Davis anemometer wind direction odd

[freddie]

I think this is a hardware question rather than Cumulus - just fishing for similar experiences / advice.

I had a replacement Davis anemo setup installed towards the end of July. I have noticed today - thanks to the wind blowing from the correct quarter - that my anemo isn't recording wind direction between NW and N. If you have a look at my current direction trace at https://www.hosiene.co.uk/weather/trends.htm (select the wind direction button, then use the 6hr link to Zoom in, and click on the "Avg Bearing" link to hide the red average trace) you will see what I mean. I've been looking at the Davis console today and have not seen wind direction indicated from that direction either. Looking at the vane itself, it is moving freely in all directions. There is no shelter if the wind is blowing from NNW - my webcam (https://www.hosiene.co.uk/webcam/) faces NNW and you can see for yourself how open it is.

To me it seems like a hardware problem. Has anyone else experienced this?

[mcrossley]

Do you have a direction correction configured in the console?
The Davis anemometer has a dead spot around North, where only a few directions are reported (Davis squeeze 360 degrees into a single byte!).

[freddie]

Yes I do. I think it's about 5 degrees, but I will need to check.

[mcrossley]

The correction will move the "dead zone" around by a corresponding value

[freddie]

I checked my console, and it says the offset is 360. I did have about 5 degrees of offset at one time, but I must have removed it. I've never seen this behaviour in my 13 years of wind recording.

[mcrossley]

Sorry, but I only just looked at your graph. VERY ODD! It looks like faulty hardware to me. Either the wind vane or the ISS.