On Aug 6, 8:16*am, Westbender wrote:
to pay an additional amount to justify the additional bandwidth
usage.
-Mark

Additional bandwidth usage? *I don't get it. We're talking about the
message that gets sent from the Spot unit through the satellite,
right? How can one additional data element constitute "additional
bandwidth"?

As long as the Spot unit itself if capable of determining it's
altitude, I would think the only change required is a software update
and the message protocol for transmit and receive via the satellite.
An extra couple of bytes of data in the message doesn't seem like it
should be a big deal.

What am I missing?

Is there an increase in bandwidth? Absolutely, and it is likely to be
about 2X just to add altitude data. The Globalstar networks uses 144-
bit (18-byte) simplex data packets which have 45-bits overhead, 27-
bits ESN (Electronic Serial Number) and 72-bit payload. I suspect SPOT
uses the same encoding scheme as other Gloablstar simplex devices with
the Lat/Lon encoded in 48 bits within the 72 bit payload. But by the
time you lose another few bytes for message type and status there is
likely no space for altitude data (there is no space left in standard
Globalstar location message packets, I suspect SPOT uses a simmilar
data layout as those, I have never see an exact spec of the SPOT
packet configuration). But you can send the altitude in an separate
packet (Globalstar supports chained packet messages or they could just
reassemble this at the application level at the other end). So my best
guess is whatever the SPOT tracking bandwidth requirement is currently
that would double it to add altitude reporting.

But does doubling of the bandwidth involve a significant increase in
cost to SPOT? I have *no* idea (and the rest of this just says that in
a long winded way...). So how do you cost the bandwidth? Well doing
that bottom-up that would take more space than I have on the back of
my envelope, but here is a flavor.... The data is encoded using CDMA
(spread spectrum) technology but the channel congestion/capacity is
not obvious. At some congestion level you start increasing loss of
data packets also the cost becomes the business cost of reputation/
guarantee to customers of data packet reliability (that's not just
SPOT customers but all Globalstar simplex data customers). And this is
a "local area" type bandwidth from your simplex modem to whatever
ground stations its signal is being bent back to. The simplest
baseline cost is the amortization of the billions of dollars it has
taken Gloabalstar to put the global system in place, you can either
calculate this at the actual cost or the steeply discounted post-
bankruptcy acquisition cost of Globalstar's assets. So you could
probably generate some scary big numbers if modeling bandwidth
congestion costs. The other way is just to look at what Globalstar is
willing to to price their bandwidth at. If bandwidth costs dominated
their service costs then adding altitude for constant margin to them
would require doubling the subscription rate. Reporting altitude and
location at 1 minute intervals would require a 20X increase in
current subscription costs. That does not seem likely, and SPOT just ~
tripled the data bandwidth requirement for tracking with the new SPOT
messenger by resending the past two position reports with each new
report and I will be surprised if we see a huge increase in the cost
of the add-on track service. The constellation and ground stations are
sunk cost. Globalstar might as well drive up usage even at deep
discount rates to make any revenue. If they manage to create a market
they can keep growing this until congestion becomes a potential issue.
And at that point they can manage this by raising subscription costs.
The other interesting thing is actual utilization - I suspect many
typical spot users never actually send much traffic at all, never use
track mode, etc. and the device sits mostly idle. And the use of the
system bandwidth by active users could cost more than the actual
bandwidth cost. I'd love SPOT to say how they model bandwidth cost :-)

There are significant costs associated with creating and marketing
different product SKUs and I would expect those costs, especially for
a small market like people who want altitude reported, to be
significant. You might produce a different version of the product that
always had altitude on to save a complete doubling of bandwidth usage
at no benefit to most customers, and that device may need physical UI
changes (buttons etc). To cover those additional costs you probably
want to market this at a higher unit and subscription price point -
this type of situation often traps you in the difficulty of escalating
pricing of products for a smaller market niches. The other attack on
this is to look at competitive pricing of Iridium tracking solutions,
on the high side, and possible lower cost future technology, but my
(marketing/business consulting) gut feel is don't expect a slight
increase in price if you want things like altitude or high frequency
track reporting.

Darryl