Marine Sonar Frequency Hopping Noise Rejection
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Solution Overview
Problem
Marine sonar devices often display unwanted noise and artifacts due to interference, causing false object representations and ring-like artifacts, which are not effectively reduced by lowering the ping rate, leading to jerky images and incomplete noise reduction.
Innovation Solution
The implementation of a marine sonar device that generates sonar beams at different frequencies on successive pings and into multiple sectors of water, using a processing element to filter out frequencies other than the specified ones, thereby reducing noise and improving image clarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the ping rate is lowered to reduce noise, then noise from interference sources is reduced, but the frame refresh rate of the display is reduced leading to jerky images
Solution Approach 1:
The patent changes the frequency parameter of the sonar beam across successive pings rather than changing the ping rate. By varying the frequency of the sonar beam on successive pings and filtering out frequencies other than the current frequency, the system reduces noise from interference sources while maintaining a high ping rate and frame refresh rate, avoiding jerky images.
2Object-affected harmful factors
If the ping rate is lowered to reduce noise, then noise from interference sources is reduced, but other noise sources are not reduced
Solution Approach 1:
The patent employs frequency variation as a selective filtering mechanism. By transmitting sonar beams at different frequencies on successive pings and applying frequency-specific filtering, the system can distinguish and eliminate noise from various sources (including interference sources and other noise) while preserving genuine sonar returns, achieving more complete noise reduction regardless of ping rate.
3Object-affected harmful factors
If frequency hopping is implemented to reduce noise, then noise and artifacts are reduced, but device complexity increases
Solution Approach 1:
The patent implements frequency hopping with frequency-specific filtering. The processing element varies the frequency of the sonar beam on successive pings and applies corresponding frequency filters to the received signals. This approach reduces noise and artifacts through frequency domain separation while managing complexity through systematic frequency assignment and filtering rather than requiring complex spatial or temporal processing.
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 significantly reduces on-screen noise and artifacts, providing a clearer representation of underwater objects by filtering out unwanted frequencies and rotating frequencies across sectors, resulting in a more reliable and stable sonar image display.
Implementation Method 1
The sonar element may be mounted on, or otherwise positioned at, the bow of a marine vessel. The sonar element may generate the sonar beam, known as a 'ping', into the water in front of the marine vessel.
Implementation Method 2
The processing element may be configured to instruct the sonar element to generate the sonar beam at a first frequency during a first ping, receive a first transducer signal resulting from received reflections of the sonar beam at the first frequency, filter the first transducer signal to exclude frequencies other than the first frequency
Implementation Method 3
receive a first transducer signal resulting from received reflections of the sonar beam at the first frequency
Data Source
AI summary
A marine sonar device comprises a display, a sonar element, and a processing element. The display displays sonar images. The sonar element generates a sonar beam during a ping and presents transducer signals. The processing element is configured to instruct the sonar element to generate the sonar beam at a first frequency during a first ping, receive a first transducer signal resulting from received reflections of the sonar beam at the first frequency, filter the first transducer signal to exclude frequencies other than the first frequency, instruct the sonar element to generate the sonar beam at a second frequency during a second ping, the second frequency being different from the first frequency, receive a second transducer signal resulting from received reflections of the sonar beam at the second frequency, and filter the second transducer signal to exclude frequencies other than the second frequency.