Data Communication and Networking – Multiplexing Demultiplexing technique – FDM / TDM / WDM / MDM MCQs

This set of Data communication and Networking Multiple Choice Questions and Answers (MCQs) focuses on “Multiplexing Demultiplexing techniques – frequency-division multiplexing (FDM) , Time-division multiplexing (TDM) , Wavelength division multiplexing (WDM) , Mode-division multiplexing (MDM)”.
 

1
. A multiplexer _______ several transmission streams while a demultiplexer _______ them
  • combines; separates
  • compresses; decompresses
  • encrypts; decrypts
  • separates; combines
2
. One _______ can be made of many _______
  • channel; paths
  • path; channels
  • path; links
  • channel; links
3
. Which of the following is a digital multiplexing method?
  • FDM
  • asynchronous TDM
  • synchronous TDM
  • b and c
4
. Which is not a basic multiplexing method?
  • FDM
  • TDM
  • WDM
  • MDM
5
. _______ is an analog multiplexing technique usually involving signals that are not in the visible light frequencies
  • FDM
  • TDM
  • WDM
  • MDM
6
. _______ is a digital multiplexing technique usually involving signals that are not in the visible light frequencies
  • FDM
  • TDM
  • WDM
  • MDM
7
. _______ is an analog multiplexing technique usually involving signals in the visible light frequencies.
  • FDM
  • TDM
  • WDM
  • MDM
8
. In FDM, the bandwidth of the link must be _______ the sum of the bandwidths of the signals to be combined
  • equal to
  • less than
  • greater than
  • an order of magnitude greater than
9
. In FDM, if five signals are to be multiplexed, at least _______ carriers, each of a different frequency, must be modulated
  • 1
  • 5
  • 6
  • 10
10
. FDM uses _______ to prevent modulated signals from overlapping
  • physical hardware devices
  • carrier frequencies
  • guard bands
  • demultiplexers
11
. In FDM, the _______ signals can all have the same frequency range
  • modulating
  • carrier
  • modulated
  • b or c
12
. The FDM demultiplexer uses a series of _______ to decompose the multiplexed signal into its constituent signals,
  • guard bands
  • filters
  • repeaters
  • amplifiers
13
. WDM is very similar in concept to _______.
  • asynchronous TDM
  • synchronous TDM
  • FDM
  • AM or FM
14
. If the sum of the data rates of the sending devices is X, TDM can be applied when the data rate capacity of the transmission medium is _______.
  • less than X
  • greater than X
  • one half X
  • two times X
15
. In _______ the multiplexer allocates exactly the same time slot to each device at all times
  • synchronous TDM
  • asynchronous TDM
  • FDM
  • WDM
16
. In _______, if a device has no data to send, its time slot remains empty
  • synchronous TDM
  • asynchronous TDM
  • FDM
  • WDM
17
. In synchronous TDM, a _______ is a complete cycle of time slots, including one or more slots dedicated to each sending device.
  • filter
  • carrier
  • signal
  • frame
18
. What is the efficiency of a system using synchronous TDM if 2 of the 5 devices have nothing to send?
  • 20%
  • 50%
  • 60%
  • 100%
19
. In synchronous TDM, if device X has data to send, the data go to _______ in the frame
  • the next available slot
  • a preassigned slot
  • the first slot
  • none of the above
20
. In asynchronous TDM, if device X has data to send, the data go to _______ in the frame.
  • the next available slot
  • a preassigned slot
  • the first slot
  • none of the above
21
. In synchronous TDM, if device X has no data to send, what happens to its allotted slot?
  • The next device in line takes it.
  • An error message is sent.
  • The bit pattern 01010101 is sent.
  • The slot remains empty.
22
. In synchronous TDM, each frame is filled with data from the devices in a fixed order. We call this _______
  • interleaving
  • synchronization
  • switching
  • line discipline
23
. _______ allow the demultiplexer to synchronize with the incoming stream
  • Slots
  • Framing bits
  • Demultiplexing bits
  • Trailers
24
. In synchronous TDM, if ten devices are each sending data at the rate of 2000 bps, what is the data rate for the line carrying the multiplexed signals?
  • 2000 bps
  • 20,000 bps
  • greater than 20,000 bps
  • less than 20,000 bps
25
. What is the major weakness of asynchronous TDM?
  • There aren't enough slots in each frame.
  • There are too many slots per frame.
  • Each slot requires an address.
  • All of the above
26
. What is the major weakness of synchronous TDM?
  • Some slots may remain empty.
  • There aren't enough slots.
  • The slots are too small.
  • All of the above.
27
. Which type of multiplexing takes data from one high-speed line and breaks it into portions that can be sent across several lower-speed lines simultaneously?
  • asynchronous TDM
  • synchronous TDM
  • FDM
  • inverse multiplexing

 
 
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