New KAIRA pages

Some of you will no doubt have noticed, but we now have some new pages linked directly through the web log. Above the web log text, you'll see links to general information about the project and also the technical specifications.

The technical specifications list the capabilities of the instrument... very useful for scientists who are thinking of making use of our facility!

KAIRA as a multi-frequency riometer

Photo: Carl-Fredrik Enell

"My name is Malefia Sinor, I’m a student in Lappeenranta University of Technology, in where I am doing a masters thesis in collaboration with Sodankylä Geophysical Observatory. My topic is to search for a parameterized model for the D-region electron density to be used in a multi-frequency riometer data analysis.

"Riometer (relative ionospheric opacity meter) is an instrument used to measure the cosmic HF radio noise absorption that is taking place in the D-region ionosphere (50-90 km). Traditionally, riometers measure the cosmic radio noise only at one or two single frequencies, typically around 40 MHz. Depending on the amount of ionization, the radio signal is absorbed when it passes through the ionosphere. The ionosphere is the partially ionized region of the Earth’s upper atmosphere. It extends from about 60 km to 1000 km. The absorption takes place mainly in the lowest part of the ionosphere, due to collisions between the free electrons and neutral particles.

"KAIRA instrument turns out to be a unique riometer, because of its capability to measure a wide range of different HF frequencies in multiple narrow beams. The multi-frequency capability is the one which makes it possible to invert the electron density since the height profile of the refractive index of the plasma depends on the radio wave frequency for a given electron density profile.

"To share experience and to get an idea about my work, I traveled to Sodankylä. When I arrived, the weather was -20oC (or more), which is for me very cold, I never imagined this kind of weather and I almost couldn’t survive from it for the first time, but peoples at SGO were very helpful. For the last week, I have had an opportunity to attend to the Finnish EISCAT campaign in Tromsø, Norway. After we drove for several hours from Sodankylä to Tromsø, we finally arrived to the EISCAT site. It was ecstatic to see the control room and the receiver when the radar equipments were introduced to us. I’m enjoying my stay on the site, seeing the magical white mountains and the sparkle of the northern lights, and gaining experience of the space physics research in practise."

Winter's day

Today's photograph shows the best light levels that you can expect at this time of year.

The KAIRA site. (Photo: D. McKay-Bukowski)

Signs of winter

Just a nice photograph to finish the week. This one is of the sign as you head past the custom station. In the distance is Saana Mountain.

The sign to Kilpisjärvi. (Photo: D. McKay-Bukowski)

Have a nice weekend!

Snow trench

Another photograph of the snow conditions on the site. This one is the path we manually dug through the snow to get to the RF-container and Barracks. At the time this photograph was taken (a couple of weeks ago now), the trench was about 70cm deep. No doubt this will fill up again very quickly.

Snow trench at KAIRA (Photo: D. McKay-Bukowski)

Kaira Local Pipeline

Today we decided to release the code for our local processing pipeline that we have been working on. We didn't have time to invent a fancy name for it, so just decided to call it the KAIRA Local Pipeline (KLP). You can download it from here: http://www.sgo.fi/~j/klp-1.0.tar.gz. The 1.0 release contains three simple processors: file recorder (to store beamlet data on disk), average power recorder (for e.g., interplanetary scintillation measurements), and a null processor that does nothing (for performance testing the udp packet processing).

While there already exists at least one program (PELICAN) with similar capabilities, we wanted a program that is very simple and allows users get going without learning how to use a larger framework. If you need a sophisticated highly configurable object oriented framework for processing LOFAR data, you should probably be considering PELICAN. If you want something simple and ANSI C based, with minimal supporting utilities and configuration files, you might want to check out KLP.

The hardware needed to run KLP is the similar to what one would have for running ARTERMIS (the pulsar processing pipeline developed at Oxford) or any other local processing pipeline on a LOFAR station. At KAIRA we currently only have one Linux PC with a quad gigabit ethernet interface. This quad gigabit ethernet is connected to the four data lanes coming out of the four RSPs that output the beamformed beamlets. For our current purposes, one machine is enough, but in the future, it would also be possible to install KLP on a Linux cluster and use, e.g., MPI for interprocess communication.

Two possible hardware configurations to run the LOFAR local processing. 

As already said, the software architecture is very simple. There is one process for each lane and there are two threads that work in parallel on the incoming data. The first thread reads the udp packets coming in from the LOFAR RSP, parses them and puts them into a double buffer. Another thread waits for the double buffer to flip and once this happens, it then calls the klp_proc() function that processes the contents of the buffer. All of the underlying threading and synchronization is hidden away from the user, who only has to implement klp_proc().

The software architecture detailing all of the inner workings of KLP. The way to implement your own processing is to define klp_proc() and klp_init() and link it with klp_core.c.  

Mounting snow

Snow levels at KAIRA continue to deepen. Additionally, there is significant drifting in places, which results in raised mounds of it. So far, the arrays are holding up well. There is uniform distribution on the LBA ground planes and snow on tope of HBA tiles is barely exceeding 5 cm due to natural clearing by the wind sheer.

Snow build-up between the LBA mausoleum and the HBA array. (Photo: D. McKay-Bukowski)