نشریه مهندسی مخابرات جنوب
پیاپی 25 (پاییز 1396)

Nowadays, biometric systems have received a lot of attention. Iris identification is one of the safest and most reliable biometric methods. Fast, reliable, and reliable algorithms are needed to implement these biometric systems in real-time. In this paper, a useful local technique for identifying the pupil and iris boundaries using the iris image histogram is presented. Two small iris sections have been used for symmetrical conversion to reduce computation time and increase system efficiency. Wavelet transform has been used to generate feature vectors. The system was tested on a hypothetical iris database we created. The results show that the proposed system increases efficiency.

QoS is a measure of the level of service provided to users and is the degree of confidence that an application can have in meeting the needs of the network. Various factors are involved in evaluating the quality of service, including availability, efficiency, the time required to communicate, percentage of successful transfers, and speed of error detection and correction. In the VoIP category, service quality is measured in terms of available and available bandwidth, packet loss rates, latency, and jitter changes. In order to have the desired quality in high-delay applications on the IP network, it must be ensured that the values ​​of the mentioned parameters for each session are in a certain range. In this paper, the presented solutions in the field of digital signal processing to improve the quality of service are expressed and in each step, the results of the simulations are compared and evaluated. Finally, an attempt has been made to select and determine the optimal method.

A new silicon ADC with digital error correction is introduced to reduce the linear error caused by inaccurate comparators and S / H offset. The operation of the new low voltage balanced current mode circuit in sampling and maintenance, signal amplification and current comparison function has been developed to detect how a silicon ADC silicon current mode with 1.5 V power supply works. Results are shown with Hspice to bring ADC at conversion rates of 10n / s and power losses of less than 2mW. In this simulation, SFDR is equal to 60 dB and ENOB is equal to 8, which are almost acceptable values.

a physical model is presented for GNR based photo detector. The photo detector structure is photodiode in which GNR is inserted between two electrodes as a tool for changing pick frequency of absorption.  Optical properties of GNR discussed using tight-binding approximation and DOS coupled with conductivity. Our calculations have shown that GNR based photo detectors have better characteristics than semiconductor devices and they have appropriate characteristic for communication applications.

A CMOS voltage controlled oscillator with a wide adjustment range is designed to operate at radio frequencies. The main advantage of this structure is the use of an active inductor. Hence the chip surface is significantly reduced. The active inductor and varactor capacitor in the proposed VCO circuit is used for frequency settings. The results of the measurements using the 0.18 µm CMOS process show phase noise -79.85dBc and amplitude noise -126.9dBm in the 1MHz offset. Also, using the S parameter, the central frequency value for this 3GHz circuit is obtained.

An equalizer is used to eliminate the effect of symbolic interference (ISI) in telecommunication channels. One of the equalizer methods that does not require the use of a training sequence is the Godard blind equalizer method. The efficiency of this method decreases significantly in the case of distortion in the phase and frequency of the sent symbols. Therefore, the use of a phase lock loop (PLL) at the output of this equalizer is recommended to eliminate the phase shift and frequency offset added by the channel. In this paper, two types of first and second-order phase lock loops are investigated and confirmed by simulation. The first-order phase lock loop can only remove the fixed phase shift, and the second-order phase lock loop, in addition to the fixed phase shift, can also remove the channel offset frequency.