Air Traffic Control Experimentation and Evaluation with the NASA ATS-6 Satellite : Volume 6. Modem Evaluation Test

PDFTech ReportDOT-TSC-FAA-76-22-6FAA-RD-75-173-6DOT-TSC-707-6Phased arraysSatellite navigation systemsDoppler effectModemsMultipath transmissionUnited States. Federal Aviation AdministrationWilson, S. G.Paulson, C. V.Reese, I. R.Boeing CompanyJohn A. Volpe National Transportation Systems Center (U.S.)NTL-AVIATION-Air Traffic ControlVolpe National Transportation Systems Center, Technical Reference CenterResults of performance evaluation of voice, digital data and ranging modems in the aeronautical satellite environment are given. Approximately 80 hours of modem performance data were acquired on board an FAA KC-135 jet aircraft operating over the North Atlantic. L-band test signals received at the aircraft were generated by ATS-6 satellite relay of transmissions from a NASA ground station. The modem evaluation tests were conducted between September 1974 and April 1975 as part of the U.S. Department of Transportation (DOT) aeronautical technology test program. The U.S. DOT tests were a component of the International ATS-6 L-Band Experiment coordinated by the NASA/Goddard Space Flight Center. Measured modem performance includes: the word intelligibility achieved by four distinct speech transmission modems; the average bit-error probability and error patterns associated with five phase-shift-keyed 1200-bps data modems; and the rms ranging accuracy achieved with two ranging modems. In each case the performance was evaluated as a function of carrier-to-noise density ratio (C/No) and direct-signal-to-multipath-signal ratio (S/I). Testing was performed with representative operational-class aircraft antennas as well as with special antennas, allowing the variation of the relative multipath level