Cumulus Support

It hadn't occurred to me before as I set it to the normal 8 points that Fine Offset WH1081 had, but does a Ecowitt HP2551 have 16 points?

I may be wrong here but doesn't CumulusMX determine the number of compass points? I have an Ecowitt station with an HP2551 and CMX certainly logs the wind bearing (in degrees and compass points with 16 'points'). I'm pretty sure that Cumulus does the bearing to compass points - in any event my HP2551 also displays 16 points for the wind (currently showing WNW 287 degrees).

Just turned data logging on and the data sent to CMX has current wind direction in degrees and average wind direction also in degrees with no compass points; so CMX must be calculating the 16 points!

Hi,

Yes, Ecowitt reports the wind direction in Degrees but I don't (yet) know what data format is transmitted over the wireless protocol (at 868 MHz) and haven't seen the resolution, let alone accuracy, specified anywhere. The old Fine Offset (WH108x, etc.) Vanes actually had 8 magnetic sensors (reeds) for the 8 primary directions (see post #2 here, but allowed an "overlap" with two adjacent reeds operating to report 16 potential directions (in a 4-bit data field). However, the "Off The Shelf" vanes gave very little overlap (but could be improved) so it was generally better to display 8 directions within Cumulus. Incidentally some overlap of the reed operations is arguably "necessary", because if not then tolerances may cause NO reeds to operate and you have no direction reported at all.

AFAIK, Cumulus works in "degrees" (and perhaps to about ten decimal places ) but for the "Wind Rose" it needs to put each measurement into a "bin" (bucket) to store accumulated values, where 8 and 16 are "sensible" numbers. With a modern computer/program almost any number of bins/points might be used, but I suspect that most users are still interested in values based on the Points of the Compass, power of 2 divisors, i.e. 8 , 16 , 32 and 64 ..?

Cheers, Alan.