H. Bulent Yagci

Implementation of a software defined FM mixed demodulator on FPGA

Software defined radio (SDR) applications are usually preferred in low power flexible communication systems. In this paper, a software defined Frequency Modulation (FM) demodulator is presented. Mixed demodulation technique is used to build a digital FM demodulator which has 16 MHz sampling rate. Proposed system was implemented successfully on a Field Programmable Gate Array (FPGA). The system uses 1247 logic elements. FPGAs power consumption is 113.56 mW. The system was tested and verified with a test bed including Analog Digital Converter (ADC) and Digital Analog Converter (DAC).

Low cost S Band communication system design for nano satellites

Nano satellite structures have limited communication ability due to limited power and size. Most of satellite includes sensors, for instance camera, also image transfer requires more data transfer speed. In this project, 2.4 GHz (S Band) communication system is designed for LEO satellites (700–900 km). System includes system-on-chip transmitter device, preamplifier, band pass filter, power amplifier and microstrip antenna array. Microstrip antenna array and RF circuit is designed on FR4. Microstrip array size is 92×84mm2 and RF circuit size is 38×53mm2. Output power of the system is 35dBm for 2.4kbaud data rate, but it can be increased to power capability of the satellite for more data rate.

Received Signal Strength Technique Performance in Sensor Network Localization Application

In this paper, we initially present RSSI vs Distance test results performed indoor and outdoor with Texas Instruments CC2431 Development Kit. In addition, Location Engine of Development Kit performance is presented with 3 and 4 reference nodes. An alternative algorithm based on Cayley-Menger Determinant, proposed by M.Cao, B.D.O. Anderson and A.S. Morse has been implemented in Matlab and it is compared with Location Engine. It is concluded that accuracy of alternative one slightly better than Location Engine with 3 reference nodes. Increasing reference node count makes Location Engine more accurate.

Ku - Band slotted rectangular patch array antenna design

In the recent years, microstrip antennas have quickly developed from a research novelty to a practical reality, with applications in a wide range of communication systems that must thank to their numerous appreciated features. The present work proposes a low nature slotted microstrip antenna with ground plane structure for Ku-band satellite communications. Firstly, a single Ku-band slotted patch antenna designed and then 2×2 array structure modelled and simulated by using Ansoft HFSS 3D electromagnetic simulation tool. High directivity of antenna has been realized by using full ground plane and via has fed array elements. Array feed circuit placed behind of antenna in the third layer. The gain of array antenna is about 12dBi and it is usable between 12.2 GHz and 13.1 GHz band frequency. The configuration of the proposed antenna shows the way to fabricate and make it appropriate for Ku-band applications in satellite communications.

The X(-Band) Files: An X-Band Microstrip Voltage-Controlled Oscillator with Wideband Tuning Range

Signal sources are essential devices for radar and communication systems. The demand for oscillators has existed for very long time. In 1888, Heinrich Hertz introduced the first known oscillator to prove Maxwells equations experimentally [1]. He used a dipole as the frequency determining structure and a spark-gap generator as the signal source. His invention signaled the birth of wireless communications because Hertz confirmed the existence of electromagnetic radiation which was postulated by Michael Faraday and James Clerk Maxwell.

Effects of substrate thickness and dielectric to microstrip dipol antenna parameters for 2.4 GHz wireless communication devices

İt is aimed to design 2.4 GHz microstrip-dipole antennas for wireless communication systems by using different substrates with different physical properties in this paper. Designs were made according to general microstrip dipole structure. Ansoft HFSS programme was used for simulations of antennas and simulations were used to indicate effects of substrate thickness, tangent loss and dielectric to antenna.

Radio trasmitter design including FPGA for micro/nano satellite

In recent years, small satellites have begun to draw attention due to reconstruction in low cost of manufacture and faster building time. In this project, radio transmitter system is built for nano and micro satellites. Transmitter broadcasts 1W power in 435 MHz free amateur satellite communication band, and also has software defined radio structure in all modules except upconvertion part. Design was capable of DE0-Nano evaluation board connection; it is regard of PC104 connector structure standard. FSK modulation and AX.25 data link layer protocol are designed using digital circuit in FPGA and implemented with VHDL.

AX.25 protocol compatible reconfigurable 2/4 FSK modulator design for nano/micro-satellites

In this paper, implementation of a FPGA-based and VHDL coded reconfigurable frequency shift keying (FSK) modulator for nano-satellite communication systems is presented. Reconfigurable FSK modulator includes 2-FSK and 4-FSK modulators. The system is compatible with AX.25 data link layer protocol for general amateur radio communication which is popular in micro/nano satellite communication. ROM based direct digital synthesizer (DDS) generates a sinusoidal wave at the output with a specified frequency and phase.

Three dimensional localization with ultrasonic at wireless sensor networks

In this work, 3D localization is produced by utilizing ultrasonic and radio signals at wireless sensor network and for this purpose time difference of arrival is used for localization. Measurement system is designed by using four hardwares (nodes) which have the same properties. One of the nodes is moving, other three nodes perform as references. The frequency used between the nodes is 2.4GHz and ultrasonic signal propagates with 40KHz. All of the nodes benefit from TinyOS operating system. After achieving appropriate number of measurement, calculations are brought about considering necessary variance and standard deviation. As a result, localization is calculated with % 2.5 error.

Design of GMSK modulated software defined radio for nano-satellites

In this paper, the construction of GMSK modulated SDR (Software defined radio) design which could be processed in nano-satellites is discussed. A Gaussian FIR filter which is controllable and has the coefficients arranged with different BT values (0.3, 0.5, 0.7, and 1.0) has been formed. After the filter which works on the Cyclone II FPGA has been transformed into analog signal with the data DAC IC which has been obtained with integrator and DDS structures, it is transmitted to the antenna by being amplified to the desired frequency and power with RF circuits. The clock of 150 MHz has been inputted into the system by the frequency which is augmented by PLL in Cyclone II. The output of 2.3 MHz has been obtained. The electronics circuits of the system have been designed with real circuit models and AWR-VSS which is a RF simulation program and it is also shown that the output of 433 MHz and 100 mW power has been obtained in the simulation.