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k9sar
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DOCSIS 3.1 downstream power levels & QAM 4096

Hi all,

New to the Gig1 service which is working fine in terms of throughput etc.

Purely out of interest I notice that my 3.1 downstream does not stay on QAM 4096, seems to end up 2048 but have also seen it drop to 1024.

Wondered if there are any hints below that might suggest why this should be?

 

3.1 Downstream channels

Channel Channel Width (MHz) FFT Type Number of Active Subcarriers Modulation (Active Profile) First Active Subcarrier (Hz)

159964K1880QAM2048728



3.1 Downstream channels

Channel ID Lock Status RxMER Data (dB) PLC Power (dBmV) Correcteds (Active Profile) Uncorrectables (Active Profile)

159Locked425.2387401580

 

Mon 28/06/2021 00:02:076CM-STATUS message sent. Event Type Code: 24; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 2.;;CM-QOS=1.1;CM-VER=3.1;
Mon 28/06/2021 07:07:225MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1;CM-;CM-QOS=1.1;CM-VER=3.1;
Mon 28/06/2021 07:19:385DBC-REQ Mismatch Between Calculated Value for P1.6hi Compared to CCAP Provided Value;CM-;CM-QOS=1.1;CM-VER=3.1;
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lotharmat
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Re: DOCSIS 3.1 downstream power levels & QAM 4096

I think it *could* negatively impact your d/l speeds as it should be 4096 - alas I do not know enough about what could cause it to drop



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Andrew-G
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Re: DOCSIS 3.1 downstream power levels & QAM 4096

Modulation drops in response to unfavourable line conditions, usually a degree of noise.  As there's plenty of headroom on the D3.1 channel, dropping modulation may not make any difference to the speed or performance of the connection, and VM won't assign a technician unless there's a demonstrable performance fault.

 

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k9sar
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Re: DOCSIS 3.1 downstream power levels & QAM 4096

Might it be better if the downstream power level were 3dB lower?

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jem101
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Re: DOCSIS 3.1 downstream power levels & QAM 4096


@k9sar wrote:

Might it be better if the downstream power level were 3dB lower?


Not really, no.

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