Signal 2018910 Outline Signal Digital signal Analog signal

Signal 陳洋升 (2018/9/10)

Outline • Signal • Digital signal • Analog signal • Modulation • Digital Modulation • • ASK PSK QAM FSK

訊號分兩種 • Digital signal • Analog signal

Modulation • 將一個或多個週期性的載波混入想傳送之訊號的技術，常用於無 線電波的傳播與通訊、電話通訊等各方面。 • Digital Modulation (digital data to analog signal) • • ASK (Amplitude-shift keying) PSK (Phase-shift keying) QAM (Quadrature amplitude modulation) FSK (Frequency-shift keying)

Digital Modulation

ASK (Amplitude-shift keying) • Amplitude difference of carrier frequency

FSK (Frequency-shift keying) • Frequency difference near carrier frequency

PSK (Phase-shift keying) • Phase of carrier signal shifted

Symbol • 2個以上不同的訊號所組成 • 例如QAM是由相位與振幅變化組合而成 • Example： • 16 -QAM (由 2種振幅與8種相位組合而成) • 2 amplitudes 90˚ 135˚ 0011 • a 1 • a 2 1011 • 8 phases • • p 1 = 0˚ p 2 = 45˚ p 3 = 90˚ p 4 = 135˚ p 5 = 180˚ p 6 = -135˚ p 7 = -90˚ p 8 = -45˚ 0010 1001 a 2 0100 a 1 1100 180˚ 0001 1010 0˚ 1000 0000 1101 0101 1110 1111 0111 -135˚ 0110 -90˚ Constellation diagram -45˚ I