Advanced tracking and data relay experiment study: Multimode transponder experiment

A series of experiments utilizing a multimode transponder mounted in an aircraft working either through a spacecraft or directly with a ground station is studied. The purpose of the experiments is to determine the best modulation and encoding techniques for combating RFI and multipath propagation and to determine the characteristics of VHF and UHF RFI in discreet bands. The experiments would also determine the feasibility and accuracy of range and range rate measurements with the various modulation and encoding techniques.