what are ideal power levels and snr
Just upgraded to 30M and got a fancy new Super Hub
are these adequate power levels/snr Downstream Channels Lock Status Modulation Channel ID Max Raw Bit Rate Frequency Power SNR Docsis/EuroDocsis locked Locked QAM256 58 55616000 Kbits/sec 307000000 Hz 8.5 dBmV 39.8 dB Hybrid Locked QAM256 56 55616000 Kbits/sec 291000000 Hz 9.1 dBmV 39.9 dB Hybrid Locked QAM256 57 55616000 Kbits/sec 299000000 Hz 8.7 dBmV 40.2 dB Hybrid Locked QAM256 59 55616000 Kbits/sec 315000000 Hz 8.4 dBmV 39.9 dB Hybrid Locked QAM256 60 55616000 Kbits/sec 323000000 Hz 9.3 dBmV 40.5 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 50 20480 Kbits/sec 35800000 Hz 37.0 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 |
Re: what are ideal power levels and snr
There is a sticky post in here...but here is the info from there.
Downstream * Knowsley networks using QAM64 are: -7 to +3 dBmV. * Knowsley networks using QAM256 are: -3 to +7 dBmV. * Langley & Bromley networks using QAM64 are: -10 to 0 dBmV. * Langley & Bromley networks using QAM256 are: -4 to +6 dBmV. Upstream * Upstream signal levels (from the modem) should be between 34 and 55dBmV. So you downstreams are a bit high. |
Re: what are ideal power levels and snr
It depends who you ask, people get number stuck in their head, if it works, don't mess with it.
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Re: what are ideal power levels and snr
Is it all going well?
Strictly speaking your downstream power levels are a bit high. Most usually, these levels work perfectly well but the "fancy" SuperHub needs not to mind being higher than +7 dBmv. The VM Techs won'r raise an eyebrow unless it's over 10. The one thing I did notice is that your street cabinet amplifier seems to be incorrectly sloped. The higher frequencies should show attenuated power and they don't. It might not matter in your case, but amplifiers should be correctly sloped as a matter of principle. Your upstream levels are OK. |
Re: what are ideal power levels and snr
I have one of them forward path attenuator 10dB - will this help get the the readings down on the downstream.
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Re: what are ideal power levels and snr
The FPA will get the downstream levels down to -1 or -2.
Are you having problems and if so what? Does the event log record errors or critical events other than at the time of reboting the modem? Is the SuperHub resetting all the time? If so are you working wirelessly which is badly imlemented in the SH? |
Re: what are ideal power levels and snr
Quote:
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Re: what are ideal power levels and snr
if it aint broken dont fix it
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Re: what are ideal power levels and snr
As per Mon General's post. Stick it on if power rises to 11 dBmv or higher and let us know. That level is unhealthy because when you have 8 downstream channels, that would hit the DOCSIS 3 input maximum for a cable modem.
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Re: what are ideal power levels and snr
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Re: what are ideal power levels and snr
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When 8 channels arrive, the lower frequency channels should have a higher power level than the higher frequency channels. Attenuation at higher frequencies riser faster with distance than lower frequencies. So you may see a c. 2 dBmv gap between the highest and lowest power levels. Nothing to worry about. The SNR isn't affected by the number of channels.
Have a read of the attached document. It explains how 11 dBmv on each channel can bust the modem; -1 dBmv won't bust it. |
Re: what are ideal power levels and snr
Thanks Seph. :)
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Re: what are ideal power levels and snr
I have just added a forward path attenuator - these are my readings now
Downstream Channels Lock Status Modulation Channel ID Max Raw Bit Rate Frequency Power SNR Docsis/EuroDocsis locked Locked QAM256 58 55616000 Kbits/sec 307000000 Hz -0.4 dBmV 37.0 dB Hybrid Locked QAM256 56 55616000 Kbits/sec 291000000 Hz 0.0 dBmV 37.2 dB Hybrid Locked QAM256 57 55616000 Kbits/sec 299000000 Hz -0.1 dBmV 37.1 dB Hybrid Locked QAM256 59 55616000 Kbits/sec 315000000 Hz -0.5 dBmV 37.0 dB Hybrid Locked QAM256 60 55616000 Kbits/sec 323000000 Hz 43.7 dBmV 39.5 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 50 20480 Kbits/sec 35800000 Hz 36.5 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 |
Re: what are ideal power levels and snr
Better, keep it on
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Re: what are ideal power levels and snr
you need a reboot to fix the power on that 5th channel
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