Application Cases

Experimental Title: Measurement and Verification of Radiation Noise from Vector/Pressure Nested Arrays in a Waveguide Environment

Research Direction:
This study addresses the measurement accuracy of underwater vehicle radiation noise. Given the influence of waveguide environments in Chinese waters on measurements, it analyzes the results of common noise measurement methods under different waveguide conditions, with a focus on the impact of waveguide environments on radiation noise measurement and a quantitative investigation of the measurement errors associated with various methods in such environments.

Experimental Objectives:

• To verify the distortion-free output capability of constant beamforming technology based on pressure nested arrays for broadband signals.

• To compare the noise measurement accuracy differences between vector nested arrays and pressure nested arrays in a waveguide environment.

• To analyze the signal fidelity performance of the power amplifier in the acoustic source excitation system.

Testing Equipment:
Signal source, power amplifier (ATA-L6B), cylindrical acoustic source, vertical line array, programmable filter amplifier, data acquisition system, anechoic water tank

Experimental Procedure:
A 2000–3000 Hz linear frequency modulation signal was amplified using the ATA-L6B power amplifier to drive a custom cylindrical acoustic source, radiating an acoustic field in the anechoic water tank. The acoustic source and a 12-element vertical line array were deployed in parallel at a water depth of 5 m (with a horizontal spacing of 4 m). A rigid bracket was used to fix the power amplifier and suppress vibration interference. Acoustic pressure signals from the array were synchronously acquired at a sampling rate of 50 kHz using the Pulse data acquisition and analysis system (B&K 3660-D). The signals were processed through a PFI 28000 programmable filter amplifier (bandpass: 200–4000 Hz) to suppress environmental noise. Based on a time-delay compensation algorithm, the acoustic field beamforming output was reconstructed. Combined with FFT spectrum analysis and a comparison of the time-frequency characteristics of vector/pressure nested arrays, the broadband fidelity and spatial gain performance of constant beamforming technology in the waveguide environment were quantitatively verified.

Figure 1: Schematic Diagram of the Experimental System

(a) Physical Image of the Cylindrical Acoustic Source
(b) Deployment of the Cylindrical Acoustic Source

Figure 2: Experimental Cylindrical Acoustic Source

(a) Physical Image of the Vertical Line Array
(b) Deployment of the Vertical Line Array

Figure 3: Experimental Vertical Line Array

Experimental Results:
This study systematically verified the broadband signal fidelity and spatial gain performance of vector/pressure nested arrays through acoustic field excitation and vertical line array measurements in the anechoic water tank waveguide environment. The experiments demonstrated that the pressure nested array achieved a spatial gain of 16.9 dB (error < 0.5 dB) within the 2000–3000 Hz frequency band. The correlation coefficient between the output signal and the source signal reached 0.92, confirming the distortion-free reconstruction capability of constant beamwidth technology for broadband linear frequency modulation signals. The vector nested array further suppressed multipath interference by calculating particle velocity components, reducing the measurement error of a single hydrophone from 3.2 dB to 1.1 dB and providing an additional 6 dB improvement in signal-to-noise ratio. The power amplifier achieved a total harmonic distortion (THD) of < 0.8% when driving the acoustic source to produce a sound pressure level of 120 dB @ 1 m, ensuring the stability and phase consistency of the acoustic source excitation. These findings provide a novel method for high-precision measurement of underwater target radiation noise, applicable to scenarios such as ship acoustic fingerprint recognition and underwater communication acoustic field monitoring, overcoming the limitations of traditional single-hydrophone systems in complex acoustic environments, such as insufficient dynamic range and weak anti-interference capabilities.

Figure 4: Noise Measurement Results Under Different Sound Speed Gradients

Figure 5: Noise Measurement Results Under Different Seabed Parameters

Product Recommendation: ATA-L Series Hydroacoustic Power Amplifier

Figure: ATA-L Series Hydroacoustic Power Amplifier Specifications and Parameters

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