Elektronik ve Haberleşme Mühendisliği Bölümü Yayın Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/260
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Article Citation - WoS: 4Citation - Scopus: 4The Performance Bounds of an Optical Communication System Using Irradiance Profile Modulation(Taylor & Francis Ltd, 2017) Eyyuboglu, Halil T.We assess the performance bounds of an optical communication system that uses irradiance profile modulation. This modulation is based on the four different orders of vortex beams. To this end, we find the turbulence induced average irradiance profiles of Gaussian, Bessel-Gaussian and modified Bessel-Gaussian vortex beams on the receiver plane. Each one is then cross correlated against the free space equivalents. Plotting the cross-correlation coefficients, it becomes possible to identify the borders of correct decision and error regions, thus, deduce the performance bounds of such a system. When measured in terms of structure constant, i.e. the turbulence strength and the propagation length being fixed to 3km, it is seen that the error region extends beyond the structure constant values of 10(-13) m(-2/3) and higher. There seem to be some variations with the beam type and the order of the vortex beam. The performance of Bessel-Gaussian vortex beam comes out to be slightly better than the rest.Article Citation - WoS: 2Citation - Scopus: 2Correction of Amplitude Distortions for Truncated Bessel Beam and Ser Estimation for 4ask(Taylor & Francis Ltd, 2016) Eyyuboglu, Halil T.We apply amplitude corrections to a truncated Bessel beam that has propagated through turbulent atmosphere modelled by random phase screens. These corrections are realized via transmitting an unmodulated beam in parallel to the one carrying the 4 amplitude shift keying (ASK) modulated message signal. On the receiver side, the amplitude corrections are obtained by dividing the intensity of the unmodulated beam by its free space equivalence. The corrections are then used to restore the amplitude distortions of the beam carrying the 4ASK modulated message signal and in the determination of decision boundaries for the received 4ASK symbols. The success of the system is visually inspected by comparing the received intensity profiles before and after the application of corrections. Furthermore, simulation analysis of symbol error rate (SER) is made, where the proposed set-up is found to be quite insensitive to wavelength difference between the unmodulated and modulated beams. On the other hand, the difference in the structure constant values of these two beams seems to have profound effect on system performance.Article Citation - WoS: 11Citation - Scopus: 12Bit Error Rate Analysis of Gaussian, Annular Gaussian, Cos Gaussian, and Cosh Gaussian Beams With the Help of Random Phase Screens(Optical Soc Amer, 2014) Eyyuboglu, Halil T.; Eyyuboʇlu, Halil T.Using the random phase screen approach, we carry out a simulation analysis of the probability of error performance of Gaussian, annular Gaussian, cos Gaussian, and cosh Gaussian beams. In our scenario, these beams are intensity-modulated by the randomly generated binary symbols of an electrical message signal and then launched from the transmitter plane in equal powers. They propagate through a turbulent atmosphere modeled by a series of random phase screens. Upon arriving at the receiver plane, detection is performed in a circuitry consisting of a pin photodiode and a matched filter. The symbols detected are compared with the transmitted ones, errors are counted, and from there the probability of error is evaluated numerically. Within the range of source and propagation parameters tested, the lowest probability of error is obtained for the annular Gaussian beam. Our investigation reveals that there is hardly any difference between the aperture-averaged scintillations of the beams used, and the distinctive advantage of the annular Gaussian beam lies in the fact that the receiver aperture captures the maximum amount of power when this particular beam is launched from the transmitter plane. (C) 2014 Optical Society of AmericaArticle Citation - WoS: 33Citation - Scopus: 38Propagation Analysis of Ince-Gaussian Beams in Turbulent Atmosphere(Optical Soc Amer, 2014) Eyyuboglu, Halil T.; Eyyuboʇlu, Halil T.We analyze the properties of Ince-Gaussian beams propagating in turbulent atmosphere. Due to analytic difficulties, this analysis is done with the aid of a random phase screen setup. Intensity profile, beam size, and the kurtosis parameter are evaluated against the changes in beam orders, propagation distance, and turbulence levels. It is found that when propagating in turbulence, Ince-Gaussian beams will no longer keep their beam profile invariant like in free space but will experience beam profile changes. These changes will cause additional beam spreading, as well as an increase in beam size and the kurtosis parameter. (C) 2014 Optical Society of America