EOSS is NOT trying to reinvent RDF. We just customize the practice a bit.

EOSS uses a custom grid to bring a common frame of reference to position reporting that is slightly more intuitive and much more easily passed via radio than straight latitude/longitude information. We can use this information coupled with a bearing from each tracker in a computer program (real-time during a flight) to generate extremely accurate position information from team members.

In order to participate:

You will need a map that exactly matches the MapsCo Inc.

Colorado Centennial Wall Map 33"x42"

The map is a 1:600,000 scale map of the state of Colorado. It is available from the MapsCo store in a fold up map, a flat paper map and a laminated version of the flat paper.

You will need the EOSS grid overlay

Get that HERE

You should have a GPS but it is NOT a requirement.

You should have a laptop computer but it is also NOT a requirement.

If you had both a GPS and a computer then you should get Nick Hanks GridCalc program. With it you don't really need the Map above as you can enter in some information into the computer program (Grid reference point) and it will get your current latitude and longitude from the GPS and convert it into a Grid Position for the tracking and recovery coordinator.

If you do NOT have a computer but you do have a GPS, DO NOT, repeat DO NOT try to tell the tracking and recovery coordinator your location by latitude and longitude. It is a very time consuming process (is that in degrees, minutes and seconds or degrees and decimal minutes or perhaps in decimal degrees, etc.) He will not be able to accurately place you on the map until he converts your position to an EOSS grid location. The T&R coordinator does NOT have time to do that.

There are two on the air resources you can use to get a grid position if you have a latitude and longitude. Nick Hanks, N0LP, who is usually at the launch site running under the callsign of AE0SS who is the author of Grid Calc can often provide you with a grid position. Rick von Glahn, N0KKZ, who does the pre and in flight predictions can convert your lat/long into a grid position.

As far as the RDF part of the operation goes, just do what you always do. However, if this is your first time DFing a balloon, consider this balloon specific RDF problem. If the balloon is directly overhead it is almost impossible to establish an accurate bearing. You are pointing your directional antenna almost straight up into the air. Move it a few inches this way and you are swinging through many degrees of azimuth. Move it that far while pointing at the horizon and you are moving through a few degrees but nowhere near the amount at the zenith. Consider, if the balloon is actually at 89� elevation at an azimuth of 270 degrees true and you move the antenna an inch or two to the east that suddenly turns into 89�  elevation with a bearing of 90 degrees true. The computer program will simply discard your bearing as it is pointing in a direction directly away from the convergence of the other tracking and recovery teams. So, be aware, the higher in elevation the more prone to inaccuracy of azimuth your bearings are likely to be. Be very careful when measuring anything above 60 degrees. It always helps to have a second team member with the compass taking the bearing by "looking over your shoulder". That way you can keep your attention focused on the airborne payload, the bearing taker can just consider the direction to the horizon your beam is pointing.

The farther away you are, generally the better your bearing until the payload systems parachute down to a lower altitude that will present a much lower elevation target to DF on.

You are encouraged to participate in the monthly Fox Hunts in the Denver area to hone your RDF skills.