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 proximity sensor for a Laser Guided Bomb (LGB) is provided. A proximity sensor for a Laser Guided Bomb (LGB) includes: an electronics package unit (EPU) configured to be connected to a front end of a warhead; and at least one sensor separate from the EPU and configured to be connected to a forward adapter that is connected to the front end of the warhead. The at least one sensor is configured to obtain data that is used to determine a height above ground of the LGB. The EPU is configured to compare the determined height above ground to a predefined value. The EPU is configured to generate a detonation signal for the warhead based on the determined height above ground being equal to or less than the predefined value.

A constellation of satellites and associated methods for Earth Observation are disclosed. One method includes transmitting a set of at least four signals towards the Earth using a constellation of at least four satellites and receiving a set of at least four reflected signals from the Earth using the constellation. The method also includes analyzing, using a set of at least four signal analyzers, the set of at least four signals to generate a set of data. Each satellite in the constellation individually houses a signal analyzer in the set of at least four signal analyzers. The method also includes deriving the set of Earth observations using the set of data. Each satellite receives a signal in the set of at least four signals from every other satellite in the constellation.

A buoy-type high-frequency ground wave radar system. A buoy platform is used as an offshore carrier of a ground wave radar. A sky wave emission subsystem is disposed on a shore base and emits a high-frequency electromagnet wave. After the high-frequency electromagnet wave is refracted by the ionosphere and is reflected by the sea surface, a sky wave signal is formed. An attitude measurement subsystem measures and acquires attitude data of the buoy platform in real time. A ground wave radar subsystem receives a ground wave signal by using the ground wave radar, and processes the signal to form a ground wave doppler spectrum. Simultaneously, the sky wave signal is received, ionosphere disturbance compensation is performed on the sky wave signal in a frequency domain and then the sky wave signal is processed to form a sky wave doppler spectrum. The ground wave radar subsystem reconstructs an actual geographic coordinate system according to the attitude data measured by the attitude measurement subsystem and then the ground wave or the sky wave doppler spectrum is used to inverse wind wave current data in the reconstructed actual geographic coordinate system. The sky wave emission subsystem and the ground wave radar subsystem carry out time synchronization by means of a GPS synchronization networking. The system can detect a sea region of any distance and is suitable for high sea detection.

The present disclosure is directed to autonomous control systems and methods for navigating an aircraft relative to a movable object. The autonomous control system may comprise: a first one or more sensors to track the movable object in a local coordinate frame; a second one or more sensors to track the aircraft in the local coordinate frame; and a flight control system having a processor that is operatively coupled with the first one or more sensors and the second one or more sensors, the flight control system configured to provide pitch, roll, and yaw commands to the aircraft. The processor may be configured to identify a perch point at a predetermined distance relative to the movable object in the local coordinate frame. The perch point may be fixed relative to the movable object. The processor may be configured to navigate, via the flight control system, the aircraft to the perch point as a function of the speed, the position, or the heading of the movable object.

In one embodiment, a radio altimeter tracking filter is provided. The filter comprises: a wireless radio interface; a processor coupled to the wireless radio interface; a memory coupled to the wireless radio interface; wherein the wireless radio interface is configured to wirelessly receive a radio altimeter signal and convert the radio altimeter signal to a baseband frequency signal, wherein the a radio altimeter signal sweeps across a first frequency spectrum between a first frequency and a second frequency; wherein the processor is configured to pass the baseband frequency signal through a filter executed by the processor, the filter comprising a passband having a first bandwidth, and wherein the filter outputs a plurality of spectral chirps in response to the baseband frequency signal passing through the first bandwidth; wherein the processor is configured to process the plurality of spectral chirps to output characteristic parameters that characterize the radio altimeter signal.

In one embodiment, a radio altimeter tracking filter is provided. The filter comprises: a wireless radio interface; a processor coupled to the wireless radio interface; a memory coupled to the wireless radio interface; wherein the wireless radio interface is configured to wirelessly receive a radio altimeter signal and convert the radio altimeter signal to a baseband frequency signal, wherein the a radio altimeter signal sweeps across a first frequency spectrum between a first frequency and a second frequency; wherein the processor is configured to pass the baseband frequency signal through a filter executed by the processor, the filter comprising a passband having a first bandwidth, and wherein the filter outputs a plurality of spectral chirps in response to the baseband frequency signal passing through the first bandwidth; wherein the processor is configured to process the plurality of spectral chirps to output characteristic parameters that characterize the radio altimeter signal.

A constellation of satellites and associated methods for Earth Observation are disclosed. One method includes transmitting a set of at least four signals towards the Earth using a constellation of at least four satellites and receiving a set of at least four reflected signals from the Earth using the constellation. The method also includes analyzing, using a set of at least four signal analyzers, the set of at least four signals to generate a set of data. Each satellite in the constellation individually houses a signal analyzer in the set of at least four signal analyzers. The method also includes deriving the set of Earth observations using the set of data. Each satellite receives a signal in the set of at least four signals from every other satellite in the constellation.

A method for measuring, using a radar or sonar, the velocity with respect to the ground of a carrier moving parallel to the ground, includes the following steps: a) orienting the line of sight of the radar or sonar toward the ground; b) emitting a plurality of radar or sonar signals (P.sub.1-P.sub.N) that are directed toward the ground, and acquiring respective echo signals (E.sub.1-E.sub.N); c) processing the acquired echo signals so as to obtain, for one or more echo delay values, a corresponding Doppler spectrum; d) for the or at least one the echo delay value, determining a high cut-off frequency of the corresponding Doppler spectrum; and e) computing the velocity of the carrier with respect to the ground on the basis of the one or more high cut-off frequencies. A system allowing such a method to be implemented.

A constellation of satellites and associated methods for Earth Observation are disclosed. One method includes transmitting a set of at least four signals towards the Earth using a constellation of at least four satellites and receiving a set of at least four reflected signals from the Earth using the constellation. The method also includes analyzing, using a set of at least four signal analyzers, the set of at least four signals to generate a set of data. Each satellite in the constellation individually houses a signal analyzer in the set of at least four signal analyzers. The method also includes deriving the set of Earth observations using the set of data. Each satellite receives a signal in the set of at least four signals from every other satellite in the constellation.