New modulation codes are presented for a random modulation cw lidar. One characteristic of these modulation codes is that for very noisy background conditions, the signal-to-noise ratio is improved by using these new sequences, and is better than for the maximum-length sequence (the M-sequence) which is commonly used as the modulation code. Another characteristic of these modulation codes is that there is no correlation between them. This fact will be useful for the simultaneous multitransmitter of the differential absorption lidar. These two characteristics of the new modulation codes were confirmed experimentally.
© 1990 Optical Society of America
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