Abstract:

In the reverse link of tracking and data relay satellite system (TDRSS), as the 30-path frequency-division multiplexing (FDM) signals are fed into the traveling wave tube amplifier (TWTA), severe inter-modulation interference to the 30element signals emerges. The interference in turn results in the distortion of the 30-element signals as well as the deterioration of digital beam forming (DBF) performance. By advanced mathematical derivation, the present work probes the explanations for magnitude and phase error among the channels derived by the amplitude to amplitude (AM/AM) and amplitude to phase (AM/PM) characteristics of the TWTA. To reduce the impairment due to these nonlinearities, dynamic equalization technique is used in Matlab. Theoretical analysis and simulation results show that the dynamic equalization technique can effectively improve the DBF performance on the earth stations and the power efficiency held by the TDRS power repeater meanwhile.