通信电路与系统(杭州电子科技大学)1463243443 中国大学mooc慕课答案2024版 m89862

Chapter1 Introduction to Basic Knowledge of Communication Electronics Circuits 3月10日课前练习

1、 What is the core of the transmitter？

答案: Modulator

2、 Which of the following circuits is not part of super heterodyne receiver

答案: Modulator

3、 FM radio signal belongs to which wave type

答案: VHF

4、 When the resistive load increases, the selectivity of LC parallel resonant circuit will be improved, but（ ）will be decreased.

答案: Pass band B0.7

5、 In the wireless communication system , the transmitter and receiver are both have oscillator circuits.

答案: 正确

6、 The frequency of High frequency signal only from 3- 30MHz？

答案: 错误

7、 The resonant frequency will be changed by adjusting the value of L and C.

答案: 正确

8、 Quality factor Q reflects the frequency-selective characteristic of the circuit, which is also related with the bandwidth.

答案: 正确

9、 When the operating frequency is greater than the resonant frequency, the LC parallel resonant circuit and the LC series resonant circuit are both capacitive.

答案: 错误

10、 LC series resonant circuit and LC parallel resonant circuit both have frequency-selective function.

答案: 正确

11、 When the operating frequency of LC parallel reasonant circuit is lower than the reasonance frequency, the whole circuit is inductive

答案: 正确

12、 The larger the rectangular coefficient, the better the frequency-selective performance.

答案: 错误

13、 Load and source resistor will affect the frequency-selective characteristic of the circuit.

答案: 正确

Chapter1 Introduction to Basic Knowledge of Communication Electronics Circuits 3月17日课前练习

1、 Can both the signal source and the load be partially access to the LC circuit

答案: Yes.

2、 Which of the following impedance conversion circuits can both increase and decrease the load

答案: All of above

3、 What will happen when the load is connected directly to the LC parallel resonant loop

答案: Impedance unmatched;
Lower transmission power;
Lower transmitting efficiency;
Lower transmitting sensitivity

4、 Why the LC impedance transformation network will be used in the circuit

答案: Reduce the influence on quality factor Q;
Improving the selectivity

5、 Typically, the Q value is negatively associated with the access factor.

答案: 错误

6、 By using impedance conversion networks, the operation frequency of LC reasonace circuits will not change.

答案: 错误

Chapter2 Radio Frequency Amplifiers 3月24日课前练习

1、 In the communication circuit system, which one is not a nonlinear circuit

答案: high frequency small signal amplifier

2、 What is the power amplifier generally classified according to

答案: Conduction angle

3、 What status dose Class C amplifier work at

答案: On-off

4、 What’s the bias point of the C class power amplifiers

答案: Below the pinch-off

5、 If the input signal of the C class power amplifier is a sinusoidal signal, the collector current is :

答案: periodic cosine pulses

6、 The higher the conduction angle, the higher the efficiency.

答案: 错误

Chapter2 Radio Frequency Amplifiers 3月31日课前练习

1、 Class C PA can realize

答案: All the above

2、 The collector current of the class C PA is the periodic cosine pulses, but the output voltage is a sinusoidal (or cosine) signal.

答案: 正确

3、 Pout=PL.

答案: 错误

4、 The load line of class C PA is the same with the low frequency PA.

答案: 错误

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