Underwater Sonar Target Bearing Determination via Bandwidth Analysis
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Solution Overview
Problem
Existing underwater vehicle sonar systems struggle to accurately determine target bearings amidst ambient noise and interference, as all sound-emitting objects are initially recognized as potential targets, leading to false readings.
Innovation Solution
The method involves distinguishing between sound waves from potential targets and decoys or interference by utilizing the broader bandwidth of target-emitted sound waves, employing a receiver arrangement with electro- and/or opto-acoustic receivers, and processing signals through beamforming, Fourier transformations, and threshold-based filtering to identify target bearings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If all sound-emitting objects are recognized as potential targets, then no target information is lost, but false readings increase and measurement precision deteriorates
Solution Approach 1:
The patent applies parameter changes by analyzing the bandwidth characteristic of sound waves. Potential targets emit sound waves with broader bandwidth compared to decoys or interference sources. The system evaluates the bandwidth parameter of received sound waves and uses this parameter to distinguish between genuine targets and false sources, thereby improving measurement precision while maintaining reliability
Solution Approach 2:
The patent introduces an intermediary evaluation mechanism that assesses the bandwidth of sound waves before determining target bearing. This intermediary step acts as a filter between raw sound wave reception and target identification, allowing the system to differentiate between potential targets and interference sources based on their acoustic characteristics
2Measurement precision
If bandwidth evaluation is added to distinguish targets from interference, then target bearing accuracy improves, but device complexity increases
Solution Approach 1:
The patent implements bandwidth evaluation as an additional parameter analysis step in the signal processing chain. By evaluating the bandwidth characteristic of received sound waves, the system can distinguish potential targets from decoys and interference sources. This parameter-based approach improves target bearing accuracy while maintaining a relatively simple processing architecture
Solution Approach 2:
The patent applies partial action by focusing bandwidth evaluation only on the specific frequency ranges and time windows where target sounds are expected. Rather than analyzing the entire signal spectrum continuously, the system selectively evaluates bandwidth parameters in relevant portions of the signal, reducing overall processing complexity while maintaining detection accuracy
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 effectively differentiates target bearings from noise and interference, enhancing the accuracy of underwater vehicle navigation by correctly identifying potential targets while filtering out irrelevant sound sources.
Implementation Method 1
sound waves being received with a receiver arrangement (12) consisting of several electro- and/or opto-acoustic receivers (14)
Implementation Method 2
directional signals being determined from the received signals (16), with each of the directional signals (20) being assigned a relative direction (21)
Implementation Method 3
a frequency spectrum and its magnitude spectrum being determined from each of the directional signals (20)
Data Source
Figure 1~3
Figure 4a~7
Figure 8~9
AI summary
The invention relates to a device and a method for determining one or more relative directions 21a to 21c as a bearing or bearings. In this process, sound waves 15 are received by a receiver arrangement 12, and received signals 16a to 16c are generated from the sound waves 15. Directional signals 20a to 20c are determined from the received signals 16a to 16c and assigned to a relative direction 21a to 21c with respect to the receiver arrangement 12. From each directional signal 20a to 20c, a magnitude spectrum 46 or a spectrum derived from the magnitude spectrum (46) is determined, and frequency bands (76a to 76h) are determined from the frequency range (66) of each magnitude spectrum (46) or each spectrum derived from the magnitude spectrum (46).The amplitude values (71) of the frequencies (68a to 68j) occurring in one of the frequency bands (76a to 76h) are then summarized as a frequency band amplitude value (78a to 78h) of the respective frequency band (76a to 76h). According to the invention, the relative direction (21a to 21c) associated with a magnitude spectrum (46) or a spectrum derived from the magnitude spectrum (46) is determined as a target bearing if the magnitude spectrum (46) associated with this relative direction (21a to 21c) or the spectrum derived from the magnitude spectrum has at least a number of frequency band amplitude values (78a to 78h) above a threshold value (31) that is above a defined number of detections (38).