26 TR News 171, March–April 1994

RESEARCH PAYS OFF

Meteor Burst CommunicationNevada Research Uses Falling Stars forData Transmission

Even in today's world of sophisticatedcommunication technology, there are stillsome remote locations that are not serv-iced by a communication system. In mostcases, this situation does not present aproblem. For those responsible for datacollection from these distant sites, how-ever, the lack of a suitable communicationsystem can be a major drawback.

Problem

The Nevada Department of Transporta-tion (NDOT) collects traffic-related dataat remote locations over an area of110,540 square miles. Fortunately, only asmall part of this area is not serviced byeither telephone lines or a cellular com-munication network. NDOT's problemlies in the fact that it locates its traffic-related data-collection sites based on needinstead of the availability of a communi-cation system. The manpower required tocollect data at these sites taxes the de-partment's resources with an annual costin excess of 1,000 man-hours. The MeteorBurst Project began with the awareness ofthis problem and the desire to find an ef-fective solution. Although Meteor BurstCommunication (MBC) has been used for30 years in military applications and forvarious types of remote environmentaldata collection, it had never been used inthis application.

Solution

MBC is based on the phenomenonwhereby radio waves at VHF (very highfrequency) are reflected by trails of ion-ized particles left by meteors entering theearth's atmosphere. Typical meteors rangefrom the size of a small pea to, morecommonly, a grain of sand. The totalnumber of these small meteors in theearth's atmosphere is estimated to be 1trillion per day, although relatively few ofthem have the required size, speed, andorientation to earth to make them usefulfor meteor scatter propagation.

Each meteor leaves an ionization trailup to 12 miles long, but lasting no longerthan several milliseconds in the upperatmosphere. "Handshaking" and datatransfer between the master MBC stationand the remote MBC station take placeduring the short duration of this trail.MBC is effective for distances between150 and 1,200 miles.

Application

Working together, NDOT and the Electri-cal Engineering Department of the Uni-versity of Nevada-Reno developed a self-contained, roadside MBC station. In addi-tion to the existing data-collection de-vices, this station consisted of a solarpanel, a rechargeable 12-volt batterypower supply, the meteor burst transmis-sion unit, an interface board, and a five-

TR News 171, March–April 1994 27

element yagi antenna (Figure 1). Thisremote roadside station is completelycontrolled by the interface board, a mi-croprocessor-based unit that acts as thebrains of the system. This board is de-signed to connect multiple traffic-monitoring devices to a single transmit-ter/receiver. It can also perform dutiessuch as automatically downloading datafrom the traffic-recording devices beforetheir memory storage overflows, ordownloading data at programmed inter-vals. Once these data are in the interfaceboard, they are reformatted and com-pressed before copies of the data aretransferred to the meteor burst transmitter.A status report of the system can also

be transmitted in order to alert operatorsthat repair or service is required.

During NDOT's research, the data weresent to an MBC master station located inBozeman, Montana. The data were thenforwarded to a data center in Kent,Washington, via telephone lines, wherethey were reformatted back to their origi-nal configuration and finally sent to theNDOT headquarters in Carson City, Ne-vada.

Benefits

On completion of this study, NDOT con-tinued to use MBC to retrieve data at one

remote station for four months, saving thedepartment approximately 150 man-hours. At that time, the cellular communi-cation network serving Nevada was ex-panded, eliminating the benefits of MBCfor current NDOT traffic data-collectionsites. However, NDOT is currently re-viewing MBC for data collection in con-junction with FHWA's continuation of theSHRP anti-icing study.

The results of this research project haveserved to break new ground in the area ofdata transmission and should provide abase of technical knowledge that willstimulate use for a variety of transporta-tion-related data transmission throughoutremote areas of the world.

For further information, contact MikeLawson, Traffic Information SystemsManager, Research Division, NevadaDepartment of Transportation, 1262 S.Stewart Street, Carson City, Nevada89712 (telephone 702-687-3443).

Suggestions for "Research Pays Off"topics are welcome. Contact G.P. Jay-aprakash, Transportation ResearchBoard, 2101 Constitution Avenue,N.W., Washington, D.C. 20418 (tele-phone 202-334-2952).