Some technical considerations related to Spot tracking performance

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, so
the front face is about at a 45 degree angle. *I get pretty good
tracking results.

You said you tested it with the logo side up and down. *I assumed that
the device was designed with the belt strap on the back side so that
the logo would face horizonally / the horizon. It appears as they
intended it to hang vertically. Did you test it in this orientation?

Chris

The SPOT messenger is a fantastic product, but because of it's
internal technology, and in spite of it's poor industrial design.
There must have been a disconnect somewhere between the product
management, *the ID team/design house and engineering. And it's likely
literally this type of issue as the engineering is all done by Axonn a
separate company than SPOT and Globalstar and I'm sure SPOT or Axonn
contracted out the industrial and mechanical design work.

So for the antennas (both the GPS and Globalstar) a planar antenna
pointing *at the horizon is far from optimal, half the usable
beamwidth would be lost in obstructions below the horizon. It is
actually worse than that simple model because of satellite orbit
geometry and satellite antenna footprint. So the belt clip is designed
to hold the unit, but not reallly while it is in use. Pretty stupid
huh.

The lack of though about how to mount the unit on a car dashboard or
other location, the overloading of the button functions, the
overloading of the dual blinking LEDs, different LED patterns that
mean things that are not clearly explained are other examples of poor
design.

However the SPOT messenger is a great device (I really like mine) and
hopefully SPOT will correct some of the ID snd usability weaknesses in
future products, and/or provide products more tailored to different
uses/markets.

Darryl

So.... that is a long way of saying "no you did not test it with the
logo facing the horizon" ;-).
I'd still be curious to know the performance of the logo facing
horizontally. Theories may abound on what might happen but until it
is tested you don't really know.
Chris

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, so
the front face is about at a 45 degree angle. *I get pretty good
tracking results.

You said you tested it with the logo side up and down. *I assumed that
the device was designed with the belt strap on the back side so that
the logo would face horizonally / the horizon. It appears as they
intended it to hang vertically. Did you test it in this orientation?

Chris

The SPOT messenger is a fantastic product, but because of it's
internal technology, and in spite of it's poor industrial design.
There must have been a disconnect somewhere between the product
management, *the ID team/design house and engineering. And it's likely
literally this type of issue as the engineering is all done by Axonn a
separate company than SPOT and Globalstar and I'm sure SPOT or Axonn
contracted out the industrial and mechanical design work.

So for the antennas (both the GPS and Globalstar) a planar antenna
pointing *at the horizon is far from optimal, half the usable
beamwidth would be lost in obstructions below the horizon. It is
actually worse than that simple model because of satellite orbit
geometry and satellite antenna footprint. So the belt clip is designed
to hold the unit, but not reallly while it is in use. Pretty stupid
huh.

The lack of though about how to mount the unit on a car dashboard or
other location, the overloading of the button functions, the
overloading of the dual blinking LEDs, different LED patterns that
mean things that are not clearly explained are other examples of poor
design.

However the SPOT messenger is a great device (I really like mine) and
hopefully SPOT will correct some of the ID snd usability weaknesses in
future products, and/or provide products more tailored to different
uses/markets.

Darryl

So.... that is a long way of saying "no you did not test it with the
logo facing the horizon" ;-).
I'd still be curious to know the performance of the logo facing
horizontally. *Theories may abound on what might happen but until it
is tested you don't really know.
Chris

On Mar 11, 6:00*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, so
the front face is about at a 45 degree angle. *I get pretty good
tracking results.

You said you tested it with the logo side up and down. *I assumed that
the device was designed with the belt strap on the back side so that
the logo would face horizonally / the horizon. It appears as they
intended it to hang vertically. Did you test it in this orientation?

Chris

The SPOT messenger is a fantastic product, but because of it's
internal technology, and in spite of it's poor industrial design.
There must have been a disconnect somewhere between the product
management, *the ID team/design house and engineering. And it's likely
literally this type of issue as the engineering is all done by Axonn a
separate company than SPOT and Globalstar and I'm sure SPOT or Axonn
contracted out the industrial and mechanical design work.

So for the antennas (both the GPS and Globalstar) a planar antenna
pointing *at the horizon is far from optimal, half the usable
beamwidth would be lost in obstructions below the horizon. It is
actually worse than that simple model because of satellite orbit
geometry and satellite antenna footprint. So the belt clip is designed
to hold the unit, but not reallly while it is in use. Pretty stupid
huh.

The lack of though about how to mount the unit on a car dashboard or
other location, the overloading of the button functions, the
overloading of the dual blinking LEDs, different LED patterns that
mean things that are not clearly explained are other examples of poor
design.

However the SPOT messenger is a great device (I really like mine) and
hopefully SPOT will correct some of the ID snd usability weaknesses in
future products, and/or provide products more tailored to different
uses/markets.

Darryl

So.... that is a long way of saying "no you did not test it with the
logo facing the horizon" ;-).
I'd still be curious to know the performance of the logo facing
horizontally. *Theories may abound on what might happen but until it
is tested you don't really know.
Chris

Yes but the long answer was to try to explain that the apparent design
of the product has nothing to do with proper use. Reading the manual
would also show you this.

I did not do any tests since I know horizontal is best and I can
arrange that in my glider. If you can't get them horizontal the
interesting question is how far off horizontal is acceptable. Going to
the extreme case of vertical is not interesting for the reasons I
mentioned.

If you don't beleive that you are welcome to do the test and report
the results here. That time might be more usefully spent reading about
antenna theory/properties, and how Globalstar and GPS work. That way
maybe not only might you realize it is not an interesting experiment
but once you get the results you will (almost no position reports),
you will be able to understand them. :-O


Darryl

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)