The performance bound of a hybrid radio frequency-underwater wireless optical communication (RF-UWOC) system with inverse Mellin transform is investigated. The RF link obeys the Nakagami-m distribution while the UWOC link undergoes the mixture Exponential-Generalized Gamma(EGG) distribution under heterodyne detection and intensity modulation direct detection. In the first place, the inverse Mellin transform technique is applied to derive closed expressions for the upper bound of the probability density function (PDF). By capitalizing on these statistics, the boundaries of the outage probability, the average bit error rate, and the average channel capacity are acquired. The expressions are verifified by the Monte Carlo simulation. The results indicate that the performance of the system is superior when the relay gain is the second case.
A refractive index (RI) sensor and its sensing characteristics based on surface plasmon resonance (SPR) of D-shape double core photonic crystal fiber (DC-PCF) are researched theoretically in this letter. The basic sensor principle is the SPR light intensity modulation of polished D-shape DC-PCF. The influence of the polished angle and depth on the DC-PCF SPR characteristics is discussed extensively by using the finite element method (FEM). The effects of the coated metal type and its layer thickness on the resonant intensity are also analyzed. The relationship between the analyte RI and resonant wavelength is numerically simulated. The theoretical results show that the sensor’s RI sensitivity exhibits about 2000 nm/RIU with the structure parameters of 60° polished angle, 58.5μm polished depth and 70nm thickness of the silver layer. Furthermore, if the single wavelength laser is chosen, the detection of the two core light intensity difference will improve the ability of resistance to environmental interference. The simple sensor structure and high sensitivity can make this technology for online refractive index measurement in widespread areas.
A novel structure of high voltage transducer's head is designed in this paper. Three pieces of quartz crystal is
sandwiched between four metal electrodes. The converse piezoelectric effect of quartz crystal is used to sense the voltage
applying on the transducer. In this paper, more attention is paid to selection of the crystal material, the shape of the
electrode, the electrode material, the dimension of the electrode, and the distance of the electrode. After simulated with
finite element method, the distribution of electric field at different condition is obtained. At last, an experiment is set up
to validate the feasibility of applying intermodal interference in elliptical-core polarization maintenance fiber (E-core
PMF) on high voltage transducer.
This paper investigates the principle of interference between modes in fiber, and gives the relationship between
interference of LP01 and LP11even mode and the axial length variety in ideal fiber. A novel scheme of voltage
transducer based on interference between modes is brought out. A PANDA fiber wrapped quartz crystal sandwiched with
two pieces of metal electrodes works as sensing interferometer. When voltage is applied on the metal electrode,
circumference of quartz crystal will change. This can modulate the light path difference of LP01 and LP11even mode in
fiber. A receiving interferometer balances the light path difference with a fiber wrapped piezoelectric ceramics and a
phase tracer. Control voltage of the receiving interferometer is output signal of the transducer. Simulation result and
adjusting method of dynamic range is given in the paper. It can provide a new method for designing voltage transducers.
KEYWORDS: Optical fibers, Transducers, Digital signal processing, Light emitting diodes, Transmitters, Power supplies, Signal processing, Temperature metrology, Dielectrics, Fiber optics
The report describes a 110kV active optical fiber current transducer (AOCT). The transducer is different from the passive one, because a special power supply is designed for high-voltage unit and none optical crystal or magneto-optical fiber is used. The AOCT consist of three parts: a high-voltage measurement unit, a low-voltage signal processing unit and an optical fiber link which connects theses two units. As a result, the safe protection is reliable for the low-voltage equipment and the operation staff. Compared to the conventional current transformer, the advantages of the AOCT are high accuracy, low cast, small size, wide bandwidth, excellent dynamic characteristics and immunity from electromagnetic interference. The 110kV AOCT has been tested and its accuracy could achieve ±0.2%.
In this paper, the disadvantages of the traditional Current Transformer (CT) on high voltage power line are described. A new method to measure the high-voltage current is studied. A Practical Hybrid Fiber Optic Sensor for High-Voltage Current is developed and the result of the experiment and the errors are analyzed. This design consists of two parts. One is in the air attached with the high voltage power line and the other one is on the ground. In the upper part, a Rogowaski Loop is used to transform the current signal into voltage one, then a V/F converter is applied to change this voltage signal into frequency. After processed, the resulted frequency signal is fed to the LED, which turns the electrical signal into light one. Then, the light signal is lead along the optic fiber down to the ground. Here, the optic fiber is used for insulation purpose. On the ground the light signal is converted back into electrical signal with a photoelectric cell. After amplified and regulated, the electrical signal is fed to a F/V converter, which changes the frequency signal back into the original current signal.
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