GlobalPositioningSystems - RAF Instruments

Operational Status: Standard instrumentation
General Description:
Measurement Characteristics: GPS position at 5 Hz reported using the GPGGA and GPRMC logs.
- Overall estimate of uncertainty: From OmniSTAR: XP service "is normally < +/- 15 cms horizontal accuracy > 95% of the time", "Vertical error will be 2 to 2.5 times greater than horizontal error" so vertical error is <~45 cm >95% of the time. Without OmniSTAR but with WAAS/SBAS corrections the horizontal accuracy is typically 0.6 m. If neither is available the accuracy specification is 1.5 m horizontal.
- Response time: 10 Hz
- Precision:
- Other measurement characteristics (comments on signal/noise, bias limits, etc): Can drop out on sharp turns, accuracy is degraded near the poles and during times of ionospheric disturbances. OmniSTAR may not be available near the poles. OmniSTAR coverage maps can be seen at http://wiki.eol.ucar.edu/sew/Aircraft/Omnistar

Description of Software, Data Handling, and Data Flow: GPS output data is logged to the ADS server.
- Software Components (data acquisition, display, processing, and analysis): ADS server
- Data Processing Chain (from flight to archival): Data processing follows the standard data path for RAF measurements: instrument -> NIDAS -> nimbus -> netCDF archives. See this page for more information.
QA Procedures and Needs:

$GPGGA,185236.20,2256.3109,N,09050.1471,W,5,09,0.9,13047.59,M,-23.90,M,07,1008*52 $GPRMC,185236.20,A,2256.3109064,N,09050.1470710,W,476.516,151.0,180112,0.0,E,D*20 $GPGGA,185236.40,2256.2877,N,09050.1332,W,5,09,0.9,13047.60,M,-23.90,M,07,1008*5F $GPRMC,185236.40,A,2256.2877272,N,09050.1331869,W,476.513,151.0,180112,0.0,E,D*24 $GPGGA,185236.60,2256.2645,N,09050.1193,W,5,09,0.9,13047.60,M,-23.90,M,07,1008*5B $GPRMC,185236.60,A,2256.2645481,N,09050.1193012,W,476.486,151.0,180112,0.0,E,D*20

Lead Contacts

Lead Contact: Chris Webster

Documentation

Presentations and Other Documents Prepared During the RAF Instrument Review

Reference Manual Novatel OmniSTAR-capable receiver reference manual

Descriptive Publications GPS Overview

Documentation of the Processing Algorithm(s)

Calibration History

Troubleshooting History and QA History

Problems from Project Reports

(Other)

Internal users: See http://wiki.eol.ucar.edu/rafscience/GlobalPositioningSystems (last edited 2012-12-10)

Global Positioning Systems

Instrument Description

Identifying Information

Measurements Made and Methods Used

Lead Contacts

Documentation