CHAPTER 19: Data Conversion pptx

CHAPTER 19 Data Conversion Objectives Describe and Analyze: • Analog vs. Digital Signals • Resolution • Digital-to-Analog Conversion • Analog-to Digital Conversion • Troubleshooting Introduction • The low cost of microprocessors and the power of using software to carry out signal processing has revolutionized electronics. • The fact that real-world signals are analog requires microprocessor-based systems to have an A/D at one end and a D/A at the other end. A Typical System <insert figure 19-1 here> Resolution Analog signals can have any value; digital signals cannot. Resolution • Analog signals are continuous, meaning that between any two values, there is always another value. For example, between 1.0000 Volts and 1.0001 Volts there is 1.00005 Volts (and an infinite number of other values). • Digital signals are discrete, meaning that the difference between any two digital values cannot be less than 1. For example, the next number after binary 1010 is 1011. There is no value between 1010 and 1011. Resolution • Resolution is the smallest difference you can “see” in a system. In a digital system, it is always 1 bit, but you need to know how many bits are in a “word”. • Resolution is a percentage of the maximum binary value. For example: suppose you have an 8-bit converter. The resolution would be: Resolution = (1 / 2 8 )  100% Resolution = (1 / 256)  100% Resolution = 0.39% Resolution • Resolution is not the same as accuracy. For example: 6 / 3 = 2.00635 has 6 digits of resolution (that’s 1 ppm!) but only 3 digits of accuracy (2.00) Resolution More bits = finer resolution = less “graininess”. Digital-to-Analog • To build an analog-to-digital, you first need a digital-to-analog converter (also called DAC or D/A). • The basic ingredients are a precise (or at least stable) voltage reference, some precision resistors, some digitally controlled switches, and an op-amp to sum it all up. • See figure on following slide. . CHAPTER 19 Data Conversion Objectives Describe and Analyze: • Analog vs. Digital Signals • Resolution • Digital-to-Analog Conversion • Analog-to Digital Conversion • Troubleshooting