Weak Signal Detector Based on DAQ and Lock-In Technology

The current weak signal measuring equipment is too large, expensive and lack of low-frequency measuring ability in the metrology support of hydro-acoustic detection. A low-cost, applicable, self-research and development weak signal detector is designed and realized through a 24-bit dynamic signal acquisition card. The software based on NI LabWindows/CVI adopts DAQmx, digital locked-in and cascade low pass filtering methods to ensure orthogonal precise measurements of frequency and amplitude for AC signals, which are partially or completely buried in noise. The functions of reference signal mathematical generation, algorithm simulation and signal analysis through software break the puzzle of the traditional design method depended on ultra-low noise amplifier and super-steady reference source. The test results show this device can extractly measure the micro-volt signal between 10 similar to 1000Hz.