PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011

Contact: Diane Ainsworth

FOR IMMEDIATE RELEASE                                                August 12, 1994


       Fifteen new, high-technology receivers are being added to a Global Positioning System (GPS) network of stations this summer, enhancing an existing array of receivers and improving data used by the Jet Propulsion Laboratory to monitor and assess earthquake hazards in Southern California.

       The new receivers -- called Turbo Rogue receivers -- are lightweight instruments originally developed at JPL. They are capable of detecting ground movement down to a millimeter.

       The Global Positioning System, operated by the U.S. Air Force, is a constellation of 24 satellites that orbits Earth every 12 hours. The GPS ground-receiver stations collect data from the satellites and, using computer analysis, allow scientists to pinpoint their precise ground locations and detect even the slightest movements of the Earth. JPL scientists collect and analyze data from the GPS on crustal strain and ground movement both globally and in the Southern California area.

       The Turbo Rogues were used recently to study ground movement in the San Fernando and Simi Valley areas after the 6.7-magnitude Northridge earthquake on Jan. 17.

       With data from the GPS and the Turbo Rogue receivers, seismologists were able to determine that Oat Mountain -- a 1,100-meter (3,600-foot) peak in the Santa Susana Range north of San Fernando Valley -- was lifted 38 centimeters (15 inches) and shoved 16 centimeters (6.3 inches) north and 14 centimeters (5.5 inches) west as a result of the Northridge temblor.

       Turbo Rogue receiver technology was first developed by JPL in the late 1980s, and later turned over to industry. Allen Osborne Associates (AOA) of Westlake Village, Calif., which specializes in high technology navigation and communications equipment, marketed the technology for a variety of uses, including seafloor studies, aerial navigation and land surveying techniques.

       Turbo Rogues were designed to provide high accuracy digital processing of GPS satellite signals. They have the ability to measure "pseudorange" -- the range between the satellite and receiver uncorrected for timing discrepancies -- on the GPS satellite's two carrier frequencies to a decimeter or better. This accuracy is instrumental in allowing the receivers to measure slight shifts in the Earth's crust from space.       

       Power, weight and size have all been reduced in the latest generation of receivers. The Turbo Rogues are about the size of a coffee table dictionary, weigh only 4.3 kilograms (9.5 pounds), and can track up to eight GPS satellites simultaneously.

       Developed primarily for military purposes and used effectively in the Persian Gulf conflict in 1991, the Global Positioning System receivers can be used in other disciplines, such as the study of the Earth's crustal dynamics, orbit determination for Earth satellites, time synchronization and accurately calibrating the Earth's ionosphere for deep space navigation.

       High-resolution measurements of ground motion are, similarly, of interest to geodesists, who study the shape of Earth, as well as the exact positions of points on the ground. In addition, data from highly sensitive GPS receivers in seismically active areas will allow geophysicists to identify almost immediately the fault on which an earthquake has occurred and forecast where aftershocks may be centered.

       The Turbo Rogue receiver design, developed at the Jet Propulsion Laboratory for NASA's Geodynamics Program, is part of JPL's Commercialization Program, designed to stimulate technology transfer and commercialization to meet the diverse needs of U.S. firms.

       The Global Positioning System ground-receiver network is managed by the Southern California Earthquake Center, a consortium of regional organizations which monitor seismic activity in the Southern California region. The program is supported in part with funding from NASA's Mission to Planet Earth program.


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8/12/94 DEA
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