Institute for Systems Research

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Author: search.filters.author.Murad, A.H.

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    A Summary of Satellite Orbit Related Calculations
    (1995) Murad, A.H.; Jang, Kap D.; Atallah, George C.; Karne, Ramesh K.; Baras, John S.; ISR; CSHCN
    The configuration of satellite network systems is based on the quantities and properties related to the satellite orbit. It is extremely important to carefully define parameters and equations describing the orbit  path correctly to make the whole configuration correct. Three different coordinate systems are in use to define satellite orbit: the Latitude-Longitude-Altitude coordinate system, the Right Ascension-Declination coordinate system and the Azimuth-Elevation coordinate system. These coordinate systems are equivalent with respect to the position of the satellite of interest and can easily be converted one to another. One of these coordinate systems would be used depending on the nature of the problem to be solved. Based upon these coordinate systems, the position of a satellite, the visibility of a satellite and antenna direction from a ground station, and a footprint radius of a satellite, etc. can be calculated.

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    Distributed Decoding of Cyclic Block Codes Using a Generalization of Majority-Logic Decoding
    (1992) Murad, A.H.; Fuja, Tom E.; ISR
    One-step majority-logic decoding is one of the simplest algorithms for decoding cyclic block codes. However, it is an effective decoding scheme for very few codes. This paper presents a generalization based on the "common-symbol decoding problem." Suppose one is given M (possibly different) codes over the same field; suppose further that the codewords share a single symbol in common. The common-symbol decoding problem is that of estimating the symbol in the common position. (This is equivalent to one-step majority logic decoding when each of the "constituent" codes is a simple parity check.) This paper formulates conditions under which this decoding is possible and presents a simple algorithm that accomplishes the same. When applied to decoding cyclic block codes, this technique yields a decoder structure ideal for parallel implementation. Furthermore, this approach frequently results in a decoder capable of correcting more errors than one-step majority-logic decoding. To demonstrate the simplicity of the resulting decoders, an example is presented.