| Summary: | The primary objective of this study is to develop and validate a method for estimating Link Margin and Doppler Shift to enhance the performance of the Ground Sensor Terminal (GST) for nanosatellite communication systems. The Link Margin estimation considers key factors such as Antenna Gain and losses, Atmospheric Effect, System Noise Temperature (Tsys), Margin (M), and Received Signal Strength (Pr). The methodology includes calculating the uplink budget using both the EB/No and SNR methods, with parameters extracted from the AMSAT IARU Link Model. Additionally, Doppler Shift is analysed as the change in frequency of the signal due to the relative motion between the satellite and the ground station. Mitigation strategies, including frequency management, adaptive modulation and coding, predictive tracking algorithms, and real-time feedback control systems, were explored as effective means to counteract the Doppler effect’s influence on signal integrity. The results indicate that for a satellite positioned at an altitude of 400 km, with a frequency of 145.825 MHz, the maximum Doppler shift at 0 degrees elevation is observed to be 4 kHz. Communication can be established with a link margin of 11.3 dB, starting from an elevation of 0 degrees, using the EB/No method, significantly improving the reliability and efficiency of data transmission in nanosatellite missions. © 2024 Institute of Physics Publishing. All rights reserved.
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