Exercise 3 (8.-12.2) (Tanenbaum pp. 77 -122)
1.Answer shortly the following questions ("review type" problem: answers
are found in lecture
notes or in Tanenbaum's book).
a) Why is digital data transmission less error prone
than analog data transmission?
b) Why digital signals cannot be carried as such
over telephone lines using analog signalling?
c) The coaxial cable can be used for data transmission
in two different ways: Baseband or
Broadband. Explain
what they mean.
d) What are attenuation and distortion. Why do they
happen?
e) How are rates in bps and in baud
related to each other?
2. Copper, fiber or wireless? Who has the future?
3. a) How do the theorems of Nyquist and Shannon relate to each other?
b) Is the Nyquist theorem true for optical fiber,
or only for copper wire?
4. a) A noiseless 4-kHz channel is sampled every 1 msec. What is the
maximum data rate?
b) If a binary signal is sent over a 3-kHz
channel whose signal-to-noise ratio is 20dB, what is
the maximum achievable
rate?
c) What signal-to noise ratio is needed to
put a T1 carrier on a 50-kHz line?
5. a) The bandwidth is 6000 Hz. What is the highest theoretical rate,
if in amplitude modulation each
signal component encodes
1, 2 or 4 bits?
b) How high frequency at least is needed if
performance requires 30 000 bps and each signal
component
carries one bit? What if each signal component encodes four bits?
6. Explain the structure of the constellation pattern diagram. Below
there are two diagrams (x is a
constellation dot, .... figures the axis ).
What kind of digital to analog modulation do they specify?
x
x x .
x x
.
.
.
x x .
x x
x . .
. . x
. . . .
. . .
.
x x .
x x
.
.
x
x x .
x x
V.22 V.22 bis
The transmission rate is 600 baud. What is the transmission rate
in bps?
At least three problems should be solved including problem 1.