Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/jplnews2/1264.pr

Text File | 1993-05-03 | 3KB | 79 lines

PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE [phone]


FOR IMMEDIATE RELEASESept. 18, 1989


    A complete, end-to-end system for land mobile
communications has been field-tested for the first time by
researchers from NASA's Jet Propulsion Laboratory.
    The field tests were made possible through the
cooperation of AUSSAT Pty. Ltd., the Australian national
satellite system, which provided local facilities used in the
experiments.
    The experiments, conducted in July and August 1989,
involved communications between a fixed base station at
AUSSAT's downtown Sydney, Australia, facility and a mobile
unit mounted in a van.
    The system evaluated in the tests uses vehicle
antennas, voice encoders and other hardware developed by JPL
under its Mobile Satellite Experiment (MSAT-X) program for
NASA.
    "Our conclusion was that the system really will
work," said Dr. William Rafferty, manager of JPL's
Communications Section.  Both voice and data calls, he noted,
were tested during the experiments.
    During the tests the mobile unit ranged as far away
as the city of Brisbane, more than 450 miles north of Sydney.
That is approximately the distance between Los Angeles and

San Francisco, or between New York City and Detroit.
    According to Rafferty, routes followed by the
mobile unit took it behind trees, under bridges and around
other obstructions, with no loss of synchronization during
calls lasting more than two hours each.
    Calls were relayed over Japan's Experimental
Technology Satellite-V (ETS-V).  When they are fully
operational, mobile communications systems would use special
dedicated Earth-orbiting satellites.
    Under the MSAT-X program, JPL has been developing
technologies that would be useful in mobile satellite
systems. Areas of research include mechanically and
electronically steered vehicle antennas, modulation encoding
and networking methods.
     A fully developed mobile system would use
satellites to extend mobile telephone services to remote
ground users and to users in the air and on the sea who
cannot be served by cellular telephone systems.
    In addition to planes in flight and ships at sea,
such a system could also serve such users as private drivers,
cross-country trucks, forestry personnel and law-enforcement
agents.
    The summer 1989 test in Australia included secure
calls in which digital voice transmission was encrypted.
This technique would be important to user agencies
participating in the U.S. National Communications System such
as the FBI and the Drug Enforcement Agency, Rafferty said.

    JPL's role is strictly to develop new technologies
required for a mobile satellite system. NASA plans to seek
cooperative agreements with the commercial operator of a
first-generation satellite system whereby the space agency
will launch the first satellite. In exchange, NASA would be
able to conduct technology validation experiments using a
small percentage of the satellite's capacity for the first
two years of operation.
    Now that a prototype system has been demonstrated,
Rafferty said, MSAT-X work at JPL will shift to more
"applications-oriented" issues.
    MSAT-X is funded by the Communications and
Information Systems Division of NASA's Office of Space
Science and Applications.
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