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# Modul – 3 Sistem Transmisi

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1. Modul – 3Sistem Transmisi TE-09-1313 2 sks Tim BidangStudi Telekomunikasi Multimedia (AchmadAnsori, DevyKuswidiastuti, GatotKusrahardjo, M Aries Purnomo) TE-09-1313-03-Transmisi-2

2. The use of the decibel and of relative levelsin speechband telecommunications TE-09-1313-03-Transmisi-2

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-09-1313-03-Transmisi-2

4. 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 This unit is not often used, having been replaced by the decibel (symbol dB) which is one-tenth of a bel. TE-09-1313-03-Transmisi-2

5. Bel • Unit dari ukuran perubahan daya • Bel = Log (P1/P2) • P1 dan P2 dalam satuan yang sama ( Watt, mWat, kWatt ) TE-09-1313-03-Transmisi-2

6. 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 () TE-09-1313-03-Transmisi-2

7. 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 TE-09-1313-03-Transmisi-2

8. 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 TE-09-1313-03-Transmisi-2

9. 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(V1R2)/V2R1) , jika R1  R2 TE-09-1313-03-Transmisi-2

10. Ringkasan (2) • Bel = 2 Log I1/I2 , jika R1 = R2 • Bel = 2 Log I1/I2 + Log R1/R2 , jika R1 R2 • Bel = 2 Log (I1R1)/(I2R2) , jika R1 R2 TE-09-1313-03-Transmisi-2

11. DECIBEL (1) • Unit yang menyatakan ratio • Bentuk logaritma dengan dasar 10 • Decibel ( dB ) = 10 Log ( power ratio ) TE-09-1313-03-Transmisi-2

12. 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 TE-09-1313-03-Transmisi-2

13. 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 (V1R2)/(V2R1) dB = 20 Log (I1R1)/(I2R2) TE-09-1313-03-Transmisi-2

14. Power Ratio & Voltage Ratio (1) TE-09-1313-03-Transmisi-2

15. Power Ratio & Voltage Ratio (2) TE-09-1313-03-Transmisi-2

16. Power Ratio & Voltage Ratio (3) TE-09-1313-03-Transmisi-2

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

18. 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 TE-09-1313-03-Transmisi-2

19. dBm, dBW, Watt & milliWatt TE-09-1313-03-Transmisi-2

20. Voltage & Current Ratio • dB(Voltage) = 20 Log ( ratio voltage ) • dB(Current) = 20 Log ( ratio current ) TE-09-1313-03-Transmisi-2

21. dBmV • Digunakan pada transmisi video • Tegangan ( Voltage ) referensi = 1 mVolt pada beban 75 Ohm • dBmV = 20 Log ( tegangan/1 mVolt ) TE-09-1313-03-Transmisi-2

22. dBmV TE-09-1313-03-Transmisi-2

23. 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 : • 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 • “affaiblissementd'insertion” and “facteurd'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. TE-09-1313-03-Transmisi-2

27. LOSS • Loss (dB ) = 10 Log(power ratio) = = 10 Log(output/input) = = 10 Log ( 1 / 1.000 ) = = 10x(-3) = -30 dB 1000 Watt 1 Watt Kabel Output Input TE-09-1313-03-Transmisi-2

28. LOSS 1000 Watt Kabel Output = ? Input Loss = 10 dB = 10 x Power Output = Power Input : Loss = 1.000 Watt : 10 = 100 Watt Power Output = Power Input - Loss = 30 dBW - 10 = 20 dBW TE-09-1313-03-Transmisi-2

29. 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 1 Watt 2 Watt Amplifier Output Input TE-09-1313-03-Transmisi-2

30. GAIN (PENGUATAN) 1 Watt Amplifier Output =? Input Gain = 6 dB = 4 x Power Output = Power Input x Gain Power Input = 1 Watt = 30 dBm Power Output = 1 Watt x 4 = 4 Watt Power Output = 30 + 6 = 36 dBm TE-09-1313-03-Transmisi-2

31. Model Sistem Komunikasi Listrik PowerOutput : 1 mW = 0 dBm Loss 10 dB Power Input : - 10 dBm Pemancar Media Transmisi Penerima Wire / Kawat / Kabel Wireless / Radio Fiber Optik TE-09-1313-03-Transmisi-2

32. Model Sistem Pemancar Power Input 27 dBW Power Output 1 kW = 30 dBW Gain = 10 dB Pemancar Antena Loss = 3 dB Wire / Kawat /Kabel / Kabel Koaxial Effective Radiated 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. TE-09-1313-03-Transmisi-2

35. Model Sistem Pemancar & Penerima -32 dBm Loss = 100 dB ERP : 68 dBm Gain 10 dB Gain 10 dB Wireless / Radio Loss = 3 dB Loss = 2 dB Penerima Pemancar Power Input = -25 dBm Power Output 1 kW = 60 dBm TE-09-1313-03-Transmisi-2

36. Series Network G 3 dB L 5 dB G 3 dB S N1 N2 N3 T 10dBm 11 dBm 13 dBm 8 dBm TE-09-1313-03-Transmisi-2

37. 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. TE-09-1313-03-Transmisi-2

38. Noise Figure (2) Noise Figure ( NF ) = SNRin - SNRout (dB) NF = 1 ( 0 dB )  Noiseless SNRout SNRin Network 40 dB 30 dB Noise Figure ( NF ) = 40 – 30 = 10 dB TE-09-1313-03-Transmisi-2

39. Noise Figure (3) NF = NF1 + (NF2 – 1)/G1 + (NF3 -1)/G1G2 + …. antena NF2=3dB Loss=3dB NF3=16dB G3=60dB kabel Penerima NF2 = 3 dB = 2 ; Loss = 3 dB = 2 = G2 = 0,5 ; NF3 = 16 dB = 40 ; G3 = 60 dB = 1.000.000 NF = NF2 + (NF3-1)/G2 = 2 + (40-1)/0,5 = 80 = 19 dB Gain = -3 +60 = 57 dB TE-09-1313-03-Transmisi-2

40. Noise Figure (4) antena NF2=3dB Loss=3dB NF3=16dB G3=60dB NF1=6dB G1=20dB kabel Penerima preamp NF1 = 6 dB = 4 ; G1 = 20 dB = 100 ; NF2 = 3 dB = 2 Loss = 3 dB = 2 = G2 = 0,5 ; NF3 = 16 dB = 40 ; G3 = 60 dB = 1.000.000 NF = 4 + (2-1)/100 + (40-1)/(100).0,5 = 4,79 = 6,8 dB Gain = 20 – 3 + 60 = 77 dB TE-09-1313-03-Transmisi-2

41. Noise Figure (5) antena NF2=6dB G2=20dB NF3=16dB G3=60dB NF1=3dB Loss=3dB preamp Penerima kabel 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 NF = 2 + (4-1)/0,5 + (40-1)/(100).0,5 = 8,78 = 9,4 dB Gain = -3 + 20 +60 = 77 dB TE-09-1313-03-Transmisi-2