Browsing by Author "Baykaş, T."

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    IEEE 802.15.7: Visible light communication standard
    (2017-01-01) Uysal, Murat; Edemen, Çağatay; Baykaş, T.; Sarbazi, E.; Shams, P.; Uğurdağ, Hasan Fatih; Celebi, H.; Electrical & Electronics Engineering; UYSAL, Murat; EDEMEN, Çağatay; UĞURDAĞ, Hasan Fatih
    Visible light communications (VLC) use the visible spectrum (wavelengths of 390-750 nm or frequency band of 400-790 THz) and provide wireless communication using omnipresent light-emitting diodes (LEDs). Since the human eye perceives only the average intensity when light changes fast enough, it is possible to transmit data using LEDs without a noticeable effect on the lighting output and the human eye. Simultaneous use of LEDs for both lighting and communications purposes is a sustainable and energy-efficient approach that has the potential to revolutionize how we use light. VLC can be used in a wide range of short- and medium-range communication applications including wireless local, personal, and body area networks (WLAN, WPAN, and WBANs), vehicular networks, and machine-to-machine communication among many others. Besides energy efficiency, VLC offer several other inherent advantages over radio frequency (RF)-based counterparts, such as immunity to electromagnetic interference, operation on unlicensed bands, additional physical security, and a high degree of spatial confinement allowing a high reuse factor.
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    Optik iletişim sistemlerinde standart CMOS fotodiyotların uygulaması
    (IEEE, 2017) Çamlı, B.; Yalçınkaya, A. D.; Pusane, A. E.; Kısacık, Rıfat; Maç, Muhittin; Uysal, Murat; Baykaş, T.; Electrical & Electronics Engineering; UYSAL, Murat; Kısacık, Rıfat; Maç, Muhittin
    Bu bildiride standart CMOS üretim süreçleri ile gerçeklenmiş, mikroelektronik sistemlere düşük maliyetlerle tümleştirilebilecek fotodiyot yapılarının optik haberleşme sistemlerine uygulanabilirliği incelenmiştir. Silikon alttaş üzerine UMC 180 nm standart CMOS üretim ile gerçeklenmiş 1.05 mm × 1.00 mm alan kaplayan bir fotodiyot, farklı görünür dalga boylarında Power LED’lerin kaynak olarak kullanıldığı bir düzenekte optik alıcı olarak denenmiştir. CMOS fotodiyotun ba¸sarımı referans olarak kullanılan bir Thorlabs PDA10A-EC fotodiyotunki ile karşılaştırılmıştır. Deneylerde, referans fotodiyotun iletim bant genişliğinin 0.87 - 1.68 MHz aralığında olduğu ve CMOS fotodiyotunun 0.70 - 1.37 MHz gibi karşılaştırılabilir değerlerde bantlara erişebildiği görülmüştür. 200 kHz frekansta bir kare dalga işaret, CMOS fotodiyot kullanan bir optik iletişim sisteminde şeklinde kayda değer bir bozulma olmadan aktarılabilmektedir.
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    Opto-electronic receiver system with post-equalization for visible light communications
    (IEEE, 2020-10-05) Kısacık, Rıfat; Erkınacı, T.; Yağan, M. Y.; Pusane, A. E.; Uysal, Murat; Baykaş, T.; Dündar, G.; Yalçınkaya, A. D.; Electrical & Electronics Engineering; UYSAL, Murat; Kısacık, Rıfat
    In this work, A significant increase in the data rate is achieved by designing an opto-electronic receiver for the visible light communication system. LEDs used at the transmitter side in the visible light communication system do not allow to transmit high data rates due to limited bandwidth. With the help of an equalizer, the data rate to be transmitted through LED can be increased. The designed opto-electronic receiver includes photodiode, trans-impedance amplifier (TIA), and equalizer blocks. First, the frequency response of the existing LED is extracted and its bandwidth is measured to be around 700 kHz. After obtaining a clear eye opening by transmitting a data at 1 Mbit/s, it is observed that the signal at the receiver side is impaired due to the intersymbol interference when the data rate is 50 Mbit/s. In the established setup, a data rate of 50 Mbit/s is achieved by using the same LED and the signal is properly received at the output of equalizer. Last, the bit error rate is obtained for higher data rates from 50 Mbit/s to 120 Mbit/s. By using only equalizer, a bit error rate of 10 -2 is achieved for the data rate of 90 Mbit/s by using LED with the bandwidth of 700 KHz.