only apply to users connected to Huawei DSLAMS.
Users connected to ECI DSLAMS have slightly different band plans anyway.

I only noticed the increased band plan & increased attenuation the other day, while trying to work out why my speeds have lowered even though my connection has been "fixed".

I will be releasing updated scripts soon, that will include the additional graphs as per my "Full_Monty" attachment.