modul – 3 sistem transmisi te-09-1313 2 sks tim bidang studi telekomunikasi multimedia (achmad...
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Modul – 3Sistem Transmisi
TE-09-13132 sks
Tim Bidang StudiTelekomunikasi Multimedia
(Achmad Ansori, Devy Kuswidiastuti, Gatot Kusrahardjo, M Aries Purnomo)
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The use of the decibel and of relative levels
in speechband telecommunications
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In transmission engineering, most often it would be rather impractical to characterize the magnitude of signals directly by a numerical value in volts or watts.
Instead, a logarithmic measure is used, expressed in "dB", to characterize the signal magnitude in relation to some chosen reference value.
Designations commonly used are "power level difference", "voltage level difference", etc., all expressed in "dB". A level difference from a standard situation is described simply as "level".
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Fundamentals about dBAlexander Graham Bell
The bel (symbol B) expresses the ratio of two powers by the decimal logarithm of this ratio.
This unit is not often used, having been replaced by the decibel (symbol dB) which is one-tenth of a bel.
Bel
• Unit dari ukuran perubahan daya
• Bel = Log (P1/P2)
• P1 dan P2 dalam satuan yang sama
( Watt, mWat, kWatt )
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Daya, Tegangan dan Arus
• Daya = Tegangan x Arus
• Satuan :Daya : Watt , Tegangan : Volt , Arus : Ampere (Amp)
• P = V x I
• V = I x Rdimana R : tahanan, Ohm ()
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Bel dan Perubahan Tegangan
• P = V x I = V²/R , dimana V : tegangan (Volt),
I : arus (Amp), R : tahanan (Ohm, )
• Bel = Log P1/P2 = Log (V1²/R1) / (V2²/R2) = Log (V1/V2)².(R2/R1) = Log (V1/V2)² + Log(R2/R1) = 2 Log(V1/V2) + Log(R2/R1)
• Bel = 2 Log (V1/V2), jika R1 = R2
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Bel dan Perubahan Arus
• P = V²/R = (I x R)²/R = I²/R
• Bel = Log P1/P2 = Log(I1²/R1)/(I2²/R2) = Log(I1²/I2²)(R1/R2) = Log(I1/I2)² +
Log(R1/R2)• Bel = 2 Log I1/I2 + Log R1/R2
• Bel = 2 Log I1/I2 , jika R1 = R2
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Ringkasan (1)
• Bel = Log P1/P2
• Bel = 2 Log V1/V2 , jika R1 = R2
• Bel = 2 Log V1/V2 + Log R2/R1 , jika R1 R2
• Bel = 2 Log(V1R2)/V2R1) , jika R1 R2
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Ringkasan (2)
• Bel = 2 Log I1/I2 , jika R1 = R2
• Bel = 2 Log I1/I2 + Log R1/R2 , jika R1 R2
• Bel = 2 Log (I1R1)/(I2R2) ,jika R1 R2
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DECIBEL (1)
• Unit yang menyatakan ratio
• Bentuk logaritma dengan dasar 10
• Decibel ( dB ) = 10 Log ( power ratio )
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Decibel (2)
• Decibel ( dB) = 10 x Bel• dB = 10 Log P1/P2
• Jika R1 = R2
dB = 20 Log V1/V2
dB = 20 Log I1/I2
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Decibel (3)
• Jika R1 R2
dB = 20 Log V1/V2 + 10 Log R2/R1
dB = 20 Log I1/I2 + 10 Log R1/R2
dB = 20 Log (V1R2)/(V2R1)
dB = 20 Log (I1R1)/(I2R2)
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Power Ratio & Voltage Ratio (1)
GaindB Power Ratio Voltage Ratio
0 1.00 1.001 1.26 1.122 1.58 1.263 2.00 1.414 2.51 1.585 3.16 1.786 3.98 2.007 5.01 2.248 6.31 2.519 7.94 2.8210 10.00 3.1620 100.00 10.0030 1000.00 31.6240 10000.00 100.00
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Power Ratio & Voltage Ratio (2)
LossdB Power Ratio Voltage Ratio
0 1.0000 1.00001 0.7943 0.89132 0.6310 0.79433 0.5012 0.70794 0.3981 0.63105 0.3162 0.56236 0.2512 0.50127 0.1995 0.44678 0.1585 0.39819 0.1259 0.354810 0.1000 0.316220 0.0100 0.100030 0.0010 0.031640 0.0001 0.0100
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Power Ratio & Voltage Ratio (3)
dBRatio Power Voltage
1 0.00 0.002 3.01 6.024 6.02 12.048 9.03 18.0610 10.00 20.0016 12.04 24.0832 15.05 30.1064 18.06 36.12
100 20.00 40.00128 21.07 42.14256 24.08 48.16512 27.09 54.191000 30.00 60.00
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Pengembangan Unit dB
• dBm = 10 Log ( power ratio ) dg ref. 1 mW• dBm = 10 Log ( power / 1mW )
• dBW = 10 Log ( power ratio ) dg ref. 1 W• dBW = 10 Log ( power / 1W )
• power output = 20 W = 10 Log (20W/1mW) = 10 Log (20.000mW/1mW) = 43 dBm
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dBm, dBW, Watt & milliWatt
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Voltage & Current Ratio
• dB(Voltage) = 20 Log ( ratio voltage )
• dB(Current) = 20 Log ( ratio current )
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dBmV
• Digunakan pada transmisi video
• Tegangan ( Voltage ) referensi = 1 mVolt pada beban 75 Ohm
• dBmV = 20 Log ( tegangan/1 mVolt )
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dBmV
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dBµV/m
• Pengukuran kuat medan listrik• Referensi 1µV/m dBµV/m = 20 Log (µV/m)
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KONSEP SISTEM TRANSMISI
Loss & Gain
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attenuation, loss :1.A decrease between two points of an electric, electromagnetic or acoustic power.2. The quantitative expression of a power decrease, by the ratio of the values at two points of a power or of a quantity related to power in a well-defined manner.
NOTE 1 : By extension, the words “attenuation” or “loss” may represent the ratio of powers in a given situation and in a reference condition; for example “insertion loss”.NOTE 2 : Although the term “loss” is not synonymous in English with “attenuation” in every context, it is used to express the ratio of two powers in certain specified conditions as for example in “insertion loss” and “return loss” equivalent in French to “affaiblissement d'insertion” and “facteur d'adaptation”.NOTE 3 : Attenuation is generally expressed in logarithmic units by a positive value. In some cases, attenuation could be used instead of gain, when the logarithmic unit value of a gain is negative.
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Gain :
1. An increase between two points of an electric, electromagnetic, or acoustic power.2. The quantitative expression of a power increase, by the ratio of the values at two points of a power or of a quantity related to power in a well-defined manner.
NOTE 1 : By extension, the word “gain” may represent the ratio of powers in a given situation and in a reference condition; for example the “gain of an antenna”.NOTE 2 : Gain is generally expressed in logarithmic units by a positive or negative value. When a gain has a negative value in logarithmic units, attenuation may be used instead of gain.
LOSS
• Loss (dB ) = 10 Log(power ratio) = = 10 Log(output/input) = = 10 Log ( 1 / 1.000 ) = = 10x(-3) = -30 dB
Kabel 1000 Watt 1 Watt
Input Output
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LOSS
Kabel 1000 Watt
Input Output = ?
Loss = 10 dB = 10 xPower Output = Power Input : Loss
= 1.000 Watt : 10 = 100 Watt
Power Output = Power Input - Loss= 30 dBW - 10 = 20 dBW
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GAIN (PENGUATAN)
• Gain (dB ) = 10 Log(power ratio) = = 10 Log(output/input) = = 10 Log ( 2 / 1 ) = 10 x 0,3013 = 3,013 dB = 3 dB
Amplifier1 Watt 2 Watt
Input Output
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GAIN (PENGUATAN)
Amplifier1 Watt
Input Output =?
Gain = 6 dB = 4 x
Power Output = Power Input x GainPower Input = 1 Watt = 30 dBm
Power Output = 1 Watt x 4 = 4 WattPower Output = 30 + 6 = 36 dBm
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Model Sistem Komunikasi Listrik
MediaTransmisi
PenerimaPemancar
Wire / Kawat / KabelWireless / Radio
Fiber Optik
Loss10 dB
PowerOutput :1 mW =0 dBm
Power Input :- 10 dBm
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Model Sistem Pemancar
AntenaPemancar
Wire / Kawat /Kabel /Kabel Koaxial
Power Output1 kW = 30 dBW
Loss = 3 dB
Power Input27 dBW Gain = 10 dB
EffectiveRadiated
Power(ERP) :37 dBW
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effective radiated power (e.r.p.) (in a given direction )The product of the power supplied to the antenna and its gain relative to a half-wave dipole in a given direction.
Note : The reference antenna, when fed with a power of 1 kW, is considered to radiate an e.r.p. of 1 kW in any direction in the equatorial plane and produces a field strength of 222 mV/m at 1 km distance.
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equivalent isotropically radiated power (e.i.r.p.) :The product of the power supplied to the antenna and the antenna gain in a given direction relative to an isotropic antenna (absolute or isotropic gain).
Note : The isotropic antenna, when fed with a power of 1 kW, is considered to provide an e.i.r.p. of 1 kW in all directions and to produce a field strength of 173 mV/m at 1 km distance.
Model Sistem Pemancar & Penerima
PenerimaPemancar
Wireless / Radio
Loss = 100 dB
Gain10 dB
Gain10 dB
Loss = 2 dB Loss = 3 dB
Power Output1 kW = 60 dBm
PowerInput =
-25 dBm
ERP : 68 dBm -32 dBm
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Series Network
N1 N2 N3 TS
10dBm
G3 dB
L5 dB
G3 dB
13dBm
8dBm
11dBm
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Noise Figure (1)
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Spot noise factor, spot noise figure (of a linear two-port network) :
Symbol: F( f ), NF
The ratio of the exchangeable power spectral density of the noise appearing at a given frequency at the output of a given linear two-port electrical network, to the spectral density which would be present at the output if the only source of noise were the thermal noise due to a one-port electrical network connected to the input and which is assumed to have at all frequencies a noise temperature equal to the reference thermodynamic temperature fixed, by convention, around 290 K.
Noise Figure (2)
NetworkSNRoutSNRin
40 dB 30 dB
Noise Figure ( NF ) = 40 – 30 = 10 dB
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Noise Figure ( NF ) = SNRin - SNRout (dB) NF = 1 ( 0 dB ) Noiseless
Noise Figure (3)
NF2=3dBLoss=3dB
NF3=16dBG3=60dB
kabel Penerima
antena
NF = NF2 + (NF3-1)/G2 = 2 + (40-1)/0,5 = 80 = 19 dB
Gain = -3 +60 = 57 dB
NF2 = 3 dB = 2 ; Loss = 3 dB = 2 = G2 = 0,5 ; NF3 = 16 dB = 40 ; G3 = 60 dB = 1.000.000
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NF = NF1 + (NF2 – 1)/G1 + (NF3 -1)/G1G2 + ….
Noise Figure (4)
NF2=3dBLoss=3dB
NF3=16dBG3=60dB
NF1=6dBG1=20dB
preamp kabel Penerima
antena
NF = 4 + (2-1)/100 + (40-1)/(100).0,5 = 4,79 = 6,8 dBGain = 20 – 3 + 60 = 77 dB
NF1 = 6 dB = 4 ; G1 = 20 dB = 100 ; NF2 = 3 dB = 2Loss = 3 dB = 2 = G2 = 0,5 ;
NF3 = 16 dB = 40 ; G3 = 60 dB = 1.000.000
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Noise Figure (5)
NF2=6dBG2=20dB
NF3=16dBG3=60dB
NF1=3dBLoss=3dB
kabel preamp Penerima
antena
NF = 2 + (4-1)/0,5 + (40-1)/(100).0,5 = 8,78 = 9,4 dBGain = -3 + 20 +60 = 77 dB
NF1 = 3 dB = 2 ; Loss = 3 dB = 2 = G1 = 0,5 ; NF2 = 6 dB = 4 ; G2 = 20 dB = 100 ;
NF3 = 16 dB = 40 ; G3 = 60 dB = 1.000.000
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