Q28.Marks: +2.0UGC NET Paper 2: Computer Science 26th Nov 2021
Which of the following statements are true?
A. Frequency division multiplexing technique can be handled by digital circuits.
B. Time division multiplexing technique can be handled by analog circuits
C. Wavelength division multiplexing technique is used with optical fiber for combining two signals.
D. Frequency division multiplexing technique can be applied when the bandwidth of a link is greater than the bandwidth of the signals to be transmitted.
Choose the correct answer from the options given below :
1.B and D only
2.C and D only✓ Correct
3.A and D only
4.B and A only
Solution
Key Points
Frequency-division multiplexing:
In telecommunications, frequency-division multiplexing (FDM) is a technique by which the total bandwidth available in a communication medium is divided into a series of non-overlapping frequency bands, each of which is used to carry a separate signal.
For example, the coaxial cable used by cable television systems has a bandwidth of about 1000 MHz, but the passband of each television channel is only 6 MHz wide, so there is room for many channels on the cable.
Time-division multiplexing:
Time-division multiplexing (TDM) is a method of transmitting and receiving independent signals over a common signal path by means of synchronized switches at each end of the transmission line so that each signal appears on the line only a fraction of time in an alternating pattern.
This method transmits two or more digital signals or analog signals over a common channel.
It can be used when the bit rate of the transmission medium exceeds that of the signal to be transmitted.
Wavelength-division multiplexing:
In WDM, the optical signals from different sources or (transponders) are combined by a multiplexer, which is essentially an optical combiner.
They are combined so that their wavelengths are different.
The combined signal is transmitted via a single optical fiber strand. At the receiving end, a demultiplexer splits the incoming beam into its components and each of the beams is sent to the corresponding receivers.
WDM allows communication in both directions in the fiber cable.
