浙江科技学院通信原理试卷

ONE：问答题
1.Draw the block diagram of a typical digital communication system.
2.Explain the difference between the bit rate and symbol rate.
3.How does the plot of a signal’s auto correlation function reveal its bandwidth occupancy?
4.Assume a binary FSK modulation. (a) Draw the structure of optimum coherent receiver. (b)
5.Gives the theoretical error probability,
P.
e
6.What are the two main performance parameters about communication system?
7.Explain bits per PCM word and bits per symbol.
8. What is the PLL? Please to draw the schematic of the basic phase-locked loop 9. 10. 11. 12. 13. 14. 15. .
TWO ：大题
1. 2FSk modulation.
In this problem we examine the probability of bit error for BSK modulation. Consider a coherent
detected orthogonal 2FSK system with equally likely waveforms 11()s t w t =
and
22()s t w t = .The addictive noise is a zero-mean white Gaussian noise process with
two-sided
power spectral density
0/2
N . Assume the reference signal
()i i t w t ψ=(i=1,2) is used in correlation-type demodulator, and ()i t ψ is basis function.
(1) Sketch the block diagram of correlation-type demodulator.
(2) Sketch the conditional probability functions, p(z|s1) and p(z|s2).
(3) Calculates the probability of bit error, B P (4) (5) (6) .
(7) If the reference signal is cos i w t (i=1,2) , how about the probability of the error , B P ?
2. Find the optimum (minimum probability of error) threshold 0λ , for detective the ‘equally
likely signals 10()s t w t = and 20())s t w t π=+in A WGN, using a
correlator receiver and assuming a reference signal of 10()t w t ψ= . Draw the block
diagram of the correlator receiver.
3. Assume that a sequence of binary symbols {k x }={0010100} is to be transmitted.
(1) Illustrate the duobinary coding and decoding rules when using the differential precoding of equation: 1k k k w x w -=⊕. where the symbol ⊕ represents modulo-2 addition of binary digits. (2) What is the basic idea of duobinary signaling.
4. The bit stream m(k)={101010111101010100001111} is to be transmitted using DPSK modulation. The encoded bit stream c(k) is encode in the way c(k)=c(k-1) m(k).
(1) Show a differentially encoded sequences that can represent the data sequence above, and explain the algorithm that generated each.
(2) Sketch the bock diagram of differentially coherent detection receiver.
5. Binary data at 4800 bits/s are transmitted using 4-ary PAM modulation with a system using a raised cosine roll-off filter characteristic. The system has a frequency response out to 1.8 KHz.
(1) What is the symbol rate?
(2) What is the roll-off factor of the filter characteristic.
6. An example of a holding circuit, commonly used in pulse systems in show in Figure 1.
(1) Determine the impulse response of this circuit, h(t).
(2) If the h(t) is the matched filter of signal s(t), please sketch the waveform of s(t) and calculate the output of matched filter at t=t0 when s(t) pass matched filter.
(3) For the above signaled s(t), draw the structure of correlator receiver.
(4) Calculate the output of correlator receiver at t=t0.
Figure 1.。