COMPARISON OF NON CHIRPED NRZ, CHIRPED NRZ AND ALTERNATE-CHIRPED NRZ MODULATION TECHNIQUES FOR FREE SPACE OPTIC (FSO) SYSTEMS

Free Space Optics (FSO) is the technology where transmission occurs through optical waveform that contains datatransformed at the transmitter from electrical signal. Since the transmission medium of FSO is atmosphere, atmosphericscattering is the major cause for interruption of FSO link. Non return zero (NRZ) modulation is the dominant modulationscheme employed in commercial terrestrial Free Space Optic (FSO) communication systems. This research are requiredto investigate three viable modulation techniques; NRZ pulse formats, non-chirped NRZ, chirped NRZ, and alternatechirpedNRZ at 10 Gb/s and 40 Gb/s data rate. The 1550 nm of continuous wave (CW) laser is modulated with threedifferent modulation formats over 1 km of FSO channel. The signal is propogated at different attenuation value based onMalaysia weather conditions. In this paper we have successfully compared the three modulation techniques in FSOsystem due to the Malaysia weather and the performance is accessed at bit error rate (BER) of 1x10-9. The presentedsimulation of these three modulation shows that alternate-chirped NRZ has slightly better performance compared to thenon-chirped NRZ and chirped NRZ modulation format at clear weather, haze, light rain, medium rain and heavy rain.We believe that, this system is an alternative for the future optical wireless network that has a potential to be installed inthe urban and sub-urban area.Key words: Free Space Optic (FSO) Non Return Zero (NRZ) Chirping Modulatio

Edible oils adulteration analysis by fiber optic multimode displacement sensor

A fiber optic sensor has been developed to detect the adulteration in edible oil, particularly coconut oil. In this paper, the sensing mechanism uses MMF-MMF based on displacement sensors by employing the lateral offset method. The distance offset set were 4.42 μm, 7.49 μm, and 7.83 μm. The refractive index for pure coconut oil, paraffin oil, and palm oil are found to be 1.4481, 1.4585, and 1.4634 respectively. The sensitivity of each sensor was determined by referring to the highest offset distance of each fiber. Upon completion, the highest sensitivity was observed for 7.83 µm lateral offset distance which is 0.406 dBm/mol for palm oil detection and 0.437 dBm/mol for paraffin oil detection. The experimental results proved that the larger the offset distance, the higher the sensitivity of the fiber sensor

Comparison of Non Chirped Nrz, Chirped Nrz and Alternate-chirped Nrz Modulation Techniques for Free Space Optic (Fso) Systems

Free Space Optics (FSO) is the technology where transmission occurs through optical waveform that contains datatransformed at the transmitter from electrical signal. Since the transmission medium of FSO is atmosphere, atmosphericscattering is the major cause for interruption of FSO link. Non return zero (NRZ) modulation is the dominant modulationscheme employed in commercial terrestrial Free Space Optic (FSO) communication systems. This research are requiredto investigate three viable modulation techniques; NRZ pulse formats, non-chirped NRZ, chirped NRZ, and alternatechirpedNRZ at 10 Gb/s and 40 Gb/s data rate. The 1550 nm of continuous wave (CW) laser is modulated with threedifferent modulation formats over 1 km of FSO channel. The signal is propogated at different attenuation value based onMalaysia weather conditions. In this paper we have successfully compared the three modulation techniques in FSOsystem due to the Malaysia weather and the performance is accessed at bit error rate (BER) of 1x10-9. The presentedsimulation of these three modulation shows that alternate-chirped NRZ has slightly better performance compared to thenon-chirped NRZ and chirped NRZ modulation format at clear weather, haze, light rain, medium rain and heavy rain.We believe that, this system is an alternative for the future optical wireless network that has a potential to be installed inthe urban and sub-urban area

Comparison of Cap and QAM-DMT Modulation Format for In-Home Network Environment

Carrierless amplitude phase (CAP) modulation format has appeared as a potential advanced modulation format candidate for spectrally efficient single-carrier modulation type due to less complexity and has competitive performance. In this paper, the comparison between 2D-CAP-4 and 4-QAM-DMT modulation format over 3 km single mode fiber (SMF) transmission link using 1310 nm vertical cavity surface emitting laser (VCSEL) has been performed for inhome network environment. The net bit rates of 625 Mb/s and 454.6 Mb/s are achieved for 2D-CAP-4 and 4-QAM-DMT, respectively. Spectral efficiencies of 1.89 b/s/Hz for 2D-CAP-4 and 1.43 b/s/Hz for 4-QAM-DMT are reported. It is observed that 2D-CAP-4 outperforms 4-QAM-DMT with 1.14 dB better receiver sensitivity. These results indicate that the privilege properties of CAP modulation format can be an attractive prospect for in-home network environment

Examination of adulterated coconut oil by fiber optics displacement sensor using lateral offset approach

A single-mode fiber (SMF) sensor for detecting coconut oil adulteration is proposed. Coconut oil is commonly used in cooking but health problems are caused by its adulteration. The lateral offset approach to the SMF-SMF displacement sensor was employed in this experiment to analyze the sensing responses of adulterant concentrations in coconut oil. The offset distances of the sensing probe were set at 6.47 µm, 11.57 µm, and 14.64 µm. Pure coconut oil, paraffin oil, and palm oil have an initial refractive index of 1.4481, 1.4585, and 1.4634, respectively. Upon completion, the highest sensitivity was observed at a lateral offset distance of 14.64 µm. These values were 0.286 dBm/mol for palm oil detection and 0.045 dBm/mol for paraffin oil detection. The findings of these experiments also showed that the larger the offset distance, the greater the sensitivity of the fiber sensor

Comparison of wavelength propagation for free space optical communications

This paper presents the effect of atmospheric attenuation during severe hazy days for Free Space Optical Communications. The usage of Free Space Optical Communications is still rare in Malaysia due to environment factor. The FSO technology is also known as unguided beam or ‘optical wireless’ or infrared broadband. This study offers quick preliminary investigation on possible FSO performance based on wavelength selection before final commissioning and installation at site. Thus, FSO installers could make quick judgment before giving recommendation of a suitable wavelength to the customers. Preliminary evaluation of system performance of system performance is done by using local weather data obtained from metrological department. Current study among designers and FSO users show that 1550nm light produce less atmospheric attenuation in the transmission under all weather conditions. In this study, a suitable wavelength for FSO system is found for a particular site in low visibility. The best wavelength selection would result in optimized quality of FSO transmission in hazy conditions