Difference between averaging and accumulating Doppler wind lidar data

The poor signal to noise ratio of Doppler lidar data, given by the small amount of back scattered radiation and the large distance to the measurement volume, enforces the need of some averaging technique. The major question at which state of signal processing the averaging should take place have been investigated. The major problems with incoherent averaging, spurious estimates and as a consequence a bias on the averaged estimate, can be overcome using accumulation technique before the estimate is determined. Computer simulation have shown that this technique shows the same efficiency as one would expect using coherent averaging.