1. Sistem Telekomunikasi, Sukiswo, ST, MT Sukiswo sukiswok@yahoo.com
Pendahuluan
Sukiswo
Sistem Telekomunikasi, Sukiswo, ST, MT

2. Sistem Telekomunikasi, Sukiswo, ST, MT
Outline
Tujuan
Materi
Referensi
Relevansi
Sistem Evaluasi
Prasyarat
Overview Materi
Sistem Telekomunikasi, Sukiswo, ST, MT

3. Sistem Telekomunikasi, Sukiswo, ST, MT
Tujuan
Menjelaskan pengolahan sinyal baseband (PAM, PWM, PPM, PCM dan variasinya) maupun sinyal passband (ASK, FSK, PSK, MPSK, MQAM) dalam sistem komunikasi dan kinerja sistem
Sistem Telekomunikasi, Sukiswo, ST, MT

4. Sistem Telekomunikasi, Sukiswo, ST, MT
Materi
Pengolahan sinyal Baseband
Modulasi Pulsa : PAM, PWM, PTM, PPM
Modulasi Kode Pulsa : PCM, dan variasinya (DPCM, Delta PCM, ADPCM, Adaptive Delta PCM)
Line Encoding
Pengolahan sinyal Passeband
Modulasi Digital : Modulasi ASK, FSK, PSK, MPSK, MQAM
Sistem Telekomunikasi, Sukiswo, ST, MT

5. Sistem Telekomunikasi, Sukiswo, ST, MT
Referensi
Bernard Sklar, Digital Communications
Wayne Tomasi, Advanced Communication System
Leon W.Cough, Analog & Digital Communications System
Sistem Telekomunikasi, Sukiswo, ST, MT

6. Sistem Telekomunikasi, Sukiswo, ST, MT
Relevansi
Teknologi komunikasi terus berkembang
Design of System
Design of circuit
New System
Old System
Sistem Telekomunikasi, Sukiswo, ST, MT

7. Sistem Telekomunikasi, Sukiswo, ST, MT
Sistem Evaluasi
Tugas : 30 %
UTS : 30 %
UAS : 40 %
Sistem Telekomunikasi, Sukiswo, ST, MT

8. Sistem Telekomunikasi, Sukiswo, ST, MT
Prasyarat
Dasistel
Jartel
Sistem Telekomunikasi, Sukiswo, ST, MT

9. Sistem Telekomunikasi, Sukiswo, ST, MT
Overview
Sistem Telekomunikasi, Sukiswo, ST, MT

10. What is a communications system?
Sistem Telekomunikasi, Sukiswo, ST, MT
What is a communications system?
Communications Systems: Systems designed to transmit and receive information
Info
Source
Sink
Comm
System
Sistem Telekomunikasi, Sukiswo, ST, MT

11. Sistem Telekomunikasi, Sukiswo, ST, MT
Pendahuluan
Sistem Telekomunikasi, Sukiswo, ST, MT

12. Sistem Telekomunikasi, Sukiswo, ST, MT
Block Diagram
Receiver Rx
received
message to
sink
Transmitter Tx
s(t)
transmitted
signal
Channel
r(t)
m(t)
from
source
Info
Source
Sink
n(t)
noise
Sistem Telekomunikasi, Sukiswo, ST, MT

13. What limits our ability to communicate?
Sistem Telekomunikasi, Sukiswo, ST, MT
What limits our ability to communicate?
NOISE!!!!!
Noise: an unwanted, random fluctuation in the signal
Without the effects of noise, a message with infinitesimally small power could be transmitted over infinitely large distances
ALL advances in communications technology are advances to combat the effects of noise
Sistem Telekomunikasi, Sukiswo, ST, MT

14. Aspect in Communication design
Bandwidth
Delay
Power : S/N, Eb/N
BER / Probability of error
Cost
Sistem Telekomunikasi, Sukiswo, ST, MT

15. Sistem Telekomunikasi, Sukiswo, ST, MT
Shannon’s Theorem
Theoretical limit for error-free transmission in a communications system in the presence of noise
Source Data Rate: R [bits/sec]
Channel Capacity:
C = B log2(1 + S/N) [bits/sec]
R < C: No Error!!!
Sistem Telekomunikasi, Sukiswo, ST, MT

16. Sistem Telekomunikasi, Sukiswo, ST, MT
Comm. Sys. Bock Diagram
Noise
m(t) Tx
Channel Rx
s(t)
r(t)
Baseband
Signal
Baseband
Signal
Bandpass
Signal
“Low” Frequencies
<20 kHz
Original data rate
“High” Frequencies
>300 kHz
Transmission data rate
Demodulation or
Detection
Modulation
Formal definitions will be provided later
Sistem Telekomunikasi, Sukiswo, ST, MT

17. Aside: Why go to higher frequencies?
Sistem Telekomunikasi, Sukiswo, ST, MT
Aside: Why go to higher frequencies?
Half-wave dipole antenna
c = f l
c = 3E+08 ms-1
Calculate l for
f = 5 kHz
f = 300 kHz Tx
l/2
There are also other reasons for going from baseband to bandpass
Sistem Telekomunikasi, Sukiswo, ST, MT

18. Sistem Telekomunikasi, Sukiswo, ST, MT
Information
Recall:
Information Source: a system that produces messages (waveforms or signals)
Digital/Discrete Information Source: Produces a finite set of possible messages
Digital/Discrete Waveform: A function of time that can only have discrete values
Digital Communication System: Transfers information from a digital source to a digital sink
Info
Source
Sink
Comm
System
Sistem Telekomunikasi, Sukiswo, ST, MT

19. Another Classification of Signals (Waveforms)
Sistem Telekomunikasi, Sukiswo, ST, MT
Another Classification of Signals (Waveforms)
Deterministic Signals: Can be modeled as a completely specified function of time
Random or Stochastic Signals: Cannot be completely specified as a function of time; must be modeled probabilistically
Sistem Telekomunikasi, Sukiswo, ST, MT

20. Sistem Telekomunikasi, Sukiswo, ST, MT
Signals and Noise
Comm. Waveform
Signal
(desired)
Noise
(undesired)
Strictly, both signals and noise are stochastic and must be modeled as such
We will make these approximations, initially:
Noise is ignored
Signals are deterministic
Sistem Telekomunikasi, Sukiswo, ST, MT