Ask China Telecom to recruit written test materials in recent years (communication engineering)

I'll give you some written test questions of China Jiangxi Telecom to see if it will help you prepare for the exam.

The first part: multiple choice questions with 25 points

The examination points are Shannon's law, analog modulation, digital modulation and the application scope of SSB in communication principle.

; Advantages of digital communication system, synchronization and quasi-synchronization; The concept of signal and linear system in the system, the relationship between Fourier transform and inverse Fourier transform, give a system expression, ask whether it is a linear system, about causal system; Some concepts in optical fiber communication system, such as multimode and single mode, refractive index of cladding and optical core, the significance of Q parameter, and the role of nodes in all-optical networks; Gateway in computer network, which layer TCP/UDP is located, which layer error control is the function, and the concept of HDLC.

In digital signal processing: give a Z transform and ask whether it is low-pass or Qualcomm;

Part two: 25 true or false questions

What I want to say is: I don't remember. ...

Fill in the blanks with 30 points in the third part

1. Multiplexing methods in digital communication include:

2. Nyquist sampling theorem

The optimization principle of 3.3. finite impulse response

4. The frequency of f (t) is1k. What is the sampling frequency of f(t)*f(2t)?

5. What is the period of COS (0.35pai * t)+2Sin (0.45pai * t)?

7. The signal with frequency of 70, 152 Hz is pumped by the window with frequency of 200. What frequency spectra are there in the frequency domain after the signal changes?

8. The period of the signal is 2n. The other is 3n. What is the period after their multiplication?

What is the demodulation method of 9.9? QPSK？

10 Which receiver has the largest signal-to-noise ratio and meets the maximum likelihood criterion?

The principle of 1 1 avalanche diode is as follows

The fourth part short answer 20 points.

1. There are several network topologies. List them.

2. What is the mechanism of error control transmission?

4 16 parallel circuit, each signal in each circuit takes up 0.02s, and there are two signal modes. What is the modulation frequency and transmission rate?