ACTS PROPAGATION EXPERIMENT - EXPERIMENT DESIGN, CALIBRATION, AND DATA PREPARATION AND ARCHIVAL

The National Aeronautics and Space Administration Advanced Communicati ons Technology Satellite (ACTS) propagation experiment was designed to obtain slant-path attenuation statistics for locations within the Uni ted States and Canada for use in the design of low-margin Ka-band sate llite communication systems. Experimenters at seven different location s have collected propagation data for more than two years, The propaga tion terminals used for the experiment were identical. A single prepro cessing program was used by the experimenters to provide for automatic calibration, generation of attenuation histograms, and data archival. In this paper, the calibration procedures are described and estimates given for measurement accuracy. ACTS provided beacons at 20.2 and 27. 5 GHz for use in making attenuation measurements. In addition to the b eacon receivers, each ACTS propagation terminal has two total power ra diometers with center frequencies at the beacon frequencies. The radio meters are used to establish the beacon signal reference levels needed for calculating beacon attenuation values. For the combined radiomete r and beacon measurement system, the attenuation measurement error was less than a maximum of 1.0 dB and was generally less than 0.3 dB. The dynamic range for attenuation measurement varied from site to sire de pending on location relative to the peak of the satellite beacon anten na pattern. For locations within the continental United States, the dy namic range was better than 20 dB.