3-D extent of the main ionospheric trough - a case study

The EISCAT radar system has been used for the first time in a four-beam meridional mode. The FAST satellite and ALIS imaging system is used in conjunction to support the radar data, which was used to identify a main ionospheric trough. With this large latitude coverage the trough was passed in 21/2hours period. Its 3-dimensional structure is investigated and discussed. It is found that the shape is curved along the auroral oval, and that the trough is wider closer to the midnight sector. The position of the trough coincide rather well with various statistical models and this trough is found to be a typical one

Simulation of post-ADC digital beam-forming for large area radar receiver arrays

In order to provide instantaneous three-dimensional radar measurements spanning the entire vertical extent of the ionosphere, the planned EISCAT 3D incoherent scatter radar system includes multiple receive-only antenna arrays, situated at 90-280 km from the main transmit/receive site. These will employ band-pass sampling at ∼80 MHz, with the input signal spectrum contained in the 6th Nyqvist zone. This paper presents simulations and methods used to investigate use of a post-ADC fractional-sample-delay (FSD) system necessary to perform true time-delay beamforming. To test the feasibility and limitations of the system an extensive simulation tool has been developed. The simulation system is implemented in matlab to provide cross-platform compatibility and can be applied to any similar system. Performance degrading aspects such as noise, jitter, bandwidth and resolution can be included in the simulations. The use of FIR-filters in the base-band of a band-pass sampled signal to apply true time-delay beam-forming is shown to be feasible.Godkänd; 2007; 20061229 (ysko)EISCAT 3

EISCAT_3D - a next-generation European radar system for upper atmosphere and geospace research

The EISCAT Scientifi c Association, together with a number of collaborating institutions, has recently completed a feasibility and design study for an enhanced performance research radar facility to replace the existing EISCAT UHF and VHF systems. This study was supported by EU Sixth-Framework funding. The new radar retains the powerful multi-static geometry of the EISCAT UHF, but will employ phased arrays, direct-sampling receivers, and digital beamforming and beam steering. Design goals include, inter alia, a tenfold improvement in temporal and spatial resolution, an extension of the instantaneous measurement of full-vector ionospheric drift velocities from a single point to the entire altitude range of the radar, and an imaging capability to resolve small-scale structures. Prototype receivers and beamformers are currently being tested on a 48-element, 224 MHz array (the "Demonstrator") erected at the Kiruna EISCAT site, using the EISCAT VHF transmitter as an illuminator.Validerad; 2010; 20090807 (gustav_j)</p