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Figure 8:Application block diagram
PIR have four op-amps (operational amplifiers) two for amplification stage and one for voltage follower and one as a comparator. The signal from the FET is amplified and the Amplifier 1 provides gain (gain is a unit less measure of the ability of an amplifier to increase the amplitude of a signal from the input to the output) and the signal is buffered in a signal adaptor and signal adapter and it is passed to the Amplifier 2 to provide another gain. Ratio Ratio gain in staged amplifiers is multiplied. Then the signal is fed into the A/D convertor D converter (Analog to Digital converter) it converts the analog voltage signal into signal into binary signals and the binary signal encodes the analog input as a result the output is in digital number.[7]
Analog-digital converter uses that comparator compares the signal value with the threshold value. The threshold value of the PIR sensor is kept low to capture weak motions if the signal value is between the two threshold values that mean there is no motion and the reading is 0 V. If signal value is higher than the threshold value then the sensor has detected a motion, and the indicator is activated to identify the detection of motion.[2],[7]
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