Publication: Comparative analysis of forward error correction and roll off factor in DVB-S2 system for consumers in Malaysia
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Date
2021-06
Authors
Sri Raam A/L Vijai Kumar, Mr.
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Abstract
In a broadcast industry, to help both broadcasters and customers achieve and maximize financial utilization, a smooth transmission is vital. Understanding the two main criteria’s in a satellite signal that affects transmission is the Forward Error Correction and the Roll off Factor. The issue faced by consumers in Malaysia who resides in a tropical region that is susceptible to weather is the extreme downpour of rain which causes a faster degradation of signal on a Kuband downlink. This also caused video pixelizations and thus ruins the customers viewing quality. As a standard antenna size is required for consumers in Malaysia by the Malaysian Communications and Multimedia Commission (MCMC), a constant degradation of signal within a fast duration during a heavy downpour has caused much dissatisfaction amongst consumers. To combat this issue, a change of a transmission setting on a modulator from 8PSK 9/10 to a 8PSK 3/5 has improved the correction rate and has combat the missing packets due to better correction ratio. The correction and the signal strength of Astro’s STB box was successfully carried out indicating a higher signal endurance during rain on an 8PSK 3/5 compared to an 8PSK 9/10 which was configured on 1kV and 3kV transponders accordingly. This can be clearly seen on the constellation diagram showing a better efficient correction output. On another note, an issue that is currently being faced by broadcasters is the constant pricy satellite transponder leasing. As leasing space is pricy and can be of a financial burden to broadcasters, they need to maximize transmission efficiency and improve transponder bandwidth utilization without allowing waste on transponder space. Hence, the second part of the research conducted was on the Roll Off Factor (ROF) that was currently being used for transmission on Measat 3b. A reduction of the ROF from 20% to 5% of the modulated stream on the modulator has gave an allowance of a much sharper carrier without unsettling the RF signal that is being uplinked to Measat. The signal has a much sharper look and the usage of the whole carrier is much prominent on a 5% ROF compared to a 20% ROF. This has permitted an increase in bit rate with the same bandwidth of a 36MHz carrier. This has allowed an increase of the number of services being encoded into a stream. By improving the number of channels being uplinked on each transponder, this has open its doors on the ability to launch more new channels and this in fact within the same budgetary. The conclusion from this research shows that a higher bit correction of FEC 8PSK 3/5 ratio helps in improving the signal strength during an increase in rain. This correction helps in maintaining customers viewing experience. Besides that, this study also shows that a lower ROF of 5% helps in increasing the bit rate without jeopardizing the signal carrier. This helps with adding few services to the current transponder, hence increasing efficiency without in need of incorporating additional cost.
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Comparative analysis of forward error correction and roll off factor in DVB-S2 system for consumers in Malaysia