An aircraft receives pseudorange input from a plurality of satellites of an augmentation system. Each pseudorange input includes a precise position solution and error data. The aircraft receives a high frequency measurement from an inertial navigation system. The aircraft applies the precise position solution, error data, and high frequency measurement to a set of parallel Schmidt extended Kalman filters to produce a corrected position solution and integrity data. The aircraft applies the integrity data to a receiver autonomous integrity monitoring system to produce a protection level for the corrected position solution. The aircraft performs an aircraft operation using the corrected position solution and protection level.

An aircraft includes an airframe with a thrust array attached thereto. The thrust array includes a plurality of propulsion assemblies that are independently controlled by a flight control system. A landing gear assembly is coupled to the airframe and includes a plurality of landing feet. An altitude sensor array includes a plurality of altitude sensors each of which is disposed within one of the landing feet such that when the aircraft is in the VTOL orientation, the altitude sensor array is configured to obtain multifocal altitude data relative to a landing surface. The flight control system is configured to generate a three-dimensional terrain map of the surface based upon the multifocal altitude data.

Devices and methods for testing altimeters are provided. A radio-frequency (RF) signal may be received from an altimeter and passed through an RF delay module to delay the RF signal. The delayed RF signal may be converted to an optical signal, which may be passed through an optical delay module to delay the optical signal. The system tests the accuracy of the altimeter based on the combined RF signal delay and optical signal delay.

Systems and methods for using velocity measurements to adjust Doppler filter bandwidth are provided herein. In certain embodiments, a method for adjusting bandwidth for at least one Doppler filter in a Doppler beam sharpened radar altimeter comprises receiving a velocity measurement; adjusting the bandwidth of the at least one Doppler filter based on the velocity measurement; and transmitting a radar beam, wherein the radar beam is aimed toward a surface. The method further comprises receiving at least one reflected signal, wherein the at least one reflected signal is a reflection of the radar beam being reflected off of at least one portion of the surface; and filtering the at least one reflected signal with the at least one Doppler filter to form at least one Doppler beam.

Methods for radar altimeter integrity monitoring are provided. One method comprises obtaining one or more GNSS measurements, or one or more hybridized GNSS/INS measurements, in an earth-centered-earth-fixed (ECEF) coordinate frame for a vehicle; obtaining one or more altitude measurements from one or more radar altimeters; transforming the altitude measurements into the ECEF coordinate frame using a terrain map and a GNSS or hybridized GNSS/INS based position estimate with ensured integrity; determining a full solution estimate of position for the vehicle based on the transformed altitude measurements, and the GNSS or hybridized GNSS/INS measurements; determining one or more sub-solution estimates of position based on a subset of the transformed altitude measurements, and the GNSS or hybridized GNSS/INS measurements; comparing the full solution estimate with the sub-solution estimates using statistical analysis; and determining an altitude protection level based on a probability of hazardous misleading information and a probability of false detection.

Embodiments described herein may relate to an unmanned aerial vehicle (UAV) navigating to a target in order to provide medical support. An illustrative method involves a UAV (a) determining an approximate target location associated with a target, (b) using a first navigation process to navigate the UAV to the approximate target location, where the first navigation process generates flight-control signals based on the approximate target location, (c) making a determination that the UAV is located at the approximate target location, and (d) in response to the determination that the UAV is located at the approximate target location, using a second navigation process to navigate the UAV to the target, wherein the second navigation process generates flight-control signals based on real-time localization of the target.

Methods, apparatuses, and systems for predicting radio altimeter failures are provided. An example method may include determining a first plurality of altitude values associated with a first radio altimeter, determining a second plurality of altitude values associated with a second radio altimeter, calculating a first level feature based at least in part on the first plurality of altitude values and the second plurality of altitude values, and determining a radio altimeter failure indicator based at least in part on the first level feature.

A method for determining wave height by means of a radar carried by an aircraft, the method implementing the following steps: a first step of pointing the antenna of the radar; a second step of determining the clutter acquisition plan according to the altitude of the aircraft; a third step of determining, for each clutter zone defined by the acquisition plan, two Doppler parameters PARA1 and PARA2 characterising the zone as a whole; a fourth step of calculating the average values of the parameters PARA1 and PARA2 over all of the zones in question; and a fifth step of estimating the wave height from the averages of the parameters PARA1 and PARA2. The wave height estimated in this way is transmitted to the aircraft and used to determine the conditions for the water landing of the aircraft.

A method of improving height measurement resolution for a radar system is provided. The method includes periodically generating, at a FFT processor, a set of FFT bins across a frequency range based on a periodic ramping of a FMCW radar signal from a first frequency to a second frequency; selecting a subset of bins from at least one set of FFT bins by implementing a leading-edge-tracking algorithm by at least one processor; implementing a second algorithm on the selected subset of bins to determine a power ratio between the leading edge tracked bin and the remaining bins in the selected subset of bins to determine an interpolated bin number within the selected subset of bins; and determining an approximate distance to the target based on the interpolated bin number within the selected subset of bins. The sets of FFT bins are indicative of a respective plurality of distances.

The invention relates to a radioelectric device for transmitting and receiving radio waves including a radio wave generator generating radio waves that are frequency-modulated by a predetermined modulation signal and a transceiver antenna system, having a transmission-reception angle with an associated antenna aperture value, able to transmit said transmitted radio wave and receive a radio wave, and an associated radio altimetry system.

The antenna system (44) comprises a first array (45) of radiating elements (50a, 50b, 50c, 50d) able to radiate in a first frequency band and at least one second array (52.sub.i, 55, 56) of radiating elements able to radiate in a second frequency band, a plurality of activation elements able to activate and/or deactivate each of the first array and second array of radiating elements, and a control module able to control said activation elements based on a selected antenna aperture value.