Application Cases

【Overview】
In this study, the Aigtek ATA-L8 underwater acoustic power amplifier was used to build a biomimetic underwater acoustic communication system. In this paper, a high-speed biomimetic underwater acoustic communication (BCUAC) method based on dolphin clicks and phase rotation modulation (ClickPRM) is proposed, transmitting information through the phase variations of the clicks. Both theoretical analysis and experimental verification confirm the covert effectiveness of this method. Using ClickPRM, real-time image transmission between two underwater Internet of Things (UIoT) nodes was achieved in a shallow water area over a communication distance of 405 meters at a transmission rate of 11.22 kb/s, demonstrating communication performance that is an order of magnitude higher than existing BCUAC methods. Moreover, this technology offers flexible switching of camouflage carriers, providing a viable solution for secure data transmission in various UIoT scenarios.

Experiment Name: Application of Power Amplifier in Biomimetic Underwater Acoustic Communication

Research Direction: Biomimetic Covert Underwater Acoustic Communication

Experimental Content:
Dolphin acoustic signals were used as information carriers, and a power amplifier was used to drive a transducer to achieve covert underwater data transmission.

Testing Equipment:
ATA-L8 underwater acoustic power amplifier, data acquisition card, transducer, hydrophone, etc.

Experimental Procedure:

Figure 1: Experimental Test System Diagram

At the transmitting end, a PC was used to generate biomimetic communication signals via a MATLAB script. Subsequently, LabVIEW software controlled a DAC to convert the discrete signals into analog signals, which were transmitted to the ATA-L8 power amplifier. By adjusting the amplifier gain, sufficient sound source level was ensured for the transducer. Finally, the transducer converted the electrical signals into acoustic signals for underwater propagation. At the receiving end, a hydrophone was used to detect the underwater acoustic signals and convert them back into electrical signals. LabVIEW software controlled an ADC to convert these electrical signals into discrete signals, which were then transmitted to the PC. Finally, a MATLAB script was used to demodulate the signals and present the experimental results.

Experimental Results:

Figure: Experimental Results

As shown in Figure 3, the constellation diagram without phase compensation exhibited significant dispersion due to severe multipath interference, with bit error rates fluctuating between 15% and 40%, resulting in nearly complete data  distortion . In contrast, the constellation diagram after equalization showed clearer clustering characteristics, and the phase rotation caused by multipath effects was effectively compensated, achieving error-free transmission in most cases. As shown in Figure 4, real-time image transmission in a shallow water environment was achieved using biomimetic communication for the first time, with a communication rate as high as 21.72 kbit/s—two orders of magnitude higher than existing levels. A certain degree of noise and trailing  effects were observed in the time-domain waveform and time-frequency distribution of the received signal, primarily caused by the multipath effects of the channel. This characteristic was also reflected in the constellation diagram before phase compensation. By calculating the phase difference between the received training symbols and locally generated noise-free training symbols, the constellation points were rotated back, bringing them closer to the standard mapping positions. Although a few bit errors remained after demodulation, these errors did not  significantly  affect the overall quality of the image transmission.

Advantages of Aigtek Amplifiers in This Application:

1. High output power and high sound source level – Core guarantee for achieving reliable long-distance underwater transmission.

2. High linearity and low distortion – Accurately reproduces the biomimetic characteristics of dolphin acoustic signals.

3. Wideband coverage and flat frequency response –  the wideband characteristics of acoustic signals.