Sydor, John T. | Search NASA

NASA NTRS1990

Recent technical advances in general purpose mobile Satcom aviation terminals

A second general aviation amplitude companded single sideband (ACSSB) aeronautical terminal was developed for use with the Ontario Air Ambulance Service (OAAS). This terminal is designed to have automatic call set up and take down and to interface with the Public Service Telephone Network (PSTN) through a ground earth station hub controller. The terminal has integrated RF and microprocessor hardware which allows such functions as beam steering and automatic frequency control to be software controlled. The terminal uses a conformal patch array system to provide almost full azimuthal coverage. Antenna beam steering is executed without relying on aircraft supplied orientation information.

Sydor, John T.↗

NASA NTRS1988

A study on the co- and adjacent channel protection requirements for mobile satellite ACSSB modulation

Samples of speech modulated by narrowband frequency modulation (NBFM) (cellular) and amplitude companded single sideband (ACSSB) radios were subjected to simulated co- and adjacent channel interference environments typical of proposed frequency division multiple access (FDMA) mobile satellite systems. These samples were then listened to by a group of evaluators whose subjective responses to the samples were used to produce a series of graphs showing the relationship between subjective acceptability, carrier to noise density (C/No), carrier to interference ratio (C/I), and frequency offset. The results show that in a mobile satellite environment, ACSSB deteriorates more slowly than NBFM. The co- and adjacent channel protection ratios for both modulation techniques were roughly the same, even though the mechanism for signal deterioration is different.

Sydor, John T.↗