WH1080 data decription

[jachym]

Hi,
I am sorry maybe this is a stupid question and Ive tried to find the answer here, but wasnt successful.
I own a WH1080 station and I have set the data logging interval to 5 min. What I would like to know is the following:
- what actually is the wind speed and wind gust? In the manual I only found that the data from the sensor are sent every 48s. So does this mean the wind speed is the average speed from those approximately 5-6 measurements received in those 5min? Or is it just simply the current speed value it received at the time of logging the values? And what exactly is then the windgust, is it the highest of the received values in those 5 min?
- my next question then is concering the maxima and minima. The station itself saves these values in the memory, but does it also transfer these into cumulus? What I mean is, does the maximum value in cumulus for example corresponds simply to the maximum value from the measured logged data or is it the maximum value from the station? It probably sounds confusing, but lets say the station logs data at 0:05, 0:10, 0:15,... then if lets say there is a maximum at 0:13, but before it is logged at 0:15, the temp decreases again, what would then be the maximum value in cumulus records? Simply the maximum from values measured at 0:05, 0:10,... or would it be the actual maximum?

If anyone knows the answer to any of my questions I would very much appreciate it. Thanx

[steve]

I own a WH1080 station and I have set the data logging interval to 5 min. What I would like to know is the following:
- what actually is the wind speed and wind gust? In the manual I only found that the data from the sensor are sent every 48s. So does this mean the wind speed is the average speed from those approximately 5-6 measurements received in those 5min? Or is it just simply the current speed value it received at the time of logging the values? And what exactly is then the windgust, is it the highest of the received values in those 5 min?

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. The station keeps writing the current values to the same area of memory every 48 seconds, until the logging interval comes around, then it moves on to the next memory location, leaving the last values it wrote as the logger data.

my next question then is concering the maxima and minima. The station itself saves these values in the memory, but does it also transfer these into cumulus? What I mean is, does the maximum value in cumulus for example corresponds simply to the maximum value from the measured logged data or is it the maximum value from the station?

Cumulus doesn't use the maximum and minimum values from the station, it maintains its own based on the 48-second updates from the station (or from the values in the logger if it's catching up using logger data when it starts up having not run for a while).

[pol]

And what is correct to use for speed calculation?
the use "speed" for avg calculation or leave it as it is?

[steve]

It's perhaps more logical to use the station's speed for the average calculation. Some people get better results using the gust, even though that seems not to make sense on the face of it.

[jachym]

Ok, thanks for your replies, well thats not ideal, because it means lot of the wind data (basically 4/5) are lost.... is there any way of tweaking this and making the station to report the average over 5min apart from setting the logging interval to 1 min?

[steve]

well thats not ideal, because it means lot of the wind data (basically 4/5) are lost

They're not lost, Cumulus reads all of the 48-second values and uses them.

.... is there any way of tweaking this and making the station to report the average over 5min apart from setting the logging interval to 1 min?

You can't change the way the station works. But you can make Cumulus calculate a 5-minute average instead of its default 10-minute average, if you want. But it's not clear what you think the problem is and what you're trying to achieve.

[jachym]

OK, sorry Steve, I forgot to mention one thing.... I do not have my station connected to a nonstop running server/PC, meaning I upload the data into Cumulus every few days from the station memory and do not use the online feature.

[steve]

In that case you're limiting yourself to the values calculated by the station, and yes, I agree, most of the wind data is effectively lost unless you set the station to a 1-minute logging interval. That would give you a capacity of 68 hours.

[jachym]

Thanks very much for your information.

Just a question then, I have already been considering buying some kind of a router which would be able to get the data and send it over wi-fi to a server. Is there any particular one you would recommend or one that you know works fine? The problem is that i am from the Czech republic and I have found some, but they always come as a complete set including the station and all the sensors and thus are much more expensive and I dont actually need a new station or sensors. I just want "something" that would collect the data and send it ideally over FTP to my server, I have set up a MySQL database and have several PHP pages which analyze and visualize the data, but currently I always add the data into the db manually. So basically just some tips for what exactly I need to make my station "online" and able to send data to mySQL. Im sure some of the models can be bought here as well or I could order it over eBay.

[jachym]

or maybe, just thinking about it, sometimes we have a problem with the internet, for example the router we have at home freezes and needs a restart and I do that when I come home in the evening, so ideally something that also saves the data in case there is no internet connection. And if nothing like that exists, maybe if there is just something that would extend the memory, some kind of a logger which would log all the 48s data - Im thinking there could be just some kind of a disk that would connect to the station USB and get the data.

[steve]

Perhaps something like Meteobridge is what you need. But I know next to nothing about it. I just support Cumulus here

[jachym]

Thats ok, Im definetely not against using Cumulus, i actually use it even now, just that I download the data manually once in a while and I set up the MySQL because I wanted more customization possibilities, but that is not to say I dont want to use Cumulus, I use it even now.

[jachym]

Hi Steve, sorry to bother you again, but I noticed a very strange thing.
I use the phpImport script to create a MySQL database. And in that database Ive always used the Windgust column to determine the windgust. Based on what you have written yesterday, it made sense - if I only save the data once every 5min, then since the sensors send every 48s, I always get just the latest measurement, because the RAM memory can only hold one series of data. Now that all made sense, but.... I now noticed there is one more column called LatestWindgust, and this one also contains numbers, which are lower or equal to windgust - from this it suddenly seems to me as if the Windgust value really was an average of all the measured data and the Latestwindgust the latest value, which I assumed would be the only one measured. Could you just please make it clear to me, what exactly is the Latestwindgust? Because technically it would seem logical as you described it yesterday, that if the station only saves every 5min, then i would always get just the latest value, but why is it then different from the Windgust value. Thx.

[steve]

I don't know anything about the script you're using, but the value which Cumulus calls 'Latest' and logs as the 15th field in the monthly log files is the 'gust' value from the station. See the FAQ - http://wiki.sandaysoft.com/a/FAQ#What_d ... tations.3F

[jachym]

Well what I mean is that when I use the standard importing PHP script from this site, it creates a MySQL table, which contains two columns regarding windgust, one called windgust, the other one Latestwindgust. Then for each 5min data I have a value for both and the windgust is either higher or same, 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.