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MicroCosm® GNSS Prep


MicroCosm® GNSS Prep is a subset of the MicroCosm® POD Software which may be used for preprocessing of Global Navigation Satellite System (GNSS) data for use within the NASA GEODYN-II program. The MicroCosm® POD Software components included in MicroCosm® GNSS 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 and Reference System 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 GNSS Space Vehicle (SV) 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® GNSS Data Formatter (GDF) reads GNSS 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 GNSS 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 GNSS navigation ephemeris data.


MicroCosm® GNSS 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® GNSS Prep products.

  1. Licensees of MicroCosm® GNSS Prep Executables must complete two copies of "SOFTWARE LICENSE AGREEMENT MicroCosm® GNSS Prep Executables."

  2. Licensees of MicroCosm® GNSS Prep Limited Source Code must complete two copies of "SOFTWARE LICENSE AGREEMENT MicroCosm® GNSS Prep 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® GNSS Prep Executables License or MicroCosm® GNSS 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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