私立中原大學八十八學年度研究所招生考試命題紙

所組別 : 電子工程學系丙組 科目 : 通訊系統 考試時間 : 05月01日第3節


  1. Given . Prove .(20%)

  2. Consider the filter of Fig.1. Consisting of a delay line and a summing device. The filter input X(t) is a low pass signal and the highest frequency component of the power spectral density SX(f) is small compared to 1/T. What the filter will act as? Justify your answer. (20%)

  3. Consider a Gaussian noise n(t) with zero mean and the power spectral density Sn(f) where

    4. and fC >>B. Find the probability density function of the envelope of n(t). (20%)

  4. (1)Describe the (a) BPSK, (b) BFSK signals Si(t) with the bit energy is Eb. (8%) (2)Describe the (a) AM, (b) FM and (c) SSB signals S(t) with the message signal m(t) and the carrier frequency at fc. (12%)
  5. A BPSK signal is applied to a correlator supplied with a phase reference that lies within f radians of the exact carrier phase. Determine the effect of the phase error f on the average probability of error of the system. Where the average probability of error of the coherent BPSK is . (20%)

Fig .1

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