Differential Mode Triaxial Cable for Sonar Self-Noise Reduction
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Solution Overview
Problem
Towed sonar arrays face significant noise interference due to mechanical vibrations, known as cable strum, which overwhelms the acoustic signals of interest, degrading signal integrity and reducing the sensitivity of sonar receivers.
Innovation Solution
A pair of hermetically sealed triaxial cables, each with an inner conductor, dialectic core, inner shield, interlayer, and outer shield, connected in a differential mode configuration with buffer amplifier circuits, where one cable is connected to the positive polarity and the other to the negative polarity of the hydrophone, effectively reducing noise by referencing capacitance and conductance to the guard rather than the shield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional cables are used to connect hydrophone to sonar receiver, then cable structure is simple, but cable strum noise mechanically vibrates the array body and overwhelms acoustic signals
Solution Approach 1:
The patent replaces mechanical noise suppression methods with an electrical solution. Instead of using rigid cable jackets or mechanical strum suppressants, the invention uses a triaxial cable configuration with driven shield circuitry that electrically references capacitance and conductance to the guard rather than the shield, thereby eliminating cable strum noise through electrical means while maintaining cable flexibility
Solution Approach 2:
The patent changes the electrical parameters of the cable system by implementing a triaxial configuration where the inner shield is driven at the same potential as the inner conductor. This parameter change eliminates capacitive coupling between the inner conductor and outer shield, removing the source of cable strum noise while preserving mechanical cable properties
2Object-affected harmful factors
If rigid cable jackets are used to suppress cable strum mechanically, then mechanical noise is reduced, but cable flexibility and ease of operation deteriorate
Solution Approach 1:
The patent substitutes mechanical noise suppression with an electrical solution. The triaxial cable configuration with driven shield eliminates cable strum through electrical means, allowing the cable to remain flexible and easy to operate without requiring rigid jackets or mechanical strum suppressants
3Loss of information
If conventional cable configurations are used, then cable structure is simple, but signal integrity deteriorates due to low-pass filter and dielectric absorption effects
Solution Approach 1:
The patent changes the electrical configuration from conventional coaxial to triaxial with driven shield, where the inner shield is driven at the same potential as the inner conductor. This parameter change eliminates capacitive coupling and dielectric absorption effects, preserving signal integrity across ultra-wideband frequencies without requiring complex external filtering or equalization circuits
4Length of stationary object
If longer cable lengths are used to tow hydrophone farther, then towing distance increases, but signal loss and noise increase proportionally
Solution Approach 1:
The patent changes the cable configuration to triaxial with driven shield, eliminating capacitive coupling between inner conductor and outer shield. This parameter change allows signal energy to be maintained at 100% even over extended cable lengths, as the driven shield configuration prevents signal degradation that would normally occur with increased cable length
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 configuration significantly enhances signal integrity by eliminating low-pass filter and dielectric absorption effects, resulting in ultra-wideband frequency response with no phase shift or signal loss, maintaining 100% of the signal energy and achieving unrivaled signal-to-noise ratios, even at low signal levels, across extended cable lengths.
Implementation Method 1
referencing capacitance and conductance to the guard rather than the shield
Implementation Method 2
eliminating low-pass filter and dielectric absorption effects
Implementation Method 3
differential mode configuration with buffer amplifier circuits
Data Source
AI summary
A differential mode instrumentation cable for improving the signal integrity of audio signals in different environments including use of a sonar hydrophone being towed to the water behind a ship and the sonar hydrophone signal receiver aboard ship to improve the hydrophone signal receiver signal output clarity, reducing strumming cable noises, comprising a first triaxial cable and a second triaxial cable, placed side-by-side, and surrounded by waterproof cable material fr to prevent any water from reaching the first and second triaxial cable from end to end from the hydrophone to the signal receiver aboard ship and mounted together, said first coaxial cable and said second coaxial cable including a wired connection that includes an active driven shield buffer circuit in each triaxial cable having an inner conductor for voltage in from the positive polarity and minus polarity and the voltage out driven guard shield with series breakout resistor connected to the each triaxial inner shield.