Breakthrough in Underwater Communication: Chinese Scientists Achieve Error-Free Transmission Over 600km

Chinese scientists have achieved error-free underwater acoustic data transmission over 600 kilometers, a significant milestone with wide-ranging civilian and military implications. Led by Professor He Chengbing of Northwestern Polytechnical University, the team developed a self-tuning system and an innovative algorithm for precise communication in noisy underwater environments. Sea trials demonstrated flawless transmission at long distances despite challenges like signal distortion and ambient noise. This breakthrough advances China’s underwater communication projects, though computational demands and environmental factors remain hurdles for real-time, widespread use.

A team of researchers in China has made a groundbreaking advancement in underwater communication, achieving flawless acoustic data transmission over 600 kilometers (375 miles) of ocean. This remarkable feat, roughly comparable to the distance between Taipei and Okinawa, holds significant potential for applications in both civilian and military domains. The achievement was detailed in a study published in May in Acta Acustica, a leading Chinese journal dedicated to acoustics.

Tackling Long-Standing Challenges in Underwater Communication

Although marine animals like whales can transmit low-frequency calls across distances exceeding 8,000 kilometers, and a U.S. Navy experiment in 2010 demonstrated communication over 550 kilometers, the challenge of maintaining zero-error transmission over such long distances has remained unresolved.

The complexities of underwater communication are immense. Sound waves traveling through seawater encounter various obstacles: they scatter into multipath echoes, Doppler effects distort signals emitted from moving platforms, and ambient ocean noise can overwhelm faint signals. By the time sound travels several hundred kilometers, even powerful transmissions are diminished to near-inaudible levels.

A Self-Tuning System for Acoustic Precision

The research team, led by Professor He Chengbing of Northwestern Polytechnical University, developed a sophisticated self-tuning system capable of adapting to noisy underwater environments without requiring prior knowledge of the seabed's features. This adaptability is particularly advantageous for naval operations.

Additionally, the team introduced an innovative algorithm that transforms turbulent, variable underwater channels into quasi-static "acoustic snapshots" through advanced mathematical techniques. This allows for iterative error correction, similar to how multiple exposures can sharpen a blurry photograph.

In sea trials conducted in 2021 at an undisclosed location with an average water depth of 5,500 meters (18,040 feet), the system demonstrated zero-bit-error transmission over distances of 324.9 kilometers and 595.1 kilometers. Using an eight-element hydrophone array attached to a buoy and coded QPSK signals, the system achieved a transmission rate of 37.5 bits per second during the longer-range test. The results affirm the system's capability for error-free long-range underwater acoustic communication.

Implications and Limitations of the Technology

Northwestern Polytechnical University, renowned for its contributions to China’s aerospace and naval research, has played a pivotal role in advancing marine technology. The university’s underwater acoustics department, established in the 1950s, has been instrumental in developing the country's cutting-edge warships and marine surveillance networks.

However, the technology is not without its limitations. Processing one transmission requires teraflop-scale computing power, making it impractical for real-time applications on smaller platforms such as drones. Furthermore, sudden environmental changes, such as storms or abrupt movements, could disrupt the system’s performance.

The study revealed that the sea trials employed a 176-decibel sound source operating in the extremely low-frequency range, although additional technical details were not disclosed.

A Step Toward Underwater Connectivity

China has been actively pursuing numerous projects aimed at enhancing underwater communication and navigation. Initiatives like "Underwater BeiDou" and "Transparent Ocean" aim to establish large-scale networks for seamless underwater surveillance and connectivity.

This latest breakthrough in underwater communication represents a significant leap forward in the field, potentially unlocking new possibilities for deep-sea exploration and military strategy.

Source: Information adapted from an article originally published in the South China Morning Post (SCMP).