The experiments comprise automated receiving systems for 150 and 400 MHz transmissions from NIMS (formerly known as NNSS) satellites that are used to determine the ionospheric electron content by means of the differential carrier phase method. Receivers are located at Ny-Ålesund, Longyearbyen, Bjørnøya and Tromsø. Measurements of electron content from the receiver network are inverted in a tomographic reconstruction algorithm to yield two-dimensional images of electron density over a wide region. The observations are used to investigate the dynamical processes responsible for the spatial structuring of the plasma distribution in the polar ionosphere. These tomographic images are complementary to measurements made using the EISCAT and EISCAT Svalbard radars and auroral optical instruments located on Svalbard.