Modul – 3 Sistem Transmisi TE-09-1313 2 sks Tim Bidang Studi Telekomunikasi Multimedia (Achmad...

Modul – 3Sistem Transmisi

TE-09-13132 sks

Tim Bidang StudiTelekomunikasi Multimedia

(Achmad Ansori, Devy Kuswidiastuti, Gatot Kusrahardjo, M Aries Purnomo)

1TE-09-1313-03-Transmisi-2

The use of the decibel and of relative levels

in speechband telecommunications

TE-09-1313-03-Transmisi-2 2


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".


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This unit is not often used, having been replaced by the decibel (symbol dB) which is one-tenth of a bel.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 )


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 ()


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


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


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


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


DECIBEL (1)

• Unit yang menyatakan ratio

• Bentuk logaritma dengan dasar 10

• Decibel ( dB ) = 10 Log ( power ratio )


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


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)


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



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



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


TE-09-1313-03-Transmisi-2 17

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


dBm, dBW, Watt & milliWatt


Voltage & Current Ratio

• dB(Voltage) = 20 Log ( ratio voltage )

• dB(Current) = 20 Log ( ratio current )


dBmV

• Digunakan pada transmisi video

• Tegangan ( Voltage ) referensi = 1 mVolt pada beban 75 Ohm

• dBmV = 20 Log ( tegangan/1 mVolt )


dBmV


dBµV/m

• Pengukuran kuat medan listrik• Referensi 1µV/m dBµV/m = 20 Log (µV/m)


TE-09-1313-03-Transmisi-2 24

KONSEP SISTEM TRANSMISI

Loss & Gain

TE-09-1313-03-Transmisi-2 25

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.

TE-09-1313-03-Transmisi-2 26

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


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


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


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


Model Sistem Komunikasi Listrik

MediaTransmisi

PenerimaPemancar

Wire / Kawat / KabelWireless / Radio

Fiber Optik

Loss10 dB

PowerOutput :1 mW =0 dBm

Power Input :- 10 dBm


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


TE-09-1313-03-Transmisi-2 33

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.

TE-09-1313-03-Transmisi-2 34

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


Series Network

N1 N2 N3 TS

10dBm

G3 dB

L5 dB

G3 dB

13dBm

8dBm

11dBm


Noise Figure (1)


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


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


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


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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Modul – 3 Sistem Transmisi TE-09-1313 2 sks Tim Bidang Studi Telekomunikasi Multimedia (Achmad...

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