SYLLABUS5.3 Data Conversion L1• Analogue Data, Digital Data;• Operation and application of analogue to digital, and digital to analogue converters, inputs and outputs, limitations of various types
DEFINING ANALOGUE AND DIGITAL DATA• Analogue – Most real life data are analogue – It can have variable value and can fit into any readings. • E.g students’ height , 165cm, 155cn, 177cm .. Etc• Discrete – Digital signal in any of the given state, example either 0 or 1. – It cannot have any reading in between.
EXAMPLES OF DATA CONVERTION• Digital to Analogue – Like CD data to speakers inputs• Analogue to Digital – Microphone outputs to digital for storage in CD.
Accuracy and Conversion• In the analogue to digital converter, there are two important features: – Accuracy – measure of how close the figure to true value. Example 1% accuracy means, for 100v, the reading can range between 99v to 101v. – Resolution – respond to the changes in value. A resolution of 100mv, will enable to digital output to 0.1 volt
ANALOGUE TO DIGITAL +VE 8 7 VREF ANALOGUE SIGNAL 6 5 4 + VOUT 3 VIN 2 1 0 0 0 0 1 1 1 1 As many as the bits 0 0 1 1 0 0 1 1 3 BIT WORD 0 1 0 1 0 1 0 1 DIGITAL SIGNAL• Thus the more bits available the greater the • The output of the comparator will be logic resolution for a given range of analogue “0” when the reference voltage is greater signal input. It can be seen from the above than the analogue input, It will be logic “1” that an ADC using an n-bit word would have when the analogue voltage is greater than a resolution of one part in 2n the reference voltage.