http://www.arrl.org/news/features/2008/03/01/2/?nc=1
D-STAR at the 2007 Medtronic Twin Cities Marathon By Erik Westgard, NY9D [EMAIL PROTECTED] March 1, 2008 Minnesota hams put the D-STAR system to work. The Hennepin County Communications Van joins other Amateur Radio vehicles and trailers in D-STAR integration testing. Ryan Westgard standing by to scan the bib numbers into the Amateur Radio tracking database of incoming injured runners at the Medical Tent at the 2007 MTCM. The 1st generation ICOM RP-1 repeater. The finish line area at the 2007 Medtronic Twin Cities Marathon. The 40x80 foot Medical Tent and attached Amateur Radio managed Interagency Dispatch Center at the MTCM 2007. Peter Corbett, KD8GBL, monitors the database server and D-STAR and packet uplink transmitters in the data trailer at the 2007 MTCM event. The MTCM 2007 Family Medical Information Tent — amateurs in yellow shirts and community medical volunteers use 802.11b networked laptops to query the Amateur Radio database of runners who have left the course. Kelly Black, KB0GBJ, (L) and Max Klingert, KB0RSQ, led the software development team for the Linux appliance back end to the D-STAR repeaters and our database uplink system for the 2007 MTCM. At first glance, the Minneapolis/St Paul Metropolitan Area has a good Amateur Radio infrastructure for public service events. We have more than 40 FM voice repeaters, (about half are on good sites) and two 1200 bit/s packet radio networks, three counting APRS. An increased focus on data applications by served agencies has strained our data capabilities. While it is certainly possible to use the operating range of commercial Internet services, our stated goal of providing backup communications makes this an imprudent choice. Many of our agencies use the Internet for primary data communications, and using the Internet to back up the Internet may be fine under normal conditions but is a poor design for truly catastrophic emergencies. The recent collapse of the I-35 bridge in Minneapolis was marked by a well publicized overload of the commercial cellular telephone networks in the area of the incident, and in some cases, cellular data and voice services share limited bandwidth to the cell sites. A Big Marathon with Big Communication Needs The Medtronic Twin Cities Marathon is one of the larger marathons in the United States in terms of starting runners, with more than 6100 in 2007. There is also a 5000 runner 10 mile race on a similar course at the same time, and hundreds of thousands of spectators and family members also participate in the weekend of events. The race organization has long relied on Amateur Radio for backup medical communications, utilizing more than 130 amateur operators spread across the racecourse and finish line area. We run five voice nets and also provide net controls for the medical channels on the rented UHF business band radios used by the medical teams. On the data side, we track the location only (for HIPAA reasons) of runners who seek medical attention or leave the course for other reasons. This data is input based on voice reports to the on-course net controls and from information input at runner bus stops and at the medical aid stations throughout the course. For inputting information out on the course, packet and a character interface have worked reasonably well, but we do not have enough data bandwidth for much in the way of database queries. Families and medical teams are always inquiring about the location of runners. This requirement is acute at the finish line, when runners do not appear in the Family Meeting Area on schedule. We set up six laptop computers in the Family Medical Information tent, where queries can be made. We also have computers in the main medical tent for runner check-in and check-out and in the communications center where finish line EMT and physician “(Cardiac) Arrest Teams” are dispatched. This much data moving around at the finish line is well beyond the capability of packet radio. We also needed an easy-to-use Web interface to our database so untrained and non-amateur volunteers could be utilized. For this reason we have implemented commercial 802.11b access points from our data trailer. Our database, called Trivnetdb, has a packet AX.25 interface and TCP/IP support for Web and telnet users. Enter D-STAR The recent release of the ICOM D-STAR L-band repeaters and radios (such as the ID-1) presented a possible solution to our problems across the course. If several wide area repeaters were installed, we could access our database of runner status across the entire course using a familiar Web interface. We could perform as many queries as we wanted, and be able to handle high data volumes if we had hot or other unfavorable weather. Doug Reed, N0NAS, bought our first RP-1D repeater under the ICOM “buy five ID-1s and get a free repeater” program. After a few sessions of testing and evaluation in monthly work sessions held at a local fire station, we decided to install the repeater on one of our good sites. The repeater as-is allows one-to-one sessions between ID-1 radios, encapsulating the 90 kbit/s of data packets in amateur call signs. This was a problem though, as our database is located in a trailer at the marathon finish line, and we wanted to have multiple users access the database at once. The repeater has an Ethernet interface on it. Multiple remote ID-1 users are allowed to reach the Ethernet. You assign an IP address to the Ethernet, and if the users of remote ID-1s are in the same subnet they can reach the Ethernet. This is used for the ICOM Internet Gateway software, or you can put your own server or router there. Max Klingert, KB0RSQ, from our software team has been experimenting with Linux appliance computers removed from point-of-sale systems. He uses a release of Slackware Linux on a flash drive so no hard drives (prone to failure in our experience) or fans would be needed on a repeater connected computer. We provide a tiny Web site on each repeater, and also a copy of Citadel, an open source mail and conferencing package. We also wrote a packet AX.25 interface for Citadel. AX.25 packet radio gateways on these appliance computers behind the repeaters are very easy to implement, as the AX.25 Linux software is readily available and the computers have serial interfaces. Good — but No Cigar This did not solve our problem though, as we wanted our database server remote from the repeater. The repeater itself stubbornly resisted attempts to allow native one-to-many connections between ID-1s. We think this was to reduce broadcast type traffic on the radio link, which is simplex — this would waste bandwidth. Max and Kelly Black decided to use the destination NAT feature of Linux- the DNAT command. So each ID-1 user connected to the Linux box, and the database system came in as well from an ID-1 to the repeater. The repeater and ID-1s do not seem to track relationships between IP addresses and call signs, so the users could go up to the repeater, and the Linux machine could establish a call sign tunnel using another IP address block back to the database server, which could be remote. This was tested and solved one major problem. We could also then allow our served agencies to set up ID-1 “data uplinks” to our repeaters from their offices or trailers/vans. The second problem was geographic. The finish line at the base of the State Capitol in St Paul, was in a low-lying area. The location of the Net 2 van was on a reverse slope of a hill a few miles away. We passed the hat and bought another repeater for Minneapolis, but a few weeks before the race we were urged to perform live radio path testing from our sites. No luck — the hills were in the way. Unlike 2 meter packet, L-band propagation is unforgiving. More team members bought more radios, and we got a third and then a fourth repeater. We called in some markers and these were installed in a round-the-clock effort the week before the race on a series of building rooftop sites in downtown Minneapolis. The Thursday before race weekend, we confirmed we had solid RF paths between our repeaters, the net control location and the finish line site. D-STAR Takes the Heat Race day was marked by hot and muggy weather and a record volume of runners dropping out and needing medical attention and/or transportation. Net 2 (miles 19-22.5) was live to D-STAR from their van out on the course, and on race day we had five D-STAR L-band data repeaters online to support the event. Despite the data volume, the system worked perfectly with no issues. In 2008, with the infrastructure now in place, we plan to focus on linking the repeaters via radio and on development of a system to allow better integration of runner information as requested by the physicians in the medical tent. This reinforces our role, clearly stated in the FCC Part 97 Rules, of advancing the state of the radio art and providing trained experts in modern emergency communications. All photos courtesy Erik Westgard, NY9D. Erik Westgard, NY9D, is an ARRL Life Member who lives in St Paul, Minnesota. He is the Volunteer Medical Communications Director for the Medtronic Twin Cites Marathon, and is employed as a consultant in the telecommunications industry. He led the development of the 14567.org Statewide Packet network in Minnesota, which is now converting to D-STAR. He has an MBA from Metropolitan State University, and is a frequent contributor to QST. ____________________________________________________________________________________ Never miss a thing. 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