Network Communication and Signal Analysis: Solved Problems

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Table of Contents
Ques 1:........................................................................................................................................................2
Answer 1:...............................................................................................................................................2
Ques 2:........................................................................................................................................................3
Answer 2:...............................................................................................................................................3
Ques 3:........................................................................................................................................................4
Answer 3:...............................................................................................................................................4
Ques 4:........................................................................................................................................................7
Answer 4:...............................................................................................................................................7
Ques 5:......................................................................................................................................................12
Answer 5:.............................................................................................................................................12
Ques 6:......................................................................................................................................................13
Answer 6:.............................................................................................................................................13
Ques 7:......................................................................................................................................................15
Answer 7:.............................................................................................................................................15
Ques 8:......................................................................................................................................................16
Answer 8:.............................................................................................................................................16
Ques 9:......................................................................................................................................................17
Answer 9:.............................................................................................................................................17
References................................................................................................................................................18

Ques 1:
Describe the difference between IP and Network Access layer in TCP protocol and also explain
the control information embedded in these two layers.
Answer 1:
In the TCP/IP model, network access layer is referred to as the lowest layer of the model. This
layer includes all the protocols which is used the computer for the transmission of data to other
devices that are connected to the network. This layer defined the usage properties of the frame
which is transmitted in the network. Data is exchanged and the data is transmitted throughout the
network. Physical address of the node is used when the data is transmitted on the local network.
Network adapter card stores the physical address of the node which is hardcoded.
The internet layer or the IP layer is used for routing the data. This layer is responsible for the
delivery of the data packet throughout the network. The packets are linked to their logical
address or IP address. These IP addresses are utilized for discovering the devices and perform
proper and smooth transmission of data. The internet protocol layer is used by every layer as it is
this layer is responsible for the transmission of data packets throughout the network.

Ques 2:
The French and Chinese prime ministers need to come to an agreement by telephone, but neither
speaks the other’s language. Further, neither has on hand a translator that can translate to the
language of the other. However, both prime ministers have English translators on their staffs.
Draw a diagram similar to Figure 1 to depict the situation, and describe the interaction and each
level.
Answer 2:
The prime minister of both the countries are conversing directly to each other via translators. The
French prime minister is talking to his/her translator and the Chinese prime minister is talking to
his/her translator. Both the translators are talking to each other by converting their respective
languages to English and hence conversing in English via telephone. The conversation is
telephonic. The translator then translates the received message in English to the respective
languages of their prime minister.
French Translator
French PM
Telephone
Telephone
Chinese PM
Chinese Translator
Telephone

Ques 3:
From the following figures, compute the maximum amplitude, frequency, time period and phase
for each of the wave. The x-axis represents the time in sec and y-axis represents the amplitude
Answer 3:
The maximum value of Amplitude (A) is 15 as shown in the graph above.
Time period (T) is 3 seconds.
Frequency (f) is,
f = 1/T
f = 1/3
f = 0.33 Hz
(ɸ) Phase angle is 0 after calculation

The maximum value of Amplitude (A) is 4 as shown in the graph above.
Time period (T) is 6.5 seconds.
Frequency (f) is,
f = 1/T
f = 1/6.5
f = 0.1538 Hz
(ɸ) Phase angle is 0 after calculation
The maximum value of Amplitude (A) is 7.5 as shown in the graph above.
Time period (T) is 2.25 seconds.

Frequency (f) is,
f = 1/T
f = 1/2.25
f = 0.44 Hz
(ɸ) Phase angle is 90 after calculation

Ques 4:
Compute the amplitude, frequency, time period and phase for each of the following equations
and also draw their respective waveforms.
a. 3𝑆𝑖𝑛(2𝜋(200)𝑡)
b. 14𝑆𝑖𝑛(2𝜋(50)𝑡 + 90)
c. 4𝑆𝑖𝑛(650𝜋𝑡 + 180)
d. 6𝑆𝑖𝑛(700𝜋𝑡 + 270)
Answer 4:
a. 3𝑆𝑖𝑛(2𝜋(200)𝑡)
Amplitude,
A = 3
Frequency,
f = 200 Hz
Time,
T = 0.005 sec
Phase angle,
ɸ = 0

b. 14𝑆𝑖𝑛(2𝜋(50)𝑡 + 90)
Amplitude,
A = 14
Frequency,
f = 50 Hz
Time,
T = 0.02 sec
Phase angle,
ɸ = 90

c. 4𝑆𝑖𝑛(650𝜋𝑡 + 180)
Amplitude,
A = 4
Frequency,
f = 325 Hz
Time,
T = 0.003 sec
Phase angle,
ɸ = 180

d. 6𝑆𝑖𝑛(700𝜋𝑡 + 270)
Amplitude,
A = 6
Frequency,
f = 350 Hz
Time,
T = 0.002 sec
Phase angle,
ɸ = 270

Ques 5:
Determine the isotropic free space loss at 6 GHz for the shortest path to a synchronous satellite
from earth (35,863 km)
Answer 5:
The isotropic free space loss is mentioned as PL,
PL = 20log10 (6x109) + 20log10 (35.863x106) – 147.56dB
PL = 199.09 dB