How does Moku:Lab's Lock-in Amplifier measure small signals with 12-bit ADCs?
Lock-in Amplifier : measuring small signals
Written by Paul Cracknell
Updated at February 8th, 2021
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Moku:Lab intelligently downsamples the input signal by averaging. The number of effective bits increases as the sampled ADC points are downsampled. For example, if the signal amplitude is 0.3 mV, but the least significant bit of the ADC is 1 mV, it would appear that the signal could not be detected.
However, when the signal is digitized, time sequential samples can be averaged. If the needed sample rate is 1/10 of the ADC rate, then we can downsample ten times. Three of the ten sample points should be 1 mV, and the other seven should read 0 mV. We can average the ten sample points and get an averaged number of 0.3 mV.