Sodankylä AARDDVARK Receivers

The Sodankylä narrow-band VLF receivers are operated within the framework of the Antarctic-Arctic Radiation belt (Dynamic) Deposition - VLF Atmospheric Research Konsortia (AARDDVARK). The nearest neighbours of our receivers are the Ny Ålesund and the Cambridge UltraMSKs of British Antarctic Survey (BAS). In SGO's long-lasting collaboration with Lancaster University, U.K., SGO constructed one more receiver system located to UK. The AARDDVARK/UltraMSK database is maintained by BAS.

SGO UltraMSK Receivers 2007-

In 2007, SGO purchased two licences for the UltraMSK receiver software. Receiver aerials and the respective interface electronics were built at SGO's workshop. The new aerials are magnetic loops of 3 m × 3 m on wooden frames with 10 turns of coaxial cable each. One of the receivers is placed at SGO. The other receiver was first deployed at our measurement station of Pittiövaara for testing before it was moved to Kilpisjärvi, which is at the border to Norway, about 85 km from the EISCAT Ionospheric Heating facility.

The UltraMSK receives are able to monitor an arbitrary amount of transmitters, limited by the processing capacity of the receiver computer. In our case we are monitoring 11 stations simultaneously at the moment. These are DHO, GBP (GVT), HWU, ICV, ITI, JXN, NAA, NDK, NLK, NPM, NRK.

The UltraMSK data logger systems (samplers, industrial PCs and software) were upgraded in 2024-2025 using still same receiver instrumentation. The new software is capable to do continuous broadband recording parallel with transmitter bands.

SGO OmniPAL 2002-2013

A narrow-band VLF receiver was operated by SGO. The receiver was initially co-located with a VeloxNET synoptic VLF experiment at Perunkajärvi near Rovaniemi, Finland, but later it was moved to the main field station of SGO at Pittiövaara.

The receiver is an old "OmniPAL" (omnifarious phase and amplitude logger) system hacked to run on Linux (thanks to Janos Lichtenberger, ELTE). It was capable of recording amplitude and phase of up to six VLF transmitters at a maximum sampling rate of 10 Hz. Since installed at Pittiövaara, the receiver was operated at maximum sampling rate all the time, because the unix-type operating system. SGO Omnipal monitored the VLF transmitters with callsigns NLK, NDK, NAA, NRK, GBP (official GVT), and DHO (see figure for great-circle paths).

Observer in Charge:

Dr Thomas Ulich
Sodankylä Geophysical Observatory
Tähteläntie 62
FI-99600 Sodankylä
Finland
Phone: +358 294 480842
e-mail