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LORAN-C Band Data Collection Efforts at Ohio University Presented by Curtis Cutright to the International LORAN Association 32 nd Annual Convention and Technical Symposium Boulder, CO November 6, 2003. Outline. Task overview Data collection system overview Airborne data collection equipment

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Outline

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  1. LORAN-C Band Data Collection Efforts atOhio UniversityPresented by Curtis Cutrightto the International LORAN Association32nd Annual Convention andTechnical Symposium Boulder, CO November 6, 2003

  2. Outline • Task overview • Data collection system overview • Airborne data collection equipment • Lab data collection equipment • Initial data collection results • Task progress Ohio University • Avionics Engineering Center

  3. Task • Field a data collection system capable of digitizing storing atmospheric noise for subsequent analysis • Integrate this system into an airborne flight platform • Perform data collection under varying atmospheric conditions Ohio University • Avionics Engineering Center

  4. Develop threat models for aircraft in flight Precipitation static (p-static) Atmospheric noise Man-made noise(cross rate, CW) Lightning Purpose Ohio University • Avionics Engineering Center

  5. Purpose • Identify all trade-off’s for E and H-field antennas, SNR, phase error, saturation, bandwidth Ohio University • Avionics Engineering Center

  6. To be determined • Is ground-based noise the same as airborne noise(E-field and H-field) • Aircraft man-made noise • CW interference environment • Determine actual P-static mechanism • Phenomena under thunderstorms • Antenna and pre-amp performance Ohio University • Avionics Engineering Center

  7. Data Collection • Simultaneous ground and aircraft RF data collection (Using DataGrabber) • 2 channels, 16-bits samples, 400 kSamples/s • LORAN receivers for performance assessment • GPS WAAS for position reference Ohio University • Avionics Engineering Center

  8. Data Processing • P-Static • Characterize E-field and H-field antenna performance • Compare measured lightning noise with predicted noise based on the national lightning detection network(NLDN) • Compare ground and airborne noise • Compare airborne E-field and H-field noise Ohio University • Avionics Engineering Center

  9. Data Collection SystemOverview

  10. Airborne Data Collection Equipment • Aircraft • King Air C-90B • Pressurized twin turboprop • 240 knot cruise speed • Equipment • Novatel OEM4 GPS receiver • LORADD-DS DataGrabber • WX-500 StormScope • Apollo 618 • Data collection PC Ohio University • Avionics Engineering Center

  11. Whip antenna (e-field) GPS antenna Apollo 618 Data Collection PC Data Collection Equipment WX-500 StormScope Pre-amp ADF antenna (h-field) Stormscope antenna Ohio University • Avionics Engineering Center

  12. Data Collection PC • CyberResearch dual backplane with 933MHz P-III CPU cards • 512MB RAM • 160GB of hard-drive space Ohio University • Avionics Engineering Center

  13. WX-500 Stormscope • RS-232 data output • 200nmi range • Heading stabilization • Data will be used in conjunction with National Lightning Detection Network (NLDN) data Ohio University • Avionics Engineering Center

  14. Loran-C H-Field vs. E-Field Antennas E-Field(Electric) H-Field(Magnetic) • Large effective height • Little voltage amplification needed • High impedance (MW) • Charge build-up (cannot be terminated) • Antenna phase pattern is omnidirectional • Whip or wire antenna • Small effective height • Large voltage amplification needed (low noise pre-amp) • Low impedance (1W) • No charge build-up (antenna is grounded) • One loop creates 0 and 180 degrees. • Conformal antenna Ohio University • Avionics Engineering Center

  15. Aircraft Data Collection Equipment Ohio University • Avionics Engineering Center

  16. Antennas E-Field II Morrow A-16 H-Field King Radio KA42A Ohio University • Avionics Engineering Center

  17. Rackmount chassis for data collection equipment AC in DC Power Supply LORADD-DS DataGrabber GPS Novatel GPS Receiver GPS antenna LAN Antenna Interface Antenna Interface H-field E-field Ohio University • Avionics Engineering Center

  18. LORADD-DS DataGrabber • Sampling rate: 400kHz • Resolution: 16 bits • Dynamic range: 96dB • Two input channels – sampled simultaneously • Differential input amplifiers for the antennas • TCP/IP data output • Clock stability: 1ppm Ohio University • Avionics Engineering Center

  19. Antenna Interface Boxes • Adjust received signal level • Provide interference isolation for the antenna cable • Impedance matching for the DataGrabber antenna inputs Ohio University • Avionics Engineering Center

  20. Novatel GPS Receiver • 1-20 Hz position data • Time synchronization • RS-232 data output (ASCII or binary) Ohio University • Avionics Engineering Center

  21. Lab Data Collection Equipment • LORADD-DS DataGrabber • 400kHz sampling • Dual channel • Data collection PC Ohio University • Avionics Engineering Center

  22. Antennas • E-field • IIMorrow A-16 Whip antenna with integral preamplifier/impedance transformer • Powered by an Apollo 618 LORAN receiver Ohio University • Avionics Engineering Center

  23. Antennas • H-field • King KA42A ADF Loop antenna • Requires a separate preamplifier/impedance transformer tuned to the LORAN-C band • Powered by 5-10VDC Ohio University • Avionics Engineering Center

  24. Initial Data Collection Results • The next 2 slides show screen captures from the initial lab data collection test using both antennas • Channel 1: h-field Channel 2: e-field • Screen capture 1 shows the RF data from each antenna • The presence of the LORAN signal can be seen in each channel • E-field channel (bottom) has more amplification than h-field (this does not affect the SNR) • Screen capture 2 shows the spectrum of the RF data • The filter bandwidth around 100kHz is apparent • Several CW interference sources are evident Ohio University • Avionics Engineering Center

  25. Ohio University • Avionics Engineering Center

  26. Example of collected data: Time domain Ohio University • Avionics Engineering Center

  27. Ohio University • Avionics Engineering Center

  28. Example of collected data: Spectrum Ohio University • Avionics Engineering Center

  29. Current Status of the Data Collection Task

  30. Airborne Collected Data • “Clear” – 10hrs • Overcast – 4hrs • Close t-storm (<20nmi) – 20min • Nearby t-storm – 2hrs • Other – 4+hrs Ohio University • Avionics Engineering Center

  31. Data Collection Flight Tracks Ohio University • Avionics Engineering Center

  32. Thunderstorm Data Conditions Ohio University • Avionics Engineering Center

  33. Ohio University • Avionics Engineering Center

  34. Ohio University • Avionics Engineering Center

  35. Future Work • Continue data collection effort • Varying environmental conditions • Different locations • Correlate National Lightning Detection Network (NLDN) data • Mobile ground data collection equipment • Calibrate the DataGrabber • Aircraft noise analysis Ohio University • Avionics Engineering Center

  36. Acknowledgements • Mitch Narins (FAA) • Wouter Pelgrum (Reelektronika) • Bryan Branham (Ohio University) • Jay Clark (Ohio University) Ohio University • Avionics Engineering Center

  37. Questions?

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