Norman E. Lay

An aeronautical-mobile satellite experiment

The authors describe the results of a recently completed joint US NASA/US FAA/International Maritime Satellite (INMARSAT) satellite experiment using a land-mobile satellite communication terminal developed by the Jet Propulsion Lab. The experiment was performed in two parts during 1989. The first segment of the experiment consisted of establishing a full duplex 4800-b/s digital data and voice communication link through the INMARSAT Marecs B2 satellite between Atlantic City, NJ, and Southway, CT. The second segment consisted of establishing the same communication link between Southbury and an aircraft flying along the East Coast of the US. During both segments, a series of tests was performed to characterize the terminal performance over the links. The experimental setup and the results of the speech and data experiments are presented. Any differences in performance between theory/simulation laboratory, and field operation are emphasized and analyzed. >

A communication protocol for mobile satellite systems affected by rain attenuation

A protocol that supports real-time data rate selection and change during rain events is presented. The protocol is developed with emphasis on being efficient yet robust to the primary channel impairment in such mobile satellite systems. The system architecture is briefly presented and the analytical framework from which the protocol originates is pointed out. Link, connection, and packet types are introduced, and the protocol procedures and design rationale are discussed. The detailed presentation focuses on link setup with the appropriate data rate(s) and the real-time switching of data rates during a voice conversation to either preserve the link or enhance its quality during rain attenuation events. >

A communications system testbed

We describe a testbed that is being developed for the evaluation of demodulation algorithms in communication systems. This testbed is intended to provide a research tool in the area of signal demodulation and is built around easily programmable, general purpose and digital signal processors. A variety of analog and digital modulations can be evaluated in real and non-real-time scenarios and under different channel conditions ranging from intersymbol interference to modulated or unmodulated co-channel interference. Testbed architectural and design details are presented along with preliminary results of our algorithm development and testing program.

New criteria for blind adaptive arrays

An alternative methodology for blind adaptive array processing is presented which generalizes the class of cost functions that are currently used. The methodology is based on the separation of independent, but not necessarily identically distributed, statistical components at the array output. Sufficient admissibility criteria are presented for blind adaptive array processing cost functions and examples based on the magnitude of complex, standardized cumulants as well as on order statistics are provided. In addition, a simple procedure for devising new candidate cost functions is discussed that can easily incorporate any available statistical information regarding the specific signal/interference environment of interest.<<ETX>>

The MSAT-X MARECS B2 satellite experiment: ground segment results

The results of a recently completed satellite experiment employing the JPL MSAT-X developed land-mobile satellite communication terminal are described. In this experiment, a full duplex 4800-b/s digital data and voice communication link was established through the INMARSAT MARECS B2 satellite between Atlantic City, New Jersey, and Southbury, Connecticut. A series of experiments was performed to characterize the terminal performance over this link. The basic experimental setup and the preliminary results of the speech and data experiments are presented. The satellite environment proved to be near to what was expected, and as a result the experimental results were very close to theory/simulation/laboratory experiments. It was found that the ground-to-ground communication links were more benign links than the ground-to-air and air-to-ground links, and this is reflected in the improved margins for the ground-to-ground links (approximately 5 dB versus 3.2 dB for the aeronautical links.<<ETX>>