Case Study 4

Calculate the effect on system noise temperature of the satellite receivers noise temperature given the following data.

  • ambient temperature 290 K
  • LNC noise figure 1.5 dB
  • LNC gain 50 dB
  • specific attenuation of IF cable 30 dB/100m
  • length of IF cable 30 m
  • Noise temp of satellite receiver 15 dB
  • Solution 4

    Without data on antenna temperature and feed loss we cannot calculate System Noise temperature. But we can look at the effect of later stages on the contribution the LNC and later stages make to system noise temperature.

    It can be seen that unless cable loss is higher than the gain of the LNC even fairly high values of satellite receiver noise temperature have little effect on overall system noise temperature.


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