1. Analogue to Digital Conversion
© D Hoult 2011

2. analogue signal

3. The analogue signal must be sampled (its voltage must be measured at regular intervals).

4. The analogue signal must be sampled (its voltage must be measured at regular intervals).
To measure the voltage, the A to D converter produces its own voltage which it increases in discrete steps until it is equal to the signal voltage.

5. The analogue signal must be sampled (its voltage must be measured at regular intervals).
To measure the voltage, the A to D converter produces its own voltage which it increases in discrete steps* until it is equal to the signal voltage.
* this voltage is said to be quantised

6. The analogue signal must be sampled (its voltage must be measured at regular intervals).
To measure the voltage, the A to D converter produces its own voltage which it increases in discrete steps until it is equal to the signal voltage.
At this point the counter is “disabled” (it stops counting).

7. Vs is the value of the signal voltage at the instant of sampling

8. The sampling process is assumed to take a very short time.

12. The precision of the process is limited by the “size of the steps”

13. This depends on the number of bits used by the counter

14. 3 bit precision and sampling frequency 1 Hz

15. 3 bit precision and sampling frequency 1 Hz

16. 3 bit precision and sampling frequency 1 Hz

17. 3 bit precision and sampling frequency 1 Hz

18. 3 bit precision and sampling frequency 1 Hz
digital signal

19. 3 bit precision and sampling frequency 1 Hz
digital signal
binary coded output

20. 3 bit precision and sampling frequency 1 Hz
digital signal
binary coded output etc

21. 3 bit precision and sampling frequency 2 Hz

22. 3 bit precision and sampling frequency 2 Hz

23. 3 bit precision and sampling frequency 2 Hz
digital signal
binary coded output

24. 3 bit precision and sampling frequency 2 Hz
digital signal
binary coded output etc

25. 3 bit precision and sampling frequency 4 Hz

26. 3 bit precision and sampling frequency 4 Hz
digital signal
binary coded output etc

27. 4 bit precision and sampling frequency 4 Hz

28. 4 bit precision and sampling frequency 4 Hz

29. 4 bit precision and sampling frequency 4 Hz
binary coded output etc

30. 4 bit precision and sampling frequency 8 Hz

31. 4 bit precision and sampling frequency 8 Hz
binary coded output

32. 4 bit precision and sampling frequency 8 Hz
etc

33. Binary coded digital output corresponding to the first four samples
etc

34. Binary coded digital output corresponding to the first four samples
etc

35. Binary coded digital output corresponding to the first four samples
etc

36. Binary coded digital output corresponding to the first four samples
etc

37. Binary coded digital output corresponding to the first four samples
etc

38. Binary coded digital output corresponding to the first four samples
In some systems, logic 1 (“true”) is represented by zero volts and logic zero (“false”) by 5 V
etc

39. Binary coded digital output corresponding to the first four samples
In some systems, logic 1 (“true”) is represented by zero volts and logic zero (“false”) by 5 V
etc