A commercial radio receiver for lower ionosphere monitoring: Initial results

A commercial computer controlled radio receiver has been used to measure signal strength of High Frequency (HF) signals in order to study the effects of geophysical events on radio communications and to test the system for ionospheric monitoring. The system was installed at the Southern Space Observatory (OES/CRSPE/INPE) in S o Martinho da Serra, Brazil (29.43°S, 53.8°W, B = 23350 nT). Initial results show that this system is able to detect ionospheric radio absorption events. The commercial radio receiver has a computer serial interface, to control the reception frequency in order to acquire the values of the received signal strength. We describe the system and some initial results on radio absorption events associated to C and M classes of x-ray solar flares. The results suggest the possibility of using this low-cost system to study the daily variation of the lower ionosphere ionization and to study events of ionospheric absorption. Long period measurements give statistical information about the magnitude and time scale of fading, that can be used for planning radio links.