Covert Analog Signal into Digital Signal
A strain gauge is used in Wheatstone Bridge configuration. The output from the Wheatstone Bridge varies from zero to a maximum strain output of 12V, that is it is in the positive quadrant.
You are required to convert this 0 -12 V analog signal into a 12 bit digital signal (Analog to Digital Conversion, ADC). The maximum frequency of the analog signal is 20 KHz (this governs the Nyquist sampling rate).
1. The relationship between the analog value of the digital signal and the input analog signal is such that it obeys the square law. The functional relationship is exhibited by the digital step having a greater sensitivity at the low voltage levels than at the higher voltage level (the analog equivalent of the digital step is smaller at the lower voltage levels than at the higher voltage levels).
2. The resultant digital signal is also converted to the Gray code in that only one bit is to change for each quantisation level change.
3. The output of the ADC or the Gray code equivalent is used to illuminate three lights using combinational logic to give
Green > 1/2 Vmax (stays on while the voltage is exceeded)
Amber > 3/4 Vmax (stays on while the voltage is exceeded)
Red >7/8 Vmax (stays on while the voltage is exceeded)
4. The Digital signal is converted back to an analog signal but each digital bit step increase has the same analog magnitude change, the digital signal is considered a linear function of voltage.
Each component (bullet point above) of the total design is to be simulated using:
NI circuit design suite (Student edition or Academic edition)
National Instruments