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

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

Reconfigurable Digital Coherent Receiver for Hybrid Optical Fiber/Wireless Metro-Access Networks

Single reconfigurable DSP coherent receiver is experimentally demonstrated for mixed-format and bit-rates including QPSK, OFDM, IR-UWB for wireline and wireless signal types. Successful transmission and detection over a deployed fiber link is achieved

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030

VISIBLE LIGHT COMMUNICATION (VLC) SYSTEM FOR AUDIO TRANSMISSION

Limited radio frequency spectrum (or bandwidth) is one of the major issues in wireless communication. Visible light communication (VLC) should be considered as the medium for wireless transmission because it has few advantages over other standard wireless transmissions. The advantages of VLC are low power consumption. The visible light spectrum have 10,000 times larger than the entire radio frequency spectrum which ranges from 428 THz to 750 THz. In this project the performance of visible light communication have been tested on the variation of distance between transmitter and receiver. Besides that the influence of the additional amplifier at the transmitter and receiver on the VLC system are also been characterized. Based on the results and analysis the implementation of the amplifier circuit at the transmitter and receiver helps to improve the signal quality of the audio signal in the VLC system. However the amplifier also increased the noise in this system. Moreover, the distance between transmitter and receiver can give influence to the system performance. The longer the distance means that the signal strength and voltage which has been received by the receiver decreased and cause the data loss in the system. As a conclusion this audio transmission in the VLC system are working properly and have been successfully demonstrated. However the maximum of distance between transmitter and receiver is limited to 20 cm.Keywords – Wireless Communication, Visible Light Communication, Audio Transmissio