Design, fabrication, and testing of a data acquisition and control system for an internally-calibrated wide-band microwave airborne radiometer

Nelson, Scott P., author
Reising, Steven C., advisor
Notaros, Branislav, committee member
Kummerow, Christian, committee member
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The National Aeronautics and Space Administration (NASA)'s Earth Science Technology Office (ESTO) administers the Instrument Incubator Program (IIP), providing periodic opportunities to develop laboratory, ground-based and airborne instruments to reduce the risk, cost and schedule of future Earth Science missions. The IIP-10 project proposed in 2010 and led by PI S. Reising at Colorado State University focuses on the development of an internally-calibrated, wide-band airborne radiometer to reduce risks associated with wet-path delay correction for the Surface Water and Ocean Topography (SWOT) mission. This airborne radiometer includes microwave channels at 18.7, 23.8, and 34.0 GHz at both H and V polarizations; millimeter-wave window channels at 90.0, 130.0, 168.0 GHz; and temperature and water vapor sounding channels near 118 and 183 GHz, respectively. These microwave, millimeter-wave window and millimeter-wave sounding channels consist of 6, 3 and 16 channels, respectively, for a total of 25 channels in this airborne instrument. Since the instrument is a prototype for space flight, a great deal of effort has been devoted to minimizing the mass, size and power consumption of the radiometer's front-end. Similar goals of minimizing the mass, size and power consumption have driven the design of the radiometer back-end, which performs the data acquisition and control functions for the entire instrument. The signals output from all 25 radiometer channels are conditioned, integrated and digitized on the analog back-end boards. The radiometer system is controlled by a Field Programmable Gate Array (FPGA) and a buffer board. Each analog back-end board conditions and simultaneously samples four signals, performing analog-to-digital conversion. The digital back-end consists of the buffer board and FPGA, which control and accept data from all seven analog back-end boards required to sample all 25 radiometer channels. The digital back-end also controls the radiometer front-end calibration (also called "Dicke") switching and the motor used to perform cross-track scanning and black body target calibration of the airborne radiometer instrument. The design, fabrication, and test results of the data acquisition and control system are discussed in depth. First, a system analysis determines general requirements for the airborne radiometer back-end. In the context of these requirements, the design and function of each component are described, as well as its relationship to the other components in the radiometer back-end. The hardware and software developed as part of this radiometer back-end are described. Finally, the back-end testing and results of these tests are discussed.
2014 Spring.
Includes bibliographical references.
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