LOPE DE VEGA NATIONAL HIGH SCHOOL
Lope de Vega, Northern Samar
THE BENEFITS OF USING LASER COMMUNICATION TECHNOLOGY
A RESEARCH PROJECT PRESENTED TO THE FACULTY OF LOPE DE VEGA NATIONAL HIGH SCHOOL IN PARTIAL FULLFILMENT OF THE REQUIREMENTS IN SCIENCE AND TECHNOLOGY IV
MARCO C. SALUDARIO
4th Year Student
MRS. MARLITA J. DELOS SANTOS
19 FEBRUARY 2013
Laser communication, often referred to as free-space optics (FSO) or free-space laser (FSL) communication, is similar to fiber optic cable in terms of carrier wavelength and bandwidth capability, but data are transmitted directly through the atmosphere via laser beams over paths from a few meters to 4 km or longer. FSL uses lasers in the near-infrared spectrum, typically at wavelengths of 850 or 1550 nm. Given these wavelengths, atmospheric attenuation must be considered, and an adequate margin of optical power (dB) must exist to support high system availability (the percentage of time that an FSL link is in operation, typically 99.9%). A visual range of 100 m can attenuate a laser beam at a rate of nearly 130 dB km−1. For short links (< 1200 m), fog and low clouds are the primary concerns. For longer links, scintillation, heavy rain, and snow frequently become issues. To address these issues, long-term climate data are analyzed to determine the frequency of occurrence of low visibilities and low-cloud ceilings. To estimate availability at a site of interest, adjustments to airport climate data are made to accommodate differences in altitude, geography, and the effects of the urban heat island. In sum, communication via FSL is a feasible alternative to fiber optic cable when atmospheric conditions are considered and properly analyzed.
Polarization shift keying (PolSK) is a new modulation technique, it uses the state of polarization of an electromagnetic wave carrier as the information bearing parameter. This paper describes a modulation/demodulation method based on PolSK, and a high-speed laser communication system, and verifies its feasibility through theoretical analysis and computer simulation. Studies have shown that the based on the parameters of laser polarization modulation and demodulation techniques have unique advantages, such as in anti-atmospheric interference, higher data rate and lower bit error rate, greatly improving the reliability of communication. In addition to polymorphism modulation can be achieved by this modulation method, which has a data capacity. In the future, the PolSK modulation and differential demodulation method has a broad space for development and application prospects in the space laser communications.
Table of Contents
Statement of the Problem2
Results and Discussion8
The technology of laser communication was concerned by great nation in the world, because of its advantage of good security, building network conveniently, large communication capacity, smallness and portable, low power consumption and the other advantages. With the achievement of micro-arc order dynamic tracking technology, in order to develop its potentials and advantages further, high-rate and long distance became the new directions of the development of the laser communication.
The technology of laser communication combined some more mature technologies of high speed optical fiber communication technology, such as front optical amplification, wavelength division multiplexing, diversity reception and the all-optical network technology, which also brought new problems into the air light coupled into optical fiber. Because of the effects of the deviation of the alignment, vibration and atmosphere, it was difficult to achieve high efficiency of air...