Architecture and design of the aquarius instrument for RF and thermal stability

McWatters, D.; Freedman, A. P.; Becker, R. A.; Granger, James; Yates, Phil; Franklin, B. J.; Borders, James; Yueh, Simon; Spencer, M.; Price, Doug; Fischman, M.A.; Cheetham, C.; Paller, Mimi; Pellerano, F.; Piepmeier, J.R.

doi:10.1109/radar.2009.4977043

Cited by 3 publications

(2 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…1. The transmit chain uses directdigital synthesis technology inherited from the Aquarius instrument [3] to generate the pair of tunable frequencies for V-and H-pol, 1-MHz chirp pulses, but modified to accept frequency updates digitally from CCP. The receiver chain uses a single-stage heterodyne downconverter with tunable LO and FPGA-based back-end digital processor.…”

Section: Control Of Radar System Parametersmentioning

confidence: 99%

See 1 more Smart Citation

RFI mitigation and detection for the SMAP radar

Chan

Fischman

Spencer

2011

2011 IEEE International Geoscience and Remote Sensing Symposium

Self Cite

View full text Add to dashboard Cite

The planned Soil Moisture Active Passive (SMAP) mission 1 will use both active radar and passive radiometer instruments at L-Band to measure and monitor both soil moisture and freeze/thaw state globally. The frequency band allocated for the SMAP radar is shared with the Global Navigation Satellite Systems and ground-based radiolocation services. Signals from those users present significant sources of anthropogenic radio frequency interference (RFI) which contaminate the radar measurements. To mitigate RFI, the radar is designed with tunable operating frequency, which allows the center frequency to be tuned to avoid RFI. The filtering scheme in the receiver is configured to get a high level of RFI suppression. To meet the high accuracy measurement requirements, RFI detection and correction will be required during ground data processing. Some candidate algorithms have been evaluated, and they have been tested against simulated SMAP data derived from the PALSAR data.

show abstract

Section: Control Of Radar System Parametersmentioning

confidence: 99%

“…An examination intended to characterize the nature of RFI yielded 87% of RFI observed from pulsed sources and 13% from "other" sources including CW. For the most part, sources seem to be relatively narrow band (2)(3)(4).…”

Section: Rfi Characterization With Palsar Datamentioning

confidence: 99%

RFI mitigation and detection for the SMAP radar

Chan

Fischman

Spencer

2011

2011 IEEE International Geoscience and Remote Sensing Symposium

Self Cite

View full text Add to dashboard Cite

show abstract

Frequency-Agile Radar Electronics for the Soil Moisture Active\/Passive (SMAP) Mission

Fischman

Chan

Huang

et al. 2015

IEEE Geosci. Remote Sens. Mag.

View full text Add to dashboard Cite

Preliminary Evaluation of Passive Thermal Control for the Soil Moisture Active and Passive (SMAP) Radiometer

Mastropietro

Kwack

Mikhaylov

et al. 2011

41st International Conference on Environmental Systems

Self Cite

View full text Add to dashboard Cite

NASA's Earth observing Soil Moisture Active & Passive (SMAP) Mission is scheduled to launch in November 2014 into a 685 km near-polar, sun synchronous orbit. As one of the four first-tier missions recommended by the National Research Council's Committee on Earth Science and Applications from Space, SMAP will provide comprehensive global mapping measurements of soil moisture and freeze/thaw state in order to enhance understanding of the processes that link the water, energy, and carbon cycles. The primary objectives of SMAP are to improve worldwide weather and flood forecasting, enhance climate prediction, and refine drought and agriculture monitoring during its 3 year mission. The SMAP instrument architecture incorporates an L-band radar and an L-band radiometer which share a common feed horn and parabolic mesh reflector. The instrument rotates about the nadir axis at approximately 14 rpm, thereby providing a conically scanning wide swath antenna beam that is capable of achieving global coverage within 3 days. In order to make the necessary precise surface emission measurements from space, the electronics and hardware associated with the radiometer in particular must meet very tight short term (instantaneous and orbital) and long term (monthly and mission) thermal stabilities. Short term orbital stabilities, for example, must not exceed 0.6 o C/orbit, while longer term mission drift must not exceed 15 o C. Maintaining these tight thermal stabilities is quite challenging because the sensitive electronics are located on a fast spinning platform that can either be in full sunlight or eclipse, thus exposing them to a highly transient environment. In the interest of providing a low cost solution to proper thermal management of the instrument, a passive design approach was first implemented early in the design cycle. A Thermal Desktop model was created in order to help evaluate the passive design and assist the project with deciding if a more advanced active control scheme would be required in order to meet the tight stabilities with sufficient margin. This paper will discuss the preliminary thermal model predictions and summarize what thermal stabilities can be realistically achieved through passive means on a fast spinning platform exposed to both direct sunlight and eclipse in low Earth orbit. The SMAP mission has not been formally approved by NASA. The decision to proceed with the mission will not occur until the completion of the National Environmental Policy Act (NEPA) process. Material in this document related to SMAP is for information purposes only.

show abstract

Architecture and design of the aquarius instrument for RF and thermal stability

Cited by 3 publications

References 3 publications

RFI mitigation and detection for the SMAP radar

RFI mitigation and detection for the SMAP radar

Frequency-Agile Radar Electronics for the Soil Moisture Active\/Passive (SMAP) Mission

Preliminary Evaluation of Passive Thermal Control for the Soil Moisture Active and Passive (SMAP) Radiometer

Contact Info

Product

Resources

About