Modul – 3 Sistem Transmisi TE sks Tim Bidang Studi Telekomunikasi Multimedia (Achmad Ansori, Devy Kuswidiastuti, Gatot Kusrahardjo, M Aries Purnomo) 1TE Transmisi-2

The use of the decibel and of relative levels in speechband telecommunications TE Transmisi-22

3 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".

TE Transmisi-24 Fundamentals about dB Alexander 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 This unit is not often used, having been replaced by the decibel (symbol dB) which is one-tenth of a bel.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 (P 1 /P 2 ) P 1 dan P2 P2 dalam satuan yang sama ( Watt, mWat, kWatt ) 5TE Transmisi-2

Daya, Tegangan dan Arus Daya = Tegangan x Arus Satuan : Daya : Watt, Tegangan : Volt, Arus : Ampere (Amp) P = V x I V = I x R dimana R : tahanan, Ohm ( ) 6TE Transmisi-2

Bel dan Perubahan Tegangan P = V x I = V²/R, dimana V : tegangan (Volt), I : arus (Amp), R : tahanan (Ohm, ) Bel = Log P 1 /P 2 = Log (V 1 ² /R 1 ) / (V 2 ² /R 2 ) = Log (V 1 /V 2 )².(R 2 /R 1 ) = Log (V 1 /V 2 )² + Log(R 2 /R 1 ) = 2 Log(V 1 /V 2 ) + Log(R 2 /R 1 ) Bel = 2 Log (V 1 /V 2 ), jika R1 R1 = R2R2 7TE Transmisi-2

Bel dan Perubahan Arus P = V²/R = (I x R)²/R = I²/R Bel = Log P 1 /P 2 = Log(I 1 ²/R 1 )/(I 2 ²/R 2 ) = Log(I 1 ²/I 2 ²)(R 1 /R 2 ) = Log(I 1 /I 2 )² + Log(R 1 /R 2 ) Bel = 2 Log I 1 /I 2 + Log R 1 /R 2 Bel = 2 Log I 1 /I 2, jika R1 R1 = R2R2 8TE Transmisi-2

Ringkasan (1) Bel = Log P 1 /P 2 Bel = 2 Log V 1 /V 2, jika R1 R1 = R2R2 Bel = 2 Log V 1 /V 2 + Log R 2 /R 1, jika R1 R1 R2R2 Bel = 2 Log(V 1 R 2 )/V 2 R 1 ), jika R1 R1 R2R2 9TE Transmisi-2

Ringkasan (2) Bel = 2 Log I 1 /I 2, jika R1 R1 = R2R2 Bel = 2 Log I 1 /I 2 + Log R 1 /R 2, jika R1 R1 R2R2 Bel = 2 Log (I 1 R 1 )/(I 2 R 2 ), jika R1 R1 R2R2 10TE Transmisi-2

DECIBEL (1) Unit yang menyatakan ratio Bentuk logaritma dengan dasar 10 Decibel ( dB ) = 10 Log ( power ratio ) 11TE Transmisi-2

Decibel (2) Decibel ( dB) = 10 x Bel dB = 10 Log P 1 /P 2 Jika R1 R1 = R2R2 dB = 20 Log V 1 /V 2 dB = 20 Log I 1 /I 2 12TE Transmisi-2

Decibel (3) Jika R1 R1 R2R2 dB = 20 Log V 1 /V Log R 2 /R 1 dB = 20 Log I 1 /I Log R 1 /R 2 dB = 20 Log (V 1 R 2 )/(V 2 R 1 ) dB = 20 Log (I 1 R 1 )/(I 2 R 2 ) 13TE Transmisi-2

Power Ratio & Voltage Ratio (1) 14TE Transmisi-2

Power Ratio & Voltage Ratio (2) 15TE Transmisi-2

Power Ratio & Voltage Ratio (3) 16TE 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 18TE Transmisi-2

dBm, dBW, Watt & milliWatt 19TE Transmisi-2

Voltage & Current Ratio dB(Voltage) = 20 Log ( ratio voltage ) dB(Current) = 20 Log ( ratio current ) 20TE Transmisi-2

dBmV Digunakan pada transmisi video Tegangan ( Voltage ) referensi = 1 mVolt pada beban 75 Ohm dBmV = 20 Log ( tegangan/1 mVolt ) 21TE Transmisi-2

dBmV 22TE Transmisi-2

dBµV/m Pengukuran kuat medan listrik Referensi 1µV/m dBµV/m = 20 Log (µV/m) 23TE Transmisi-2

24 KONSEP SISTEM TRANSMISI Loss & Gain

TE Transmisi-225 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 Transmisi-226 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 / ) = = 10x(-3) = -30 dB Kabel 1000 Watt1 Input Output 27TE Transmisi-2

LOSS Kabel 1000 Watt Input Output = ? Loss = 10 dB = 10 x Power Output = Power Input : Loss = Watt : 10 = 100 Watt Power Output = Power Input - Loss = 30 dBW - 10 = 20 dBW 28TE Transmisi-2

GAIN (PENGUATAN) Gain (dB ) = 10 Log(power ratio) = = 10 Log(output/input) = = 10 Log ( 2 / 1 ) = 10 x 0,3013 = 3,013 dB = 3 Amplifier 1 Watt2 Input Output 29TE Transmisi-2

GAIN (PENGUATAN) Amplifier 1 Watt Input Output =? Gain = 6 dB = 4 x Power Output = Power Input x Gain Power Input = 1 Watt = 30 dBm Power Output = 1 Watt x 4 = 4 Power Output = = 36 dBm 30TE Transmisi-2

Model Sistem Komunikasi Listrik Media Transmisi PenerimaPemancar Wire / Kawat / Kabel Wireless / Radio Fiber Optik Loss 10 dB PowerOutput : 1 mW = 0 dBm Power Input : - 10 dBm 31TE Transmisi-2

Model Sistem Pemancar Antena Pemancar Wire / Kawat /Kabel / Kabel Koaxial Power Output 1 kW = 30 dBW Loss = 3 dB Power Input 27 dBW Gain = 10 dB Effective Radiated Power (ERP) : 37 dBW 32TE 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 Transmisi-234 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 Penerima Pemancar Wireless / Radio Loss = 100 dB Gain 10 dB Gain 10 dB Loss = 2 dB Loss = 3 dB Power Output 1 kW = 60 dBm Power Input = -25 dBm ERP : 68 dBm -32 dBm 35TE Transmisi-2

Series Network N1N1 N2N2 N3N3 T S 10dBm G 3 dB L 5 dB G 3 dB 13 dBm 8 dBm 11 dBm 36TE Transmisi-2

Noise Figure (1) 37TE Transmisi-2 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) Network SNR out SNR in 40 dB30 dB Noise Figure ( NF ) = 40 – 30 = 10 dB 38TE Transmisi-2 Noise Figure ( NF ) = SNR in - SNR out (dB) NF = 1 ( 0 dB ) Noiseless

Noise Figure (3) NF 2 =3dB Loss=3dB NF 3 =16dB G 3 =60dB kabel Penerima antena NF = NF 2 + (NF 3 -1)/G 2 = 2 + (40-1)/0,5 = 80 = 19 dB Gain = = 57 dB NF 2 = 3 dB = 2 ; Loss = 3 dB = 2 = G 2 = 0,5 ; NF 3 = 16 dB = 40 ; G 3 = 60 dB = TE Transmisi-2 NF = NF 1 + (NF 2 – 1)/G 1 + (NF 3 -1)/G 1 G 2 + ….

Noise Figure (4) NF 2 =3dB Loss=3dB NF 3 =16dB G 3 =60dB NF 1 =6dB G 1 =20dB preamp kabel Penerima antena NF = 4 + (2-1)/100 + (40-1)/(100).0,5 = 4,79 = 6,8 dB Gain = 20 – = 77 dB NF 1 = 6 dB = 4 ; G 1 = 20 dB = 100 ; NF 2 = 3 dB = 2 Loss = 3 dB = 2 = G 2 = 0,5 ; NF 3 = 16 dB = 40 ; G 3 = 60 dB = TE Transmisi-2

Noise Figure (5) NF 2 =6dB G 2 =20dB NF 3 =16dB G 3 =60dB NF 1 =3dB Loss=3dB kabel preamp Penerima antena NF = 2 + (4-1)/0,5 + (40-1)/(100).0,5 = 8,78 = 9,4 dB Gain = = 77 dB NF 1 = 3 dB = 2 ; Loss = 3 dB = 2 = G 1 = 0,5 ; NF 2 = 6 dB = 4 ; G 2 = 20 dB = 100 ; NF 3 = 16 dB = 40 ; G 3 = 60 dB = TE Transmisi-2