大学MOOC 通信电路与系统(杭州电子科技大学)1462450162 最新慕课完整章节测试答案

3月11日课前练习

1、单选题：
‏What is the core of the transmitter？‎
选项：
A: Mixer
B: Modulator
C: Oscillator
D: Amplifier
答案: 【 Modulator】

2、单选题：
​Which of the following circuits is not part of super heterodyne receiver?‍
选项：
A: Local oscillator
B: Mixer
C: Intermediate frequency amplifier
D: Modulator
答案: 【 Modulator】

3、单选题：
‏FM radio signal belongs to which wave type?​
选项：
A: VLF
B: VHF
C: UHF
D: HF
答案: 【 VHF】

4、单选题：
When the resistive load increases, the selectivity of LC parallel resonant circuit will be improved, but（ ）will be decreased.
选项：
A: Quality factor Q
B: Resonant frequency f0
C: Rectangular coefficient K0.1
D: Pass band B0.7
答案: 【 Pass band B0.7】

5、判断题：
‎In the wireless communication system , the transmitter and receiver are both have oscillator circuits.‌
选项：
A: 正确
B: 错误
答案: 【 正确】

6、判断题：
Quality factor Q reflects the frequency-selective characteristic of the circuit, which is also related with the bandwidth.
选项：
A: 正确
B: 错误
答案: 【 正确】

7、判断题：
When the operating frequency is greater than the resonant frequency, the LC parallel resonant circuit and the LC series resonant circuit are both capacitive.
选项：
A: 正确
B: 错误
答案: 【 错误】

8、判断题：
LC series resonant circuit and LC parallel resonant circuit both have frequency-selective function.
选项：
A: 正确
B: 错误
答案: 【 正确】

9、判断题：
‍When the operating frequency of LC parallel reasonant circuit is lower than the reasonance frequency, the whole circuit is inductive‍
选项：
A: 正确
B: 错误
答案: 【 正确】

10、判断题：
‎The larger the rectangular coefficient, the better the frequency-selective performance.‍
选项：
A: 正确
B: 错误
答案: 【 错误】

3月18日课前练习

1、单选题：
‏Which of the following impedance conversion circuits can both increase and decrease the load?‌
选项：
A: Auto-transformer
B: Transformer
C: Capacitor divider
D: All of above
答案: 【 Transformer】

2、单选题：
‏Can both the signal source and the load be partially access to the LC circuit?‎
选项：
A: Yes.
B: No.
C: Only the load can.
D: Only the signal source can.
答案: 【 Yes.】

3、多选题：
‏What will happen when the load is connected directly to the LC parallel resonant loop?‎
选项：
A: Impedance unmatched
B: Lower transmission power
C: Lower transmitting efficiency
D: Lower transmitting sensitivity
答案: 【 Impedance unmatched;
Lower transmission power;
Lower transmitting efficiency;
Lower transmitting sensitivity】

4、多选题：
‌Why the LC impedance transformation network will be used in the circuit?‏
选项：
A: Reduce the influence on quality factor Q
B: Improving the selectivity
C: Increase operation frequency
D: Simplify circuit structure
答案: 【 Reduce the influence on quality factor Q;
Improving the selectivity】

5、判断题：
‏Typically, the Q value is negatively associated with the access factor.‍
选项：
A: 正确
B: 错误
答案: 【 正确】

6、判断题：
‍By using impedance conversion networks, the operation frequency of LC reasonace circuits will not change.‏
选项：
A: 正确
B: 错误
答案: 【 错误】

3月25日课前练习

1、单选题：
​What is the power amplifier generally classified according to?‎
选项：
A: Amplitude of the input signal
B: Conduction angle
C: Magnification
D: Output power
答案: 【 Conduction angle】

2、单选题：
‎Where is the bias point of  C class power amplifiers?‌
选项：
A: Above the pinch-off
B: On the pinch-off
C: Below the pinch-off
D: None of above
答案: 【 Below the pinch-off】

3、单选题：
If the input signal of the C class power amplifier is a sinusoidal signal, the collector current is :
选项：
A: sinusoidal signal
B: cosine signal
C: periodic cosine pulses
D: DC signal
答案: 【 periodic cosine pulses】

4、单选题：
‎In the communication circuit system, which one is not a nonlinear circuit ?‍
选项：
A: high frequency small signal amplifier
B: mixer
C: oscillator
D: detector
答案: 【 high frequency small signal amplifier】

5、判断题：
‏The higher the conduction angle, the higher the efficiency.‌
选项：
A: 正确
B: 错误
答案: 【 错误】

6、判断题：
The input and output of power amplifier both need impedance matching networks.
选项：
A: 正确
B: 错误
答案: 【 正确】