Broadcast Underwater Positioning Network for Expanded Service Range
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Solution Overview
Problem
Underwater navigation positioning technologies face challenges such as limited service range, low capacity for terminal users, and poor precision due to sound velocity errors and geometric observation intensities, which are exacerbated by the need for numerous base stations and complex calibration processes.
Innovation Solution
A broadcast-type underwater navigation positioning system integrating bottom-mounted and mooring sonars with inertial measurement units, utilizing conductivity-temperature-depth instruments and current meters for real-time calibration and sound velocity correction, and employing a broadcast-mode for precise time synchronization and sound velocity error tomographic inversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the distance between seabed base stations is increased to expand service range, then the coverage area is improved, but the base station height must be increased by about 3m for every 1km distance increase to maintain acoustic ray visibility, which greatly increases construction and maintenance costs
Solution Approach 1:
The patent combines multiple base stations into a networked system where each base station covers a smaller local area, but the collective network provides wide coverage. The base stations work cooperatively through signal sharing and coordinated positioning, achieving both compact individual station design and extensive service range.
Solution Approach 2:
The patent divides the large service area into multiple smaller coverage zones, each served by an individual base station. This segmentation allows each base station to maintain optimal height and configuration while the aggregate network provides extensive coverage, avoiding the need for any single station to be excessively tall or expensive.
2Measurement precision
If transponder-type positioning mode is used to distinguish interrogator signals from different user terminals, then positioning function is achieved, but the number of users being served at the same time is extremely limited and active mode exposes user positions
Solution Approach 1:
The patent inverts the traditional active-transponder positioning mode by using passive receiving terminals that listen for positioning signals without actively transmitting interrogator signals. This inversion allows multiple terminals to simultaneously receive and process positioning data from base stations without signal collision, dramatically increasing system capacity while maintaining positioning accuracy and providing inherent position concealment.
3Measurement precision
If seawater sound velocity measurement is performed with conventional methods, then sound velocity data is obtained, but the measurement error is generally not less than 5cm/s and spatio-temporal changes are not accurately captured, leading to poor positioning precision
Solution Approach 1:
The patent introduces acoustic signal propagation time as an intermediary measurement parameter. Instead of directly measuring sound velocity with complex instruments, the system measures the time for acoustic signals to travel between base stations and terminals, then calculates sound velocity from these time measurements. This intermediary approach achieves high precision (better than 5cm/s error) while avoiding the complexity of direct sound velocity measurement devices.
Solution Approach 2:
The patent replaces conventional mechanical sound velocity measurement instruments with an acoustic signal-based measurement system. By using acoustic propagation time measurements and computational processing, the system achieves superior measurement precision without the mechanical complexity and limitations of traditional sound velocity meters.
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
The system achieves a wide service range, high terminal capacity, and improved precision, with real-time position calibration and sound velocity correction, enabling large-range, long-distance, and high-precision underwater navigation.
Implementation Method 1
the bottom-mounted sonar and the mooring sonar are connected through a cable and are configured for ranging and communication through an underwater acoustic signal
Implementation Method 2
the user terminal is provided with a passive sonar configured to unidirectionally receive an underwater acoustic signal sent by the mooring sonar for ranging and communication
Implementation Method 3
an inertial measurement unit I is integrated on the mooring sonar
Data Source
AI summary
The disclosure provides a broadcast-type underwater navigation positioning system and method, wherein the system comprises a base station network consisting of a plurality of underwater base stations distributed on a seabed and a to-be-positioned user terminal located underwater, wherein the underwater base station comprises a bottom-mounted sonar and an mooring sonar, the bottom-mounted sonar and the mooring sonar are connected through a cable and are configured for ranging and communication through an underwater acoustic signal, the mooring sonar is integrated with an inertial measurement unit I, and the user terminal is provided with a passive sonar configured to unidirectionally receive an underwater acoustic signal sent by the mooring sonar for ranging and communication. The underwater navigation positioning system and method disclosed in the present invention can expand the service range of the base station, increase the capacity of the user terminal and improve the precision of regional sound velocity products.