Off-line synchronization of measurements based on a common pseudorandom binary signal.

Postprocessing (or off line) synchronization methods rely on some overlap of information between two or more simultaneous measurements. The methods vary in the amount of explicit data needed to record the overlap: on the one hand, the full recording of an (absolute) time source for each measurement or, on the other hand, the reliance on information overlap of different parameters in the measurements. Whenever it is impossible to record the time from a central clock in all the simultaneous measurements, it is often possible to record asimple common signal. Using a binary pseudorandom noise (PRN) code to modulate the common signal enhances extraction of relative time information. The simplicity of this binary code makes it suitable for recording on various media (digitally or within audio and video streams) without the requirement for specialized and/or complex converters. The PRN technique has been applied successfully by NLR in several projects executed in a range of environments over the last decade and has been shown to provide time difference information with high precision.