November 2002 2500 0225-2329-MTDC
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Remote Telemetry System for Particulate Monitoring

Andy Trent, Project Leader

Over the past several years, the Missoula Technology and Development Center (MTDC) evaluated commercial real-time particulate instruments used to monitor smoke particulate concentrations from prescribed burns and wildland fires. The results of these evaluations are documented in three reports (figure 1): Laboratory Evaluation of Two Optical Instruments for Real-Time Particulate Monitoring of Smoke (9925–2806–MTDC), Evaluation of Optical Instruments for Real-Time Continuous Monitoring of Smoke Particulates (0025–2860–MTDC), and Real-Time Smoke Particulate Sampling: Fire Storm 2000 (0125–2832–MTDC).

Images of the covers of the three MTDC reports about smoke particulate monitoring.

Figure 1—These reports document the evaluation of
commercial instruments to measure smoke particulate
in real time.

The U.S. Department of Agriculture, Forest Service, and the U.S. Department of the Interior, Bureau of Land Management have purchased several DataRams manufactured by Thermo-Andersen, Inc., to monitor real-time smoke particulate during prescribed and wildland fires. The DataRams have been deployed during a number of prescribed burns and wildland fires across the country. The first few deployments revealed problems in efficiently obtaining the real-time information. Although the instruments are designed to provide real-time information, someone had to personally view the instrument's display panel to learn the particulate concentrations or had to download stored information from the instrument to a personal computer or laptop for viewing later. This required someone to download the instruments on a regular basis (once a day, for example) or to periodically look at the DataRam screen to determine the reading. These methods had several problems, including:

MTDC was asked to develop a system to remotely access the information from the DataRams, eliminating the need to physically download or access the data. Criteria for the remote telemetry system included:

Telemetry System  Graphic of a satellite.

MTDC investigated several different methods to remotely access the smoke monitoring information. These methods included using modems with standard phone lines, cellular phone modems, and satellite modems. Each of these methods has advantages and drawbacks. Modems using phone lines are the least expensive method, but limit the deployment sites to areas where a phone line is present. This would prohibit locating the DataRam in areas away from buildings or phone lines. Cellular modems would eliminate the need for phone lines, but coverage is still limited to larger populated areas and may not exist in areas where the instruments will be located. Also, data transmission can be easily interrupted or lost. Satellite modems are more expensive than phone line equipment, but provide the best coverage. A DataRam could be located almost anywhere as long as the modem antenna has a relatively unobstructed view of the sky. Depending on the frequency and amount of data being sent, satellite transmission costs can be comparable to cellular phone costs.

Because the characteristics of the satellite modem best matched the established criteria, MTDC began working with Applied Digital Security, Inc. (ADSI), to develop a remote telemetry system for the DataRam. ADSI is a communications business located in Chula Vista, CA, that specializes in providing unique telemetry systems. They work with satellite, radio, and cellular services across the country to provide cost-effective solutions to individuals, businesses, and agencies.

ADSI, with the guidance of MTDC, has developed a self-contained telemetry system using the ORBCOMM satellite data transmission service to effectively transmit data from the DataRam. ADSI programmed the satellite modem to retrieve all the collected internal data from the DataRam (particulate concentration, time-weighted average concentration, internal temperature, relative humidity, and mean particle size). The data are averaged every 5 minutes and sent hourly from the modem to ADSI's Web server. A global positioning system (GPS) receiver relays the exact location of the instrument.

The AQD4-2000 Telemetry System

The original satellite telemetry system, model AQD4-2000, is housed in an environmentally protected briefcase (figure 2). All cables and the antenna are mounted in the briefcase for shipping. The AQD4-2000 uses a 3-foot-long antenna that is mounted on a magnetic base. An RS-232 cable serves as the interface between the DataRam and the AQD4-2000. The satellite modem, batteries, a battery charger, LED (light-emitting diode) indicator lights, and the GPS unit are mounted permanently inside the case.

Photo of a DataRam particulate monitor.

Figure 2—A DataRam particulate monitor and
the AQD4-2000 remote telemetry system.

The AQD4-2000 is simple to operate. Connect the RS-232 cable to the back of the DataRam and to the connector mounted on the briefcase. Screw the antenna into its magnetic base and attach the antenna cable to the connector on the briefcase. Attach the power cord to 110-volt power. Start a run on the DataRam and turn on the telemetry unit by pressing the on/off switch.

Three LEDs inside the system serve as status indicators and help troubleshoot problems. The top LED indicates power is supplied to the modem. This LED illuminates shortly after the unit has been turned on. The middle LED indicates that the unit is communicating with the DataRam. The bottom LED indicates that the unit is communicating with the satellites. It should illuminate within a few minutes after the unit has been turned on-if it does not, move the antenna.

The AQD4-2000 MK II Telemetry System

The original AQD4-2000 system was upgraded to the MK II system (figure 3), which has several enhancements. The size of the case has been reduced from 18.5 by 14 by 6.5 inches to 13.5 by 12 by 6 inches. The weight has been reduced by nearly 10 pounds, to about 16 pounds. The antenna was replaced with a multipiece unit that screws together (figure 4). A faceplate was installed to protect the internal components. The on/off switch and LEDs are mounted on the faceplate (figure 5). An RS-232 connector for troubleshooting the modem is also mounted on the faceplate. The MK II system operates similarly to the AQD4-2000 that it replaces. The AQD4-2000 MK II costs about $2,000.

Photo of a telemetry system sitting a table.

Figure 3—The AQD4-2000 MK II telemetry system.

Photo of the four pieces of the antenna.   Photo of a person connecting two pieces of the antenna.

Figure 4—Assembling the AQD4-2000 MK II antenna.

Photo of an opened telemetry unit.

Figure 5—Faceplate of the AQD4-2000 MKII system.

Web Site

All data sent from the units through the satellite telemetry units are posted (figure 6) on the Internet at the address:

Image of the Web Site showing a map of the U.S.

Figure 6—Main home page of the telemetry Web
site for Forest Service DataRams. The DataRam
units are listed on the left while the deployment
location is shown on the map.

The home page shows a map of the United States with green or red dots. The dots indicate the last reporting location of a unit. Green means the units are operating. Red means they are not. The map can be expanded (zoomed) twice by clicking on the approximate area of the map for finer details. All the units are listed in a frame to the left of the map. Specific information may be viewed by selecting individual unit numbers either on the map or the list. This information includes:


The AQD4-2000 MK II remote telemetry system is a compact package that allows convenient, real-time access to particulate concentrations estimated by the DataRam. The system is easy to set up and sends data by satellite transmission to a Web server. Here, the data can be viewed and accessed in tabular and graphical form. A GPS device is used to relay the precise location of the instrument. A mapping feature is used on the Web site to graphically show the location. The Web site also shows running averages of particulate concentrations as well as the current voltage of the telemetry system. The AQD4-2000 MK II hardware package includes all the cables, the antenna, and the batteries needed to operate the DataRam. All the electronics are housed in a briefcase that protects them from water and dust. LEDs indicate the modem has power, satellites are in view, and that the DataRam and the telemetry system are communicating.

About the Author

Andy Trent is a Project Engineer at MTDC. He received his bachelor's degree in mechanical engineering from Montana State University in 1989. Before coming to MTDC in 1996, Andy worked as a civilian engineer for the Department of the Navy. Andy works on projects in the nurseries and reforestation; forest health protection; and watershed, soil, and air programs.

Additional single copies of this document may be ordered from:

USDA Forest Service
Missoula Technology and Development Center
5785 Hwy. 10 W
Missoula, MT 59808
Phone: 406-329-3978
Fax: 406-329-3719

For more information about the remote telemetry system, please contact Jim Drewitt at:

Applied Digital Security Systems, Inc.
1031 Bay Blvd., Suite A
Chula Vista, CA 91911
Phone: 619-585-0435

For additional technical information, contact Andy Trent at the Center's address.

Phone: 406-329-3912
Fax: 406-329-3719

The Forest Service, United States Department of Agriculture (USDA), has developed this information for the guidance of its employees, its contractors, and its cooperating Federal and State agencies and is not responsible for the interpretation or use of this information by anyone except its own employees. The use of trade, firm, or corporation names in this document is for the information and convenience of the reader and does not constitute an endorsement by the Department of any product or service to the exclusion of others that may be suitable.

The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or part of an individual’s income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA’s TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410, or call (800) 795-3272 (voice) or (202) 720-6382(TDD). USDA is an equal opportunity provider and employer.



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