Sharif Digital Repository

RF amplifier are one of the most important part of communication industry. microwave tubes are of the most sensitive and expensive parts of such systems, protection measures are of high importance. One of the phenomena that cause failure or degradation of tubes is electric arc in cathode of the tubes and dissipating energy due to that. In order to prevent the tubes from undergoing such harm, protection must be put into consideration. Furthermore, the limit of this dissipating energy determines the capacitor needed at the output of the power supply of the cathode. Since the value of the capacitor is directly proportionate to the amount of ripple of the output voltage, an exact calculation of... 

The purpose of this project is to detect the instantaneous frequency of an unknown signal which has a frequency range from 2GHz to 18GHz, and its amplitude is limited. In the first step, this signal is amplified, and its amplitude is limited and then it is converted to a digital sequence using a mono-bit scheme and entered the FPGA through an ultra-fast serial port. After that, the algorithm of this project is supposed to do two main processing stages on the received stream of pulses. Detection should be performed in the first phase. It means that it should be determined whether the received pulse sequence is a random sequence made by noise or an almost regular sequence due to a sinusoidal... 

Nowadays, increasingly improvements in the digital technology and the advantages of using digital signal processing methods lead engineers to use digital signal processing instead of analog processing in variant domains. However, speed limitations in analog to digital converters (ADCs) and data transfer ports prevent its penetration to high frequency signals region. In this thesis, an Instantaneous Frequency Measurement (IFM) system that can measure frequency in the range of 2-18 GHz is implemented fully digital (DIFM) on FPGA. To do so, monobit sampling technique with the sampling rate of 10 GHz is selected, and GTX high speed serial port is configured to transfer digital data into FPGA.... 

One of the major Ethernet challenges for entering the communication networking infrastructure, is the problem of damage prevention caused by the loop formation in the network. Since for offering many of the new services and such required for data it is necessary to provide features such as the ability of protection with short recovery time in service. ITU-T G.8032 Recommendation by providing Ethernet Ring Protection Protocol (ERP) could reduce the recovery time of failure to 50ms, while it takes a few seconds for other protocols. This protocol is one of the optimal solutions to respond these challenges and to complete the benefits of Ethernet as the best technology infrastructure. In this... 

Implement of smart grid has three mail reasons: Energy crisis caused by lake of traditional fuels, climate changes that can bring a lot of difficulties for human and great potentials of renewable energies. There are many diverse concepts in smart grid. Increase power quality, decrease power cuts, increase active consumer participations, effective way r of using distribution generation units are most important advantages of smart grid.I I;.Emerging new technologies are forced smart grid operators using this new technologies. Wireless Sensor Networks are one of these new technologies that can be used in smart gird. In this thesis we are going to study the rule of wireless sensor networks in... 

There are many methods for direction finding (DF) of radar targets, while the complexity and time elapsed calculation are their main drawbacks, thus the real time implementation of this methods are difficult. Artificial neural network (ANN) for DF is one of the optimum and good ways to implementation that have better result versus other techniques. In this thesis, direction finding problem for radar targets by using artificial neural networks have been studied. A new method is presented to detect the multiple targets simultaneously, that it can be implemented in digital form easily. Here one-dimensional DF by using uniform linear array (ULA) discussed and formulated, then the proposed...