Towed Sonar Torpedo Detection via Bearing Angle Cotangent Rate
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Solution Overview
Problem
Existing sonar systems on watercrafts have a blind spot in the aft sector due to their positioning and noise interference, making it difficult to detect torpedoes approaching from the rear, particularly those guided by a wake, which can lead to imperfect detection and delayed response.
Innovation Solution
A method using a towed sonar with an underwater antenna to monitor the rate of change of the cotangent of bearing angles, combined with normalization of reception levels across directional characteristics, to accurately determine the speed and distance of an approaching torpedo, triggering a warning alarm and enabling precise targeting of effector deployment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a hull mounted sonar is used for torpedo detection, then the detection capability in the forward sector is improved, but the detection capability in the aft sector deteriorates due to blind spots and screw noise
Solution Approach 1:
The sonar system is segmented into two independent components: a hull mounted sonar for forward sector detection and a towed sonar for aft sector detection. Each sonar operates independently in its optimal detection zone, eliminating the blind spot problem and allowing the system to achieve reliable all-around coverage without compromising detection precision in either sector
Solution Approach 2:
A towed sonar acts as an intermediary detection device positioned behind the vessel to detect torpedoes in the aft sector. This intermediary sensor overcomes the limitations of the hull mounted sonar by providing dedicated aft sector coverage, thereby improving detection reliability in the previously vulnerable region
2Reliability
If passive torpedo location using towed sonar is implemented, then the detection coverage in the aft sector is improved, but the signal processing complexity increases
Solution Approach 1:
The system replaces complex mechanical all-around scanning sonar with a simpler passive acoustic detection system using a towed sonar. By substituting active scanning mechanisms with passive spectral analysis of torpedo noise, the system achieves reliable aft sector coverage while reducing mechanical complexity and signal processing requirements
Solution Approach 2:
The system changes the detection parameter from active sonar beam scanning to passive spectral frequency analysis. By monitoring the spectral lines of torpedo propulsion noise rather than using active pinging, the system simplifies signal processing while maintaining reliable detection coverage in the aft sector
3Ease of operation
If the rate of change of bearing angle is monitored for torpedo detection, then the detection simplicity is improved, but the precision in determining torpedo distance and speed deteriorates
Solution Approach 1:
The system uses feedback from the rate of change of bearing angle measurements to continuously update torpedo position and speed estimates. By processing the time derivative of bearing angle data and feeding it back into the tracking algorithm, the system maintains simple operational procedures while achieving precise real-time measurement of torpedo distance and velocity through iterative refinement
Solution Approach 2:
The system performs preliminary calculations of torpedo position and speed based on bearing angle rate of change before the torpedo reaches critical distance. By pre-processing the kinematic data and establishing trajectory predictions in advance, the system maintains detection simplicity while ensuring high measurement precision when combat deployment decisions must be made
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 method provides a reliable and precise detection of torpedoes approaching from the rear, reducing false alarms and ensuring timely and effective combat readiness by accurately determining the torpedo's position and speed, thereby closing the vulnerability gap in the aft sector.
Implementation Method 1
the torpedo is passively located using a so-called towed sonar, which has an underwater antenna towed by the ship
Data Source
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AI summary
In a method for production of a danger warning against a torpedo which is attacking a watercraft from astern, in particular a wake-guided torpedo, the direction of the torpedo which is approaching from astern is found continuously, with the bearing angle and bearing time being emitted, the cotangent of the bearing angle is calculated, and the rate of change of the cotangent is compared with a preset value, at least in a medium bearing angle range, in order to achieve efficient protection of the watercraft against a torpedo attack from the stern direction by means of a sonar having an underwater antenna which is towed by the watercraft. If the rate of change of the cotangent of the bearing angle exceeds the preset value, an initiation signal is emitted for a warning alarm.