Time-Shifted PN Codes for CW LIDAR, RADAR, and SONAR

NASA’s Langley Research Center has developed a waveform processing technique to eliminate signal noise resulting from sources of interference (scatterers) that can degrade continuous wave (CW) lidar return data. The algorithm was developed to enable CW lidar measurement of atmospheric gas concentrations as part of NASA’s Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) program, but can be used to test any chemical species, such as poison gas or other trace elements in the atmosphere. The algorithm demonstrated reduction in interference resulting from thin cloud layers and other scatterers. The improvement holds the potential for significant advancement of CW lidar systems that are less expensive, of simpler design, and can be operated at higher average power than pulsed lidar systems.