These pages document a wiring standard that was created to aid us in the rapid integration of radios to TNCs. This wiring scheme allows for the rapid deployment of packet radio for Emergency Service.
We originated this cabling scheme for the 1996 Baker-to-Vegas Challenge Cup Relay. Since the wiring worked so well in 1996, most of our technical efforts for the 1997 race were focused towards consistent packaging of the mobile trackers. For the 1998 race, we adapted our systems to use the TAPR Mic-Encoder for our mobile operations, and these trackers have performed very well..
Simply put, we rely on loaned equipment each year, we need to be able to integrate this gear in a short amount of time. We knew we would have many vehicles that need 'GPS packages', but; 1) We don't know how many of each type/model of TNC we may get on loan 2) We don't want to build a bunch of custom cables for each package 3) We need to have interchangeable parts, for troubleshooting and spare-swapping! We needed to design a modular system. This meant adding extra connectors. However, we realized that the extra connectors could add potential points of failure to the system. We considered that the ability to easily swap a GPS or TNC for troubleshooting would be worth the risk, but it also helped emphasize that reliability needs to be a primary goal during the assembly as well. This wiring scheme has helped us in other efforts as well, making the deployment of packet radio as easy as deploying voice radios for many events. The results of our planning is a wiring standard for APRS packages, shown in the diagram below. (Note parts D and E, the TNC-to-Radio interconnect.)
Select Other Pages Here a) GPS antenns and receivers a2) GPS antenna information b) GPS to TNC data cables c) TNC GPS Data interconnect d) TNC-interconnect cables d+e) TNC-Radio interconnect e) Radio-interconnect cables h) Power Splitter Harness i) Mag-mount antennas -) Baker-to-Vegas HQ Page
The image above is an overview of the cabling plan. We will need many cables for each 'package'; a) Low-loss coax between the GPS unit, and a roof-mounted GPS antenna Also a GPS Antennas special page. (New Info!) b) GPS Data interconnect from GPS *TO* the TNC, plus power *TO* the GPS (Newer Info!) c) Adapter from the interconnect (MONO mini-phone plug) to the TNC (New Info) d) Analog signal cable from TNC to the Interconnect (audio/ground/PTT, Corrected Info!!) e) Analog signal cable from Interconnect to the Radio (New Info) f) Power cable from the TNC to the standard power connector g) Power for the Radio, to a special connector (to the power harness) h) Power Splitter Harness (from vehicle battery to the packages) --(double-fused at the battery, comes to a 'hydra' for the voice radio, and the APRS Package) i) Mag-mount VHF antennae for the 2-meter radio (Typically Larson equipment, NMO mounts...)
You can also view detailed images of our first packages from 1995, or you can check out the plans for packaging from 1996 and 1997, an APRS Grab-and-Go that you can use at home, too!
ARES and RACES note: Please try to convert your own radios and TNC's to this interconnect cabling standard. Make an interconnect cable for each of your radios, and your TNCs. In an emergency, you will be able to deploy packet radio more quickly. If you have a failing radio or TNC, you will be able to quickly and easily swap another device (and interconnect cable). If you don't have the ability to make any of these cables yourself, but you're willing to buy the parts, we will have a volunteer make the cables for you. All you need to do is ask me for details by email. (Approximate cost is $5-10 for the Radio-to-TNC cable pair, depending on the devices. Power harnesses are also available.) Minute Man Electronics has been a good supplier of connectors, fuse holders, wire, and cable for our efforts. While they do not directly donate supplies to our Baker-to-Vegas efforts, they DO offer a 10% discount to Hams. If you want to find them (in Fremont, CA), there is more information from our Minute Man Electronics page.
Other Technologies
We are also experimenting with the TAPR Mic-E (Mic Encoder) in an effort to reduce the number of radios that we need to borrow for this event. The diagram below shows how our tracker package wiring changes with the Mic-E instead of a TNC and GPS combination.