Desenvolvimento de um sistema de correção de fase para o radar ionosférico de São Luís do Maranhão

Abstract

This dissertation will present details of the development and construction of the phase correction unit, which was successfully implemented, with the help of the participating technical staff and collaboration with other scientific groups. It is needed for efficient functioning of the transmitting system it is required to achieve phase stabilization and correct phase relationship of the signals transmitted by the different antennas. The unit was tested with the radar at "São Luís" when its successful operation was conducted during an operational and observational campaign in August 1998. During this campaign the first data on the dynamics of electrojet irregularities were registered with a resolution of 6s in time and 2.6 km in height resolution. The data collected during a few days of the campaign are now being analyzed. Preliminary results of analysis of some data are presented in this thesis. The analysis software utilizes Fast Fourier (FFT) technique to extract the Doppler frequency of the electrojet irregularity echoes, and hence their velocities, at a large number of height bins that can be adjusted to cover height regions of specific interest, for electrojet or plasma bubble investigations. It also provides the integrated spectral power at each height, which permits plots of RTI (Range Time Intensity) maps as a function of local time. Analysis done for 31 August, which was a magnetically disturbed day, shows large variation in electrojet intensity. Such variations are found to be associated with fluctuations in the Auroral Electrojet (AE), Equatorial Electrojet (EEJ) magnetic field intensities and in the Dst indices. Also the height of the electrojet irregularities on this day appears to show a minimum near local midday. Detailed analyses are under way.