UVS Canada 2006 Conference (Montebello) 1 Abstract—Project RAVEN is a research project at Memorial University of Newfoundland, whose aim is to establish an Uninhabited Aerial Vehicle (UAV) presence off the Eastern coast of Canada in support of maritime surveillance operations conducted by manned aircraft. Until recently, the use of radar on the small low altitude long endurance (LALE) class of UAV being considered for this role was thought impossible due to restrictive payload size and weight limits. However, RAVEN has acquired the use of a small Synthetic Aperture Radar (MicroSAR) that will be integrated onto the Aerosonde UAV, through a cooperative research project with Brigham Young University (BYU) in Utah, and the University of Colorado at Boulder. The intent is to use the MicroSAR system on an Aerosonde to take high-resolution imagery of sea ice off the Newfoundland Coast in 2007. The end application for such technology includes monitoring of sea ice changes in the Arctic, support for the Iceberg Patrol in the North Atlantic, and target detection and characterization. This paper presents the work done to date to integrate the MicroSAR onto the Aerosonde UAV in preparation for this mission and initial test results. Index Terms — Aerosonde, Ice Patrol, MicroSAR, Maritime Surveillance, Project RAVEN, Synthetic Aperture Radar. I. INTRODUCTION HE MicroSAR system was developed at the Brigham Young University (BYU) Microwave Earth Remote Sensing Laboratory, with the specific intent to image sea ice using a small UAV flying at low-level [1]. Table I gives a summary of the characteristics of this miniature Synthetic Aperture Radar (SAR) system. A full description of the details of this system is provided in reference [2]. The current paper will deal primarily with the physical integration of the system on the Aerosonde UAV. The MicroSAR system is shown in Fig. 1. The System consists of an electronics package (RF module), two patch J. D. Stevenson, M. Eng. (Aero) is a Ph.D. candidate with Project Raven, Memorial University, St. John’s, NL A1B 3X5. Telephone: (709) 737-3771, e-mail: stevenson@engr.mun.ca . David G. Long, Ph.D., is director of the BYU Center for Remote Sensing, 459 CB, Brigham Young University, Provo, UT 84602. Telephone: (801) 422-4383, email: long@ee.byu.edu . J. Maslanik, Ph.D., is a Research Professor at the Department of Aerospace Engineering Sciences, University of Colorado, CCAR, 431UCB, Boulder, Colorado, 80309. Telephone: (303) 492-8974, e-mail: james.maslanik@colorado.edu . Siu O’Young, Ph.D., is Principal Investigator with Project Raven, Memorial University, St. John’s, NL A1B 3X5. Telephone: (709) 737-8345, e-mail: oyoung@engr.mun.ca . antenna arrays, and a set of cables, which may be extended up to 1.82m (6 ft) in length to allow flexibility in positioning the antenna arrays. Including cables and antennas, the mass of the system is less than 2 kg. The RF module consists of a stack of circuit boards, which includes an integral A/D data collection board (topmost board as shown in Fig. 1). Lower boards control power levels, transmit and receive antennas and the overall operation of the SAR. A set of 4 DIP switches located on the digital synthesizer board is used to select the appropriate PRF to use for the planned flight altitude and speed of the UAV. When power is supplied to the system, the MicroSAR conducts a 24 sec boot/self-check sequence then proceeds to collect data. Raw SAR image data is recorded on one of the pair of CompactFlash cards at a rate of 0.67 MB/sec. Each 1 GB CompactFlash card holds up to 25 minutes of data, for a total recording time of approximately 50 minutes. When one card is full, recording automatically switches to the other card. Once this card is filled, the system reverts back to the start of the first card and begins overwriting previous data. Data recording terminates when power is turned off. For practical use on the Aerosonde, a means of remotely controlling the MicroSAR power supply is necessary. On the Mk4 Aerosonde a conditioned 18 VDC bus supply is available which may be controlled through the built-in avionics [3]. Jonathan D. Stevenson, David Long, Jim Maslanik, and Siu O’Young Integration of a Miniature Synthetic Aperture Radar (MicroSAR) on the Aerosonde UAV T TABLE I SUMMARY OF MICROSAR SYSTEM [2] Frequency: 5.56 GHz Bandwidth: 80 MHz. Signal Type: Linear frequency modulated continuous wave (LFM-CW) Oscillator Type: 100 MHz stable local oscillator (STALO) PRF: 128 to 2880 Hz (selectable through DIP setting) Transmit Power: 28 dBmW (total less then 1W) Power Supply: 18 VDC (1.1A steady state, 1.5A peak) Power Consumption: Approximately 18W Beam Pattern: Azimuth 3dB beam width: 8.8 deg Elevation 3dB beam width: 50 deg Maximum resolution: Azimuth: 0.15m x Range: 1.85m Maximum swath size (at 344m altitude): 1024m Data Recording Rate: 0.67 MB/sec to pair of 1 GB CompactFlash cards (1 GB = 25 minutes of data) Physical Characteristics: RF electronics module: 127mm cube envelope, mass 900g Antennas: 2 patch antenna arrays, each 127 x 330 mm, 150 to 175g. Full System, including cables: less then 2 kg