Bài giảng "Xử lý tín hiệu số - Chapter 2: Quantization" gồm có những nội dung chính sau: Quantization process, quantization error, digital to analog converters, A/D converter, A/D converter-example, . Mời các bạn cùng tham khảo. | Chapter p 2 Quantization Ha Hoang Kha to edit Master subtitle style Ho Chi Minh City University of Technology @ Email hhkha@ https tailieudientucntt 1. Quantization process Fig Analog to digital conversion The quantized sample xQ nT is represented by B bit which can take 2B possible values. values An A D is characterized by a full-scale range R which is divided into 2B quantization levels. l l Typical T l values l off R in practice are between 1-10 volts. Ha H. Kha 2 Quantization https tailieudientucntt 1. Quantization process Fig Signal quantization R Quantizer resolution or quantization width Q 2B R R bip l ADC A bipolar xQ nT lt 2 2 A unipolar p ADC 0 xQ nT lt R Ha H. Kha 3 Quantization https tailieudientucntt 1. Quantization process Quantization error Quantization by rounding replace each value x nT by the nearest q antization le quantization level. el Quantization by truncation replace each value x nT by its below quantization level. Quantization error e nT xQ nT x nT Q Q Consider rounding quantization e 2 2 Fig i Uniform if probability b bili density d i off quantization i i error Ha H. Kha 4 Quantization https tailieudientucntt 1. Quantization process Quantization error Q 2 Q 2 1 The mean value of quantization error e Q 2 ep e de Q 2 e Q de 0 Q 2 2 Q 2 1 Q The mean square error power σ 2 e2 e 2 p e de e 2 de mean-square Q 2 Q 2 Q 12 Q Root mean square rms error erms σ e2 Root-mean-square 12 R and Q are the rangesg of the signal g and quantization q noise then the signal to noise ratio SNR or dynamic range of the quantizer is defined as R SNR dB 20 log10 20 log10 2 B B log10 2 6 B dB Q which is referred to as 6 dB bit rule. rule Ha H. Kha 5 Quantization https tailieudientucntt 1. Quantization process Example In a digital audio application the signal is sampled at a rate of 44 KHz andd each h sample
