Exploration of hybrid inertial/GPS systems to provide continuous positioning through varying environments represents a growing field of interest to researchers. In particular, first responders and public safety professional would like to see robust systems that can operate indoors. This article describes work under way to develop a pedestrian navigation system based on inertial sensors and an assisted GNSS receiver. Special attention is paid to efforts being made in "gait analysis" to fine-tune the behavior of the inertial sensors as well as the stochastic models used in the system.