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

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

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

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

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

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

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

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

Sistem Telekomunikasi, Sukiswo, ST, MT Overview Sistem Telekomunikasi, Sukiswo, ST, MT

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

Sistem Telekomunikasi, Sukiswo, ST, MT Pendahuluan Sistem Telekomunikasi, Sukiswo, ST, MT

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

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

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

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

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

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

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

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

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