Some technical considerations related to Spot tracking performance

On Mar 11, 9:00*am, wrote:
On Mar 11, 4:24*am, Darryl Ramm wrote:



On Mar 10, 7:56*pm, wrote:

I have mine on my parachute chest strap and I am seated reclined...

(Sorry for the previous blank post).

I used SPOT all last flying season and never found significant loss of
tracking function for my needs. I "secured" it to my parachute chest
or shoulder strap, either of which worked well enough for all purposes
but bailout (my conjecture only). When cooler weather arrived, I
secured it in a zippered shoulder pocket of my down jacket, also
experiencing no fall-off in tracking, and maybe with some increased
modicum of security that it would not be lost during a bailout. The
chest and shoulder positions are both relatively vertical at rest but
change with ambient pitch and roll as noted. Secure attachment is a
priority goal for this season.

I understand the interest in using SPOT for tracking gliders, however,
it was intended to track people and, should I depart my glider, I need
to have SPOT depart with me. I could care less if they find the
glider after that. If I don't depart the glider when it suffers an
adverse encounter with terrain, I will need SPOT within forearm's
reach or less if it is to be of any use to me. Dale Kramer's
experience was the genesis for this opinion. Finally, if I am unable
to activate SPOT, it's highly probable that urgent S&R will prove
unnecessary.

Skip
ASW-24 JS

On Mar 11, 11:03*am, wrote:
I will need SPOT within forearm's
reach or less if it is to be of any use to me. *

Why is that? My interest is in finding a position that will give good
performance in tracking mode which requires no user interaction.

Andy

I just got my SPOT in time for the Seniors, and I also opted for the
parachute harness mounting option. In my well-reclined position, and
with the glider straight and level, the unit is oriented almost
horizontally.

Mark Hawkins, the creator of the very cool spot mapping app being
tested right now at the Seniors, has told me that my SPOT tracking
messages are getting through about 90-95% of the time for the 7 days I
have flown so far here in sunny Florida.

BTW, just to add credence to Steve & Darryl's comments about patch
antenna performance, I also make (or made) my living designing and
analyzing the performance of antennas of all types. A patch antenna
such as the type on the SPOT system has a pretty broad pattern with
it's main lobe oriented perpendicular to the plane of the patch (i.e,
straight out the front of the unit), and is typically mounted such
that the rest of the electronics blocks the back lobe, causing the
degradation noted by Steve in his gazebo testing.

The good news, so to speak, is that a SPOT-sized patch antenna at
these frequencies will have such a broad pattern that the degradation
in performance between perpendicular and 45 degrees off probably isn't
all that bad;-).

Regards,

Frank (TA)