In this paper we present design and implementation of high-speed transmission system toward Terabit/sec based on Denise Wavelength Division Duplexing (DWDM) system. The presenting system consider new ...solution to carrying rise data rate for long-haul optical transmission system. The system examined for various number of channel (4, 8, 16, and 25). The obtained results show that the propose system immunity for the non-linear impairments. As well as, the performance analysis of different number of optical channels with different data formatting technique such as Return-to-Zero (RZ) and Non-Return-to-Zero (NRZ) is presented.
A 40km long error free optical fiber at 10Gb/s bit rate is demonstrated. The analysis includes the consumption of power, dependency on temperature, Q factor and BER of the system model. The ...performance analysis is done at 1550 nm wavelength for NRZ-OOK, RZ-OOK and 8-QAM modulated system. The temperature can be extended up to 125° C for 2 mA bias current. Overall performances of the system are analyzed by varying temperature, bit rate and fiber length.
Background: Classification systems for use in the diagnosis of mental disorders have been developed based on a categorical model of psychopathology. Although current categorical diagnostic ...classification systems have been found to have good utility and reliability, studies have questioned whether these systems have adequate validity. Dimensional models of psychopathology have been examined as an alternative to categorical diagnostic classification systems and found to be more strongly related to clinical parameters, such as the severity and outcome of mental disorders. A literature review found a small evidence base on dimensional models of psychopathology experienced by adults with intellectual disabilities. However, the findings were limited by small sample sizes, biased samples and inclusion of only a limited range of items of psychopathology. Furthermore, the methods of exploratory factor analysis used do not meet established best practice guidelines. Informed by the existing literature, this thesis aimed to; 1. identify a dimensional model of psychopathology experienced by adults with intellectual disabilities 2. examine the associations of a dimensional model of psychopathology with measures of the severity and outcome of mental disorders 3. compare the predictive validity of dimensional and categorical models of psychopathology. Methods: The Psychiatric Present State- Learning Disabilities (PPS-LD) was used as a structured instrument to collect psychopathology data. Exploratory factor analysis (EFA) following best practice guidelines was used to identify dimensions of psychopathology. Continuous measures representing the dimensions of psychopathology were calculated. Meeting criteria for the diagnosis of a mental disorder from the Diagnostic Criteria for Psychiatric Disorders for use with Adults with Learning Disabilities (DC-LD) was used as the variable representing the categorical model of psychopathology. Baseline data was collected on four measures of severity; the Health of the Nation Outcome Scales- Learning Disabilities (HoNOS-LD), Global Assessment of Functioning (GAF), Clinical Global Impression (CGI), and the Camberwell Assessment of Needs for Adults with Developmental and Intellectual Disabilities- Research version (CANDID-R) unmet needs. These measures were completed again at follow up 4-5 years later and change over time used as a measure of longitudinal outcome. Bivariate statistics and multivariate linear regression were used to examine the associations of the dimensions of psychopathology, and DC-LD diagnosis, with the measures of the severity of and longitudinal outcome of mental disorders. Relevant socio-clinical variables, associated with psychopathology in previous populationbased intellectual disabilities studies were included in the analyses: gender, age, living circumstances, level of intellectual disabilities, autism, Down syndrome, epilepsy, sensory impairments, mobility problems and incontinence. Key results: A model of psychopathology with four dimensions was extracted from the EFA. This model was stable in two additional EFA using random samples. There were no significant correlations between the four dimensions which were labeled depressive,organic, behaviour-affective and anxiety. Only the anxiety dimension of psychopathology was not associated with any of the measures of severity of mental disorders. The depression dimension was independently associated with severity on the HoNOS-LD (β=.413, p<.001), GAF (β=-.402, p<.001) and the CGI (β=.457, p<.001). The organic dimension was independently associated with severity on the HoNOS-LD (β=.205, p=.004), GAF(β=-.326 p<.001) and CGI (β=.266, p<.001). The behaviour-affective dimension was independently associated with severity on the HoNOS-LD (β=.332, p<.001), GAF (β=-.286, p<.001), CGI (β=.253, p<.001) and CANDID-R unmet needs (β=.178, p=.018). Level of intellectual disabilities was independently associated with severity on the HoNOS-LD and CANDID-R unmet needs. Finally, younger age (β=-.208, p=.010), living independently (β=-.599, p<.001) and not having a visual impairment (β=-.191, p=.009) were associated with greater CANDID-R unmet needs. None of the baseline measures of psychopathology were associated with longitudinal outcome on the CANDID-R unmet needs. Baseline scores on the depressive dimension were significantly associated with longitudinal outcome on the HoNOS-LD(β=.297, p=.034), GAF (β=.342, p=.002) and CGI (β=.373, p=.001). Similarly, the behaviour-affective dimension was significantly associated with longitudinal outcome on the HoNOS-LD (β=.292, p=.033), GAF (β=.244, p=.036) and CGI(β=.298, p=.009). The organic dimension was only associated with longitudinal outcome on the HoNOS-LD (β=-.382, p=.006). Individuals with mild intellectual disabilities had poorer outcomes on all four measures of longitudinal outcome. Hearing impairment was associated with poorer outcome on the GAF (β=-.483, p=.000) and CGI (β=-.331, p=.004), and poorly controlled seizures with poorer outcome on the CGI (β=-1.638, p=.004).The variable representing the categorical model of psychopathology was only independently associated with severity on the HoNOS-LD (β=.178, p=.026), and longitudinal outcome on the GAF (β=.259, p=.045) and CGI (β=.257, p=.044). However, when categorical and dimensional models were both included in the regression analyses only the dimensional model of psychopathology was retained as independently associated with these measures of severity and outcome. Conclusions: The description of a stable dimensional model demonstrates the value of using multivariate statistical methods to examine psychopathology experienced by adults with intellectual disabilities. Since the findings suggest that dimensional models have better validity than categorical models of psychopathology, the use of EFA, and other multivariate methods, could contribute to the development of valid diagnostic classification systems. The presence of affective items of psychopathology across the depressive, behaviour-affective and anxiety dimensions highlights the possible relevance of a global affective model of psychopathology. Findings reported in this thesis support the potential relevance of models of affect regulation and affective arousal to developing an understanding of psychopathology experienced by persons with intellectual disabilities. There are similarities between the dimensional model in this thesis and the tripartite model of depression and anxiety psychopathology, described in the literature- which has depressive, anxiety and general distress dimensions. Overlaps between the behaviour-affective dimension, and general distress dimension within the tripartite model, suggest that there may be an association between affective psychopathology and problem behaviours. However, it could be that this association is with affective psychopathology in the general distress dimension, rather than with depressive psychopathology, as examined in previous studies. Confirmatory factor analyses should be considered to examine the four dimension model of psychopathology. Future studies involving individuals with intellectual disabilities should examine the relevance of global affective models of psychopathology.
The performance of radio over fiber (RoF) links using low cost optoelectronic components is assessed for distributed antenna applications in next generation wireless systems. Important design issues ...are discussed and an example link design is presented for a wireless system requiring the transmission of one radio channel per link direction, the proposed optical fiber system is designed to transmit 2 Gbits/s over 5000 km. 1300 nm wavelength is used in the proposed system and single mode optical fiber. Firstly, a random data, RZ pulse generator, 10 dBm 1300 nm laser sources and Mach-Zehnder Modulator (MZM) are used to transmit the 2 Gb/s. The initial link was proposed by using 50 fiber cables are connected every single cable has length of 100 km. Therefore, the total link becomes 5000 km. 50 optical EDFA amplifiers with power of 20 dB have used to amplify the transmitted light power. The results that the received data has BER of 4\times 10-37 by using RZ pulse generator, provided that the wireless system has uplink power control. Finally, a comparison was made between and performance of RoF links for this application and alternative link types that use digitized radio transmission and show that RoF is the optimum choice from a cost perspective..
With the growth in population, the number of devices connected to internet are expected to increase exponentially. The current wireless communication system which is based on radio frequency (RF) ...technology, is not able to satisfy the requirement of high speed data consumption due to limited spectrum availability and network congestion. In this paper we analyse the performance of LiFi communication system by employing an LED with 450 nm wavelength as optical source for communication using RZ-OOK modulation format. Performance of the system has been evaluated through Q factor and BER values for different bit rates and link ranges. The system can support 50 Mbps data rate upto 3.4 m of link range with a Q Factor of 10.71.
This paper proposes and demonstrates a novel all-optical return-to-zero (RZ) to nonreturn-to-zero (NRZ) data format conversion using a semiconductor optical amplifier (SOA) loop mirror. The format ...conversion has been performed between the most widely used data formats—NRZ and RZ formats. The format conversion scheme is based on gain variation by an intensity-dependent phase change in an SOA-loop mirror. 10 Gb/s error-free fiber transmission up to 78 km for the converted NRZ format data is achieved. Further, the proposed method shows improved transmission performance than the conventional Mach-Zehnder modulation technique.
The performance of the Visible Light Communication (VLC) system in a closed room measuring \mathbf{5}\ \mathbf{m\ x}\ 5 \mathbf{m\ x}\ \mathbf{3}\ \mathbf{m} using the Return-to-Zero On Off Keying ...(OOK-RZ) scheme and Non-Return-to-Zero On Off Keying (OOK-NRZ) has been investigated in this paper. The effect of modulation on VLC performance was examined by changing the distance of the receiver to the sender to produce a maximum point of 3.19 m for OOK-NRZ modulation, 2.91 m for OOK-RZ modulation with the threshold Bit Error Rate (BER) around 10 −3 . Using a 7 Watt Light Emitting Diode (LED) light that is positioned at an altitude of 3 m at one end of the roof of the room with the initial position of the receiver 2.15 m. Each of the maximum distances generated by the two types of modulation mentioned has the value of a wide range of communication coverage OOK-NRZ obtained 13.8 m 2 and OOK-RZ obtained 11.3 m 2 , with the OOK-NRZ coverage area wider than OOK-RZ.
One way to support the large need for information services is by building reliable network architectures such as optical networks. The challenge faced in providing an optical network is the process ...of deploying cables that can change the spatial layout of an area. An alternative solution of that problem is by applying the concept of optical wireless communication such as Free Space Optics. The application of optical wireless communication is affected by barriers between transmitter and receiver. This study focuses on weather factors and atmospheric turbulence factors that affect network performances of Free Space Optics measured by Bit Error Rate (BER) values using Signal-to-Noise Ratio (SNR) calculations. SNR calculation is based on the On - Off Keying modulation scheme which is divided into two, NRZ - OOK and RZ - OOK. In addition, the use of different wavelengths between 690, 780, 850, and 1550 nm will be compared to find out the factor of wavelength selection to the value of BER obtained. The results of this study indicate that the use of the RZ-OOK modulation scheme gives around 10 10 lower BER value than NRZ-OOK in fog conditions. The wavelength of 1550 nm is very suitable for FSO technology because the BER value is around 10 50 lower than the other wavelengths. The difference is very significant. Network implementation in accordance with the parameters used in this study can only be implemented in the range of 0 - 1.2 km to get acceptable BER which is correlated to optical communication standard.
Optical fiber is the link and the backbone of the communication system. This is especially where fiber optic undersea is found low loss, high efficiency and large effective area major for enabling ...system to transmit big data up to thousand kilometers with less distortion. In this paper, we designed 220 Km fiber optic system with data rate 40 Gb/s in the term of two scenario: the first scenario used fiber optic cable with 80 \mu M core diameter and the second scenario used optic fiber cable with 17 \mu M core diameter which made the transmission signal for long distance very difficult. Observing the first scenario, the signal transmitted with less dispersion and less bit error rate 2.956^{\star}10^{-44} over 220 Km. the signal transmitted over 220 Km with high chromatic dispersion in the second scenario. To avoid chromatic dispersion using, an ideal dispersion compensation FBG, was used to reflect the undesired signal. The received signal on the other side with bit error rate of 4.8625 *10^{-13}.
