A terrestrial positioning and timing system (TPTS) comprising a ground segment and user segment is disclosed that is comprised of a spread-spectrum based range and bearing reference signal, with respect to a reference time, transmitted by an antenna over a broad region of space; and a spread-spectrum based bearing variable signal with bearing specific modulation referenced to a reference time, transmitted using a scanning antenna over a spatial region of space that is more narrow than the spread-spectrum based range and bearing reference signal transmission spatial area. Various embodiments enable the TPTS station and user to support various position, velocity or time services. Most notably, an embodiment with a single TPTS station, active interrogation/transponder reply, and data delivery subsystem can provide a position, velocity, and time solution for the user. Additional embodiments disclosed provide varying levels of user solutions to include bearing, position, velocity, or time.

A method, system, and computer-readable medium for performing a hazard analysis of navigation aid equipment using an external safety monitor. Aspects include monitoring performance of the navigation aid equipment. In addition, determination is made if an improper performance of the navigation aid equipment is detected. Furthermore, removal of a signal from an antenna of the navigation aid equipment may occur when improper performance of the navigation aid equipment is detected.

A communication device and a corresponding device operating method include an ultra-wideband (UWB) communication unit enabling UWB communication with at least one external communication device, and a processing unit performing a ranging session between the communication device and the external communication device. The ranging session includes one or more distance measurements based on messages exchanged between the communication device and the external communication device. The messages are exchanged through the UWB communication unit. The device also includes a prioritization unit configured to prioritize the ranging session using a synchronization indicator associated with the ranging session.

A position of an aircraft is computed, associated with the radius of a sphere centered around the estimated position of the aircraft and within which the actual position of the aircraft is located with a probability equal to or greater than a predefined threshold. For this purpose, the computation is based on distances from radio transmitters each having a fixed position in a geographical reference frame. The positions of the radio transmitters are converted into a terrestrial reference system, before solving a system of equations linking, in the terrestrial reference system, the position of the aircraft and the positions of the radio transmitters. After solving the system of equations, the position of the aircraft is converted from the terrestrial reference system into the geographical reference frame.