Featured Research

from universities, journals, and other organizations

Emergency Links: 'Sweet Spot' For Radios In Tunnels Identified

Date:
May 20, 2008
Source:
National Institute of Standards and Technology
Summary:
Researchers have confirmed that underground tunnels -- generally a difficult setting for radios -- can have a frequency "sweet spot" at which signals may travel several times farther than at other frequencies. The finding may point to strategies for enhancing rescue communications in subways and mines.

Electronics engineer Dennis Camell (foreground) aligns antennas in an old California silica mine for a NIST study identifying optimal frequencies for radio signal transmissions in tunnels.
Credit: G. Koepke/NIST

As part of a project to improve wireless communications for emergency responders, researchers at the National Institute of Standards and Technology (NIST) have confirmed that underground tunnels--generally a difficult setting for radios--can have a frequency "sweet spot" at which signals may travel several times farther than at other frequencies. The finding, which uses extensive new data to confirm models developed in the 1970s, may point to strategies for enhancing rescue communications in subways and mines.

The optimal frequency depends on the dimensions of the tunnel. For a typical subway-sized tunnel, the sweet spot is found in the frequency range 400 megahertz (MHz) to 1 gigahertz (GHz). This effect is described in one of two new NIST publications.* The reports are part of a NIST series contributing to the first comprehensive public data collection on radio transmissions in large buildings and structures. Historically, companies have designed radios based on proprietary tests. The NIST data will support the development of open standards for design of optimal systems, especially for emergency responders.

NIST researchers were surprised by how much farther signals at the optimal frequency traveled in above-ground building corridors, as well as underground. Tunnels can channel radio signals in the right frequency range because they act like giant waveguides, the pipelike channels that confine and direct microwaves on integrated circuit wafers, and in antenna feed systems and optical fibers. The channel shape reduces the losses caused when signals are absorbed or scattered by structural features. The waveguide effect depends on a tunnel's width, height, surface material and roughness, and the flatness of the floor as well as the signal frequency. NIST authors found good agreement between their measured data and theoretical models, leading to the conclusion that the waveguide effect plays a significant role in radio transmissions in tunnels.

Lead author Kate Remley notes that the results may help design wireless systems that improve control of, for example, search and rescue robots in subways. Some handheld radios used by emergency responders for voice communications already operate within the optimal range for a typical subway, between around 400 MHz and 800 MHz. To provide the broadband data transfer capability desired for search and rescue with video (a bandwidth of at least 1 MHz), a regulatory change would be needed, Remley says.

The tunnel studies were performed in 2007 at Black Diamond Mines Regional Park near Antioch, Calif., an old complex used in the early 1900s to extract pure sand for glass production.

The second new NIST report** describes mapping of radio signals in 12 large building structures including an apartment complex, a hotel, office buildings, a sports stadium and a shopping mall.

The research is supported in part by the U.S. Department of Justice and the Department of Homeland Security.

Both reports will be available on NIST's Metrology for Wireless Systems Web page. http://www.boulder.nist.gov/div818/81802/MetrologyForWirelessSys/


Story Source:

The above story is based on materials provided by National Institute of Standards and Technology. Note: Materials may be edited for content and length.


Journal References:

  1. * K. A. Remley, G. Koepke, C. L. Holloway, C. Grosvenor, D.G. Camell, J. Ladbury, R.T. Johnk, D. Novotny, W.F. Young, G. Hough, M.D. McKinley, Y. Becquet and J. Korsnes. "Measurements to Support Modulated-Signal Radio Transmissions for the Public-Safety Sector". NIST Technical Note 1546, April, 2008.
  2. ** C. L. Holloway, W.F. Young, G. H. Koepke, K. A. Remley, D. G. Camell and Y. Becquet. "Attenuation of Radio Wave Signals Into Twelve Large Building Structures". NIST Technical Note 1545.

Cite This Page:

National Institute of Standards and Technology. "Emergency Links: 'Sweet Spot' For Radios In Tunnels Identified." ScienceDaily. ScienceDaily, 20 May 2008. <www.sciencedaily.com/releases/2008/05/080516164822.htm>.
National Institute of Standards and Technology. (2008, May 20). Emergency Links: 'Sweet Spot' For Radios In Tunnels Identified. ScienceDaily. Retrieved October 22, 2014 from www.sciencedaily.com/releases/2008/05/080516164822.htm
National Institute of Standards and Technology. "Emergency Links: 'Sweet Spot' For Radios In Tunnels Identified." ScienceDaily. www.sciencedaily.com/releases/2008/05/080516164822.htm (accessed October 22, 2014).

Share This



More Matter & Energy News

Wednesday, October 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Chameleon Camouflage to Give Tanks Cloaking Capabilities

Chameleon Camouflage to Give Tanks Cloaking Capabilities

Reuters - Innovations Video Online (Oct. 22, 2014) — Inspired by the way a chameleon changes its colour to disguise itself; scientists in Poland want to replace traditional camouflage paint with thousands of electrochromic plates that will continuously change colour to blend with its surroundings. The first PL-01 concept tank prototype will be tested within a few years, with scientists predicting that a similar technology could even be woven into the fabric of a soldiers' clothing making them virtually invisible to the naked eye. Matthew Stock reports. Video provided by Reuters
Powered by NewsLook.com
Jet Sales Lift Boeing Profit 18 Pct.

Jet Sales Lift Boeing Profit 18 Pct.

Reuters - Business Video Online (Oct. 22, 2014) — Strong jet demand has pushed Boeing to raise its profit forecast for the third time, but analysts were disappointed by its small cash flow. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
Internet of Things Aims to Smarten Your Life

Internet of Things Aims to Smarten Your Life

AP (Oct. 22, 2014) — As more and more Bluetooth-enabled devices are reaching consumers, developers are busy connecting them together as part of the Internet of Things. (Oct. 22) Video provided by AP
Powered by NewsLook.com
What Is Magic Leap, And Why Is It Worth $500M?

What Is Magic Leap, And Why Is It Worth $500M?

Newsy (Oct. 22, 2014) — Magic Leap isn't publicizing much more than a description of its product, but it’s been enough for Google and others to invest more than $500M. Video provided by Newsy
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

 

Space & Time

Matter & Energy

Computers & Math

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