A light scattering photometer signal-enhancement systems includes an
adaptive sample and subtract circuit controlled by a computer or
microcontroller (MCU). The MCU controls the gain of a programmable-gain
amplifier (PGA) cascade that is used to amplify the raw photometer
signal. In order to maintain the DC accuracy, the DC offset contained in
the raw signal from the photometer is estimated by an algorithmic within
the MCU and then subtracted from the raw signal before allowing it to be
amplified by the PGA cascade. In addition to DC estimation and adaptive
cancellation, the MCU applies a digital filtering scheme to compensate
irrelevant frequency bands in the amplified signal and offers user
determined averaging functions for additional signal conditioning.
Moreover, hardware filters are used to prevent signal aliasing by the
analog to digital converters (ADC) and a 60 Hz notch filter suppresses
general electrical noise.