Superhub : How do VM increase the upstream power level?

[SnoopZ]

I have been wondering for a while now, just how do VM increase the up stream power level if it is too low and is there anything i can do?

My upstream is currently 37.8 dBmV just above the minimum and upto 2 weeks ago it was a rock steady 44 dBmV, so although it is stable what can be done to increase it if needed?

Downstream Channels
Lock Status Modulation Channel ID Max Raw Bit Rate Frequency Power SNR Docsis/EuroDocsis locked
Locked QAM256 55 55616000 Kbits/sec 323000000 Hz -0.7 dBmV 36.0 dB Hybrid
Locked QAM256 49 55616000 Kbits/sec 291000000 Hz 0.4 dBmV 35.1 dB Hybrid
Locked QAM256 50 55616000 Kbits/sec 299000000 Hz 0.1 dBmV 35.3 dB Hybrid
Locked QAM256 53 55616000 Kbits/sec 307000000 Hz 0.4 dBmV 35.7 dB Hybrid
Locked QAM256 54 55616000 Kbits/sec 315000000 Hz -0.5 dBmV 35.4 dB Hybrid
Unlocked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV 0.0 dB Unknown
Unlocked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV 0.0 dB Unknown
Unlocked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV 0.0 dB Unknown
Upstream Channels
Lock Status Modulation Channel ID Max Raw Bit Rate Frequency Power
Locked ATDMA 2 20480 Kbits/sec 35800000 Hz 37.8 dBmV
Unlocked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
Unlocked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
Unlocked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
Primary Downstream Service Flow
Downstream(0)
SFID 5882
Max Traffic Rate 66000000 bps
Max Traffic Burst 3044 bytes
Mix Traffic Rate 0 bps
Primary Upstream Service Flow
Upstream(0)
SFID 5881
Max Traffic Rate 3072000 bps
Max Traffic Burst 8160 bytes
Mix Traffic Rate 0 bps
Max Concatenated Burst 8160 bytes
Scheduling Type Best Effort

[craigj2k12]

its changed at the cabinet, by moving your cable to a different tap, It probably changed because of either network maintenance, or someone else needed the tap you were on. Either way, as long as its in spec (which yours is) it doesnt matter

[SnoopZ]

I know i am already on the highest tap as i am far from the cabinet and my downstream was originally -11 dB so i guess something must have changed or my downstream would have got lower and i know the minimum is 35 dB.

[craigj2k12]

as you say it will be something else further down the line

[jb66]

you cant raise the upstream without lowering the downstream or lowering the downstream and removing forward path attenuators, a low upstream is usually a good thing

---------- Post added at 21:43 ---------- Previous post was at 21:41 ----------

Originally Posted by SnoopZ

I know i am already on the highest tap as i am far from the cabinet and my downstream was originally -11 dB so i guess something must have changed or my downstream would have got lower and i know the minimum is 35 dB.

the higher the tap the lower the upstream

[qasdfdsaq]

What he said.

Upstream power auto-adjusts to be as low as possible but still high enough to work. Low upstream power isn't really a bad thing, unless the transmitter/amplifier is working out of spec.

[SnoopZ]

Thanks for the info jb66 i had no idea a low upstream was a good thing.

[Sephiroth]

It's a good thing up to a point where noise injection power sort of swamps modem output power.

Fwiw, my 20 meg modem for years ran on 29 dBmv without problem; the street amplifier is < 80m cable distance away.

The upstream power level is commanded by the CMTS at the VM end. It commands the minumum power necessary (+ a small margi, I believe) for the CMTS to be able to make sense of what it is receiving from the modem. That can vary every 30 seconds or so depending on line conditions.

Other than that, it's what JB says; more attenuation at the street cabinet will raise the upstream power output by the same amount.

[SnoopZ]

Originally Posted by Sephiroth

It's a good thing up to a point where noise injection power sort of swamps modem output power.

Fwiw, my 20 meg modem for years ran on 29 dBmv without problem; the street amplifier is < 80m cable distance away.

The upstream power level is commanded by the CMTS at the VM end. It commands the minumum power necessary (+ a small margi, I believe) for the CMTS to be able to make sense of what it is receiving from the modem. That can vary every 30 seconds or so depending on line conditions.

Other than that, it's what JB says; more attenuation at the street cabinet will raise the upstream power output by the same amount.

In your opinion do you think all my levels are ok? I once suffered from a really low downstream power level but since a repull all my levels are like this and this is the best downstream i can get as i don't have any forward path attenuators on unless there is outside my property.

Unusually my SNR has increased 1/2 dB and my upstream had dropped 0.5 dB today as it was normally rock solid.

Downstream Channels
Lock Status Modulation Channel ID Max Raw Bit Rate Frequency Power SNR Docsis/EuroDocsis locked
Locked QAM256 55 55616000 Kbits/sec 323000000 Hz -1.1 dBmV 37.0 dB Hybrid
Locked QAM256 49 55616000 Kbits/sec 291000000 Hz 0.0 dBmV 36.2 dB Hybrid
Locked QAM256 50 55616000 Kbits/sec 299000000 Hz -0.2 dBmV 36.5 dB Hybrid
Locked QAM256 53 55616000 Kbits/sec 307000000 Hz 0.0 dBmV 36.8 dB Hybrid
Locked QAM256 54 55616000 Kbits/sec 315000000 Hz -0.8 dBmV 36.5 dB Hybrid
Unlocked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV 0.0 dB Unknown
Unlocked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV 0.0 dB Unknown
Unlocked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV 0.0 dB Unknown
Upstream Channels
Lock Status Modulation Channel ID Max Raw Bit Rate Frequency Power
Locked ATDMA 2 20480 Kbits/sec 35800000 Hz 37.3 dBmV
Unlocked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
Unlocked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
Unlocked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV

[Sephiroth]

Those levels are very good. Verging on perfect. There is wide tolerance on the levels and the upstream in particular needs to punt only what it takes to have the CMTS unerstand your transmissions.

[SnoopZ]

Originally Posted by Sephiroth

Those levels are very good. Verging on perfect. There is wide tolerance on the levels and the upstream in particular needs to punt only what it takes to have the CMTS unerstand your transmissions.

Thanks again for your help.

[jb66]

A long rg6 would show results like that, id be very happy with those stats