MicroCosm® GPS Prep is a subset of the MicroCosm® Software which may be used for preprocessing of GPS and/or GLONASS data for use within the NASA GEODYN-II program. The MicroCosm® Software components included in MicroCosm® GPS Prep are:

1. The EOP & SGO Tables Program (TABLES) is used for Earth Orientation Parameters (EOP) and Solar & Geomagnetic Observation (SGO) Table creation. Since EOP & SGO are time dependent, these tables need to be regularly maintained. Both observed and predicted values of EOP & SGO are extracted by TABLES from reports published on the Internet by the International Earth Rotation Service (IERS) and the U.S. Department of Commerce, National Oceanic and Atmospheric Administration (NOAA).

2. The EOP & SGO Tables Report Program (REPORT) may be used to generate reports of segments of the EOP & SGO Tables File. REPORT may also be used to produce a modified version of the EOP & SGO Tables File based on the file created by TABLES as altered by user input to REPORT.

3. The MicroCosm® FixClock program reads RINEX observation and navigation files and optionally MicroCosm® or GEODYN-II Binary Trajectory files and performs the following functions: Apply GPS or GLONASS clock corrections to pseudorange measurements; Solve for receiver clock corrections at each epoch and fit to polynomials; Using the solved-for receiver clock polynomials, correct the pseudorange, the carrier phase and observation epochs to GPS time or GLONASS time (UTC-R); and Apply Van Martin Systems, Inc. implementation of the Blewitt cycle slip technique to compute the carrier phase ambiguities and correct the data for cycle slips. When P-code data are not available, use the navigation ephemeris in conjunction with the C/A-code pseudoranges to resolve ambiguities and remove major cycle discontinuities. Corrected data are output by MicroCosm® FixClock in RINEX format.

4. The MicroCosm® GPS Data Formatter (GDF) reads GPS and GLONASS observation data from files in RINEX format, forms differences as requested and outputs the data in either the "MicroCosm® Binary Metric Tracking Data Format" or the "MicroCosm® Binary Tracking Data Format". GDF additionally reads GPS and GLONASS navigation ephemeris data and produces Earth-fixed ephemeris data as "PCE" observations in "PCE Data Format" or the "MicroCosm® Binary Tracking Data Format". Spacecraft initial conditions (SATPAR, EPOCH, ELEMS1 & ELEMS2) are also generated from GPS and GLONASS navigation ephemeris data.

MicroCosm® GPS Prep Licenses

VMSI requires all licensee's of MicroCosm® products to sign software license agreements prior to shipment of these products. Copies of these licenses are provided by VMSI with all letters of quotation. Duplicate originals of each license must be signed by an authorized representative of the purchasing organization and must accompany the purchase order. One fully executed original of each license will be returned to the purchaser at the time of product shipment. Two forms of software licenses are used by VMSI for MicroCosm® GPS Prep products.

Licensees of MicroCosm® GPS Prep Executables must complete two copies of "SOFTWARE LICENSE AGREEMENT MicroCosm® GPS Preprocessor Executables."
Licensees of MicroCosm® GPS Prep Limited Source Code must complete two copies of "SOFTWARE LICENSE AGREEMENT MicroCosm® GPS Preprocessor Source Code."

The full text of these licenses is available in "Portable Data Format" (PDF) which is readable using the Adobe Acrobat Reader. If you do not have Acrobat Reader, it may be downloaded for free from the Adobe web site at www.adobe.com. The MicroCosm® license PDF files may be viewed and/or downloaded by following the links for MicroCosm® GPS Prep Executables License or MicroCosm® GPS Prep Source Code License. You may also contact Van Martin Systems, Inc. to have these licenses sent to you via mail or facsimile.

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