Ultrasonic Acoustic Remote Sensing

Acoustic Sensing

Sound waves can be used to sense the environment. This technique has been developed in nature and in our technology.

In Nature

This technique is broadly coined by the term "Echolocation" to describe its variants in different species. Some examples:

• Bats
  • Bats echolocate with a frequency of 11-212kHz with most operating between 20-60kHz (Jones & Holderied, 2007).
• Cetaceans (Whales & Dolphins)
  • Chong et. al. (2021) performed an experiment to test the ability of dolphins to decipher objects of various materials (but otherwise identical) with their biosonar. In their experiment, their bottlenose dolphin, Ginsan, produced frequencies in the range of 50kHz-130kHz.
• Shews
  • Shrews echolocate with a frequency of 30-60kHz (Thomas & Jalili, 2004). According to Chai et. al (2020), genome data suggests that bats, cetaceans and shews experience convergent evolution, sharing the same set of genes for this skill.

In Technology

This technique is employed by different types of technology, such as in SONAR or in Seismic Inversion.

• SONAR
• Seismic Inversion

Fundamental Principle & Additional Principles

The most basic principle behind this technique rely on round trip Time-Of-Flight (TOF) measurements of reflected sound waves. However, more complicated principles can be involved. For example:

• In Seismic Inversion (oversimplified), one considers a delayed response composed of multiple reflections of waves propagating through a geologic medium to reconstruct structural layers.
• In Echolocation, bats use Doppler Shifts to locate moving targets.

Project Overview

In this project, we will use sound to sense the environment. From the previous section, it is clear that

Tools

On the most basic level to run our experiment, we require a source of ultrasonic sound, a receiver sensitive to ultrasonic wavelengths, and a board to control these devices. Arduino provides a convenient solution these requirements.

1. . Arduino UNO R3
2. . HC-SR04 Ultrasonic Emitter/Sensor

Experiment 1 Distance Measurement

Hardware

Caption

Caption

We connect the HC-SR04, which serves as the source and receiver, to the Arduino UNO R3 based on the above described circuit. From left to right of the HC-SR04: VCC-5V, Echo-pin 10, Trigger-pin 9, Ground-Ground. This completes the hardware of the set-up.

Analysis/Reflection on Experiment

To better understand this part of the experiment, it is important to know the characteristics of the HC-SR04.

References

Jones, G., & Holderied, M. W. (2007). Bat echolocation calls: adaptation and convergent evolution. Proceedings. Biological sciences, 274(1612), 905–912. https://doi.org/10.1098/rspb.2006.0200

Wei, C., Hoffmann-Kuhnt, M., Au, W.W.L. et al. (2021). Possible limitations of dolphin echolocation: a simulation study based on a cross-modal matching experiment. Sci Rep 11, 6689. https://doi.org/10.1038/s41598-021-85063-2

Thomas, J. A., Moss, C., & Vater, M. (2004). Review of echolocation in insectivores and rodents. In Echolocation in bats and Dolphins. essay, University of Chicago Press. https://www.researchgate.net/publication/258835904_Review_of_echolocation_in_insectivores_and_rodents

Chai, S., Tian, R., Rong, X., Li, G., Chen, B., Ren, W., Xu, S. & Yang, G. (2020). Evidence of Echolocation in the Common Shrew from Molecular Convergence with Other Echolocating Mammals. Zoological Studies 59: 4. https://doi:10.6620/ZS.2020.59-4