Spot Messenger 2: thumbs down

[ILUVSWTAS]

Hahaha, good point well made.

[Nuts]

I copied that article to post here but then thought again. However accurate the tracking is it could be argued (yawn) that the hour that tracking failed in the bottom of a 700m deep, narrow canyon With heavy tree cover could be the very time you need the associated emergency beacon..

[rsser]

I have been doing some more testing of the Messenger 2 fix cp a Garmin h/h GPS and will report the comparison when I've got time to do the numbers.

Also loooked at the distance between 'OK' activation and location transmission walking on the BHP with good exposure to the north sky (single instance). About 400m as the crow flies acc to the Google map marker provided by Spot. (Correction: closer to 600m by eyeball reexamination).

[Nuts]

hi rsser, sounding like you have a problem, either spot or gps? While its not unheard of to be that far out if you look at data points mentioned here on the forum and elsewhere (there are many associated with marked track walks), to be that far out regularly is very unusual. Good luck.

[rsser]

Thanks. Just let me clarify: 600m was not an error; it was the distance I walked between hitting the msg button and the message being sent with a fix.

Here is the other test data cp. a Garmin hand-held GPS....

Conditions: from a known feature in a valley roughly open to the north sky but with some snowgums in the way and a spur blocking about half the NW/W sky. 'Warm boot' for both units.

The Garmin took 2 mins to acquire 7 satellites. Eventually picked up an 8th. Reported accuracy of 5m. Spot on (ahem) when checked against the map.

Messenger 2 at the same time & place: 8m off the Garmin coords.

Messenger 2 at the same place 2 days later, under cloud and in light snow: 5m off the Garmin.

So that's a good result for the Spot in those conditions.

[rsser]

Folk have asked about what data exists from S&R.

There's some in the link below from the Birkie NSC based at Mt Beauty/Falls Ck.

You'll see that 'missing person' is the commonest reason for call outs. But no data on how the the person was located or how the alarm was initiated.

Presumably some proportion of the 'missing person' call-outs were non-life-threatening delays that a Messenger, Connect or Satphone may have prevented.

http://birkebeiner.org.au/search-rescue/history/

[photohiker]

Just to add some factual data to the thread, I have just completed the first part of the Heysen Trail this week - Cape Jervis to Victor Harbor. Starting Monday morning, I pressed and Ok at the beginning and end of each days walking and ran tracking throughout the day. One Ok message did not get through according to my contacts, but I have not had a chance to inspect the online log yet.

Here's the link to the data, best look at it soon, not sure how long it stays there: http://tinyurl.com/mfchally (its backwards, starts at the end of the trip...)

Will try and archive it and compare it against my GPS log, haven't looked at that either yet, but happy to share it as well for comparisons sake.

[andrewbish]

Some more actual data for Spot 2, from a recent hike around Mt Bogong. Signal transmission was fine on the ridge tops. I was disappointed to find that signals did not generally get through when I was in valleys.

Start of Staircase Spur start - Did not transmit
Bivouac hut - Did not transmit
Mt Bogong - Transmitted ok
Near camp saddle - Transmitted ok
Mt Arthur - Transmitted ok
Spion Kopje fire trail - Transmitted ok
Johnson Hut - Transmitted ok
Roper hut - Did not transmit
Big River - Did not transmit
T-spur Knob - Transmitted ok
Howman Falls - Did not transmit
Cleve Cole Hut - Transmitted ok

Andrew

[rsser]

Hmm.

By Big River I take it you mean at the bottom of Duane and T-Spurs?

Not sending from Ropers Hut is peculiar, if sky view is the key variable.

Were you pointing the device Northish with each test?

[andrewbish]

Yes, btwn the spurs.

I wore the Spot on my shoulder strap, facing fwds.

Andrew


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I am here: http://maps.google.com/maps?ll=-37.784168,145.284017

[photohiker]

More data.

8 day walk in the Tarkine rainforest. Ok's sent morning and afternoon:



4 Ok's missing in action. The first one may be my fault (pressed track progress too soon) The other locations I remember as very heavy covered canopy. I could have easily moved to a better location but I would rather see what the performance was with no effort to improve the view of the sky.

Tracking was activated once on the move. there were misses, worst in the deeper valleys with heavy timber coverage. I didn't spend the whole time watching the spot, but I did notice that it was struggling to maintain GPS lock in the thicker forest valleys while on the move. As soon as I stopped for a minute it would generally regain GPS lock and indicate that messages were being sent ok again. I had the spot in the top of an aarn front pocket - it may have been better up on my shoulder harness strap.



This is more compromised than other trips I have done in more open areas, but on balance it shows that the Spot coverage is not too bad and it would be worthwhile to move it to more open ground in heavy forested areas. Plenty of treefall in the Tarkine, could have easily done that.

No idea if a PLB would do better under these circumstances. Pity there is no way of testing them like this as this trip would have been ideal.

[rsser]

Thanks. Useful data.