Pulsed Laser Ranging Method Using Cyclostationary Random Sequences

To avoid deterioration in the ranging accuracy caused by pulse-timing errors, a pulsed laser ranging method using cyclostationary random sequences is proposed. In this method, echo pulse-timing signals arc mapped onto periodic reference signals to construct cyclostationary random sequences, which converts measurements of pulse-timing moments into parameter estimation of these sequences. The use of periodic stationary changes in time for cyclostationary stochastic processes enables the accurate estimation of parameters from the measurement data with timing jitter errors. High-precision target distances can then be obtained. An ergodic undersampling method is also proposed to overcome the difficulty of using equivalent and equally-spaced sampling for obtaining the measurement data of cyclostationary random sequences when the sampling and signal frequencies arc very different. A pulsed laser rangefinder based on these principles is developed with the advantages of high accuracy and simple structure. When the laser exit pupil average power is 1 mW and the signal-to-noise ratio is 10, tests show that the non-cooperative target range is 300 m and the range accuracy is +/-(2 mm + 2 x 10(-6) D).