Self-Organizing Sensor Node for Radar Array Synchronization
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Solution Overview
Problem
Large and sparse array antennas in radar systems require precise positioning of antenna elements, which is challenging to maintain, especially when elements are distributed over large areas and subject to changes during operation.
Innovation Solution
A node configuration in a sensor network that uses a combination of high-speed communication channels (e.g., microwave) and low-speed channels (e.g., ultrasonic) to determine distances between nodes, allowing for self-organization and synchronization without prior knowledge of node positions, enabling flexible and wind-resistant networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If large and sparse array antennas are used to increase radar resolution, then the resolution is improved, but the positioning precision and stability of antenna elements deteriorate due to distribution over large areas and susceptibility to environmental changes
Solution Approach 1:
The system performs self-organization and self-positioning through autonomous node interactions. Nodes automatically determine their positions relative to each other using signal exchange and time difference of arrival measurements, without requiring external positioning infrastructure or manual configuration. This self-service mechanism maintains positioning stability despite environmental changes.
Solution Approach 2:
The system uses time difference of arrival (TDOA) as a key parameter to determine node positions. By measuring the difference in arrival times of synchronization signals at different nodes, the system dynamically calculates and updates position information, allowing the array to adapt to changing environmental conditions while maintaining precise relative positioning.
2Measurement precision
If antenna elements are distributed over several square kilometres to form large array antennas, then the radar coverage and resolution are improved, but the complexity of maintaining position information and synchronization increases
Solution Approach 1:
The large array antenna system is segmented into independent, autonomous nodes that each perform local signal processing and position determination. This segmentation distributes the complexity across multiple independent units, eliminating the need for centralized position management and reducing overall system complexity while maintaining large-aperture radar capabilities.
Solution Approach 2:
Nodes perform preliminary synchronization and position determination actions before radar signal processing. Each node autonomously acquires synchronization signals from neighbors, determines its position, and adjusts its internal clock accordingly, preparing the distributed array for coherent signal processing without requiring complex real-time coordination.
3Ease of manufacture
If fixed beacon nodes are used for positioning, then the position establishment is simplified, but the system loses flexibility and adaptability to dynamic changes in node positions
Solution Approach 1:
The positioning system transitions from static beacon-based positioning to dynamic peer-to-peer positioning. Nodes continuously exchange synchronization signals and update their position information based on real-time signal measurements, allowing the system to adapt to moving nodes and changing environmental conditions while maintaining accurate position awareness.
Solution Approach 2:
The system implements feedback mechanisms where nodes continuously measure signal arrival times and use this information to update their position estimates. This closed-loop feedback allows nodes to detect and compensate for position changes, maintaining accurate positioning information without requiring fixed reference beacons.
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 flexible self-organization of sensor networks, allowing for accurate synchronization and adaptation to changes in node positions, enhancing the resolution and reliability of radar systems without requiring initial position data, and reducing sensitivity to environmental displacements.
Implementation Method 1
a transceiver circuitry configured to transmit and receive signals over at least a first communication channel and a second communication channel with non-equal speed of propagation
Implementation Method 2
determine a distance to the at least one other node by measuring the travelling time for a signal over the second communication channel
Data Source
Figure 1~2b
Figure 3~6
Figure 5
AI summary
The present invention relates to a node for use in a sensor network, e.g. for use in radar systems, using the antenna elements in each separate node as antenna elements in an array antenna configuration. The node transmits and receives signals over a first and a second communication channel having non-equal speeds of propagation. When the node identifies that a reset signal has been received over the first communication channel (S10), it adjusts the internal clock (Sll), transmits an acknowledgement signal (S12) and initiates an acknowledgement process (S17). When the reset signal has not been identified, the node transmits the reset signal over the first communication channel (S13) and receives a response signal from one node (S14). If the response signal is an acknowledgement signal, an acknowledgement process is initiated (S17), or if the response signal is a non-acknowledgement signal, the internal clock is adjusted (S16) and an acknowledgement process is initiated (S17). In the acknowledgement process (S17), the node determines a distance to the other nodes by measuring the travelling time for a signal over the second communication channel (S18), exchanges distance information with the other nodes (S20), and fine tunes the internal clock of each node when transmitting over the first communication channel (S20). According to an aspect, the node's transceiver circuitry consists of a radio frequency part being able to transmit and receive electromagnetic signals and an acoustic part being able to transmit and receive acoustic signals (e.g. ultrasound). Each node determines the distance in the acknowledgement process (S17) by transmitting a signal to a specific node and receive a return signal with information regarding internal processing time in the addressed node, thereby calculating the distance based on the travelling time Furthermore, each node mutually exchanges distance information between the plurality of nodes. This results in fine tuning of the clock. Nodes that have successfully undergone fine tuning repeat the same process to nodes in their range. Repeating this process, all nodes of the radar system will have clocks ideally synchronous.