The need to increase data-rate capabilities of the Tracking and Data Relay Satellite System (TDRSS) has prompted NASA to investigate bandwidth-efficient modulation schemes. Based upon current technology the most promising scheme is Trellis-Coded Modulation (TCM) operating with Octal Phase Shift Keying (8 PSK). In conjunction with NASA, New Mexico State University's Manuel Lujan Jr. Center for Space Telemetering and Telecommunications Systems has constructed a system to test this new candidate TDRSS modulation scheme, TCM 8 PSK. This system was tested through the TDRSS channel to demonstrate that this coding scheme operates as well over the actual channel as it has in lab experiments and simulations. Two interchangeable codecs, implementing separate TCM techniques, were tested. The results of this experiment and subsequent data analysis are presented in this paper.