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Symbol rate, Bandwidth and Bit rate Calculation

In satellite communication bandwidth (BW), symbol rate and bit rate are the most vital fact for proper signal transmission. There are many commercial software for BW, Symbol rate and bit rate calculation for TV signal transmission. But the equations of these parameter calculation are as follows. BW= (1+Roll of factor)* Symbol rate In general Roll of factor is 35% Symbol Rate =BW / (1+Roll of factor) and Bit Rate = Symbol rate * Modulation* FEC* (188/204)                                     [when 188 is encoder packet length] or Bit Rate = Symbol rate * Modulation* FEC* (204/188)                                     [when 204 is encoder packet length] Here, FEC = Forward Error Correction. In general FEC is in the range from 1/2 to 7/8. 188/204 = constant Unit ** BW= Hz, KHz, MHz, GHZ ** Sym...
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Azimuth and Elevation Angle for Satellite tracking

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Azimuth (Az) The earth station needs to know where the satellite is in the orbit. Then the earth station engineer needs to calculate some angles to track the satellite correctly. These angles are called antenna look angle. The look angles for the ground station antenna are the azimuth and elevation angles required at the antenna so that it points directly at the satellite. With the geostationary orbit the situation is much simpler than any other orbit. As the antenna beam width is very narrow and tracking mechanism is required to compensate for the movement of the satellite about the nominal geostationary position. Three pieces of information that are needed to determine the look angles for the geostationary orbit are a. Earth station latitude b. Earth station longitude c. Satellite orbital position Using these information antenna look angle can be calculated using Napier’s rule (solving spherical triangle). Azimuth angle denotes the horizontal angle measured a...
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Terminology: EIRP, G/T, Input Back-Off, Output Back-Off

  EIRP:   Used to indicate the power transmitted from an antenna. EIRP=Power +Antenna Gain, Both EIRP and Power is expressed in dBW and Gain in dBi. G/T:   It is the figure of merit for an earth station and is expressed as dB/K (dB per K). G/T= Antenna Gain-10*Log (System Noise Temperature) The higher the better-G/T can be raised by using a higher gain antenna or a lower temperature LNA. The earth station G/T determines the received carrier to noise ration. Increasing station G/T will increase the C/N of the received carrier. Input Back-Off (IPBO):   The level of a signal at the input of an amplifier relative to that level at the input that would result in the maximum possible output level. For example, if an input level of -20dBm causes max output and the actual input level is -25dBm, the IPBO is 5dB. Both IPBO and OPBO are commonly used to determine the operating levels in a satellite transponder TWTA. Output Back-Off (OPBO)   The level of...
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