It was a hurricane-force storm!

In order to analyse the causes of damages at KAIRA, we need to see the wind directions and wind speeds during the storm. Here are the FMI 10 minute averages from the Kilpisjärvi village and Saana top. It was indeed a hurricane-force storm in the Beaufort scale!

LBA aerial problems

Along similar lines to yesterday's web log report, we've also carried out tests for all the aerials of the Low-Band Array (LBA). Here, we also have problems, although the situation is more complicated. Like yesterday, we shall start with a plot of all subbands for all RCUs configured for the LBA aerials.

As can be seen, there are a number which show abnormalities. Most of these are suppressed signals, sometimes causing a shift in the peak amplifier response frequency. This is likely to be caused by snow, as seen in one of our previous reports.

However, the effect on RCUs 68 and 69 is more serious. This looks like a destroyed aerial.

If we plot these onto a map of the array, the positions of the affected aerials are as follows:

One thing to note is that the signal processing chains can be cleared of any faults. The problem with the HBA was on RCUs 80 and 81, but this was absolutely fine for the LBA. The same applies the other way; for example, RCUs 68 and 69 are down here, but were okay on the HBA.

What needs to be done now is to evaluate the situation, especially with aerial #34.

KAIRA Gale Damage

We report the damages at KAIRA site due to the high winds during the weekend. HBA tile 75 is destroyed! Damages are self-explained by photographs!

HBA tile #75 flat-lining

Following the high winds of 08-Mar-2013, we carried out a series of remote system tests to verify that KAIRA is still okay and functioning correctly. The best way to do this is to examine the spectrum of every antenna for each polarisation. These are processed by the Receiver Units (RCUs) and there is one for each antenna/polarisation.

The first test we did was for the High-Band Array (HBA). The following is the collected set of spectra for the entire HBA. We expect a broad "Saana-shape" spectrum with occasional vertical spikes of radio-frequency interference (RFI).

As can be seen, there are a couple of weak channels which show non-typical spectra. The RCUs are 80 and 81, which correspond to tile #75 X-polarisation and Y-polarisation. This indicates that there is a problem with the entire tile, and further investigation is needed. Here is the location of the tile in the array:

Given that this is the leading edge against the northwest gales that we have had makes us very nervous.

An expedition to the site will be required.

High winds at KAIRA

Last night we had some pretty extreme weather at KAIRA. In Kilpisjärvi the highest average wind speed was 38.7 m/s on Saana and around 25 m/s in the village. The record on Saana was 44.3 m/s! Fortunately, there are heavy snow depth conditions on the site, meaning that the antennas should mostly be weighed down and, thus, safer.

The weather page from www.fmi.fi .
Note the wind-graph at the bottom.

And despite the wind, it is still mostly cloudy.  :-P

Reindeer jerky

It is the season to prepare a Lappish delicacy, air-dried reindeer meat. Yesterday I bought 5 kg reindeer hearts (yep, the inner organs) and put them to a salty water for one day (salt percentage around 6). After that I let the meat pieces hang in the spring weather for 2-3 weeks. The best weather for drying meat is when we have some plus degrees during the daytime with sunshine and some minus degrees during the nights! This variation of the temperature "pumps" the liquids out the meat and hence we get air-dried reindeer meat. In addition, dry windy weather helps!

2-3 weeks and nam nam !!!

EISCAT UHF in hipster style

All right, it's Friday and time for weekend activities. We call the week by a photoshopped version of the EISCAT UHF antenna (by A. Kero). Have a nice weekend!