Abstract-A new Unmanned Aerial Vehicle (UAV) Synthetic Aperture Radar (SAR) has been developed at Multimedia University, in collaboration with Agency of Remote Sensing Malaysia. The SAR operates at C-band, single V V -polarization, with 5 m × 5 m spatial resolution. Its unique features include compact in size, light weight, low power and capable of performing real-time imaging. A series of field measurements and flight tests has been conducted and good quality SAR images have been obtained. The system will be used for monitoring and management of earth resources such as paddy fields, oil palm plantation and soil surface. This paper reports the system design and development, as well as some preliminary results of the UAVSAR.

Abstract:Inertial navigation unit (INU), which is commonly composed of three orthogonally aligned accelerometers and gyros, is well known for its short term measurement accuracy in position, velocity and attitude. However, such measurement accuracy degrades with time due to various types of errors. In this paper, a practical approach is proposed to estimate both the deterministic and random errors of an INU. The deterministic errors, which include bias and scaling errors, can be estimated through a simple experimental setup; while the random noise is modeled using Allan Variance (AV) analysis method. The empirical values of the errors are then fed into the INU's system model for error correction using Kalman filtering. Finally, the calibrated INU shows promising results in preserving long term accuracy of the motion sensor.

A Strapdown Inertial Navigation Unit (SINU) is a low cost motion measurement device commonly used for navigation solutions. Global Positioning System (GPS) is usually adopted as an external reference source to minimize the SINUʹs accumulation errors by applying a Kalman filter to obtain best estimations in positions, velocities and orientations. However, due to the low sampling rate of GPS, such a configuration does not provide intensive orientation estimation. In this paper, a new and efficient real-time GPSaided SINU system with incorporated magnetometers is developed to enhance the orientation estimation. An intensive orientation estimation algorithm is developed by combining the extra sensory inputs from magnetometers with the inputs from accelerometers. The estimated orientation was applied in the Kalman filtering, replacing the GPS-aided orientation estimation. The offline implementation shows promising results in reducing both the accelerometersʹ and gyroscopesʹ errors. Finally, the design is successfully implemented in real-time.

Abstract-Radar waveform synthesizer is a key component in radar system as it determines the best achievable resolution. In this paper, a miniature and low cost radar waveform synthesizer is proposed. The synthesizer is targeted for Unmanned Aerial Vehicle (UAV) based radar system applications that require miniaturized equipment due to limited space in aircraft's fuselage. The waveform synthesizer has been developed using Altera DE3 development board (Stratix III FPGA) and a custom made dual-channel 420 MSPS HS-DAC board. The proposed system is capable of generating various types of radar waveforms: a) Linear Frequency Modulated (LFM) or chirp pulse, b) Frequency Modulated Continuous Wave (FMCW), and c) Calibration Tone (Cal-Tone), for use in different types of radar applications. The distinguishing feature of the proposed synthesizer is its capability in re-configuring the signal properties in real-time. The performance of the synthesizer has been benchmarked with commercially available radar waveform synthesizer and comparable performance has been observed.

Synthetic Aperture Radar (SAR) is widely known as a high resolution imaging system in microwave remote sensing. Large number of frequency-modulated received echoes must be acquired in real time. A typical SAR data acquisition unit (DAQ) involves high speed analog-to-digital conversion, front-end pre-processing, and data recording. Subsequent processes consist of computationally intensive digital signal processing for image formation. In this paper, an efficient data acquisition and SAR processing method is proposed. It is based on a modified discrete Fourier Transform algorithm, which requires lesser system's computational load as compared to conventional Fast Fourier Transform. The proposed system has been implemented on an UAVSAR (Unmanned Aerial Vehicle SAR) and the flight tests have shown promising results for real-time imaging.