ACR&Artex Vecta3 - Manual (Page 12)

Y1-03-0235-1C 12
RANGE EXERCISES
1. Selecting a location for the test beacon
Range exercises involve placing the test beacon in an area similar to
where rescues are expected to take place, then moving away from the
beacon in measured distances and recording the signal strength. For
open water searches, anchor the beacon in an area where there is at
least 8 nautical miles of open water in all directions. Secure the beacon
so it cannot be moved or pulled under by wind or current. Attaching the
beacon to an orange life buoy or similar floatation device in addition to
the supplied floatation
collar will improve the beacon’s visibility in heavy
seas.
If the application is an oil platform, anchor the test beacon in an area
around the platform. If at an airport, place the test beacon somewhere
on the airport grounds. If you expect to conduct a search in more than
one environment, do a range exercise in each environment. This will
help you build experience with the Vecta™
3
and how the effects of your
particular search environment impact the radio waves traveling from a
beacon.
2. Recording observations
Once the test beacon is placed and the location accurately determined,
turn the test beacon on and point the Vecta™
3
directly at the beacon.
Record the NUMBERS and MICRO reading. Move away from the test
beacon, recording NUMBERS and MICRO readings at intervals of 0.25,
0.75, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 5.0, 6.0, 7.0, 8.0 (nautical and/or
statutory miles) etc., until it can no longer be heard under any
circumstances. A form similar to the following may be helpful in
recording the results of your range exercise:
0.0 0.25 0.5 0.75 1.0 1.5 2.0 2.5 3.0 3.5 4.0 5.0 6.0 7.0 8.0
Radio signal level (example) 999 950 810
When doing a range exercise in the ocean, especially at greater
distances, wave height can cause a beacon to be heard intermittently as
it rides up out of a trough to the crest of a swell or wave and back down.
A GPS is invaluable in ensuring accurate distance intervals.
Emergency transmitters that emit the VHF 121.5 MHz frequencies are
limited to line of sight and will be detectable at a much greater range or
distance on the open ocean than on land. This is a function of the
transmitted signal being absorbed by hilly terrain, vegetation and
buildings.