Intro to Dmapper in “Search & Rescue”
by David Neys W7PDQ   2005

Search & Rescue   (SAR)

In the world of Search and Rescue there is always a need for some sort of mapping and resource tracking. As computers become commonplace in the SAR command post, it is only natural that computer mapping is used along with the common paper maps.

Computer mapping

There are many computer mapping programs out there, but only a few of them are more than just a basic “consumer product used mainly for the fun and enjoyment of knowing where you are and where you are headed”. While the common web and street level maps such as “Delorme’s Street Atlas” are great for the every day user, more complex maps are sometimes needed for Search and Rescue missions and other critical operations.

Search and Rescue MAPPING

SAR mapping resources are used for all activities and phases of a mission from Initial size-up, planning, briefings, tracking resources and clues, guiding searchers, to documenting the search progress and accomplishments for later review, just to name a few.

When mapping in a SAR environment you may need several things;

-A level of detail that fits the mission needs such as terrain, trails, bodies of water, major and minor roads, and even three dimensional views to help give a perspective of a search area.

-Ability to display the maps in both print and electronic form in various sizes and detail levels.

-Measurement aids to determine distances and elevations in feet or meters.

-Location designations such as Political boundaries, Townships, Sections, and GPS coordinates of all types.

-Map markers with text notation, in a variety of colors, shapes, and sizes, for plotting the positions of different mission critical features and resources.

Its not to say that the above list is required or even inclusive of all the things needed for a SAR mission, but it is important to consider a variety of possible needs before selecting a mapping program.

Many times it is found that “no one mapping program will do everything needed to support a mission” and search managers will find they have a need for a variety of different maps and map programs in their SAR toolkit.

Whatever you choose, make sure you are well practiced in using the features before you find yourself in a highly stressful and time constrained mission. There is a time to try new computer technology and there is also a time to set it assign and use tried and true methods such as paper maps and even the good old compass. If you have staff available, then it is possible to run a mission with several mapping methods, but never compromise the safety of your searchers or those who may be lost in order to show off new technology.

Global Positioning Satellite (GPS) in SAR

An exciting technology introduced in the 20th century is the use of Global Positioning Satellite receivers to locate positions on the globe. Now that this technology is very common in the consumer market it is helping the searchers find the lost, the lost find themselves, and mission managers to get a tactical view of the search area and its progress.

As maps, including computer maps, added GPS coordinate references, it enhanced the Search and Rescue function and allowed the GPS receiver to become the primary navigation aid for missions. (NOTE: A good GPS is still no substitute for a good paper map and compass which should always be carried as a backup.)

GPS coordinates can be provided to searchers as an aid in identifying a destination, or the searchers can provide GPS locations to mission managers to aid in planning, tracking, and implementing the objectives of a mission.

Many SAR units transfer the “track” or path that a searcher traveled at the end of an assignment as well as any “waypoint” markers they may have stored while searching. This data is usually transferred from the GPS to a computer once the team has returned to base camp and plotted to a map for search managers to use. Some coordinate data is used for longer term records and some is used for planning the next operational period.

Sometimes GPS coordinate data is needed for more “time critical” search needs and cannot wait for the return of the search team from the field. Its during these times when some form of remotely communicating the data to those that need it becomes important.

2-way Radio Communications (Coms)

Wireless communications, whether it be Cell phone, Satellite phone, or the common 2-way radio, is a very important tool for the SAR community. We use them to exchange information of all types including calling for help and letting others know where we are. While “wireless phone” technology has come a long way toward supporting this communication, the 2-way radio is still the foundation for communications in a variety of terrain and with a large group of individuals.

While a search can be conducted without radio communications, its efficiency, accuracy, and success, could very well be diminished. Radio Coms within all levels in a search organization has become a key to its basic operations and one that should not be overlooked or discounted as just a frill. Communicating important information, such as critical GPS coordinates between those involved in a search, has proven time and time again to raise the probability of a successful mission and assures the safety of all involved.

Connecting GPS and radio functions to computer mapping

A typical search scenario would go like this....

A crackling radio call comes in to the base camp operations center.
“SAR base, this is Team 4, the subject has been located.”
“Team 4, this is Sar base, can you advise the condition of the subject?”
“Sar base, the subject is cold with injuries, request a medical evac as soon as possible.”
“Team 4, can you provide your GPS coordinates so we can arrange evac?”
“Sar base, This is team 4, our current position coordinates are.....”

At this point in a search mission it is obvious that radio communications and GPS coordinates play an enormous role in successful completion of a mission. What the mission leaders do with the information depends on what mapping technology they are using.

In a computer mapping scenario the coordinates, as given by the searchers, would be hand entered, using the computer keyboard, for display on the computerized map . With the information shown on the map, a search manager would then be able to plan and implement the next action based on a “real-time” position location. While passing a long string of GPS coordinates can be time consuming and must be repeated for accuracy confirmation, it is essential the location be correct in order to save time and resources when acting on the needs of a search team.

Communicating and plotting gps coordinates on a large search with multiple teams can become a big tactical advantage for mission planners and operations staff, but it is not without its problems.

The constant coordinate updates needed to fulfill the needs of the mission can strain both field and base camp resources. The ongoing process of reading coordinates over the radio, repeating them for accuracy, then hand entering them in the computer, will draw more resources and cause increased radio use which, in addition to more quickly running down the batteries, will clog the airwaves and may delay other critical communications if not managed properly. The balance between knowing where your teams are at any given moment and reducing radio traffic is a fine line that will change depending on the mission type.

Automatic position reporting and mapping solution.

Now that we have seen the value of GPS, Radio, and Computer Mapping, it is time to introduce another technology that is being used to improve the efficiency and accuracy of GPS-Radio-Mapping functions.

The volunteer “Amateur Radio service” community has been using a variety of “data” transmission technologies for many years. One of the key wireless technologies for passing computer data has been “packet radio”. This method uses radios, connected to computer type devices, to pass digital data back and forth just as is done with the internet and its functions such as email.

By hooking a specially equipped radio to a GPS receiver in the field, and to a mapping computer at base camp, the GPS position coordinates can be exchanged “digitally” within a few seconds with a great degree of accuracy.

“APRS” and SAR

While there are many ways to “electronically” pass information via radio, one method, called APRS, is being used above all others for GPS tracking needs.

The “Automatic Position Reporting System” (APRS) is a specialized packet radio system developed by Bob Bruninga/WB4APR, and was first introduced to Amateur Radio folks in 1992. Since then, APRS usage has grown and expanded across the globe and has made its way to include Search and Rescue organizations.

Imagine a searcher throwing a switch on a package the size of a cigar box, then placing this light package in their pack before starting out. The package contains the special gear needed to immediately send a constantly updating feed of the team’s GPS position coordinate back to a computer map display at base camp. Better yet, the process of sending, receiving, and posting their position to a map requires no human intervention other than to turn it on. That is the reality of an APRS equipped search team and the primary reason for the creation of the “Dmapper” program.

DMAPPER’s purpose

While APRS includes some pretty innovative mapping programs, many are limited to certain commonly used functions and are not necessarily developed specifically for SAR activities. While they still do a good job providing accurate position reporting along with some other valuable features like messaging, they may not always have the detail or functions needed to fully integrate with an existing SAR unit’s mapping program.

There are also some very nice topographic map programs available for Search and Rescue, but they likely don’t have the ability to receive remote APRS data. What was needed is a utility program that will receive and interpret incoming APRS position data and post it to the topographic map programs.

Now you know the purpose of “Dmapper”! To interpret the incoming position data from the field, and post it to those map programs best suited for the SAR environment.

How Dmapper works.

The DMAPPER program is designed to act as a "translator" between your incoming packet position reports and your mapping program. Below are some of the basic steps it goes through to convert the position data.

1-DMAPPER runs on your local computer and monitors the communications/serial port for TNC packet data and detects those strings that contain GPS position reports.

2-Incoming position data strings are sorted by radio "callsign" from the sending units. If the incoming callsign is designated for "tracking" it will be decoded and posted to the DMAPPER screen display.

3-DMAPPER then takes the "GPS position" part of the string and converts it to standard Decimal Degree Lat/Long coordinates for display to the DMAPPER screen next to the designated callsign.

4-If selected, the individual positions of each sending unit will be written to a data file for import by a variety of mapping programs.

** SAFETY is also an important factor considered when DMAPPER was developed. One of the unique features of DMAPPER is the "OVERDUE WARNING" display that alerts the program user when a sending field unit has not been heard from in a preset amount of time. The "Last Heard" time of each sending unit is clearly displayed for tracking safety.

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DoodleBug Software LLC
P.O. Box 862
Astoria, OR 97103

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