Abstract: A system and method of identifying and responding to a GPS denial of service includes: configuring a mode S transponder for transmitting a GPS time-of-day message as a downlink format message using a BDS register, and configuring an aircraft surveillance system for receiving one or more GPS time-of-day messages transmitted as a downlink format message. The surveillance system compares the received time-of-day message(s) from the aircraft to a comparison time of day, and validates reception of authentic GPS signals by the aircraft when the received time-of-day message is within a threshold amount of the comparison time of day. The comparison time of day may be the GPS time of day of one of a plurality of aircraft in the surveillance volume or may be the GPS time of day determined by the aircraft surveillance system. An indicator on the transponder indicates counterfeit GPS signals, permitting mitigation od induced navigation error.

Abstract: The antenna uses X Band frequencies for long-distance weather monitoring and W Band frequencies for imaging of terrain and obstacles, for use in a radar system in aircraft nose radome to operate effectively in a degraded visual environment. The antenna's feed structure includes concentrically positioned first and second horns. First and second rectangular waveguides are positioned on a cylindrical portion of the first horn, and at a first and second radial positions spaced 90 degrees apart. First and second coaxial cables respectively couple the first and second rectangular waveguides to a polarization converter, which launches linearly polarized waves received from each of the first and second coaxial cables to form a W-hand circularly polarized wave. The feed structure collects and disseminates W Band and X Band electromagnetic energy.

Abstract: A system for determining a location in a disadvantaged signal environment includes three aerial vehicles hovering at high altitude and spaced apart to form a triangle, and a mother aerial vehicle positioned a distance away and at a lower altitude. The mother aerial vehicle acquires and transmits coarse geolocation information, using a pulse compression, high-power X Band radar and directional antenna, to each of the three aerial vehicles to direct them to coarse geo-positions above designated respective ground locations. One of the three aerial vehicles has a synthetic aperture radar for producing a terrain strip-map that is mensurated against a map database to provide fine position adjustments for each of the three aerial vehicles, which are also also configured to transmit a respective signal coded with its latitude, longitude, and altitude, for a computing device to perform time difference of arrival measurements of the signals to determine its location.

Abstract: A system for determining a location in a disadvantaged signal environment includes three aerial vehicles hovering at high altitude and spaced apart to form a triangle, and a mother aerial vehicle positioned a distance away and at a lower altitude. The mother aerial vehicle acquires and transmits coarse geolocation information, using a pulse compression, high-power X Band radar and directional antenna, to each of the three aerial vehicles to direct them to coarse geo-positions above designated respective ground locations. One of the three aerial vehicles has a synthetic aperture radar for producing a terrain strip-map that is mensurated against a map database to provide fine position adjustments for each of the three aerial vehicles, which are also also configured to transmit a respective signal coded with its latitude, longitude, and altitude, for a computing device to perform time difference of arrival measurements of the signals to determine its location.