Chinese underwater acoustic communication machine achieves long-distance transmission

BEIJING, Dec. 20 (Xinhua) -- A Chinese-made underwater acoustic communication machine has achieved long-distance transmission at a high rate.

The acceptance test of the sample machine showed that the underwater acoustic communication machine, developed by a research team from the Ocean College of Zhejiang University, realized 90 percent of transmission rate at a speed of 3.07 KBps (kiloBytes per second) over 14 km.

Underwater wireless communication is an important technology to ensure the interconnection of underwater equipment. And underwater acoustic communication is a unique solution for high-speed and long-distance underwater wireless communication since electromagnetic waves are difficult to transmit through seawater.

The acoustic signal at a lower frequency can be transmitted farther underwater, said Qu Fengzhong, a professor with Zhejiang University. But the bandwidth available for communication at low frequencies is very limited. Thus it is difficult for underwater acoustic communication to meet the requirements of high speeds and long distances.

The relative position movement of the underwater communication transceiver causes Doppler frequencies to shift, which seriously affects the decoding of communication, according to the university.

The research team led by Qu applied an anti-Doppler frequency shift underwater acoustic communication algorithm to make the machine be capable of working at high speed.

The researchers also tried to design a smaller and lighter machine to make it applicable for underwater robots, submersible vehicles and underwater wireless sensor nodes.