Wind speed offset of .7 mph - Fine Offset (ambient ws-2080)

[skeezaroonie]

This is a fairly new set-up, running the Ambient Weather WS-2080 with cumulus 1.9.0 (158) in a Win7 system. Everything runs great, or did until yesterday when the wind-speed indicator started indicating a wind speed of 0.7 mph in the "latest" window in dead calm air. It shows the average speed correctly as dead calm - 0.0 though. Also it seems to read moving air okay although I suppose with that same 0.7 mph offset. I am guessing it will take a cold reboot (batteries out of both sensor and main unit) to clear this error, or is there something else I should be looking at or reconfiguring to reset this offset? And does a batteries out reboot reset all the configuration right back to factory defaults so that I'll have to reconfigure all my station and internet settings? Any suggestions will be appreciated.

[steve]

Is it just Cumulus which is showing a reading when it's calm, or the console too (the 'gust' figure on the console)? Are you using any 'calibration' or 'spike removal' settings? Do you have the option set for Cumulus to calculate a 10-minute average?

[steve]

I looked at your wind speed graph on your web site and it seems reasonable; your gust figure is sometimes going to zero. Bear in mind that the 'latest' figure in Cumulus corresponds to the 'gust' on the console, so if the anemometer moved even slightly over a 48-second period, you could well get a 'gust' reading even though the average was effectively zero.

[Gina]

0.7 mph represents just one pulse from the anemometer so an invisibly small movement can cause this.

My experiments with the anemometer have shown that the rotor is prone to stopping with the magnet above one end of the red switch due to the magnetic attraction. A minuscule breath of air can move the rotor very slightly (opening the switch) and the magnet attraction move it back (closing the switch) - you would not see any movement. I found this happen quite often with my test setup as I varied the air speed below that which caused rotation. It also occurred with the fan off if someone walked past the test rig and produced a slight draught. Gust of 0.7 mph or 0.35m/s and average of zero (I ran my tests using m/s as that's the inherent unit of speed).

[skeezaroonie]

Hey, Steve & Gina - many thanks to you both, your answers helped clarify my question a lot. i expect the behavior was just what you were describing, Gina, with the anemometer stopping on the reed switch trigger point. That's my best guess anyway. Was just puzzling to me because I hadn't seen that happen before. Last night when the wind stopped it was right back to reporting zero wind speed.

Sure is a neat little unit at a remarkable price and with the Cumulus software it really is a gem.