At 11:06 AM 01/07/2010, you wrote:
> > Curious if anyone knows for ocean container tracking, obviously they
>use a GPS
> > module to get the location, but for transmitting data back to the
>"home" monitoring
> > station, I would assume that a single satellite transmitter collects
>data via wifi
> > or some other network from each GPS unit?  I can't imagine any other
>way of it
> > working.  Anyone have knowledge on this?
>
>Isn't it done by knowing what ship a container is placed on? I know
>there are web sites where you can track ships in the ocean using the GPS
>data they send back (apparently one of the sources of info Somalian
>pirates use, from what I have heard) but I don't know the web site
>address.

Ships (over a certain size- 300 tons, IIRC) and passenger ships
are required to transmit their position, bearing and some other
data regularly (less often when they are docked). The system is
called "AIS".

For example:

Flag: Marshall Is
Ship Type: Cargo
Status: Underway
Speed/Course: 7.2 kn / 292
Length x Breadth: 190 m X 32 m
Draught: 6.7 m
Destination: NEW YORK
ETA: 2010-06-30 17:00 (UTC)
Received (69): 0h 4min 55s ago

http://www.marinetraffic.com/ais/

It is a VHF-based system that uses base station receivers, and
depends on the limited range of VHF.

There has been some work using small satellites in LEO to monitor
ships further out at sea-- it's quite difficult to separate the
signals from thousands of ships in congested areas such as the
Mediterranean sea, but apparently possible.

I don't know about containers having individual tracking.. there
have been sophisticated _logging_ devices on containers for years,
but it would seem to be impossible to either receive GPS signals
or transmit data to a geostationary, Iridium or whatever satellite
when a container is buried deep in the bowels of a container ship,
surrounded by thousands of other steel boxes.

Best regards,









>--
>Scanned by iCritical.
>
>--
>http://www.piclist.com PIC/SX FAQ & list archive
>View/change your membership options at
>http://mailman.mit.edu/mailman/listinfo/piclist

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com



-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist