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Record glitch

Discussion specific to Fine Offset and similar rebadged weather stations
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steve
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Posts: 26702
Joined: Mon 02 Jun 2008 6:49 pm
Weather Station: None
Operating System: None
Location: Vienne, France
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Re: Record glitch

Post by steve »

I had problems with my VP2 not long after I bought it. First, the temperature sensor - not spikes, it would just start rising until it was showing about 10C above the actual temperature, then a few hours later would come back down again to reality. Then the anemometer stopped giving speed data.

I got a meter out and determined that the anemometer was sending data, so Davis swapped the ISS board and the temperature sensor, and it's all been fine ever since.

Steve
Steve
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GeniSim
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Joined: Sun 10 Aug 2008 11:52 am
Weather Station: National Geographic 265NC
Location: Jonquiere Quebec Canada
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Re: Record glitch

Post by GeniSim »

Hi,

Glitchs elimination is an important aspect of Cumulus fonction as glitchs do accure on a continious basic due to the weak USB communication protocole between the station and the computer.

Glitchs look obvious to us when we look at a graph, but one needs a numerical scheme to eliminate them automatically using a software like Cumulus. I would propose the following numerical scheme:

1) compute the mean and standard deviation of the last 10 readings

2) compute the acceptable range for the new reading as: mean value - 3 time the standard deviation to mean value + 3 time the standard deviation

3) reject the new reading if it is outside that range

This logic should work for any slow evolving variables like the pression and the temperature regardless of the unit used. It would not work for fast evolving variable like the wind speed and the rain fall rate unfortunately.

Marc
Marc

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