Instrumentation system 1

Why signal conditioning is done in instrumentation system? Bhadra 2074

• Ans:- As we know that signal conditioner makes the output of primary sensing element into a suitable form so that the signal can be processes by the rest of the system. So due to this reason signal conditioning is done in instrumentation system.

Working of Dual Ramp ADC (Dual Slope ADC)

The figure shows the various components of dual ramp ADC. It consist of integrator which produces ramp signal(voltage i.e. Vc) from constant sampled analog input (VA ) whose slope is equal to                  (-VA/RC) and this ramp voltage become input to comparator and another input is grounded  so comparator output is high. Then gate opens. So up counter    will start counting and it will count until Vc =VA or up to its full scale (111 for 3 bit) and then resets. As it resets it send signal to control logic  to switch input to reference voltage(-Vref).

Now input to integrator is (-Vref):

Now voltage Vc will increase with positive slope of (Vref/RC) then the comparator output will be high and gate opens and up counter again start recounting and it will count until Vc = 0 then gate will be closed and counter will stop. The digital code seen in the counter will be the equivalent output to the input analog voltage(VA).