Research on echo signal processing in the marine particulate organic carbon detection system

The ocean plays an important role in the global carbon cycle. Carbon is transmitted along the food chain in the form of particulate organic carbon (POC), starting from the photosynthesis of phytoplankton. Therefore, detecting the content of POC in the ocean plays a significant role in estimating the carbon sink capacity of the ocean. With the help of LIDAR detection systems, the profile concentration information of POC in seawater can be detected based on the optical property changes caused by phytoplankton. In order to satisfy the detection requirements of a LIDAR system, a detection capability with sensitivity up to the single photon level, dynamic range of 50dB, and response bandwidth of 180MHz, the echo optical signal detection and processing system is designed combining the analog detection and photon counting detection. By means of theoretical analysis, simulation analysis and experimental analysis, the analog detection channel output signal meets the following ADC acquisition requirements, and the photon counting channel can accurately discriminate the input pulse signal accurately. This echo optical signal detection and processing system is capable of providing a signal bandwidth of 180MHz and a fixed time delay without distortion, oscillation or pulse width broadening.