MIMO Sonar Detection Using Doppler-Orthogonal Signal Sequences
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing sonar systems for underwater and water-based object detection are costly and complex due to the high number of elements, particularly on the receiver side, limiting their widespread application in securing critical water-based infrastructure.
Innovation Solution
A sonar method utilizing a MIMO processing approach with a central transmitter and distributed, low-cost receivers, generating orthogonal acoustic signals that are processed using digital correlators and matched filters to determine object position, speed, and direction with reduced computational effort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional sonar systems use multiple elements in transmitters and receivers to achieve accurate object detection and positioning, then measurement precision and reliability are improved, but device complexity and cost increase significantly
Solution Approach 1:
The system divides the monitoring area into multiple zones and uses a single transmitter element that sequentially transmits different signal sequences to different zones. The receiver processes these segmented signals separately, achieving comprehensive area coverage and accurate object detection without requiring multiple simultaneous transmitter elements.
Solution Approach 2:
The transmitter element operates periodically, transmitting different orthogonal signal sequences at different time intervals to cover different spatial zones. This periodic transmission pattern allows a single element to achieve the functional equivalent of multiple simultaneous elements, reducing hardware complexity while maintaining detection precision.
2Reliability
If continuous real-time signal processing is performed to detect approaching objects immediately, then response time and reliability are improved, but computational effort and energy consumption increase
Solution Approach 1:
The system pre-processes the transmitted signal sequences to create orthogonal codes before transmission. The receiver uses these pre-defined codes to perform correlation-based detection, which is computationally more efficient than general signal processing. This preliminary preparation reduces real-time computational energy requirements while maintaining reliable detection.
Solution Approach 2:
The system changes the temporal parameters of signal transmission, using orthogonal codes with specific time-domain characteristics that enable efficient correlation processing. By optimizing the signal waveform parameters, the system achieves reliable real-time detection with reduced computational complexity and lower energy consumption.
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 reliable, cost-effective detection and tracking of underwater and water-based objects with reduced hardware complexity, allowing flexible expansion and lower operational costs.
Implementation Method 1
A SONAR system consists of transmitters (projectors) and receivers (hydrophones)... a single transmitter element is often operated, which transmits a sequence omnidirectionally. This signal propagates in all directions of the area to be monitored and is reflected by objects.
Implementation Method 2
The (radial) speed of the object is determined via the Doppler shift of the transmission sequence.
Data Source
AI summary
A sonar method and assembly for detecting and/or determining the position and/or speed of objects underwater and/or on the water in a specified region. The orthogonality of Doppler-shifted transmission sequences is explored. First, a transmission sequence is generated, spread for some possible Doppler shifts and output via the transmission elements. If the transmission sequence is chosen carefully, the spread versions become orthogonal to each other and enable MIMO signal processing. If one of the assumed spreads matches the speed of the object, the spread is canceled out again to form the original transmission signal. This allows the binary detection of the presence of an object with the correlation of only one sequence and reduces the computing effort at the respective receivers enormously.