School of Aeronautics and Astronautics What I Did During My Summer Vacation

School of Aeronautics and Astronautics 4/08/20032 NASA Wallops Trip Opportunity to Fly APL L1/L2 Signal Sampler Goal: To Obtain Higher Resolution Ocean Reflected Data Not Successful!

School of Aeronautics and Astronautics 4/08/20033 GSFC, Code 596 Goddard Space Flight Center Applied Engineering and Technology Directorate Guidance Navigation and Control Center Hardware and Component Systems (Code 596)

School of Aeronautics and Astronautics 4/08/20034 Code 596 & PiVoT PiVoT  Position Velocity Time Space Flight Ready GPS Receiver Radiation Hardened Components Low Power Gnucleus Embedded OS

School of Aeronautics and Astronautics 4/08/20035 PiVoT 1.0 Based on GPS Builder Card Uses Mitel 2010/2021 Chipset Software based on GPS Builder Card Software ♠ Old, Buggy, Undocumented ♠ Several Unresolved Bugs ♠ Mix of Pipes & Shared Memory for Thread Communication ♠ Low Performance

School of Aeronautics and Astronautics 4/08/20036 PiVoT 2.0 New Generation GPS Receiver ♠ Totally In House High Performance ♠ Uses Motorola ColdFire™ Processor ♠ 42 seconds TFF from Cold Start ☺ Via FFT Acquisition ☺ Implemented in Actel Rad-Hard FPGAs ♠ Low Signal Level Tracking ☺ 20ms Integration Time ♠ 24 Correlators ☺ Attitude Determination

School of Aeronautics and Astronautics 4/08/20037 GPS Signal Sampler Flexible, Low Cost Solution Utilizes Off the Shelf Components ♠ RF Front-End ♥2 Signal Generators ♥A Couple of Band Pass Filters ♥A Few RF Amps ♥Downmixes GPS Signal to 35.4 MHz ♠ EchoTek ADC Card ♥Samples GPS Signal at MHz ♠ High End PC w/ SCSI Raid Array

School of Aeronautics and Astronautics 4/08/20038 PiVoT 2.0 Software Decision to Abandon PiVoT 1.0 Code Base ♠ Intellectual Property Issue ♠ Code is a Monstrosity Rewrite From Scratch ♠ Utitilizing C++ OOP ♠ Modular As Possible ♠ 1 Method Of Thread Communication ♥Pipes

School of Aeronautics and Astronautics 4/08/20039 Actual Work Begin 2.0 Code Base Goal: Produce Navigation Solution using Luke W.’s acquisition/tracking code, GPS Signal Sampler, and Real GPS Signal

School of Aeronautics and Astronautics 4/08/ Results Proved Validity of GPS Signal Sampler Nav Solution Completed ♠ ~2km Error Proved Real-Time Software Correlators ♠ ~50% CPU Usage for 12 Channels ♠ Utilizing only MMX Optimizations ♥Further Improvement Expected from SSE/SSE2 Code

School of Aeronautics and Astronautics 4/08/ This Fall All Pieces in Place ♠ Real Time Software Correlators ♠ GPS Signal Sampler ♠ Ability to Write Real Time Multithreaded Code ♠ Code Base for Nav Solution Goal: ~10m Real Time Nav Solution by End of Fall 2003 ♠ Off of sampled data ♠ Move to Real Time Operation (Directly Off of EchoTek Card) in Spring ♠ Write a Paper