Elearn 4

Câu 1 : The attenuation of fiber-optic cable does not depend on :

• Electromagnetic interference

• Category

• Bend radius and number of bends

• Distance

Câu 2 : I. The errors of received data must be corrected II. The data with errors must be retransmitted III. The data with errors must be discarded

• None is correct

• III.

• I. and II.

• II.

• I.

Câu 3: What is correct about the benefits of fiber-optic communications?

• High attenuation, narrow bandwidth, slight, non-electromagnetic interference, high security

• Low attenuation, wide bandwidth, slight, non-electromagnetic interference, high security,cheap

• Low attenuation, wide bandwidth,slight, non-electromagnetic interference, high security

• Low attenuation, narrow bandwidth, slight, non-electromagnetic interference, high security

Câu 4: Which of the following aspects does not make the received signal distorted?

• Limited signal bandwidth

• Distance

• Limited channel bandwidth

• Noise

Câu 5: Synchronous transmission is done between...

• 2 PCs via network interface card

• 2 PCs via network interface card

• Mouse and PC

• Keyboard and PC

Câu 6 : The minimum Hamming distance of an error control coding scheme is dₘᵢₙ = 5, this scheme is able to...

• Detect up to 4 error bits or correct up to 1 error bits

• Detect up to 4 error bits or correct up to 2 error bits

• Detect up to 5 error bits or correct up to 1 error bits

• Detect up to 5 error bits or correct up to 2 error bits

Câu 7 : A signal is sampled at 8000 samples/s and the amplitude of the signal is quantized by 256 levels. The data rate is...?

• 64Kbps

• 16Kbps

• 64Kbps

• 128Kbps

Câu 8 : Selecting a proper transmission media for a particular application depends on...

• Bussiness manage

• Data rate

• Distance

• Cost

Câu 9 : FDM technique is applied to 5 data streams, each stream occupies 200 KHz. A guard bandwidth of 10 KHz between adjacent streams is provided. What is the minimum bandwidth required for the transmission channel?

• 1050KHz

• 1000KHz

• 1010KHz

• 1080KHz

• 1040KHz

Câu 10: Which one is wrong?

• Synchonization is always used in synchronous transmission

• Actual data bits are high in synchronous transmission

• Actual data bits are low in asynchronous transmission

• There is no synchronization in asynchronous transmission