Extremely low frequency based communication link

The paper discusses the literature review and the possibility of using the ground itself as transmission medium for various users’ transceivers and an administrator transceiver using Multi-Carrier-Direct Sequence-Code Division Multiple Access (MC-DS-CDMA), Orthogonal Frequency Division Multiplexing (OFDM),16-Quadrature Amplitude Modulation (16-QAM), Frequency Division Duplex (FDD) and Extremely Low Frequency (ELF) band for the applications of Oil Well Telemetry, remote control of power substations or any system that its responding time is not critical

Performance of Di-code Pulse Position Modulation Technique in Diffuse Indoor Wireless Optical Communication Systems

The bandwidth of the indoor optical wireless Pulse Position Modulation (PPM) system can be exploited to improve the receiver sensitivity by using Di-code Pulse Position Modulation (Di-PPM) technique. This paper analysis the receiver sensitivity of indoor optical wireless Di-PPM systems, over a slightly dispersive channel, uses a bandwidth-limited PIN-bipolar (PINBJT) optical receiver, zero guard interval and pre-detection filter based on a simple third-order Butterworth filter, that authorizes the receiver to operate over channels with bandwidth as low as 1.2 times the bit rate. The received pulse shape is a convolution between the impulse response of a diffuse optical wireless link in a ceiling bounce model and rectangular waveform, the operating bit-rate chosen is 100Mbit/s. In this paper the performance analysis is extended in order to include the effects of intersymbol interference (ISI) on error probability and some important errors: wrong slot, erasure and false alarm. A mathematical model is then presented showing how the transfer function of the indoor optical wireless Di-PPM receiver can be calculated. Results are obtained and the pulse shape at input of receiver decision device is illustrated by using MathCAD software

Optical fibre digital pulse-position-modulation assuming a Gaussian received pulse shape

The abundance in bandwidth available in the best monomode fibres may be exchanged for improved receiver sensitivity by employing digital PPM. The paper presents a performance and optimisation analysis for a digital PPM coding scheme operating over a fibre channel employing a PIN-BJT receiver and assuming a Gaussian received pulse shape. The authors present original results for a 50 Mbit/s, 1.3 μm wavelength digital PPM system and conclude that, provided the fibre bandwidth is several times that of the data rate, digital PPM can outperform commercially available PIN-BJT binary PCM system

WLAN 802.11e evaluation performance using OPNET

The low cost and easy deployment of Wireless LAN 802.11 standard means it becomes more and more popular, but it has a vital drawback with regard to Quality of Service (QoS). QoS defines the ability of network to introduce consistent services for data transmission, and is evaluated in terms of specific parameters such as jitter, delay, and packet loss. These parameters describe data traffic quality over a network. Service differentiation should be offered to let higher priority multimedia traffic to get a preferred treatment. This deficiency of Wireless LAN 802.11 MAC mechanisms in offering QoS support is a major obstacle in the adaptation of modern multimedia applications in Wireless LAN 802.11 networks. This paper aims to build different scenarios to evaluate QoS characteristics and to examine the effect of enhancement on the QoS. The evaluation, implemented using the OPNET simulator, will contain the different parameters of Wireless LAN 802.11e to see how this enhancement in distributed channel access increases the performance over the Wireless LAN 802.11 standard. The results give a clear picture that the enhanced standard offers a very effective service mechanism to provide QoS support

Visible Light Communication Based On Offset Pulse Position Modulation (Offset-PPM) Using High Power LED

In this paper, the performance of a visible light communication (VLC) system based on offset pulse position modulation (Offset-PPM) has been demonstrated using a commercial high power white single LED (30 W) and the new coding scheme. Data at a speed of 11 Mbps has been successfully transmitted over a distance of 1 m with zero bit error rate (BER), and 18 Mbps with 1.15 × 10^-6 of BER through the simplest transceiver circuits

Practical implementation of duobinary pulse position modulation using FPGA and visible light communication

Low bandwidth expansion modulation schemes are preferred for free space and optical fibre data transmission, where limited bandwidth is available. One such scheme is duobinary pulse position modulation (DuoPPM), which is the subject of this paper. DuoPPM scheme is not as sensitive to bandwidth expansion issues as digital PPM, with a line rate of twice the data rate. This paper discusses first time practical implementation of DuoPPM coding scheme and its application in free space using visible light LED (30 W) for transmission purposes. Experimental results achieved at the data rate of 14 Mbit/s indicate an error rate that is better than 1 error in 109.The main aim is to analyse the practicality, robustness and limitations of DuoPPM

Chrysalis Spring 1984

https://commons.lib.jmu.edu/chrysalis-1980s/1001/thumbnail.jp

Visible light communication based system using high power LED and dicode pulse position modulation technique

In this paper a dicode pulse position modulation (DiPPM) technique has been successfully implemented for an indoor visible light communication (VLC) based system using an FPGA and a commercial high power white LED (30W). A data rate of 13 Mbps has been achieved with a bit error rate (BER) <10-11 at a free space distance of 1.2 m through a basic transceiver circuit, and 14.5 Mbps with 1.15x10-6 of BER. Furthermore, a data rate of 13 Mbps has been successfully transmitted over a distance of 1.8 m with BER of 10-5. This proves that the application of DiPPM is a viable modulation system over free space communication links

Fault detection algorithm for multiple GCPV array configurations

In this paper, a fault detection algorithm for multiple grid-connected photovoltaic (GCPV) array configurations is introduced. For a given set of conditions such as solar irradiance and photovoltaic module temperature, a number of attributes such as power, voltage and current are calculated using a mathematical simulation model. Virtual instrumentation (VI) LabVIEW software is used to monitor the performance of the GCPV system and to simulate the theoretical I-V and P-V curves of the examined system. The fault detection algorithm is evaluated on multiple GCPV array configurations such as series, parallel and series-parallel array configuration. The fault detection algorithm has been validated using 1.98 kWp GCPV system installed at the University of Huddersfield. The results indicates that the algorithm is capable to detect multiple faults in the examined GCPV plant and can therefore be used in large GCPV installations