In wireless channel the noise has a zero mean. This channel property can be used in the enhancement of the noise performance in the digital receivers by oversampling the received signal and calculating the decision variable based on the time average of more than one sample of the received signal. The averaging process will reduce the effect of the noise in the decision variable that will approa...

In this paper, we present an analytical model to analysis the kirk effect onstatic and dynamic responses of quantum well heterojunction bipolar transistor lasers(HBTLs). Our analysis is based on solving the kirk current equation, continuityequation and rate equations of HBTL. We compare the performance (current gain,output photon number and small signal modulation bandwi...

Last years, Wavelet Packet Modulation (WPM) or Wavelet Packet Transform based Orthogonal Frequency Division Multiplexing (WPT-OFDM) have been introduced to wired and wireless communication fields as efficient Multicarrier Modulation (MCM) techniques. The wavelets have interesting features such as flexibility, compatibility and localization in both time and frequency domains with no need to use ...

Abstract The design can measure and display other parameters such as the modulation system of measured signal output by source, identify mode signal, demodulation signal. measurement module is composed an automatic gain amplifier circuit, a broadband amplifier, low-pass filter DDS generation amplification circuit. working principle measuring device that demodulated AM obtained after spectrum tr...

background and objective: vep is a powerful method to study visual system via evaluating evoked potentials. technologic and instrumental restrictions may be the reason of having studies on optical modulation and induction such as color, spatial frequency and contrast. developments of computer software and hardware may lead to an increase in the flexibility of pattern designs. material and meth...

The modulation response, relative intensity noise (RIN) and frequency noise (FN) characteristics of quantum dot (QD) lasers are investigated theoretically in the presence of an external optical beam. Using small signal analysis of the rate equations for carriers and photons, it is demonstrated that by injecting excess carriers into the QDs excited state through optical pumping, the modulation r...

introduction: atherosclerosis, hypertension, ischemic diseases, alzheimer’s disease, parkinson disease, cancer and inflammation emerge from imbalance between antioxidant and oxidants. cancer is a most important public health problem in both developed and developing countries. natural antioxidants such as polyphenols are being used for prevention and treatment cancer. polyphenols include phenoli...

Artificial neural network (ANN) has application in communication engineering in diverse areas such as channel equalization, channel modeling, error control code because of its capability of nonlinear processing, adaptability, and parallel processing. On the other hand, wavelet transform (WT) with both the time and the frequency resolution provides the exact representation of signal in both doma...