Satellite Navigation Receiver for Spinning Projectiles
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Solution Overview
Problem
GPS receivers struggle to accurately determine the rotational orientation of spinning projectiles, such as artillery shells, which is crucial for proper guidance and flight control, as existing systems do not effectively account for the rotational position in calculating spatial position and velocity.
Innovation Solution
The use of an adaptive sideband filter and a SV power modulation tracker to filter sidebands and center frequencies of correlated in-phase and quadrature-phase signals from GPS signals, allowing for the determination of the angular orientation of spinning objects based on these filtered signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional GPS receivers are used to determine spatial position of spinning projectiles, then spatial position can be calculated, but rotational orientation cannot be accurately determined
Solution Approach 1:
The GPS signal processing is segmented into in-phase (I) and quadrature (Q) components. By separately processing these components through correlation with pseudo-random noise codes, the system extracts rotational orientation information that would be lost in conventional combined signal processing.
Solution Approach 2:
The system transitions from conventional 2D spatial position calculation to 3D orientation determination by utilizing the phase relationship between I and Q signals. This dimensional extension allows extraction of rotational position as an additional degree of freedom.
2Reliability
If existing signal processing methods are used, then basic GPS positioning works, but the system is vulnerable to jamming and cannot maintain accuracy in hostile environments
Solution Approach 1:
The system employs feedback mechanisms through phase-locked loops that continuously track the Doppler-shifted GPS carrier frequency. This feedback allows the receiver to maintain lock on legitimate signals while rejecting jamming attempts that cannot replicate the precise phase and frequency characteristics.
Solution Approach 2:
The receiver dynamically adjusts processing parameters including integration time, correlation threshold, and frequency tracking bandwidth based on signal quality indicators. These parameter changes enable the system to maintain reliability under varying jamming conditions by optimizing the balance between signal acquisition and interference rejection.
3Measurement precision
If simple filtering is applied to GPS signals, then processing is fast, but rotational orientation information is lost
Solution Approach 1:
The filtering process is made dynamic by adjusting filter characteristics based on the detected rotational frequency of the projectile. The system continuously adapts the bandpass filter center frequency and bandwidth to track the rotating antenna's modulation frequency, maintaining measurement precision without requiring excessively complex fixed-filter designs.
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 enables accurate determination of the rotational position of spinning projectiles, improving guidance systems by providing precise timing for actuating control surfaces, thus enhancing the accuracy and reliability of projectile guidance.
Implementation Method 1
sidebands due to power modulation from rolling of a spinning object
Data Source
AI summary
Apparatus and methods determine the rotational position of a spinning object. A satellite positioning system can be used to determine the spatial position of an object, which in turn can be used to guide the object. An adaptive sideband filter is used to provide increased robustness against interference. However, when the object is spinning, such as an artillery shell, then the rotational orientation should be known in order to properly actuate the control surfaces, such as fins, which will also be spinning.