Recap of EOSS-48

Discussion of EOSS#48 Tracking and Recovery Team Results


Note: Spreadsheet Data and Charts provided below.

The Tracking and Recovery Team performed well during EOSS#48 with 7 member teams (tactical calls Alpha � Golf).

  • Congrats to the 4 tracking stations that scored one or more bearing bulls-eyes (zero degree errors): N0PUF, KB0UBZ, WB5YOE, N0WRE
  • N0WRE, Peter and N0QWX, Mat joined the hunt for their first time. While they didn�t receive a standard grid in time for use during tracking of EOSS#48, Rick, N0KKZ and Nick, N0LP provided their grid coordinates using their GPS position.
  • The Separation in Miles between the GPS and tracking team fixes for EOSS#48 (12.7 miles) was greater than for EOSS#47 (3.3 miles). These results are due to an increase in Average Tracker [bearing] Error from 9 to 12 degrees for EOSS#47 and EOSS#48, respectively.
  • The Separation in Miles between the GPS and tracking team fixes were large for Sample Times 1-3 (30.9, 21.9, and 30.2 miles, respectively). One reason for this is the tracker bearings crossed each other with acute angles. When bearings cross at such small angles over a great distance, even small bearing errors can cause large fix errors. See First Chart to see the bearings and the resulting triangulated points.
  • One way to avoid acute angles for this case would be to increase the tracker north-south separation distances. Another way would be to wait until the balloon is closer (50 vs. 100 miles downrange) before taking bearings�as was done with EOSS#47.
  • The large Average Tracking Team Errors for Sample Numbers 8-10 occurred when the balloon was overhead. It is difficult to take an accurate RF bearing when the beacon is above 45 degrees elevation. Any tracker recognizing the balloon to be overhead should refrain from providing an RF bearing unless he can aim his DF antenna upwards and get a trusted bearing.
  • The final bearing before LOS is the team's most important. If GPS fixes become unavailable during descent, the Tracking Team's final fix will provide the best clue to locating the payload. For EOSS#48, the Tracking Team's Fix (53.3,45.8) was 7.9 miles from touchdown (61.2,45).
  • It is practical for a 7-member Tracking and Recovery Team to comb an area of 100 square miles from the Tracking and Recovery Teams final fix to locate a beacon. In such a situation, the field coordinator�s direction is vital.

De Paul,  WB3JZV

 


Absolute Bearing Errors in Degrees, by Tracker, by Sample Time, Based on GPS Fix
             
            Average
 Sample Number==>12345678910Tracker
 Sample Time==>9:309:4510:0010:1510:3010:4511:0011:1011:1711:22Error
W0CBHBenjiAlpha8121272918    14
KB0YRZChrisBravo16231351722173112
N0PUFDanCharlie95310010224281511
KB0UBZBenDelta6110603615 167
WB5YOERichardEcho121300137 336515
N0WREPeterFoxtrot3617552 17 01312
WA0GEHMartyGolf  711922121  12
Average Tracking Team Error at Sample Time==>10966881221202812
             
Tabulated Results of Tracking Team vs GPS Fixes by Sample Time
             
X
Y
 Tracking Team Fix==>-55.8
63.6
10.8
47.8
-13.5
73.2
17.1
57
29.5
50.4
28.7
50.3
34.7
58.3
42.3
51.3
51.1
47.2
53.3
45.8
Average
X
Y
 GPS Fix==>-24.9
64
-7.2
60.3
11
55.5
19.9
52.5
22.8
52.3
27.9
52.4
35.5
51.6
50.9
46
57
46.7
59.6
49.1
Separation
 Separation in Miles==>30.921.930.25.36.92.26.710.15.9712.7

Paul's Spreadsheet - All data from this spreadsheet is displayed above, but you might want it to get a larger view of the charts. IMPORTANT: Download this as a file and then run it in Excel. It doesn't seem to display properly when Internet Explorer tries to display it with Excel running as a "plug-in".