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Most cable modems are incapable of transmitting higher than 51 dBmV (upstream power). For example, I've read the specifications sheets for the Arris SB6183, SB6190 and TM822. They all have a maximum upstream power of 51 dBmV.
- Should I Use a Cable Amplifier
To summarize, there are some situations where a quality...
- Should I Use a Cable Amplifier
5 Δεκ 2018 · 0 dBmV is said to be ideal (a reference point). -15 dBmV is not really great (and should be avoided) and breaks more easily when noise is present. Your -12 dBmV is not a great value, but your...
As for levels being different for different brands or models, for the most part, no. They are all based on what is called DOCSIS which is a standard across all modems/gateways. DOCSIS 3.1 added some things like OFDM to DOCSIS 3.0 and I think changed SNR to MER but those are small things.
Although it possible to estimate a DOCSIS 3.1 cable modems transmit power, it would be quite difficult to do so in a live HFC network. It is more important to focus on ensuring cable modems are transmitting in an optimal range, typically between 40-47 dBmV, assuming four or more DOCSIS channels.
You can use the values below as a guideline as to what good "signal levels" are. Downstream Power (-15dBmV to +15dBmV) - measure of the signal level received by the cable modem. Most modems are rated from -15dB to +15dB, however it's best to have it between +8dB and -8dB.
Downstream looks good. SNR is good. You want downstream power to come in as close to 0 as possible, but anything plus or minus 12dB tends to work. The upstream power is pretty high; your cable modem has to scream pretty hard to be heard by the CMTS and is probably nearly maxed out.
Ideal levels are approximately 40 to 50 dBmV for single channels, 37 to 48 dBmV each for 2 to 4 channels. The Signal to Noise Ratios should also all be within three dB of each other. However, for power level -15 to -6 dBmV the SNR should be 33 dB or higher and for -6 to +15 dBmV the SNR should be 30 dB or higher.
