This is what I would like to achieve:

Step 1: Use Arduino to collect real-time voltage data into Processing Environment. For example, data acquisition continues for 20 seconds.

Step 2: Split the the data sample into 40 fragments, each lasts 0.5 second.

Step 3: Set the voltage at time 0 of each fragment 0 V. 

Step 4: Add all the data samples up and calculate the average waveform of the voltage change during that 0.5 second interval. This is just signal averaging to reduce the noise because noise is random. 

Step 5: Measure the amplitude of the signal in the averaged waveform. If the signal is larger than an threshold value, say 3V, turn on the LED light controlled by the Arduino. 

This is could easily be done on Matlab or LabVIEW, but those equipment/software are just too expensive. I am trying to realize this function in the Arduino-Processing environment. Please let me know whether this is possible? Please give me some directions so I can pursue further at the right direction. Thank you so much!!!