120M : Power Levels Step Change

[XVar]

This is a question more out of curiosity than anything else, my connection's working perfectly fine and I'm still getting max speeds. About a month ago I was bored one weekend and set up Zabbix monitoring of the superhub stats using a Python script to scrape the data. Had a look at it just and noticed that 3 days ago my downstream power levels went from -2~ to +5~ over the space of 10 minutes. It also seems the the upper 4 of the 8 downstream channels are now in perfect sync whereas previously they all had different power levels:




Taking a closer look at "the event" shows that RxMER briefly shot up to around 50, the connection completely went for 15 minutes, and then came back with the higher power level and a 30 minutes wave of Post RS errors:





What would the likely cause of this be, maintenance of some sort? Like I said, no adverse effects that I've noticed just interested really.

[alanbjames]

Someone might have moved u to a different tap in the Cab maybe

[Skie]

Just out of interest, how are you collecting detailed power stats like that?

[XVar]

Originally Posted by Skie

Just out of interest, how are you collecting detailed power stats like that?

I modified a python script I found on GitHub and added a load more functionality to it, and then created a Zabbix template which polls the stats using the python script every 30 seconds. I've dumped the script and the zabbix template on GitHub here: https://github.com/ben-wallis/SuperHub/tree/master Basically the script just scrapes the HTML tables available under "Router Status" on the SH when you aren't logged in and returns the data. For example, to query Downstream Channel 10's Power Level:

[ben@daedalus zabbix]$ python /usr/sbin/SuperHubStats.py -i 192.168.100.1 -c 10 -g ds -s "Power Level (dBmV)"
4.48

I'll warn you though, if you've never used Zabbix before it's not exactly the most user-friendly of applications, I'm only familiar with it because I set ours up at work. The template also isn't particularly "release ready" as it has hard-coded channels in - I was planning to implement Discovery so that it can auto-find the available downstream and upstream channels but never got round to it.

It'll be a pretty useful diagnosis tool if I do ever have trouble with my connection though

[MUD_Wizard]

Whatever (maintenance) happened, it's an improvement.

[mmm]

7dB delta is big - did the channel frequencies also change? I noticed a step down when the allocated frequencies went up. Guess it's not a SH3, I'd like to know about Errors ... manually monitoring...

[XVar]

Originally Posted by mmm

7dB delta is big - did the channel frequencies also change? I noticed a step down when the allocated frequencies went up. Guess it's not a SH3, I'd like to know about Errors ... manually monitoring...

I've not been logging frequency data as I didn't know it was liable to change - I've started now though. And nope it's an SH2. As an aside, there was another change yesterday, a drop of 1dB across all channels.

[Kushan]

How are you automating your monitoring?

[MUD_Wizard]

Bear in mind that temperature variations will affect power levels. Around a 1 dBmV change is nothing significant. You see changes up to 3 dBmV between winter and summer.

Originally Posted by alanbjames

Someone might have moved u to a different tap in the Cab maybe

A different tap won't improve his RxMER / SNR.

[XVar]

Originally Posted by Kushan

How are you automating your monitoring?

Read about 4 posts up

[Kushan]

Originally Posted by XVar

Read about 4 posts up

Oops! Missed that. I have used Zabbix before at work as well though, so that's neat.