Abstract: An improved technique for acoustic sensing involves, in one embodiment, launching into a medium, a plurality of groups of pulse-modulated electromagnetic-waves. The frequency of electromagnetic waves in a pulse within a group differs from the frequency of the electromagnetic waves in another pulse within the group. The energy scattered by the medium is detected and, in one embodiment, may be used to determine a characteristic of the environment of the medium.

Abstract: A virtual peak register system is provided that allows individuals who have climbed various mountains to record and display information concerning their ascents over the Internet. The information recorded can be displayed in the form of a general peak register or a personal peak register. The general peak register can display information that includes the names of the individuals who have climbed a particular mountain and the dates of their respective climbs, the information being displayed in reverse chronological order. The personal peak register can display information that includes the names and dates of mountains personally climbed by an individual. The personal peak register can display the information concerning the individual's ascents according to any number of criteria, such as the elevations of the mountains climbed or the dates of the climbs.