Monopulse Receiver Angle Estimation Using Sum Signal Timing
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Solution Overview
Problem
In satellite communication systems, especially on moving vehicles, maintaining accurate antenna pointing towards a satellite is challenging, particularly at the edge of satellite coverage where signal-to-noise ratios are low, leading to difficulties in determining the angle between antennas and the signal source.
Innovation Solution
The method involves generating sum and difference signals from multiple antennas to derive timing information, which is then used to adjust and refine the angle estimation, allowing for precise antenna direction towards the signal source, even in low signal-to-noise conditions, by leveraging the relationship between sum and difference signal parameters such as frequency and phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If non-coherent amplitude measurements are used for angle estimation, then the system is simpler to implement, but the measurement precision deteriorates at low signal-to-noise ratios
Solution Approach 1:
The patent introduces sum signals as an intermediary element that mediates between the weak difference signals and the angle estimation process. The sum signals serve as a reference that contains timing information (frequency and phase) which is used to process the difference signals, enabling accurate angle measurement even when the difference signals are weak due to low signal-to-noise ratios
Solution Approach 2:
The patent changes the measurement parameters from direct amplitude comparison to timing information extraction. By deriving frequency and phase parameters from sum signals and applying them to difference signals, the system achieves more precise angle estimation at low signal-to-noise ratios compared to traditional amplitude-based methods
2Reliability
If difference signals are used directly for angle determination, then the angle information can be obtained, but the reliability deteriorates due to weak signal strength at low signal-to-noise ratios
Solution Approach 1:
Sum signals act as an intermediary that facilitates reliable detection of angle information. The sum signals contain strong timing information that mediates the difficult measurement of weak difference signals, enabling reliable angle determination even when difference signals are buried in noise
Solution Approach 2:
The system uses feedback by deriving timing information from sum signals and applying it back to process difference signals. The frequency and phase information extracted from sum signals is fed back to enhance the processing of difference signals, creating a feedback loop that improves reliability
3Measurement precision
If coherent processing with sum signals is implemented, then the measurement precision improves at low signal-to-noise ratios, but the device complexity increases
Solution Approach 1:
The sum signals serve multiple functions simultaneously: they provide timing information (frequency and phase), act as a reference for processing difference signals, and enable both angle estimation and signal tracking. This multi-functionality reduces the need for separate processing paths, making the increased complexity more manageable
Data Source
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AI summary
A receiver comprising a plurality of antennas immobilized in relation to each other and positioned on a movable carrier, each antenna being adapted to receive a signal and output a corresponding, received signal. From the signals from the antennas a sum signal and one or more difference signals are generated. From the sum signal, timing information is derived, and on the basis of the sum signal, the difference signal(s) and the timing information, information is output relating to an angle between a direction of the antennas and a direction of reception of the signal. Thus, timing information may be derived from the sum signal and used for deriving information from the difference signal(s) in which such timing information may be much more difficult to identify.