Dig Com A
of 38
-
Upload
aleksandros-nikas -
Category
Documents
-
view
64 -
download
1
Transcript of Dig Com A
7o
., . . 210 - 7721639 e-mail: [email protected]
:
--
N.
:
--
N.
* (Information Technology): , . / (acquisition/collection) / (formatting/coding) (processing) (transmission) (storing) (presentation) . : -N.
* ( + )
( - , 350 .)
=
(*) : . , , , 1997 , . ,16 1999 : -N.
1839 (Cooke, Wheatstone) 1844 Morse ( --) 1850-1860 1876 (A. G. Bell, E. Gray) 1879 (PBX) 1896 (Marconi) 1916-1920 1926-1936 1936 TV () 1935 RADAR (Sir R. Watson-Watt) 1954 standard (NTSC) 1960 . (Echo I)
:
--
N.
()
1962 TDM 1966 (K.C. Kao*, G.A. Hockman) 1970- ARPANET: 1970- 1980- 1980- 1990- World Wide Web Internet
* 2009
:
--
N.
( : 0 , 1) .. (.. )
:
--
N.
0100 0100 00110100 1110100101 1101010111 10100011100 101100110011 1111000011100
: --
N.
& !01001111010010110010 0001
ASCII
0101 0100 0011 0010 0001 0000 1001 1010 1011 1100
&
0010 1010 1011 0010 0011 0000 1100 1010 0001 1001 1011 0001 0101 0101 0011 1001 1001 0001 0011
:
--
N.
/video() 2D 1D digital () 2D sampling
1
: 625 525 25 30 : -N.
/ /video = DCT DCT F(u,v)
f ( x, y )
F (u , v) = f ( x, y ) cosx = 0 y =0
N 1 N 1
u (2 x + 1)2N
cos 2 N
v(2 y + 1)2N
BHMATA
Blocks NxN (.. 8 x 8) ( block) ( ) DC . zig-zag AC (Runlength, Huffman) : -N.
11
JPEG (Baseline)Offset DCT /0 0 0 8 0 0 8 8 0 8 8 4 8 8 4 4 68 -23 -4 -3 -23 -28 17 3 -4 17 20 -11 -3 3 -11 -12
Q-table Zigzag /
Ac Q Dc68 -23 -23 -4 -28 -4 -3 17 17 -3 3 7 -2 -2 0 -3 0 0 2 2 0 0 2 0 -1 -1 -1 11110 101 101 0 11100 0 0 110 110 0 0 110 0 100 100 100
VLC(Huffman)
DCT: Dicrete Cosine Transform Q: Quantization VLC: Variable-Length Coding
20 3 -11 -11 -12
:
--
N.
ASCII , , .. 01001111 01001011!
8 bits00100001
!
:MSB
0 1 0 0 1 1 1 1 0 1 0 0 1 0 1 1 0 0 1 0 0 0 0 1 time
0time
1
0
0
1
0
1
1 BFSK 0 1 00 01 10 11
0 1 0 0 1 0 1 1T
4FSK
:
--
N.
0 1 0 0 1 0 1 1
On-Off Keying
Manchester NRZ Bipolar MLT-3
T
:
--
N.
(..)
:
--
N.
(distortion) (attenuation)
:
--
N.
: (.. )
:
--
N.
()1.5
T=5.5/fo1.5 1
1
0.5
0.5
0
0
1.5
T/3H( f )fo
1.5 1 0.5 0 1.5
1
0.5
0
1.5
T/6
1
1 0.5 0
0.5
0
()
()
:
--
N.
??
:
--
N.
x
T
T
x
T
T
:
--
N.
(II) 1 0 1 1
1
0
1
1
: -N.
1 0 1 1 0 0
:
--
N.
1
0
1
1
0
0
error ! : -N.
( )
( )
( ..)
( BER) : -N.
& ASK, PSK, QAM, MSK, FSK MATLAB : -N.
& ( ) , . : -
: -N.
& :
()
C={M1, M2, MM} : P={P1, P2, PM} :
( i ):
Ii log2 1 Pi pi Iii=1 M
:
:
--
N.
1
H( b i t s/ )
0 .8
0 .6 0 .4 0 .2 0
0
0 .2
0 .4
0 .6
0 .8
1
P1 = 1 -P 2 : -N.
Huffman
. 0 0 0.27 1 0 0.22 1 0 0.15 10.63
M1 M2 M3 M4 M5 M6 M7 M8
0.36 0.14 0.13 0.12 0.10 0.09 0.04 0.02 00.06
0
00 010 011 100 101 110 1110 1111
1 00.37
1
1
1
:
--
N.
(efficiency): M2 5 42 1 41 8 67 2 11 ....
(baud rate): : :
symbols/sec . log2M R bits/sec e = BH/R 1
Code Efficiency:
Huffman: H=2.63 , R=2.7 3 bits: R=3
e=0.97 e=0.88
:
--
N.
( ) ( ) . : bit 0 1 1 1 1 0 0 0 0 0 0 0 0 0 1 0 0 1 1 0 1 1 0 1 0 1 1 1 0 1 1 0 0 1 0 0 1 1 0 0 1 1 0 1 1 0 0 0 0 0 0 0 0 0 0 1 1 1 1 0 0 1 1 1 1 0 0 1 0 1 0 0 0 0 0 0 0 1 0 1 0 0 1 1 1 1 0 0 0 0 0 0 0 0 0 1 0 0 1 1 0 1 1 0 1 0 1 1 1 0 1 1 0 0 1 0 0 1 1 0 0 0 1 0 1 1 0 0 0 0 0 0 0 0 0 0 1 1 1 1 0 0 1 1 1 1 0 0 1 0 1 0 0 0 0 0 0 0 1 0 1 0
!
Bits
:
--
N.
( )
, key +
0 0 1 1 1 0 0 1 1 0 ... 1 0 0 0 1 0 1 1 1 0 ...
1 0 1 1 0 0 1 0 0 0 ... key +
1 0 1 1 0 0 1 0 0 0 ... 1 0 0 0 1 0 1 1 1 0 ... 0 0 1 1 1 0 0 1 1 0 ...
:
--
N.
/
/
/
/
/ /
/
:
-- N.
:
:
--
N.
INTERNETRM RM
Stub AD S1
Transit AD T1
Transit AD T2
Stub AD S2
RM RM
Host A
Host B
S1 T1 T2
S2
: border router : (router/switch) :host internal network element
: : :
physical links and best-effort SD "medium" SD 'Premium" SD
: leaf router
:
--
N.
[1] N. M, , , , 2008 [2] B. Sklar Digital Communications, Fundamentals and Applications, 2 , Prentice Hall, New Jersey 2001. [2a] ( ), 2011 [3] . Rice, , Pearson Education 2009, ------- ( : ) [4] J.G. Proakis, M. Salehi, ( , , , . . , 2002) [5] S. Haykin, Digital Communications, Wiley, 1988. [6] J.G. Proakis, Digital Communications, 3rd edition, Mc Graw Hill, 1995. : -N.
&
, &
2008
( )
:
--
N.
: , 2009
:
--
N.
