DGPS Ground Stations
The Avionics Engineering Center maintains two differential GPS ground reference stations as a part of a local CORS network. One station is located in Stocker Center on the Ohio University Campus; other station is located at the Ohio University Airport in Albany, OH. The Stocker CORS is also a part of the NGS CORS network.
To access data from these stations, use these links :
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Stocker GPS Station
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UNI Airport Station
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Past files are recorded on CD-ROM and can be made available if requested.
Downloads
Related Links
Contact Information
Purpose
To provide GPS receiver data which can be used as base station information for Differential GPS (DGPS).
- Operation: A dual frequency GPS receiver collects data at 5-second intervals 24 hours a day. Files are created hourly and are available through this site.
- Receiver: Ashtech Z-XII - 12 channels, dual-frequency
- Antenna: Geodetic microstrip antenna with pre-amp, mounted on the roof of Stocker Engineering
- Location: Stocker Center Engineering Building rooftop at Ohio University in Athens, Ohio;a 75-foot tower at the Ohio University airport at Albany,Ohio.
Data Files (ASHTECH FILE FORMATS)
- B-file: Binary measurement file. Contains pseudo-range, carrier phase, and Doppler measurements. Also computed stand-alone positions per epoch.
- E-file: Binary GPS satellite ephemeris file.
- Alm-file: Almanac file. Contains satellite orbit information.
Data is collected at 5-second intervals 24 hours a day. Some airport data files may contain data at one-second intervals. This occurs during local Ohio University flight tests.
Directory and file naming conventions
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gpsdata 20AA
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AA = year (ex. 00, 01, ...)
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Month.BBB/
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BBB= month (ex. jan, feb, mar, ...)
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Day.CC/
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CC= day of month (ex. 01, 02, ...)
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FILES
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bstkrXYY.ZZZ
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X = GMT hour (ex. 'a' = 00:01 - 01:00
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GMT,
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estkrXYY.ZZZ
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'b' = 01:01 - 02:00
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GMT,
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'c' = 02:01 - 03:00
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GMT, ...)
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almYY.ZZZ
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YY=year ( ex. 97, 98, ...)
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ZZZ=day of year ( ex. 108, 109, ...)
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YY.ZZZ= same values as above>
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EXAMPLE
Collected GPS survey data on October 16, 2000, from 10:20 to 13:45 EST. To find matching base files, add 5 hours to EST time to get GMT time of survey, i.e. 15:20 - 18:45 G.M.T. Go to directory gpsdata2000\Month.oct\Day.16\. Using the GMT time of survey,determine hours of base files needed. In this case, 15:01 - 19:00 GMT. These will be files with hour identifiers ("X" from above) "o,p,q and r".
Download the following files:
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bstkro97.289
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estkro97.289
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bstkrp97.289
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estkrp97.289
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bstkrq97.289
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estkrq97.289
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bstkrr97.289
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estkrr97.289
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Note: Local time (EST) = GMT - 5 hours
Add 5 hours to time of survey (EST) to get corresponding time in GMT
Base Station Coordinates - Antenna Reference Point (ARP)
ITRF00 (EPOCH 1997.0) Reference Frame
STOCKER CENTER
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Geodetic:
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Cartesian:
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Latitude=N 39° 19' 33.85269"
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x=678454.119m
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Longitude=W 82° 6' 25.64439"
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y=-4893824.462m
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Orthometric Height* =210.968 m
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z=4020518.314
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*(height above sea level) NGS derived (09/20/02)
OHIO UNIVERSITY AIRPORT
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Geodetic:
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Cartesian:
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Latitude=N 39° 12' 33.14520"
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x=669596.657m
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Longitude=W 82° 13' 25.93487"
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y=-4903367.024m
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Orthometric Height* =254.710m
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z=4010501.021
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*(height above sea level) NGS based, derived from STOCKER (09/20/02)
