Thanks for replying. Your comments are interesting.
First of all, may I ask what Upstream Power Backoff entails? I've never heard of that term before.
You say that, in your own case, your stats show an upstream power output level of even less than my 2.9dB. So, what level do you yourself have for that, then?
I'd agree that the particular modem used can influence the figure, because I've just changed (supposedly upgraded) from one particular Billion VDSL modem-router to a more-advanced Billion modem router, and have seen the upstream output power drop from 5.1dBm on the former modem-router to 2.9dBm on the new one.
If I remember correctly my electronics from 50 years ago, relative power (in dB's) is:
10 x log-to-base-10 of actual watts/1 watt (or actual milliwatts/1 milliwatt)
So, log-to-base-10 of actual watts = 0.29
Therefore (looking up the antilog on a table published on the Web), actual watts = 1.95 approximately.
Does that look right? These days I can barely recall how to use logs, but I think the above is correct.
In this situation we'd be working in milliwatts, rather than watts, so the actual wattage, over a metre, is 1.95 mW.
Edited by meditator (Thu 13-Dec-18 16:41:51)