On Jun 17, 9:14*am, Greg Arnold wrote:
Ramy
Spot uses the Globalstar L-Band simplex links. L-band *is relatively
immune to rain attenuation, rain/water droplets suspended in storm
clouds are likely the worse case scenario. A guess for bad rain
attenuation might be something like only a dB or so at L-band. The GPS
signals are in the same frequency bands and will have similar
attenuation. So my first guess is clouds, even storm clouds are not
likely to be the issue.
So the next question is did anybody else flying in the genral area
have the same problem? I was flying in the Mendocinos at the same time
and had no SPOT problems but that is probably far enough away to not
count, except to exclude more systemic problems. The next question is
did the unit have a full view of the sky or are you still mounting it
on your parachute harness? *I'm not sure if this is on your shoulder -
in which case your head (hopefully opaque at L-band :-) ), RF opaque
parts of the fuselage/canopy frame area, etc. will be obscuring lots
of the sky, or vertical on your harness in which case far more of the
sky will likely be obscured. Both of these will affect coverage as
Global star satellites fly into and out of the now fairly restricted
sky view or as you turn the direction of the obscured antenna to bring
Globalstar or GPS satellites into view.
I think SPOT is fantastic, fly with one all the time in SPOTcast mode,
but I'm not giving up on my 406MHz PLB on my parachute harness.
Darryl
I have a SPOT on order. *Where is the best place to mount it so it has a
full view of the sky (excluding the top of the glare shield)? * Will it
work under a fiberglass glare shield?
Greg
People are mounting them on their harnesses and apparently getting
them to work, but the problems that Ramy reports may show this is not
as reliable as a less obscured location. I'll remind people of Allen
Silvers' (experienced parachutist/parachute rigger) warning against
mounting them on the shoulder area of a parachute.
Ideally you just want it mostly flat and not obscured. I mount mine on
the right canopy rail of my ASH-26E using 3M dual-lock tape. You can
see it here
http://www.flickr.com/photos/darrylramm/2082630811 The
glareshield should not present a problem for RF signals but you need
to unit where you can press buttons, check LEDs (flat batteries etc.).
On the canopy rail I have to pop the unit off to check the LEDs etc.
This may not work on all gliders but even on my DG-303 with a thin
rail I would have just installed a mounting plate on the narrower
canopy rail.
If you do need to end up mounting on the glareshield area the bright
orange color/reflections are likely to be a distraction. A black cloth
covering could work. SPOT also make a sturdy looking black nylon bag/
holster for the SPOT (purchased separately, does not come with it). I
saw a Holster for sale at at Williams Soaring but have not seen them
elsewhere, I think they had a SPOT logo on them. You might be able to
mount that holster on the glareshield and slip the spot unit into it
for use. Hopefully it won't get too hot in the sun. Braver people
could disassemble the SPOT (disassembly is easy) and paint it with
Krylon Fusion flat black paint, but I'd be worried of the paint
scratching off over time or the unit getting too hot in the Sun.
This all assumes you care mostly about use in flight, I do, and thing
the SPOTcasting/tracking feature is the best thing. If you mostly care
about the "911" feature and the SPOT unit going with you in a bailout,
then put it on your parachute harness with a Silver Parachute SMAK
pack (the large size, see
http://www.silverparachutes.com/smak_pak.html
) or similar.
Darryl