ABSTRACT
Digital communication systems using the narrow pulses generated by a mode-locked laser are extremely efficient in their use of average laser power. However, these narrow pulses require precise system timing and decision intervals matched to the pulse width. This paper extends previous work by Gagliardi in this area to consider the effects of pulse timing errors and pulse width mismatch on the probability of bit error for on-off keying, binary pulse position modulation, and quarternary pulse position modulation formats. The general expressions are derived, and a number of examples are plotted.
ABSTRACT
The possible effects of the atmosphere on the propagation of short optical pulses are estimated, and experiments are described using real time pulse-comparison techniques over a 1.6-km path. With a pulse duration of 1.5 nsec, an optical thickness of 2.8, and a typical angular beamwidth and field of view, pulse distortion was not observed. It is concluded that multiple scattering due to aerosols comprises the only mechanism of possible importance, and should be observable with shorter pulses or large angle optics. The results are pertinent to recently proposed, sophisticated optical communications and radar techniques.
