RF Direction Finding System Attitude Compensation
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Solution Overview
Problem
Military platforms face challenges in accurately locating radio frequency emitters due to aircraft attitude uncertainty and motion, which introduces significant geo-location uncertainty, making it difficult to target threats with conventional or GPS-guided weapons.
Innovation Solution
A radio frequency direction finding (RFDF) system incorporating an angle-of-azimuth system, attitude measurement system, geo-location system, and processor to calculate the position of RF emitters, utilizing a RF interferometer with a multiple signal classification algorithm, differential GPS, and inertial navigation, along with topological data and built-in-test systems for precise measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional RFDF systems are used on moving platforms, then the system can detect RF emissions, but the geo-location accuracy deteriorates due to platform attitude uncertainty and motion greater than 0.1 degrees
Solution Approach 1:
The patent introduces an inertial navigation system as an intermediary that measures platform attitude with high precision (better than 0.1 degrees) to compensate for platform motion and attitude uncertainty, enabling accurate geo-location despite platform movement
Solution Approach 2:
The system continuously monitors platform attitude through the inertial navigation system and uses this feedback to correct RFDF measurements in real-time, maintaining geo-location accuracy despite changing platform orientation
2Measurement precision
If high precision inertial navigation systems are used to measure platform attitude, then attitude measurement accuracy improves to less than 0.1 degrees, but system cost increases significantly
Solution Approach 1:
The patent applies partial action by using inertial navigation specifically for attitude measurement only when and where needed for RFDF corrections, rather than implementing a full high-precision navigation system throughout the platform, reducing overall cost while maintaining necessary measurement precision
3Measurement precision
If multiple dispersed direction finding receivers are used for triangulation, then geo-location accuracy improves, but system complexity and deployment difficulty increase
Solution Approach 1:
The patent merges multiple direction finding receivers into a single integrated RFDF system on one moving platform, combining their capabilities to achieve triangulation-like accuracy without the logistical complexity of deploying and coordinating multiple separate receivers
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
Enables high precision geo-location of RF emitters within a small volume, allowing accurate targeting of threats with reduced uncertainty, even from moving platforms, by combining phase and amplitude measurements with accurate attitude and geo-location data.
Implementation Method 1
an angle-of-azimuth (AoA) system configured to determine an azimuth of a RF emitter with respect to the mobile platform... The AoA system can include a RF interferometer
Data Source
AI summary
High precision radio frequency direction finding systems are described that can determine an angle-of-arrival and geo-location of a RF emitter with respect to a mobile platform. A radio frequency direction finding (RFDF) system for determining a position of a RF emitter with respect to a mobile platform can include an angle-of-azimuth (AoA) system configured to determine an azimuth of a RF emitter with respect to the mobile platform; an attitude measurement system configured to measure the attitude of the mobile platform; a geo-location system configured to calculate the geo-location of the RF emitter; and a processor system configured to calculate a position of the RF emitter.