Question

1. The power of a signal is 50 mW and the power of the noise is 3 μW; what are the values of SNR and SNRdB?

&

2. Distinguish between multilevel TDM, multiple-slot TDM, and pulse-stuffed TDM? (Min:100 Words)

Answer 1

Solution :

(a.) Given :

The power of a signal, S = 50 mW

power of the noise, N = 3 μW

= 0.003 mW

  The values of SNR and SNRdB can be calculated as follow:

SNR = S/N ratio

= 50 mW / 0.003 mW

= 16666.667

  SNR(dB) = 10 log (SNR)

= 10 log( 16666.667 )

= 10 * 4.2218

= 42.218 dB

(b.)  Distinguish between multilevel TDM, multiple-slot TDM, and pulse-stuffed TDM :

  multilevel TDM : multilevel TDM are used when the data rate of the input links are multiples of each other.

for example if u have two i/p lines with data rate of 100kbps each and another (third) i/p line with data rate of 200kbps

we multiplex the 1st two together (100k + 100k) to produce a data rate of 200kbps

multiple - slot TDM : It is used when there is a GCD between the data rates. The higher bit rate channels are allocated more slots per frame, and the output frame rate is a multiple of each input link.

for example if u have one i/p line with data rate of 200kbps and another (second) i/p line with data rate of 100kbps

we apply serial to parallel converter on the 1st one to change into two i/p lines with data rate of 100kbps each

  Pulse-Stuffed TDM :  Pulse-Stuffed TDM is used when there is no GCD between the links. The slowest speed link will be brought up to the speed of the other links by bit insertion, this is called pulse stuffing,

  for example if u have one i/p line with data rate of 100kbps and another (second) i/p line with data rate of 99kbps

we make the 1st one the dominant one and add 1kbps of dummy bits to the second one (99k + 1k) to be equal the first one.