Multipoint weak signal acquisition based on orthogonal vector of the lock-in amplifier

In the optical fiber sensor signals, most of them are weak. Generally, they are converted to weak current or voltage through the sensor unit. But the signal is too weak to measure because of the sensing unit background noise, circuit noise and external interference noise which is stronger than the useful signal. It is unable to detect the weak signal only by the amplification because amplification of the measured signal also amplified the noise. In this paper, a multi point acquisition system of weak signal is designed, which is based on the quadrature vector type lock-in amplifier, it can detect the weak signal effectively and effectively.