After etching the pre-amp board and populating it with parts, my quick test showed that the device did not work. No smoke, but no amplification either. And then some personal issues came up that I had to take care of. Over the last few nights I got some time to start debugging and quickly found that I had usd a 1K resistor and not a 10K resistor for the opamp feedback resistor. Quick fix and the pre amp started to work.Next I connected the pre amp to the rest of the system and started working on the software controlled AGC circuit. Got the offset working well but got hung up on the gain. The gain operates by looking for the peak signal value after each sensor rotation and adjusting the digital pot that controls the gain to place the peak at about 75% max range. But the peak value make no sense in that it was less than the computed average. Hope to solve this issue this week so I can take the unit outside for its first field trials.

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