Tracking and Recovery

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Triangulation Report
by Paul Ternlund, WB3JZV

EOSS#64 Tracking and Recovery Team Results using the WB3JZV Triangulation Program � 30 March 2003

  • The Tracking and Recovery (T&R) Team comprised 6 DF teams
    • Chris, KB0YRZ
    • Larry, N0NDM/Benjie, W0CBH
    • Dan, N0PUF
    • Mike, KC0CNT
    • Mark, KC0JHQ
    • Jim, K0JLZ.
  • There were four 2m beacon (payload) fixes computed between 8:00 and 8:49AM, and two 70 cm (balloon) fixes computed after separation, during decent.
  • The fourth (last) 2m computation tabulated was a re-run using refined (last known) bearings before Loss of Signal (LOS) from the original 3 stations, plus KC0CNT and K0JLZ were in range and provided their data.
  • The best performance (lowest bearing error) was 3 degrees by KC0CNT.
  • The lowest Average Tracker Error was 10 degrees by K0JLZ.
  • The average tracker bearing error was 20 degrees.
  • Separations in miles between GPS and the T&R group fixes ranged from a worst case of 34 miles (1st sample) to 3.8 miles.
  • The final or LOS fix error �most important one�was 3.8 miles for the payload beacon and 4.3 miles for the balloon beacon. These are very good team results.
  • The distance between the 2 LOS triangulation fixes and the 2 pickup point GPS fixes were 3.8 and 4.2 miles. This relates to a 14.4 and 18.5 square mile uncertainty, respectively. The latter is well within the program�s goal of a 100 square mile T&R team search area.

FYI, the WB3JZV Triangulation Program is designed to provide a good fix when most (more than half) of the LOBs are �good� for the given sample time. The goal of the program is to obtain a final fix to within 100 square miles of the beacon�s touchdown point (i.e., within a 10 mile by 10 mile area). Mobile tracking units can easily patrol this size area while listening for a beacon.

The following is true�

  1. Single-digit bearing errors are better than double-digit
  2. When a station has multiple double-digit bearing errors, it is likely the station is having equipment and /or technique problems.
  3. Every station will encounter LOB errors some time for many reasons especially multi-path.
  4. The greater the T&R team participation (i.e., the more lines of bearing (LOBs) submitted) for a sample time, the better the chance of a good fix resulting from the program. Of course equipment capability and technique play a vital role too.
  5. The T&R team group error is commonly largest during the initial sample times when the beacon is farthest away and the T&R group has a small perpendicular dispersion. This is because the lines of bearing cross at more acute angles and small bearing errors can result in large fix displacements.
  6. Once in the field, prior to a launch, a DF team may request an LOB test to my station to practice/validate a DF process.

VHF Beacon DF Analysis


UHF Beacon DF Analysis