Erratic readings peaks and troughs

[Grenville]

Will someone please look at the screenshots and explain simply why I get a graph with so many spikes and troughs.

Thanks
John

[ejay]

When Cumulus is running, the graphs are drawn with a 'live' sample rate. If you restart Cumulus, it will force the graphs to be re-drawn and will appear to be 'smoother' - but only because the live data has been discarded and Cumulus is only relying on saved data which is sampled at a less frequent interval.

By default, the samples are stored at a 10-minute interval. If you set the (Cumulus) intervals to be one or two minutes, you will always see the graph drawn with many fine spikes and troughs whenever it is running.

It also depends on the data logger interval on the Fine Offset station. If you don't leave cumulus running all the time, it will rely on the data logger in the station for catching up on missed data next time you run it, and if this is set to 10 or 30 minutes (FO default), your graphs will look a lot more sparse.

Edit: By the looks of your graphs, you turn your PC off last thing at night (from around 21:30) and turn it back on first thing in the morning (from approx 06:30).

[Grenville]

Good Morning Australia............Thank you Ejay for the explanation. I will try to understand what you have said. Yes you are right, I do normally shut down the PC around 9.30 pm. Mainly to save mobile data used. (I am on a dongle with limited mega bits a month)

Thanks again

[ejay]

Attached is a screenshot of the outside temperature graph.
My computer has been off for the past 20 hours. It has been on and running cumulus for the past four hours. You can see the 'fuzzyness' in the Apparent Temperature plot. If you look carefully, you can see the other plots have a more bumpy appearance. But this is due to a higher sample rate (48 seconds for FO stations). All the other plots prior to 18:00 are at 10 minute intervals (6 per hour).

cum_graph_outsidetemp_2012-05-14.png

After a quick restart of Cumulus, here's what I get:

cum_graph_outsidetemp_2012-05-14_restart.png

Notice how the Apparent Temperature plot has lost its fuzzyness. That's because most of the instantaneous data has been discarded.

Hope this answers your question.

[Spider-Vice]

It's because you have the graph plotting set to one minute, so values update every 48 seconds and it varies every minute. Apparent temperature also depends on wind so it "spikes" a lot. Don't worry, it's legit.