This paper investigates the multiplicative spread spectrum watermarking method for the image. The information bit is spreaded into middle-frequency Discrete Cosine Transform (DCT) coefficients of each block of an image using a generated pseudo-random sequence. Unlike the conventional signal modeling, we suppose that both signal and noise are distributed with Laplacian distribution, because the ...

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...

In this paper, we present a high accuracy laser range finder and velocimeter using ultra-fast time-to-digital converter (TDC). The system operation is based on the measuring the round-trip time of a narrow laser pulse. A low-dark current high-speed PIN photodiode is used to detect the triggered laser beam and to produce start signal. The pulsed laser diode generates 45W optical power at 30ns du...

Settling time is one of the most important parameter in design of DLLs. In this paper we propose a new high speed with low settling time Delay Locked Loop (DLL) in which a digital signal processor (DSP) is used instead of using phase-frequency detector, charge pump and loop filter in conventional DLL. To have better settling time, PRP conjugate gradient algorithm is used to optimize delay of ea...

this paper presents the design and simulation of a typical ka band satellite beacon receiver for propagation experimentation. using satellite beacon signal as a reference signal in satellite wave propagation study, is one of the most important methods. satellite beacons are frequently available for pointing large antennas, but such signals can be used for measuring the effect of natural phenome...

This paper addresses an approximation-based anti-windup (AW) control strategy for suppressing the windup effect caused by actuator saturation nonlinearity in proportional–integral–derivative (PID) controlled systems. The effect of actuator constraint is firstly regarded as a disturbance imported to the PID controller. The external disturbance can then be modeled by a linear differential equatio...