A synthetic radio altimeter system is provided. At least one sensor is used to generate sensor data that is used at least to determine a then current vehicle location. At least one controller is configured to determine an elevation of terrain under a vehicle based on the determined then current location of the vehicle and terrain information in the terrain database. The at least one controller is further configured to determine a height of the vehicle above terrain based at least in part on the determined elevation of terrain under the vehicle and the sensor data. The at least one controller further configured to augment the determined height of the vehicle above terrain with at least in part navigation database information when the vehicle is near one of a travel path origin and a travel path destination. The height above terrain may also be augmented based on a navigation radio.

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.

A radio altimeter includes an electronically scanned array antenna. Orthogonal sweeps by the electronically scanned array antenna are used to identify a highest point in a region beneath the aircraft without the need for strong reflection. The electronically scanned array antenna may be reconfigured to scan a subregion including the highest point with a higher frequency beam and/or integrate multiple sweeps over time for a more accurate measurement.

A vehicle location accuracy enhancement system is provided. A digital active phased array radar is configured to generate a profiled terrain including terrain altitude information. A controller is configured to implement operating instructions in memory to conduct profile matching between the generated profiled terrain from the at least one digital active phased array radar and terrain altitude profile information in a terrain database to determine profiled location solutions. The controller is further configured to at least augment sensor location solutions from at least one other location determining system, including a GNSS, with the profiled location solutions to enhance accuracy of the sensor location solutions. The controller is also configured to determine location errors in the GNSS based on the profiled location solution and to broadcast the determined location errors.

Systems, methods, apparatuses, and computer program products for coexisting cellular networks with aeronautical radio altimeters. The method may include receiving a first command from a network manager to reduce emissions. The method may also include reducing the emissions based on the received first command In certain example embodiments, the first command may be for one or more network nodes in a cluster including the network node.

The method carries out a measurement of the distance from the ground of an aircraft by undertaking the emission of waveforms making it possible to obtain, after demodulation, of the signals received in return and sampling of the demodulated signals at a frequency F.sub.éch, two signals E*.sub.0(t) and E*.sub.1(t), taking the form of two frequency ramps, of respective slopes K.sub.0 and K.sub.1, of respective passbands B.sub.0 and B.sub.1 and of respective durations T.sub.E0 and T.sub.E1, the N-point FFT spectral analysis of which is carried out. The values of the durations T.sub.E0 and T.sub.E1 as well as those of the passbands B.sub.0 and B.sub.1, are defined in such a way as to be able to determine, on the basis of the spectra of the signals E*.sub.0(t) and E*.sub.1(t), a measurement of non-ambiguous distance d.sub.1 covering the maximum distance d.sub.max to be instrumented and an ambiguous distance d.sub.0 exhibiting the desired distance resolution. The distance d to be measured being determined by combining these two measurements.

A radar measuring device with a housing at least partially filled with a potting compound, a general-diffuse planar antenna arranged in the housing, at least one transmitter and at least one receiver that are connected to the planar antenna, and a lens arranged in a main emission direction of the planar antenna for radiation emitted from the planar antenna, wherein a separating apparatus is arranged in the housing and is designed and arranged in such a way that a penetration of the potting compound into an area within the separating apparatus and between the antenna and the lens is prevented.

The embodiments described herein provide ranging and location determination capabilities in RF-opaque environments, such as a jungle, that preclude the use of Global Positioning System (GPS) and/or laser ranging systems, utilizing transponders and Global Positioning System (GPS) receivers located on aerial vehicles. The aerial vehicles operate above the RF-opaque environment, and communicate with a ranging device within the RF-opaque environment on frequencies that propagate in the RF-opaque environment. The ranging device transmits RF signals to the transponders, which are received by the transponders and re-broadcasted back to the ranging device on a different frequency. The aerial vehicles also provide their coordinates to the ranging device using their GPS receivers. The ranging device uses information about the transmitted and received RF signals and the GPS coordinates of the aerial vehicles to calculate a perpendicular distance to a property line from the ranging device, and/or to calculate a coordinate location of the ranging device.

A low range altimeter (LRA) may include a transmitter, a receiver, at least one antenna, an active leakage cancellation circuit, and a microcontroller unit (MCU). The transmitter may be configured to transmit a first signal (or transmitted signal) via the at least one antenna. The receiver may be configured to receive a second signal (or received signal) via the at least one antenna. The active leakage cancellation circuit may be configured to receive a portion of the transmitted signal from the transmitter, and may be configured to inject the portion of the transmitted signal into the receiver after an adjustment of the portion of the transmitted signal to reduce leakage observed in the received signal. The MCU may be coupled to the transmitter and the receiver, and may be configured to adjust the portion of the portion of the transmitted signal.

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.