Doppler Filter Bandwidth Adjustment for Radar Altimeter Power Optimization
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Solution Overview
Problem
Aircraft navigation systems face challenges in obtaining reliable velocity measurements due to errors in different sensors, and Doppler radar altimeters consume unnecessary power with fixed bandwidth filters based on maximum aircraft speed, which is inefficient when speed is lower.
Innovation Solution
The method involves adjusting the bandwidth of Doppler filters in a Doppler beam sharpened radar altimeter based on real-time velocity measurements, using multiple Doppler beams and trigonometric calculations to determine aircraft velocity, and dynamically controlling Doppler filters to match current velocity, thereby improving navigation accuracy and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the bandwidth of Doppler filters is based on the maximum speed of the aircraft, then the system can handle the full range of possible velocities, but the Doppler filters consume unnecessary power and resources when the aircraft is traveling at lower speeds
Solution Approach 1:
The patent applies dynamics by making the Doppler filter bandwidth adjustable rather than fixed. The system dynamically adapts the filter bandwidth to match the actual velocity of the aircraft, allowing it to optimize performance for current operating conditions while maintaining the capability to handle the full velocity range when needed.
Solution Approach 2:
The patent changes the parameter of filter bandwidth from a fixed value based on maximum speed to a variable parameter that adjusts according to actual velocity measurements. This allows the system to maintain adaptability across different velocity ranges while reducing power consumption by using only the necessary bandwidth for current operating conditions.
2Reliability
If multiple sources of velocity measurements are used (GPS, inertial navigation system, airspeed measurements), then the system can provide navigation solutions when GPS is unavailable, but the different errors in these sources increase the challenge of gathering reliable measurements of ground speed
Solution Approach 1:
The patent uses feedback by measuring the actual velocity of the aircraft using the Doppler radar altimeter and using this measurement to adjust the Doppler filter bandwidth. This closed-loop approach allows the system to optimize its performance based on real operating conditions, improving measurement precision while maintaining reliability across different velocity ranges.
Solution Approach 2:
The Doppler radar altimeter serves dual purposes: it provides altitude measurement and simultaneously measures aircraft velocity to optimize its own filter bandwidth. This self-service approach allows the system to improve its own measurement precision without requiring external intervention, while maintaining reliable navigation capability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances navigation accuracy, especially in GPS-denied environments, and optimizes power usage by adjusting filter bandwidth to match the aircraft's actual speed, reducing unnecessary resource consumption.
Implementation Method 1
a Doppler beam sharpened radar altimeter
Implementation Method 2
Doppler filters to form the Doppler beams
Data Source
Figure 1~2
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AI summary
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.