Accession Number : ADA293015

Title :   A Prototype Ionospheric Tomography System (ITS).

Descriptive Note : Final rept. 30 Jul 91-30 Apr 94,

Corporate Author : NORTHWEST RESEARCH ASSOCIATES INC BELLEVUE WA

Personal Author(s) : Fremouw, E. J. ; Secan, J. A.

PDF Url : ADA293015

Report Date : 15 JUN 1994

Pagination or Media Count : 32

Abstract : Northwest Research Associates has developed a prototype ionospheric tomography system (ITS) for use with the "Transit" satellites of the U.S. Navy Navigation Satellite System (NNSS). The NNSS satellites transmit I coherent signals at 150 and 400 MHz. The ITS consists of a data-collection subsystem made up of five newly F designed, largely digital ITS 105 coherent radio receivers for recording dispersive phase between the two NNSS signals. a data retrieval subsystem, and a central processor. In addition to dispersive phase, the receivers measure the signal intensities, all at 50 samples per sec (sps), for recording signal scintillation due to scattering in medium-scale of order km) plasma-density irregularities. The dispersive phase is smoothed to one sps for use as a measure of the path-integral of plasma density (the "total electron content," or TEC). Data may be retrieved from on-line personal computers associated with each receiver either on diskettes or by means of modems that constitute the primary data retrieval subsystem. The data retrieval subsystem also includes one "data collection platform" for satellite relay of data from a remote station to CONUS for subsequent modem retrieval. The central processor consists of six FORTRAN programs developed for tomographic inversion of The data by means of a weighted, damped, least squares formulation of discrete inverse theory. This report describes application of that theory to the central processor and briefly describes the data collection and data retrieval subsystems.

Descriptors :   *NAVIGATION SATELLITES, *TOMOGRAPHY, PLASMAS(PHYSICS), ELECTRON DENSITY, REFRACTIVE INDEX, PROTOTYPES, RADIO RECEIVERS, LEAST SQUARES METHOD, INFORMATION RETRIEVAL, DATA ACQUISITION, INVERSION, MICROCOMPUTERS, ONLINE SYSTEMS, MODEMS, RADIO SIGNALS, IONOSPHERIC SCINTILLATION, COMMUNICATION SATELLITES, NAVAL EQUIPMENT, MILITARY SATELLITES, ATMOSPHERIC REFRACTION, DISPERSIONS, RADIO RELAY SYSTEMS.

Subject Categories : Atmospheric Physics
      Radiofrequency Wave Propagation

Distribution Statement : APPROVED FOR PUBLIC RELEASE