Characterization of acoustic signals due to surface discharges on H.V. Glass insulators using wavelet radial basis function neural networks

A hybrid model incorporating wavelet and radial basis function neural network is presented which is used to detect, identify and characterize the acoustic signals due to surface discharge activity and hence differentiate abnormal operating conditions from the normal ones. The tests were carried out on cleaned and polluted high voltage glass insulators by using surface tracking and erosion test procedure of international electrotechnical commission 60587. A laboratory experiment was conducted by preparing the prototypes of the discharges. This study suggests a feature extraction and classification algorithm for surface discharge classification, which when combined together reduced the dimensionality of the feature space to a manageable dimension, by “marrying” the wavelet to radial basis function neural network very high levels of classification are achieved. Wavelet signal treatment toolbox is used to recover the surface discharge acoustic signals by eliminating the noisy portion and to reduce the dimension of the feature input vector. A radial basis function neural network classifier was used to classify the surface discharge and assess the suitability of this feature vector in classification. This learning method is proved to be effective by applying the wavelet radial basis function neural network in the classification of surface discharge fault data set. The test results show that the proposed approach is efficient and reliable

Bandwith efficient hybrid wireless-opical broadband-access network (WOBAN) based on OFDM transmission

In this paper, a simple and bandwidth efficient hybrid wireless-optical broadband access network (WOBAN) based on orthogonal frequency division multiplexing (OFDM) is pro- posed and designed. It is an optimal combination of an optical backhaul and a wireless front-end for an e±cient access network. The bandwidth e±cient WOBAN based on OFDM provides an effective solution to eliminate intersymbol interference (ISI) caused by dispersive channels. There are two factors considered important here; multipath fading in wireless link and dispersion effects in fiber link. The physical layer performance is analyzed in terms of bit error rate (BER), error vector magnitude (EVM), and signal-to-noise ratio (SNR). An 8 Gb/s data rate has been achieved by the optical backhaul along optical ¯ber length of 20 km. The wireless front-end access point supports data rate up to 240 Mb/s along an outdoor wireless link

Capacity improvement of TWDM-PONs exploiting the 16-qam technique for downstream side with a nonlinearity effect study for upstream DML

Currently, the main goal of developing time-wavelength-division multiplexing passive optical networks (TWDM-PONs) is to acquire capacity improvement in a scalable and cost-effective manner. In response to the challenge, this paper demonstrates a full-system TWDM-PON through physical layer simulation that provides 56 Gb/s downstream and 40 Gb/s upstream bandwidths. We propose a simple and cost-effective scheme to improve the capacity of the downstream signal by utilizing highly spectrally efficient 16 quadrature amplitude modulation (QAM) with 20 GHz radio-over-fiber signal distribution using a single sideband signal that is generated by an optical dual-arm modulator. In addition, we study the effect of nonlinearity on a directly modulated laser (DML) as the upstream laser of an optical network unit. The outcomes obtained revealed good transmission quality in both directions, where bit error ratios of 10-6 and 10-5 are obtained for the downstream and upstream transmissions, respectively. This leads to the ability to support up to 128 users over 40 km of single-mode fiber

Single and multiple transceiver simulation modules for free-space optical channel in tropical Malaysian weather

Free space optics (FSO) is an optical communication technology that uses light propagating in free space to transmit data for telecommunications or computer networking, and is exposed to atmospheric attenuation, like absorption and scattering. These types of attenuations seriously degrade the strength of transmitted signal, especially when single beam FSO system is used. So to overcome this problem, a multiple beam FSO transceiver system has become dominance and is usually used. In this paper simulation models are obtained by using average rain attenuation which is evaluated from the five months collected rain intensity data. These models are obtained to demonstrate the results concerning link distance and received optical power of using multiple beam FSO system and comparing it with single beam FSO system. Comparison is carried out in terms of signal to noise ratio (SNR), geometrical losses, atmospheric losses, and bit error rate (BER). From the results it is clear that, by using up to four beams has improved geometrical loss, sensitivity of the receiver, SNR, and link distance

Scalability analysis of hybrid optical wireless access network (HOWAN)

The hybrid optical wireless access network (HOWAN) is a prestigious architecture for next generation (NG) access network. NG access networks are proposed to provide high data rate, broadband multiple services, scalable bandwidth, and flexible communication for manifold wireless end-users (WEUs). In the proposed HOWAN, the optical backhaul and the wireless front-end are implemented by using wavelength division multiplexing/time division multiplexing passive optical network (WDM/TDM PON), and WiFi wireless access technique respectively. In this paper, the scalability of the optical backhaul in terms of the number of supported APs and link reach range are analyzed. The scalability of the optical backhaul based on maximum split ratio of 1/32 for each wavelength channel and a fiber length around 23 km from the central office (CO) to the access point (AP) is analyzed with bit error rate (BER) of 10-9

Cost-effective 2.5 gb/s bidirectional WDM pon using single optical source at the central office

Nowadays, the bandwidth demand of the telecommunication network is growing rapidly due to the increasing number of technology-intelligent users. Optical broadband access networks have emerged to address two issues: (1) channel capacity sharing fairly to the customers, and (2) adequate capacity assignment according to service requirements. The wavelength division multiplexing passive optical network (WDM PON) is a promising solution to provide high data rate, excellent scalability, good protocol transparency and easy upgradability. In this paper, a cost-effective bidirectional WDM PON is proposed to provide symmetrical 2.5 Gb/s by using just single optical laser diode (LD) at the central office (CO). The optical frequency upconversion (OFU) technique is used to implement the proposed network. At the optical network unit (ONU), the reflective semiconductor optical amplifier (RSOA) reuses and amplifies the downlink wavelength to modulate the upstream data. The bit error rate (BER) performance and eye diagrams of the designed system are investigated

Emerging optical broadband access networks from TDM PON to OFDM PON

The bandwidth requirements of the telecommunication network users increased rapidly during the last decades. The emerging optical access technologies must provide the band-width demand for each user. The passive optical access networks (PONs) support a maximum data rate of 100 Gbps by using the orthogonal frequency division multiplexing (OFDM) technique in the optical access network. In this paper, the enabling optical broadband access networks with many techniques are presented and compared. The architectures, advantages, disadvantages, and main parameters of these access networks are discussed and reported. A combination of differ-ent techniques in a hybrid PON network introduces a cost-effective, reliable and efficient access network. The hybrid optical broadband access technologies are presented which have many ad-vantages to become next-generation broadband access networks. The concept and architecture of the hybrid optical broadband access networks are discussed

Experimental characterization and analysis for ultra wideband outdoor channel

This paper reports on an experimental characterization of ultra wideband (UWB) outdoor channel over a frequency range of 3.1–5.3 GHz. Time domain measurements were conducted for line-of-sight scenarios. The acquired measurement data are characterized in terms of path-loss exponents, root mean square (RMS) delay spread, K-factor and channel capacity. Results show that the path-loss exponents range between 1.4 and 2.1 for the log-distance propagation model and the RMS delay spread was found to be between 1.2 and 3.4 ns. Different statistical distributions for the delay spread were also investigated. Results of the statistical analysis also show that the correlation between RMS delay spread and transmitter receiver separation distance is very low. The small-scale fading analysis indicated that UWB signals experience Rician fading, where the maximum value of K-factor is 11 dB