Re: ARLA/CLUSTER: SPOT - Localizador por Satélite

[Radiophilo]

Para quem quiser mais nformações sobre o SPOT, aqui deixo um extracto do "Guia
do COSPAS-SARSAT<http://www.sarglobal1.ca/00native/Guide_to_COSPAS-SARSAT.pdf>
".

73,
António Vilela
CT1JHQ

"There may be some confusion between PLBs and SPOT devices since both use
satellites to signal for assistance. These two systems are completely
unrelated
with nothing shared in common between the SPOT and SARSAT systems. They
determine beacon locations by different methods. Notification of distresses
travel
via different communicate routes to different organizations.
The SPOT device must acquire signals from GPS satellites in order to
determine
its own position. It then transmits this location to a communications
satellite for
routing through a commercial communications network to the SPOT Response
Center in Houston, Texas. The Response Center must determine the
appropriate SAR resources for the location and situation, and telephone that
organization.
This is in contrast to a PLB which does not need to know its own position
and
only one of several available satellites needs to receive the signal in
order for the
position to be determined. Additionally notification of the distress is
automatically
routed to the official SAR agency for Canada as opposed to a private company
in
the U.S.

Advantages to the SPOT system include the fact that unlike a PLB, it can be
used for lower-level calls for assistance, transmitting progress
information, and
signaling that all is well. A PLB should only be used for severe emergency
situations only.

Shortcomings of the SPOT system include the requirement that the unit be
able
to have communications with multiple satellites (both GPS & communications)
which can introduce significant delays and unreliability. There are many
reports
of messages from SPOT devices being significantly delayed, or not being
received at all. Also since the system requires a paid subscription, after a
few
years the total cost of operating a SPOT can exceed the cost of a PLB
despite
the lower initial cost of the SPOT device itself. A PLB has a higher initial
cost,
but after purchase the only cost of owning a PLB is occasional battery
replacement."



2010/12/3 João Gonçalves Costa <joao.a.costa  ctt.pt>

>
> SPOT - Localizador por Satélite
>
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