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GPS IN SITU REFERENCE SYSTEM (ISRS)

GPS IN SITU REFERENCE SYSTEM (ISRS). PRESENTED BY: J. FACUNDO, C. BOWER, & J.FITZGIBBON NOAA/NWS. Why do we need ISRS?. Observing technologies taking measurements above the surface to the Ionosphere are becoming more dependent on GPS

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GPS IN SITU REFERENCE SYSTEM (ISRS)

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  1. GPS IN SITU REFERENCE SYSTEM (ISRS) PRESENTED BY: J. FACUNDO, C. BOWER, & J.FITZGIBBON NOAA/NWS

  2. Why do we need ISRS? • Observing technologies taking measurements above the surface to the Ionosphere are becoming more dependent on GPS • COTS vendors are using a wide range of GPS engines/techniques • NOAA/other agencies/industry require a lower-cost/excellent performing reference system for in situ applications aloft

  3. Evaluating the Performance of Upper Air GPS Data

  4. Sterling Upper Air Operations Sterling Upper Air Operations Sippican MKIIA Rev "I" Functional Precision Sippican MKIIA Rev "I" Functional Precision Geopotential Height vs. Time Pressure vs. Time Flight252 09/11/2004 13:52 UTC Flight253 09/11/2004 17:53 UTC 130 130 120 120 110 110 Elasped Time (minutes) 100 100 ) 90 90 80 80 70 70 60 60 50 50 40 40 30 30 20 20 IAD3-Rev I IAD4-Rev I IAD4-Rev I IAD3-Rev I 10 10 0 0 0 0 100 5 200 10 300 400 15 500 20 600 700 25 800 30 900 1000 35 Geopotential Height (km) Pressure (hPa) IAD4 IAD3 IAD3 IAD4 GPS-derived Pressure/Heights

  5. GPS height measurements agreed on average to within ± 20 m from the surface to 34 km. At 30 km pressure sensors were in error by values between -70m (Vaisala) up to +120m (SRS). The pressure sensors considered were of extremely good quality compared to earlier generations of sensors, but were unable to provide very reliable heights at pressures lower than 10 hPa. GPS Geopotential Height Differences vs Hypsometric calculations

  6. Computing Radiosonde Winds

  7. IN SITU (GPS) REFERENCE SYSTEM MOBILE-ISRS [IN-SITU TIME (1-sec), POSITION VALUES SENT TO ISRS] 5-METERS [LAT, LONG, HTGEOM, TIME, u, v] 1-SEC u u v v BASE STATION (LOCAL GPS) OPUS DUAL CORS NGS Benchmark ISRS

  8. National Geodetic Survey Benchmark Future CORS Site

  9. Possible Flight-train Configuration M-ISRS

  10. BLOCK DIAGRAM BALLOON LAUNCH POINT CORRECTION M-ISRS HI-RES GPS ENGINE + CLOCK 403-MHz ANTENNA TELEMETRY ISRS – GROUND SYSTEM DUAL CORS GPS-PITS RECEIVER OPUS GRAPHICS/DISPLAY GPS-SIM

  11. GPS-PITS GRAPHICS DISPLAYS Reference Flight Path and Smoothed Wind Speed

  12. Position Error Profiles

  13. Velocity Error Profiles

  14. GPS SIMULATOR TEST INSTRUMENT GPS-SIMULATOR GPS-PITS

  15. Conclusions • GPS has become increasing critical for measuring the upper atmosphere • Demonstrates great reliability and measurement accuracy/precision. • In the future, new applications could be derived directly from high-resolution in situ GPS-computed measurements. • Can serve as an independent reference for a wide range of legacy and new technologies. • NOAA LEADING THE WAY!

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