Personal Navigation Device Operable in GNSS-Denied Environment

A personal navigation device comprising a body, a star tracker, an inclinometer, a clock, a GNSS receiver, and first and second position calculation modules. The first position calculation module is configured to calculate latitude and longitude of the body based on respective outputs from the star tracker, inclinometer, and clock. The second position calculation module is configured to calculate latitude and longitude of the body based on satellite signals received by the GNSS receiver. In one implementation, the star tracker includes a short-wave infrared camera and the inclinometer includes three accelerometers having non-coplanar axes. The personal navigation device may further include a display device, a display engine, and a user interface configured to enable selection of a particular method of calculating latitude and longitude depending on whether GNSS is available or not.