Teknik Modulasi Pertemuan 07 Matakuliah : H0484/Jaringan Komputer Tahun : 2007 Teknik Modulasi Pertemuan 07

Pada akhir pertemuan ini, diharapkan mahasiswa akan mampu : Learning Outcomes Pada akhir pertemuan ini, diharapkan mahasiswa akan mampu : Menjelaskan teknik modulasi Bina Nusantara

Outline Materi Teknik Modulasi Modulasi analog Modulasi digital Bina Nusantara

Analog data, carrier analog signal Digital data, carrier analog signal Encoding Techniques Analog data, carrier analog signal Digital data, carrier analog signal Analog Modulation Analog data, carrier digital signal Digital Modulation Digital data, carrier digital signal Encoding Bina Nusantara

Analog Data, Analog Signals Why modulate analog signals? Higher frequency can give more efficient transmission Permits frequency division multiplexing Types of modulation Amplitude Frequency Phase Bina Nusantara

Analog Modulation Bina Nusantara

Memperbesar jarak jangkau sinyal informasi. Modulasi Tujuan: Mengubah sinyal komputer yang digital menjadi sinyal analog yang diperlukan oleh saluran komunikasi. Memperbesar jarak jangkau sinyal informasi. Modem merupakan perangkat keras untuk kedua proses ini Bina Nusantara LST/FASKD/CINQ

Type Modulasi Digital /Analog Bina Nusantara

Modulation Techniques Bina Nusantara

Frequency Shift Keying Most common form is binary FSK (BFSK) Two binary values represented by two different frequencies (near carrier) Less susceptible to error than ASK Up to 1200bps on voice grade lines High frequency radio Even higher frequency on LANs using coax Bina Nusantara

Phase of carrier signal is shifted to represent data Binary PSK Phase Shift Keying Phase of carrier signal is shifted to represent data Binary PSK Two phases represent two binary digits Differential PSK Phase shifted relative to previous transmission rather than some reference signal Bina Nusantara

Each element represents two bits Quadrature PSK More efficient use by each signal element representing more than one bit e.g. shifts of /2 (90o) Each element represents two bits Can use 8 phase angles and have more than one amplitude 9600bps modem use 12 angles , four of which have two amplitude Bina Nusantara

4-PSK Constellation Bina Nusantara

Quadrature Amplitude Modulation QAM used on asymmetric digital subscriber line (ADSL) and some wireless Combination of ASK and PSK Logical extension of QPSK Send two different signals simultaneously on same carrier frequency Use two copies of carrier, one shifted 90° Each carrier is ASK modulated Two independent signals over same medium Demodulate and combine for original binary output Bina Nusantara

4-QAM and 8-QAM Bina Nusantara

PULSE AMPLITUDE MODULATION Pulse amplitude modulation has some applications, but it is not used by itself in data communication. However, it is the first step in another very popular conversion method called pulse code modulation. Bina Nusantara

Pulse Code Modulation (PCM) Bina Nusantara