9. g ( t ) 01100010
0 ,0 t 1
1,1 t 3
g ( t ) 0 ,3 t 6
1, 6 t 7
0 ,7 t 8
8
an
2
T
1
4
3 sin( nt / 4 ) dt 7 sin( nt / 4 ) dt
6
1
1
4
[ 4 /( n ) cos( nt / 4 ) |t 1 4 /( n ) cos( nt / 4 ) |t 6 ]
g ( t ) sin( 2 nft ) dt
0
3
7
4 /( n )[cos( 3 n / 4 ) cos( n / 4 ) cos( 7 n / 4 ) cos( 6 n / 4 )]
9
10. a n 1 /( n )[cos( n / 4 ) cos( 3 n / 4 ) cos( 6 n / 4 ) cos( 7 n / 4 )]
bn
2
T
8
1
3
0
4
1
7
[ cos 9 nt / 4 ) dt
[ sin( nt / 4 ) |
4
n
1
4
g ( t ) cos( 2 nft ) dt
1
n
4
n
3
t 1
cos( n / 4 ) dt ]
6
sin( nt / 4 ) | ]
7
t6
[sin( 3 n / 4 ) sin( n / 4 ) sin( 7 n / 4 ) sin( 6 n / 4 )]
10
11. c
2
T
8
g ( t ) dt
0
2 3
1 dt
1
8
1
4
3
7
6
1 dt
3
4
Note: The maximum value of sin(x) and cos(x) is
1 and the minimum value is -1. The maximum
and minimum values of cos(x1) - cos(x2) + cos(x3) cos(x4) and sin(x1) - sin(x2) + sin(x3) - sin(x4) are 4
and -4, respectively. Hence,an and bn converge to
zero when n becomes infinite.
11
12. A binary signal and its rms Fourier amplitudes.
amplitude
1
0 1 1 0 0
0 1 0
0.5
0.25
0
1 2
3
4
5
6
7
8
9 10 11 12 13 14 15
Successive approximations to the original signal
1
1 harmonic
0
1
Time
Harmonic number
12
13. Successive approximations to the original signal
1
2 harmonies
0
1
2
1
4 harmonies
0
1
2
3
4
1
8 harmonies
0
1
Time
2
3
4 5 6
7
8
Harmonic number
13
16. • The PSTN (Public Switched Telephone Network) is the world's
collection of interconnected voice-oriented public telephone
networks. It's also referred to as the POTS (Plain Old Telephone
Service).
(a) Fully-interconnected network.
(b) Centralized switch.
(c) Two-level hierarchy.
16
19.
Defines the Interface Between the Host (DTE)
and the Carrier's Equipment (DCE)
X.25 Has 3 Layers:
Physical (X.21 and X.21 bis)
Frame
Packet
Will Look at Digital Interface (X.21). 15 pins
19
21. Signal lines used in X.21
T (Transport)
C (Control)
R (Receive)
I (Indication
DTE
DCE
S (Signal, i.e. bit timing)
B (Byte timing) optional
Ga (DTE common return)
G (Ground)
21