Omer Ozdil

Automated fixed-point precision optimization

An algorithm which minimizes the hardware resources of fixed-point operations for a given accuracy is presented. For range analysis, forward propagation is used in order to determine the ranges of the intermediate signals. For the precision analysis, a search algorithm is used. Analytical quantization error models are used with the precision search algorithm. The main novelty of this work is the use of the weighted search algorithm which can minimize the hardware resources for a specific FPGA. By using weights, the search algorithm is modified to produce an optimum result for the target FPGA for a specific hardware resource such as multipliers or blok rams.

Hyperspectral image segmentation based on spatial model

This paper proposes the use of data-driven segmentation methods for spatial segmentation of hyperspectral images. In this context, hyperspectral images are represented with 3 PCA bands and they are divided into segments via Structured Forest Model which is prepared by supervised learning techniques. These segments are used for tree detection in the hyperspectral datacubes. Experimental results show that spatial information can be used effectively in the solution of various problems in the field of hyperspectral imaging.

Real-time frequency parameter extraction for electronic support systems

In this research, real time automatic frequency parameter extraction methods for electronic support systems are implemented on FPGA. The frequency parameter is extracted by using digital instantaneous frequency measurement (DIFM) and fast fourier transform (FFT) methods. Estimation performances of these two different methods for different type of radars at different signal to noise ratios (SNR) are analyzed. This design is implemented on Xilinx Virtex-6 based processing board that samples in 2.5 GHz. Experimental results of the design for FPGA implementation are presented.

Implementation of Doppler noise jamming techniques using DRFM

In this paper, hardware implementation of Doppler noise and narrow band Doppler noise techniques those are jamming of Doppler frequency based on FPGA is explained. Pulse Doppler radar signal generator and receiver parts and algorithms of techniques are implemented on the Xilinx Virtex-4 FPGA. Besides, effective jamming to signal ratios of Doppler noise and narrow band Doppler noise techniques are compared.

Hardware noise generator

We present a noise generator capable of generating different distributions based on the Box-Muller algorithm. The Gauss noise generators in the literature are modified in order to generate noise which follow Rayleigh, Rice and Exponential distributions. An implementation on a Virtex5-FXT70 FPGA occupies 1065 slices, 10 multipliers and 2 Block RAMs. The noise generator implemented on FPGA generated 2×12-bit noise samples at every clock sample. The throughput of the noise generator running at 250MHZ clock frequency is 500 million samples/seconds. Noise generator, can be used in radar simulations for generating radar echo returns or in wireless communications channel simulations.

Vegetation detection with spatial segmentation and spectral indices

This paper proposes a new vegetation detection approach using spatial segmentation and vegetation indices. For this purpose, hyperspectral images are segmented by using the previously trained spatial segmentation model. Thereafter, grape plants are tried to be detected in hyperspectral data by using the obtained segments and related vegetation indices. Experimental results on Salinas data cube show that the use of the spatial segmentation models with vegetation indices produces promising results.

Forming representative signature for vegetation detection in hyperspectral images

In this study, the effect of utilizing different type of signatures on plant detection success is evaluated on hyperspectral aerial images. Plant regions are tried to detect using spectral signatures of leaf, stem and tassel belonging to the plant separately and the plant representative signature created by averaging of signatures of selected region on the aerial images. The signatures used for detection are generated from hyperspectral images taken from 10m distance to target plant. The Spectral Angle Mapper(SAM) and Generalized Likelihood Ratio Test(GLRT) algorithms is used to target detection. Performance evaluation are made using on Receiver Operating Characteristic (ROC) curves. When the results were evaluated, the performance of the detection is higher with the use of plant representative signature.

Real-time instantaneous radar frequency measurement for pulse on pulse condition

In this research, a method which is implemented on FPGA for real-time extraction of the instantaneous frequency parameters of two simultaneous radar pulses (POP) in electronic support systems is presented. The frequency parameters of two different radars overlapped on time are extracted separately by using digital instantaneous frequency measurement (DIFM) method. Estimation performances of this method for different type of radars at different signal to noise ratios (SNR) are analyzed. This design is implemented on Xilinx Virtex-7 based processing board. Experimental results of the design for FPGA implementation are presented.

Channelizer structure in DRFM systems for real signals

In this paper, a channelized DRFM structure for DRFM(Digital Radio Frequency Memory) systems is presented. The novelty of this design is the modifications in the structure for supporting real signals without increasing the system delay. One of the most important parameters of a DRFMsystem is the system latency and the proposed architecture has less latency then the structures presented in the literature. The proposed architecture is implemented on a Virtex-6 SX475T and can run at 200 MHz clock speed.

K-distributed radar clutter sequence generator on FPGA

In this work, we present a sequence generator module on FPGA that provides the generation of K-distributed samples used in sea clutter modelling. Sequence generator is obtained by modification of widely used Box-Muller based Gaussian sequence generators into Rayleigh and Gamma sequence generators. The sqrt and ln functions in Box-Muller algorithm are approximated using piecewise polynomial function approximation method. The design implemented on a Xilinx Virtex-4 XC4VSX35- 12 FPGA can generate 5 million samples per second.