Fleet Tracking on Inmarsat 4F3

Most of the popular Inmarsat activity is associated with ships and planes in AOR-E, AOR-W, POR and IOR. There is an Inmarsat satellite called 4F3 parked at 98W that gives CONUS coverage. This satellite is inclined and so does move up and down a bit. This satellite has quite a bit of BGAN services but there is also low rate paging (standard-D) and well as mini-c (standard-C) for fleet tracking. What is fleet tracking? It gives the ability to a company to track and communicate with all of the vehicles that make up a “fleet”. Two way message is possible as well as “polling” (group or individual). The dispatcher can see truck location and provide driving directions as needed.

Example of truck with fleet management.

Example of truck with fleet management.

98W coverage is on left.

98W coverage is on left.

On 98W there are currently two mini-c signals, both designated as “private LES” with LES ids of 252 and 253. The protocol is the same as the usual standard-c for the ocean regions but the NCS and LES stations are combined into one. Making some small changes to an existing decoder it was really quite easy to see what fleet tracking is all about. See screenshot below for one bulletin board packet identifying services.

Bulletin Board output.

Bulletin Board output.

See the screenshot below for example decode of both private LES simultaneously.

Example fleet tracking decode.

Example fleet tracking decode.

There are many different kinds of trucks that are tracked, some carry petroleum, some carry UPS, FED-EX and AMAZON loads, others more clandestine loads.

Below is a sample antenna that you may see on the top of some trucks that are under fleet management.

Sample mini-c antenna.

Sample mini-c antenna.

Category(s): Inmarsat
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4 Responses to Fleet Tracking on Inmarsat 4F3

    Don DeGregori says:

    I’m an experimenter and live in Los Angeles area. The only Inmarsat satellite I can point at easily is 98.14 West, or 4-F3. Can I find a demo or free mini-C decoder to use with my 10 turn helix antenna, rtl-sdr dongle and Windows 7 PC? The project is purely for fun.

    Thanks,
    Don

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