Fishing Sonar Phase-Modulated Impulse Signal Processing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current sonar systems for fishing applications face challenges in achieving flexible, cost-effective, and accurate object separation and range resolution due to limitations in signal-to-noise ratios and sidelobes, particularly when using CHIRP techniques.
Innovation Solution
The method employs phase-modulated impulse sonar signals and phase-only correlated (POC) signal processing to improve range resolution and object separation by reducing sidelobes and enhancing signal-to-noise ratios, allowing for precise localization of fish and other underwater objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If shorter sonar pulses are used to improve range resolution and detect closely-spaced objects, then range resolution improves, but very high peak powers are required
Solution Approach 1:
The patent applies phase modulation to sonar pulses, creating periodic phase variations that enable pulse compression. By modulating the phase of the transmitted pulse and then correlating the received echo with a reference signal, the system achieves high range resolution without requiring extremely high peak powers, as the energy is distributed over the pulse duration rather than concentrated in a short high-power spike.
Solution Approach 2:
The patent changes the phase parameter of the sonar signal over time according to a predetermined pattern. This phase modulation allows the system to encode information in the phase domain, enabling differentiation of closely-spaced objects through phase correlation while maintaining lower peak power requirements compared to time-domain pulse shortening alone.
2Power
If longer sonar pulses are used to reduce peak power requirements, then power requirements decrease, but accuracy in range resolution and target separation degrades
Solution Approach 1:
By implementing periodic phase modulation in longer pulses, the system maintains the ability to achieve fine range resolution through correlation processing. The periodic phase structure allows the longer pulse energy to be effectively compressed in the correlation domain, preserving range resolution accuracy while benefiting from the lower peak power requirements of longer pulse durations.
Solution Approach 2:
The patent applies preliminary phase modulation to the transmitted pulse before transmission. This pre-encoding of phase information allows the received signal to be correlated with a known reference pattern, enabling accurate range resolution to be extracted from the modulated signal even when using longer pulse durations that would otherwise degrade resolution.
3Measurement precision
If CHIRP sonar techniques are used to improve range resolution and background noise rejection, then range resolution improves, but many large sidelobes are produced resulting in poor object separation
Solution Approach 1:
The patent employs phase modulation instead of frequency modulation (CHIRP), changing the approach from varying frequency over time to varying phase according to a predetermined pattern. This phase-based approach produces a correlation function with significantly reduced sidelobe levels compared to CHIRP techniques, while maintaining improved range resolution through the phase-encoded pulse structure.
4Measurement precision
If phase-modulated impulse sonar signals with phase-only correlated signal processing are used, then range resolution and object separation improve, but system complexity increases
Solution Approach 1:
The system uses correlation processing where the received signal is compared with a predetermined reference signal that matches the transmitted phase modulation pattern. This feedback-like comparison allows extraction of range information while suppressing sidelobes and noise, achieving high resolution without requiring overly complex real-time signal processing algorithms.
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 enables accurate determination of object distances and separation, providing valuable insights for fishing activities by improving range resolution, object separation, and signal-to-noise ratios, allowing for precise identification and localization of fish.
Implementation Method 1
emitting, by means of a fishing sonar module comprised in the fishing sonar apparatus, a phase-modulated impulse sonar signal having a first frequency into the body of water
Implementation Method 2
receiving a reflected phase-modulated impulse sonar signal from the body of water. The received reflected sonar signal comprises a reflection of the emitted sonar signal being incident on at least one first object surrounded by the body of water
Implementation Method 3
determining a correlated signal between the reflected phase-modulated impulse sonar signal and a reference signal at least partly constructed based on the reflected phase-modulated impulse sonar signal. The correlated signal is a phase-correlated signal determined based on a phase difference of the reflected sonar signal and the reference signal
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present disclosure relates to a method (300) for scanning a body of water (5), a fishing sonar apparatus (2), a computer program carrier and a vessel (1) comprising the fishing sonar apparatus. The method comprises emitting (301), by means of a fishing sonar module (3) comprised in the fishing sonar apparatus, a phase-modulated impulse sonar signal (101) having a first frequency into the body of water and receiving (303) a reflected phase-modulated impulse sonar signal (103) from the body of water. The received reflected sonar signal comprises a reflection of the emitted sonar signal being incident on at least one first object (25a, 26a, 27) surrounded by the body of water. The method further comprises determining (305) a correlated signal between the reflected phase-modulated impulse sonar signal and a reference signal at least partly constructed based on the reflected phase-modulated impulse sonar signal. The correlated signal is a phase-correlated signal determined based on a phase difference of the reflected sonar signal and the reference signal. Further, the method comprises obtaining (309) at least one object-related information associated with the at least one first object surrounded by the body of water based on the phase-correlated signal.