Superior signal-to-noise ratio of a new AA1 sequence for random-modulation continuous-wave lidar

In an earlier work [Proc. SPIE 4484, 216 (2001)] we proposed a new AA1 modulation sequence for random-modulation continuous-wave lidar. It possesses significantly better signal properties than other pseudorandom codes (the M, A1, and A2 sequences). We derive and compare the signal-to-noise ratio (SNR) of the new AA1 sequence with those of previous modulation sequences. Using a figure of merit proposed for pseudorandom sequences in additive (and generally colored) noise, we show that the SNR of the AA1 sequence in 1/f noise can be as much as 50 times better than that of the commonly used M sequence. This improved SNR should permit as much as a 7:1 increase of the maximum lidar sensing range in baseband-modulation direct-detection infrared lidar with no significant changes to the transmitter and receiver.