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Komunikacioni Model
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Transcript of Komunikacioni Model
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() ( )
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( ( ):
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( )
(Am, A)( )
(f) T = 1/f
(, )
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s(t) = A sin(2ft +)s(t) = A sin(2ft +)
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( ).
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f 3 f (T=1/f)
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()
(DC)
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( (a
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(Data)
(Signals)
- (Transmission) - (Transmission)
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P1 P1 P1 P1 :
PdB = 10log10 (Pa / Pb)
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: :
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NdB=10log (P2/P1) je:
P1 P2
je: NdB = , P1,2 = ,, , log10 = 10.
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: NdB=10log (P2/P1) :
(G - Gain) (L - Loss) .
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P2 = P1*10 **(NdB/10) = 10 log (5/10) = 10 (-0.3) = - 3dB = 10 log (10/5) = 10 (0,3) = 3dB
1: P2=P1 NdB=10log10 (P2/P1) =10 log 10 (P2/P1) = NdB=10 log 10 1 =0
0 100 = 1
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(dBW)= 10 log [(W) /1W] (dBW) 10 log [(W) /1W] NdBW=10log10 (P2/ 1W)
(dBmW)= 10 log [(W) /1mW] NdBmW=10log10 (P2/ 1mW)NdBmW 10log10 (P2/ 1mW)
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P1 = 1 W P1 1 W 1 W.
2: 1 kW (1000 W) 2: 1 kW (1000 W) : NdBW=10log10 (P2/ 1W) =NdBW 10log10 (P2/ 1W) 10log10 (1000/ 1) =10 log10 (103) = 3*10 log10 (10) g ( ) = 30dB
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3: 1mW (0,001 W) 3: 1mW (0,001 W) : NdBW=10log10 (P2/ 1W) =10log10 (0,001/ 1) =10
log10 (10-3) =(-3)*10 log10 (10)
30d = -30dB
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dBi dBi dB(isotropic)
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:
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: 1 0 0
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( )
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(
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(Repeaters)(Repeaters) ( ) ( )
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LSI/VLSI
(E ti ) (Encryption)
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+ +
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( ) )
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2f0 4f0.
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( )
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bps (b/s)
H - Hz
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B, 2B
, , B Hz 2B b/s
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M
: C= 2B log2M
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= 2*tb => f=1/(2*tb) R=1000b/s =>tb=1/1000=1ms, = 2*tb = 2ms, f=1/(2* 10-3) f = 0 5kHz f1 = 0,5kHz
R= 1M b/s => tb=1/ 106 =1s, T = 2*10-6 = 2s, f = 1/(2* 10-6)= f1 = 0,5 MHz
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R=1kb/s => f1 = 0,5kHz1 B = 5f1 - f1 = 4 f1 = 4*0,5kHz = 2kHz
R=1Mb/s => f1 = 0,5MHz B = 5f1 - f1 = 4 f1 = 4*0,5kHz = 2MHzB 5f1 f1 4 f1 4 0,5kHz 2MHz
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, ,
, , ,
, () .
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( ) db
db.
SNdB=10 log10 (S/N), dB g10 ( ), S- , N - .
: C = B log2(1+ S/N)C = B log2(1+ S/N)
S/N = 30dB B=3000 Hz S/N = 30dB B=3000 Hz, C=30000 b/s