Underwater Acoustic Communication Quiz

5 Questions

Explain some of the challenges of underwater acoustic communication.

Factors such as multi-path propagation, time variations of the channel, small available bandwidth, and strong signal attenuation make underwater communication difficult.

What is the most common method of employing underwater acoustic communication?

Using hydrophones is the most common method of employing underwater acoustic communication.

How does underwater communication differ from terrestrial communication?

Underwater communication has low data rates because it uses acoustic waves instead of electromagnetic waves, unlike terrestrial communication.

How were submarine signals competitive with maritime radionavigation in the early 20th century?

Submarine signals were competitive with primitive maritime radionavigation at the time, and the later Fessenden oscillator allowed communication with submarines.

What were some early methods of underwater communication used by ships?

Some ships communicated by underwater bells and used the system for navigation at the beginning of the 20th century.

Study Notes

Underwater Acoustic Communication Challenges

Multipath effects and signal reflections from the seafloor and water surface cause signal distortion and interference
High attenuation rates of acoustic signals due to water's high absorption and scattering properties
Noise from marine life, ocean currents, and human activities can interfere with signal transmission
Limited bandwidth and low data transfer rates due to the physical properties of sound in water

Common Method of Underwater Acoustic Communication

Using acoustic modems that transmit sound waves through the water to convey digital information

Differences from Terrestrial Communication

Speed of sound in water is approximately 1500 m/s, compared to the speed of light in air (approximately 300,000 km/s)
Water's high absorption and scattering properties limit the range and reliability of underwater communication

Submarine Signals and Maritime Radionavigation

In the early 20th century, submarine signals were competitive with maritime radionavigation due to the development of underwater sound-based navigation systems
These systems allowed for more accurate and reliable navigation and communication underwater

Early Methods of Underwater Communication

Early methods used by ships included:
- Flashing lights or flags to convey simple messages
- Bells or other sound-based signals to convey messages
- Submerged bells or other underwater sound sources to convey messages
- Early forms of underwater telegraphy using submerged wires or cables