Monday, January 21, 2008

Final Transeiver Practice

(Well, not the last ever, just the last time before we go to Fernie).

Yesterday we went to the beach again to work with the beepers. With it being less than a week before we head out, it was nice to meet up and share the building excitement, but also useful to practice a little more with the transceivers.

There's nothing to show really, but we did learn some stuff about the differences between the Tracker DTS and the Ortovox M2, which is the unit that Simon owns.

After practicing with both the Tracker and the M2 we found the second phase of the search (single burial) to be much quicker with the Tracker, due to the 5 directional lights on the top of the unit. (The second phase being the time from when you get a signal to closing within 3 meters).

With regards to the first phase, acquiring a signal and the thrid phase, the pinpoint search, the same methods can be used for both models and there isn't much difference between them.

With the Ortovox M2 the directional indicator works by showing a solid triangle on the display when the unit is pointing in the right direction. That, plus the audio signal and the distance read out make it possible to orientate yourself towards the beacon.

The difference with the Tracker is that the unit is constantly updating your direction; you simply turn when the lights change. With the M2 there are two things that make this update less straight forward. First, once the unit is no longer pointing in the right direction you have to stop and find the right direction by re-orientating it; you're not told the direction to turn. Second, the unit has a variable sensativity that needs manual adjustment as you get closer.

We were looking for a reproducible method, which we found after reading some generic guidelines. It is:

  • First find a signal
  • When a signal is found, find the direction in which the signal is strongest
  • Take five steps in that direction
  • Find the direction in which the signal is strongest
  • Adjust the sensativity if necessary
  • Take five steps in that direction
  • Repeat until within 3 meters of the beacon
  • Do the pinpoint search

It works really well.

After trying it a couple of times, I followed Simon on his search path and marked out the path in the sand. I then searched for the same beacon with the Tracker, starting in the same place. We marked the second search path as the Tracker moved in on the beacon.

As you might expect, the two transceivers took almost identical paths, with the M2 forming a less smoothe curve because we were moving in a series of straight lines. This goes to show that understanding the pattern of the electromagnetic field that a beacon emits can help you with the search. Once you detect that you're on one of the flux lines, you should have an inclination or which direction you'll be turning when you re-orientate.

I wish I'd taken my camera with me. Marking out the different approach lines in the sand was useful in understanding how the units work, and I could have shown that with a few pictures.

We've made other observations about the differences between the two models; each have their strenghts. I'll save the rest of it for a full review, most likely after we get back from Fernie.

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