WH1080 data decription

[steve]

which suggests as if the station logs both the latest value, but also an average, but that would contradict what you wrote about how the station works with the data it has in its temporary memory and how it overwrites them.

How does that contradict what I said? I said:

"Fine Offset stations measure wind over 48-second intervals, divided into 24 2-second intervals. At the end of each 48-second period, they report the highest of those 24 values as 'Gust', and the average of those 24 values as 'Wind'. The logged values are the latest values of those two measurements at the time the entry is logged."

So as I said, the station logs the gust value and the average value. And as in the FAQ, those are the values that Cumulus calls 'latest' and 'average' respectively.

[jachym]

OK, sorry I am completely confused now. In the cumulus log I have three values for wind:
- wind (I assume this is the average speed)
- gust
- latestgust
These values are sent to the station every 48s. The station only saves the data every 5 minutes. My question then is, what is the difference between these. I thought that wind = average over 48s, gust = highest of those 24 values averaged, but what is the latest gust then? Just the last of those 24 values the sensor received?

[steve]

I don't know what those Cumulus log names are or where you're getting them from. I'll repeat it all again just once more.

The station measures wind over 48-second intervals, divided into 24 2-second intervals. At the end of each 48-second period, it reports - on the console - the highest of those 24 values as 'Gust', and the average of those 24 values as 'Wind'. At the same time the station also writes those two values into its memory, overwriting the previous values. So the station saves the data every 48 seconds, and if Cumulus is running, it reads those values so they don't get lost. If Cumulus isn't running, the overwritten values do get lost, until...

When the logger interval expires (e.g. every five minutes), the station moves on to the next memory location, so it leaves behind the last values that it wrote to the previous memory location. The last values that it wrote to the previous memory location then effectively become part of the logger or 'archive' data, which Cumulus can use later on if it needs to (i.e. if it isn't currently running).

When Cumulus reads the data from the station, it reads those two wind values from each logger location and:

The station 'Gust' value becomes the 'Latest' figure on the Cumulus main screen, and Cumulus writes the value into its logs in the 15th position (field 14 numbering from zero as in the wiki here: http://wiki.sandaysoft.com/a/Monthly_lo ... n_the_file).

The station 'Wind' value becomes the 'Average' figure on the Cumulus main screen, and Cumulus writes the value into its logs in the 6th position (field 5 numbering from zero as in the wiki). If you have told Cumulus to calculate a 10-minute average speed instead of using the station value directly, then obviously the displayed and logged values are the calculated values rather than the values read directly from the station.

Cumulus also maintains a third value which is the highest value over the previous 10 minutes of that first figure - the one the station calls 'Gust' and Cumulus calls 'Latest' - and it displays that on the main screen as 'Gust' and writes it into the logs in the 7th position (field 6 numbering from zero as in the wiki).