PN-CW lidar using hardware correlator

After simulation studies confirmed the feasibility of a low cost system the foundation “Deutsche Bundesstiftung Umwelt” started to support an experimental project to develop a PN-CW-mini-lidar system. The project work is carried out in cooperation of Fachhochschule Merseburg and an industrial company. Different to common pulse lidars the laser energy is uniformly spread over time modulated by pseudo noise sequences. Due to the very low signal to noise ratio of the received signal the main work consists in developing a signal processing unit in order to enable reliable measurements. After an overview of the lidar system consisting of: CW diode laser transmitter, transmitter imaging system, receiver telescope, linear APD photo detector, correlation unit for signal processing and a Personal Computer for controlling and additional signal processing the paper focuses on a comparison of different methods for signal processing and several concepts of correlation units for lidar