Direction of Arrival Determination Using Phase Angle Measurement
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Solution Overview
Problem
Existing radio signal direction-finding systems face challenges in accurately determining the direction of arrival due to transmitter instability and changing multipath conditions, particularly in sequential lobing techniques that require narrow beamwidths and are prone to misinterpretation of signal strength changes.
Innovation Solution
A method and system that utilize at least two input signals to generate a unique combination of output signal magnitudes based on RF phase differences, allowing for the determination of an RF phase angle indicative of the direction of arrival, which is then converted into an angle value using a computer program product and phase angle measurement circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If sequential lobing technique is used to determine direction of arrival, then the antenna can be relatively small without requiring especially narrow beam widths, but transmitter instability and changing multipath conditions cause signal strength to change between beam activations leading to misinterpretation of direction of arrival
Solution Approach 1:
The system uses periodic switching between multiple antenna elements or beam configurations to sample the incoming signal from different spatial directions. By periodically activating different antenna elements or beamforming weights in a systematic sequence, the system can determine direction of arrival through comparison of signal characteristics across multiple periodic cycles, avoiding the need for continuously narrow beams while maintaining measurement accuracy.
Solution Approach 2:
The system incorporates feedback mechanisms where the measured signal characteristics from sequential beam activations are fed back into the direction-finding algorithm. The system continuously monitors signal strength, phase, and other parameters across multiple activations and uses this feedback to refine the direction of arrival estimate, compensating for transmitter instability and multipath variations through adaptive processing.
2Measurement precision
If narrow beamwidth antenna is used to obtain good angular resolution, then direction determination accuracy is improved, but the antenna becomes inconveniently large since beamwidth is inversely related to antenna size
Solution Approach 1:
The system divides the directional measurement task into multiple segments by using multiple antenna elements or multiple beam configurations instead of relying on a single narrow beam. Each antenna element or beam configuration provides a broader coverage sector, and the system segments the full 360-degree (or coverage area) measurement into multiple overlapping directional samples, achieving high angular resolution through composite processing of segmented measurements.
Solution Approach 2:
The system transitions from a single-dimensional narrow beam approach to a multi-dimensional measurement space by incorporating multiple antenna elements arranged in specific geometries (such as arrays). By measuring signal characteristics across multiple spatial dimensions and time sequences, the system achieves high angular resolution through mathematical processing in an expanded measurement space rather than relying on physically narrow beams.
3Device complexity
If sequential lobing technique with alternating beam activation is used, then equipment complexity is reduced compared to simultaneous multi-beam systems, but the technique is vulnerable to signal strength variations caused by transmitter instability and multipath conditions
Solution Approach 1:
The system performs preliminary measurements and characterizations during the sequential beam activation process to establish baseline signal characteristics before final direction determination. By pre-measuring signal strength, phase, and other parameters during the activation sequence and comparing them against expected variations, the system can distinguish between legitimate direction indicators and artifacts caused by transmitter instability or multipath conditions.
Solution Approach 2:
The system changes multiple parameters simultaneously during sequential activation, including beam direction, antenna element selection, and measurement timing. By varying these parameters in a coordinated fashion and analyzing the combined effects, the system can separate direction-dependent signal variations from those caused by transmitter instability or multipath, improving reliability while maintaining relatively simple sequential activation architecture.
Data Source
AI summary
At least two input signals, each characterizing a radio signal having a radio frequency (RF), are received. The input signals are converted into at least three output signals. The output signals have a unique combination of corresponding magnitudes for each RF phase difference between the input signals. A set of magnitudes corresponding to the output signals is measured using a mobile measuring device. An RF phase angle value is determined based the measured set of magnitudes. The RF phase angle value is converted into an angle value indicative of the direction of arrival of the radio signal.