Use of the A1- and the A2-sequences to modulate continuous-wave pseudorandom noise lidar

The A1-sequences and the A2-sequences have been proposed to replace the M-sequence that is generally used to modulate continuous-wave pseudorandom noise lidar. These new sequences, under two hypotheses, provide a reduction in the background noise, which is especially significant in noisy conditions when one uses M-sequences. We show that one of these two hypotheses is not verified for cloudy atmospheric conditions. Thus, the A1- and the A2-sequences cannot be used for such conditions.