Info

ll

S ■■

a»;«

time, but it is limited to the Los Angeles area.

A more general program with many additional features has been developed by Paul Ternlund WB3JZV. He is an engineer and computer scientist with the Department of Defense, Jiving in Aurora, Colorado Hrs favorite ham radio activities include foxhunting and tracking ATV balloons.

Tm a nut for accurate bearings," Paul says. Tm trying to gel a practical understanding of 2 meter bearing-taking and all the phenomena that go with It. When I'm ihe fox on Denver's competitive hunts I ask hunters to give their bearings to me as Ihey hunt, and I give bonus points for the best ores." A program for calculating and displaying multiple bearings must have fast math functions, sophisticated plotting routines, and a tabular user interface. Paul's T-hunt partner, Tim Moffltt N0NXI, suggested using Microsoft® Excel instead of creating a complete executable application.

Paul wrote a set of macros that accept bearing data from up to 20 RDFers, triangulate each pair detect and throw away "wllcT fixes average the good fixes to give a best guess of the Ts location, and more. The results appear in just a few seconds on a PowerBook or other Macintosh computer. (The routines should also work on the PC version of Excel, but Paul has not verified this.) WB3JZVls algorithm deduces the predicted T location using double averaging. To show how it weeds out the bad bearings, let's go through a hypothetical cooperative hunt. Assume that it's just after dinnertime and a continuous carrier has appeared on a popular packet frequency in the Los Angeles basin, blocking all message forwarding.

Another Stuck TNC

Several T-hunters get together on a voice repeater. All have a good direct signal from the QRMing station at their homes except for WA6PYE. Steve's house is blocked from the signal source by the Ghino Hills and the Santa Ana Mountains. He doesn't realize itt but the signa' is getting to him by reflecting off Mount Baldy in !he San Gabriel Mountains to his northwest.

Each station reports antenna heading in degrees azimuth and location, given as coordinates on an agreed-upon map. This group uses the AAA Los Angeles County and Vicinity map, marked with a grid of one-mile squares. The one-mile lines are numbered in ascending order to 1he north and east, beginning with zero In the lower left corner.

You are the search coordinator, so you start Excel and load Fast-Workspace to begin the triangulation process. This opens the Calculations spreadsheet (Figure 1) and some other files that will be described later You type in the catisignT name and

0 0

Post a comment