By: Sam PriceAdvisor: Dr. In Soo Ahn

Overview of GPS Overview of Receivers Current Projects Patents Datasheet Preliminary work Schedule of tasks

L1 Carrier wave 1575.420MHzC/A code 1.023MHz

Satellite IdentificationNavigation Message 50.000 Hz

Time of weekEphemeris (Current position)Almanac-Global data

Startup AcquisitionTracking

LoopPosition

Calculation

AcquisitionUses C/A code to find satellites

TrackingPerforms phase lock loop to

keep track of satellites

3 satellites solve for X,Y,ZInaccurate receiver clock. 4 satellites solve for receiver time bias.

Sampling frequency Plays role in error.

Process faster than sampling rate. Solution must be accurate within 100m

◦ Implies sampling rate greater than or equal to 4Mhz

For industry◦ Minimum amount of Ram.

Acquisition time will dictate this space. Hardware costs

◦ Minimum amount of processing power How fast you clean up Ram Tracking loop efficiency Acquisition algorithm efficiency Dictate battery life & cost of processor.

SoftOSGPS  12-7-2008 “It is able to process IF files or real time data from the GPS1A or SiGe with

various options for sub sampling and packing of the data. Please read the file READMEFIRST for more detailed instructions.”

GPS Toolkit GNU LGPL, Signal Tracking Simulation , Ionospheric modeling, Positioning 

GPS-SDR Uses FPGA board to supply computer with IF frequency.

Pervious Project Locates current position once. Takes 4 minutes.

Patent Number Description 20060074554 Software-defined GPS receivers and distributed

positioning system 20067046193 Software GPS based integrated navigation 20067002515 GPS receiver using software correlation for

acquisition and hardware correlation for tracking 2007213932 Computer Programmed with GPS Signal

Processing Programs 2005162313 GPS Receiver (Software)

•LNA (Low Noise Amp)•IF frequency of 4MHz•Sampling frequency of 16MHz•Performs A/D conversion•Outputs 1 byte signed value (-4 to 4) via USB.

Acquisition◦ Created chart of signal correlation strength.◦ Used for future optimizations of acquisition stage.

Tracking◦ Performed timing analysis.◦ Implemented optimizations.

Structure◦ Designing layout of new structure.

C/A code aligned.

C/A code not aligned.

Tracking time (Seconds)

Last years code 210

Trig metric lookup table 126

Decimation 1 98

Decimation 2 82

Removed multiplication 60

Combined 3 for loops to 1 29

Switched to release build 12

Removed decimation 22

Total Optimization Speed increase of 10x

Task Refresh Finish Date

Continuous importing of signal data 16MHz 1/27/09

Continuous deleting of signal data 3ms 2/10/09

Acquisition from data 20 sec 2/17/09

Continuous tracking of data 1ms 3/2/09

Continuous solution update 1 sec 3/16/09

Develop GUI 3/30/09

Optimize Acquisition(Optional) 4/13/09

Write final report 4/20/09

Prepare final presentation 4/27/09

Final Presentation 5/5/08

Borre, Kai et.al. Software-Defined Gps and Galileo Receiver. Basel: Birkhhäuser, 2007.

Tsui, James. Fundamentals of Global Positioning System Receivers. Hoboken: John Wiley & Sons Inc, 2005.

Hurn, Jeff. GPS A Guide to the Next Utility. Wikipedia, “Global Positioning System”

[online], available from World Wide Web: <http://en.wikipedia.org/wiki/Global_Positioning- _System>.

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