Speaker
Description
Radio astronomical observations have increasingly been threaten by the march of today telecommunication and wireless technology. Performance of radio telescopes lies within the fact that astronomical sources are extremely weak, e.g more than 15 orders of magnitude weaker than most mobile phones. The National Astronomy Research Institute of Thailand (NARIT) has initiated a 5-year project, known as the Radio Astronomy Network and Geodesy for Development (RANGD), which includes the establishment of 40-metre and 13-metre radio telescopes. Possible locations have been narrowed down to three candidates, situated in the Northern part of Thailand, where the atmosphere is sufficiently dry and suitable for K and Q band observations. The Radio Frequency Interference (RFI) measurements were carried out with a DC spectrum analyser and directional antennas at 1.5 metre above ground, from 20 MHz to 6 GHz with full azimuth coverage. The data from a 3-minute pointing were recorded for both horizontal and vertical polarisations, in maxhold and average modes. The detection threshold is approximately 80 dB(W/m^2/Hz) higher than the recommended RFI level at L band for radio astronomical observation by the International Telecommunication Union (ITU-R RA.769-2). The results, for which we used to make preliminary site selection, show signals from typical broadcast and telecommunication services and aeronautics applications. The signal intensity varies accordingly to the presence of nearby population and topography of the region. More RFI measurements at the best candidate are being planned.
Keyword – astronomy radio telescope interference survey narit
