Methods and systems for monitoring vibrations introduce baseline vibrations into a fiber optic cable with one or more of a designated frequency or a designated amplitude. Changes in the baseline vibrations are monitored using the fiber optic cable. Information about environmental conditions outside of the fiber optic cable and/or moving objects can be determined based at least in part on the changes in the baseline vibrations that are monitored. The information that is determined about the objects, such as vehicles, can be modified based on the changes in the baseline vibrations.