② Example of旨s Digitization 1 original signal =o 321 received signal Benefit time time How fix(确定) Analog signal 0110111011 higher, lower, a2d (e.g., audio, video) may digitized signa/西1 0厂 lose quality time飞 tir Can fix- distinguish(辨别) e Voltage levels Not a perfect re-creation Os/1s. restore not saved/ due to a2d and d2a copied/ Let bit encoding be: transmitted 1V“01” 0110111011 2v“10”3 perfectly 3v“11 d 2a Higher sampling rate and more bits per 42 encoding improves re-creation
42 42 Example of Digitization Benefit Analog signal (e.g., audio, video) may lose quality Voltage levels not saved/ copied/ transmitted perfectly time Volts 0 1 2 3 original signal lengthy transmission (e.g, cell phone) time 0 1 2 3 received signal How fix（确定） -- higher, lower, ? lengthy transmission (e.g, cell phone) 01 10 11 10 11 0110 11 10 11 Volts digitized signal time 0 1 a2d Volts 0 1 2 3 d2a time Can fix—distinguish（辨别） 0s/1s, restore 0 1 Higher sampling rate and more bits per encoding improves re-creation Not a perfect re-creation due to a2d and d2a Let bit encoding be: 1 V: “01” 2 V: “10” 3 V: “11
② Example of 0E0s Digitization Benefit Original signal 8 1iHeceived signal Digitized time time version enables How fix -higher, lower 110111011 near-perfect a2d savelcpy/tran digitized signa/ 5 “ Sample” 0 voltage at time飞 time particular rate, a Can fix-distinguish OS/Is, restor save sample using bit encoding Not a perfect re-creation due to a2d and d2a 011011101 e Voltage levels still not kept d2a perfectly 9 峰 But we can Higher sampling distinguish os rate and more bits per 3210 43 rom is encoding improves re-creation
43 43 Example of Digitization Benefit Digitized version enables near-perfect save/cpy/tran. “Sample” voltage at particular rate, save sample using bit encoding Voltage levels still not kept perfectly But we can distinguish 0s from 1s time Volts 0 1 2 3 original signal lengthy transmission (e.g, cell phone) time 0 1 2 3 received signal How fix -- higher, lower, ? lengthy transmission (e.g, cell phone) 01 10 11 10 11 01 10 11 10 11 Volts digitized signal time 0 1 a2d Volts 0 1 2 3 d2a time Can fix—distinguish 0s/1s, restore 0 1 Higher sampling rate and more bits per encoding improves re-creation a Not a perfect re-creation due to a2d and d2a
oDigital Logic Design and Application(数字逻辑设计及应用) 1.2 Analog versus Digital (模拟与数字) 原始信号 衰减 放大 模拟信号在传输过程中失真 数字信号仍然可以保持0、1 44
44 原始信号 衰减 放大 模拟信号在传输过程中失真 数字信号仍然可以保持 0、1 1.2 Analog versus Digital (模拟与数字) Digital Logic Design and Application (数字逻辑设计及应用)
oDigital Logic Design and Application(数字逻辑设计及应用) 1.2 Analog versus Di gital (模拟与数字) The problem for Analog signal ◆ Easy to be disturb(干扰) Shift with temperature ◆ Hard to be recorded Can not express abstract information 45
45 1.2 Analog versus Digital (模拟与数字) Digital Logic Design and Application (数字逻辑设计及应用) The problem for Analog signal ◆Easy to be disturb (干扰） ◆Shift with temperature ◆Hard to be recorded ◆Can not express abstract information
oDigital Logic Design and Application(数字逻辑设计及应用) 1.2 Analog versus Di gital (模拟与数字) The advantage of digital signal On each data line, the signal is very simple Not influenced by circumstance and device 2 Can be recorded and transmitted easily C Any information can be code 46
46 1.2 Analog versus Digital (模拟与数字) Digital Logic Design and Application (数字逻辑设计及应用) The advantage of digital signal ◆On each data line, the signal is very simple ◆Not influenced by circumstance and device ◆Can be recorded and transmitted easily ◆Any information can be code