Featured Research

from universities, journals, and other organizations

Sensor Network Mimics Synchronized Calling By Frogs, Cicadas

Date:
November 26, 2004
Source:
Vanderbilt University
Summary:
The modern world is filled with the uncoordinated beeping and buzzing of countless electronic devices. So it was only a matter of time before someone designed an electronic network with the ability to synchronize dozens of tiny buzzers, in much the same way that frogs and cicadas coordinate their night-time choruses.

Professor Kenneth Frampton, center, with graduate students Isaac Amundson, right, and Stephen Williams, left, holding nodes of the synchronous calling network.
Credit: Photo by Daniel Dubois, Vanderbilt University

The modern world is filled with the uncoordinated beeping and buzzing of countless electronic devices. So it was only a matter of time before someone designed an electronic network with the ability to synchronize dozens of tiny buzzers, in much the same way that frogs and cicadas coordinate their night-time choruses.

Related Articles


"Several years ago I was on a camping trip and we pitched our tent in an area that was filled with hundreds of tree frogs," says Kenneth D. Frampton, an assistant professor of mechanical engineering at Vanderbilt University, who dreamed up the project. "The frogs were so loud that I couldn't get to sleep. So I began listening to the chorus and was fascinated by how the pattern of synchronized calling moved around: Frogs in one area would croak all together for a while, then gradually one group would develop a different rhythm and drift off on its own."

Last summer's emergence of cicada brood X brought back that memory and prompted Frampton to assign undergraduates Efosa Ojomo and Praveen Mudindi--working under the supervision of graduate student Isaac Amundson--with the task of simulating this complex natural behavior using a wireless distributed sensor network. They presented the results of their project on Nov. 16 at the annual meeting of the American Acoustical Society in San Diego.

Consulting the literature about animal vocalizations, the engineers discovered that a number of different theories have been advanced to explain such naturally occurring synchronized behaviors. They may have evolved cooperatively in order to maximize signal loudness, to confuse predators or to improve call features that attract potential mates. Or they may have evolved competitively in order to mask or jam the calls of nearby animals.

"Whichever theory is true, it is clear that these behavior patterns are complex and offer an interesting inspiration for group behaviors," says Frampton.

One thing that these behaviors have in common is that they are produced by groups of animals who are in communication with each other but who are acting on their own. Networks consisting of nodes that communicate with each other but act independently according to simple rules are becoming increasingly popular and were the obvious system to use.

"There is a great deal that we do not yet know about the group behavior of such systems," says Frampton. "So, in addition to being a lot of fun, the synchronized calling experiment is adding to our understanding of the behavior of this kind of network."

The engineers began with a wireless network of 15 to 20 "Motes," a wireless network designed by computer scientists at the University of California, Berkeley and manufactured commercially by Crossbow Inc. These are small microprocessors equipped with wireless communications. The researchers added a microphone and a buzzer to each node.

To mimic synchronized calling behaviors, the researchers first programmed a single leader, dubbed the alpha node, to begin calling (buzzing) with an arbitrary duration and frequency. The alpha node was set so it called at this rate regardless of any other calling in its vicinity. The remainder of the devices, referred to as beta nodes, were programmed differently. They were instructed to listen with their microphones and when they hear a call that is sufficiently loud, to estimate its duration and frequency and then begin calling in synch with the detected call.

"Although this behavioral algorithm is quite simple, it produces some interesting group behaviors," Frampton reports.

When all is quiet and an alpha node begins calling, at first only those beta nodes nearby hear the call and respond. Then, as more betas swell the chorus, nodes farther away hear the call and join in. In this fashion, synchronized calling gradually spreads concentrically out from the alpha node until all the nodes are synchronized.

A second interesting behavior occurs when a beta node "hiccups" and starts buzzing out of synch with its neighbors. Such hiccups can be caused by measurement noise, operating system jitter and other factors. Occasionally, when such a hiccup occurs, neighboring nodes resynchronize to the errant node. Normally, these transients quickly disappear as the wayward group resynchronizes with the larger group.

The most interesting behavior pattern appeared when the researchers introduced a third kind of node that they labeled omega. This node was programmed identically to an alpha node but set to a different duration and frequency. When introduced into the array, an omega node begins to attract neighboring nodes to its call cycle. Unlike the hiccup case, however, the omega group does not resynchronize with the original group. Rather, the omega node eventually recruits a growing number of nodes to its calling cycle until a "balance of power" is reached with the alpha node. The eventual balance between the two groups depends strongly on the initial arrangement of the sensors.

"While this is a rather whimsical application of a sensor network, it demonstrates the unique system behaviors that can arise in truly distributed processing," says Frampton. Even when nodes follow very simple rules, the behavior of the group can be quite complex. Although this project is not likely to improve knowledge on synchronized calling in nature, it does demonstrate the types of complex behavior patterns that will be important for future developments in sensor networks, Frampton says.

###

For more news about Vanderbilt research, visit Exploration, Vanderbilt's online research magazine, at http://www.exploration.vanderbilt.edu.


Story Source:

The above story is based on materials provided by Vanderbilt University. Note: Materials may be edited for content and length.


Cite This Page:

Vanderbilt University. "Sensor Network Mimics Synchronized Calling By Frogs, Cicadas." ScienceDaily. ScienceDaily, 26 November 2004. <www.sciencedaily.com/releases/2004/11/041123204241.htm>.
Vanderbilt University. (2004, November 26). Sensor Network Mimics Synchronized Calling By Frogs, Cicadas. ScienceDaily. Retrieved December 20, 2014 from www.sciencedaily.com/releases/2004/11/041123204241.htm
Vanderbilt University. "Sensor Network Mimics Synchronized Calling By Frogs, Cicadas." ScienceDaily. www.sciencedaily.com/releases/2004/11/041123204241.htm (accessed December 20, 2014).

Share This


More From ScienceDaily



More Plants & Animals News

Saturday, December 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Researchers Test Colombian Village With High Alzheimer's Rates

Researchers Test Colombian Village With High Alzheimer's Rates

AFP (Dec. 19, 2014) In Yarumal, a village in N. Colombia, Alzheimer's has ravaged a disproportionately large number of families. A genetic "curse" that may pave the way for research on how to treat the disease that claims a new victim every four seconds. Duration: 02:42 Video provided by AFP
Powered by NewsLook.com
Monarch Butterflies Descend Upon Mexican Forest During Annual Migration

Monarch Butterflies Descend Upon Mexican Forest During Annual Migration

Reuters - Light News Video Online (Dec. 19, 2014) Millions of monarch butterflies begin to descend onto Mexico as part of their annual migration south. Rough Cut (no reporter narration) Video provided by Reuters
Powered by NewsLook.com
Birds Might Be Better Meteorologists Than Us

Birds Might Be Better Meteorologists Than Us

Newsy (Dec. 19, 2014) A new study suggests a certain type of bird was able to sense a tornado outbreak that moved through the U.S. a day before it hit. Video provided by Newsy
Powered by NewsLook.com
Navy Unveils Robot Fish

Navy Unveils Robot Fish

Reuters - Light News Video Online (Dec. 18, 2014) The U.S. Navy unveils an underwater device that mimics the movement of a fish. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins