The computationally intensive portions of MicroCosm® POD are embodied in MicroCosm® Executive. To provide users with a timing benchmark for MicroCosm® POD, a Seasat 7-day orbit was computed using three different gravity models: GEM-T1 (36x36), JGM-3 (70x70) and EGM-96 (360x360). Atmospheric drag, solar radiation pressure and solid Earth tides were also modeled. The spacecraft ephemeris was output every 15 minutes and the numerical integration was performed using a 60 second step size and 11th order. MicroCosm® Executive utilized approximately 24 MB of memory when processing with the EGM-96 gravity model instead of the approximately 2 MB of memory required for the smaller gravity models. A GPS precision orbit determination (POD) was also performed on these same computers. This POD determined the orbits of 22 GPS SV’s using 155,569 dual frequency double difference carrier phase measurements from 24 GPS receivers. A total of 2303 parameters were simultaneously adjusted including 132 orbit elements, 22 radiation coefficients, 66 GPS Y-bias accelerations, 183 tropospheric scale biases and 1900 carrier phase ambiguity biases. The results of these comparison are presented below:
| Computer Used | Execution Time | Sample Execution |
|---|---|---|
| Apple MacBook® w/ OS X 10.5 Leopard®, 2.4 GHz Intel Core 2 Duo®, 256 GB Solid State Disk and 4.0 GB 1067 Mhz DDR3 Memory. Computer was new in Apr 2009. |
0.34 Seconds 1.03 Seconds 36.40 Seconds 191.49 Seconds |
GEM-T1 (36x36) JGM-3 (70x70) EGM-96 (360x360) GPS POD w/ JGM-3 (12x12) |
| H-P e9280t w/ Microsoft Windows 7 Ultimate® 64, 3.33 GHz Intel Core I7 975 Quad Processor and 18.0 GB 1067 MHz DDR3 Memory. Computer was new in Nov 2009. |
0.27 Seconds 0.92 Seconds 15.05 Seconds 122.40 Seconds |
GEM-T1 (36x36) JGM-3 (70x70) EGM-96 (360x360) GPS POD w/ JGM-3 (12x12) |
| H-P z400 w/ RHEL® 6.2 64-bit Linux®, 3.33 GHz Intel Xeon® W3680 6-core Processor and 24.0 GB 1333 MHz ECC Memory. Computer was new in Jan 2012. |
0.19 Seconds 0.64 Seconds 8.51 Seconds 81.06 Seconds |
GEM-T1 (36x36) JGM-3 (70x70) EGM-96 (360x360) GPS POD w/ JGM-3 (12x12) |
®H-P is a registered trademark of Hewlett-Packard Corp.
®RHEL or Red Hat Enterprise Linux is a registered trademark of Red Hat, Inc.
®AMD64 is a registered trademark of Advanced Micro Devices, Inc.
®MacBook and OS X Leopard are registered trademarks of Apple, Inc.
®Xeon, Core 2 Duo and Core I7 are registered trademarks of Intel Corp.
®Windows 7 Ultimate is a registered trademark of Microsoft Corp.
®SUSE is a registered trademark of SUSE Linux, AG
®Linux is a registered trademark of Linus Torvalds
®MicroCosm is a registered trademark of Space Geodesy Analysis Centre, Pty, Ltd.
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