EGC / LES std-C decoder

LATEST NEWS: Experimental version being tested with EGC "polygon area" and oil-rig mapping:

Screncapture of version v1.5.0 below:

*The tuner section now has a spectrum analyzer and a "tuner needle". Unlike previous decoder versions, the panel is now interactive, so you can click on the signal you see and tuning is done! To start decoding now simply click on the most "energy rich" part of the signal bringing in such way the green "tuner needle" indicator there. The signal bar will immediately rise and the quality bar will soon follow. I want to thank Thomas Gerlach for making the spectrum analyzer publicly available!

*The "Terminal" window has been replaced by a 3-tab, tabbed pane. These tabs are:


1) Terminal - The classic window that spits out data from NCS and LES channels (all messages are processed and displayed in their entirety)


2) EGC tab - NEW tab (as shown in video below) providing a tremendously more user friendly interaction. The map that used to be generated outside the program, still is, but is now also shown on this window as well. Depending on the EGC message, the map will be either hidden or shown. All messages are kept persistently in an SQLite database and the last batch is always available for review even after firing up the program for a new session. Non-read messages will be in bold to indicate they are new messages that haven't been read. 


3) LES tab - NEW tab window giving an overview of the received LES messages, columns indicate received date, coding format, originating MES ID or email and message length. Just like the first PRO version, received binary messages are analyzed, appended with the correct extension (PDF, PNG, ZIP etc) and put in a folder.

*The Help menu that used to be a dead link now actually brings up a nice help-style menu window. My intention is to fill it with as much information as possible needed to get a newbie started and also provide, tips and hints for the more experienced.

This update will be sent to all of you who already have the old pro version as soon as the status on the download section changes from "NEW RELEASE SOON" to a date.

This software is closed source and has been since it was first released around 2009. At that time I made a choice to keep the source private but share the executable EGC app for free with the public, so that others could have some fun on the L-band!

The "pro" EGC-LES version was developed in parallel the same year but kept private, nobody even knew it existed. Although I recognized its potential financial value I didn't take "advantage" of it. Firstly because it was a personal hobby project (can't put a price on intellectual property) and second, because I didn't want to help to further expose people's private communications to the open public.

In February 2017 a raw clone of my de-compiled code was made public, to be later withdrawn with an apology. That is the moment I decided to release the PRO version as payware to the public. Many new features present in today's PRO version have been proposed by users and my aim is to satisfy everyone's wishes.

Recently another similar project was released from the same author, with lots of documents to support the code and only minute traces of the initial de-compilation. This time one could indeed claim to have built it "from scratch" - codewise at least. The fact still remains that *part* of the knowledge (not 'code' necessarily) required to put it together was obtained from this initial reverse engineering process.

Despite the negativity surrounding this case, I decided to withdraw my takedown request on the project in exchange for an acknowledgement to the original Tekmanoid decoder, as this person himself wished to include from the start anyway.

To end it with another positive note, I can only hope this newcomer will bring something new to the scene, and that we will see some interesting things!

Features of "pro" LES+EGC std-C decoder

full GUI interface Yes
visual quality, volume, sync, locked center frequency Yes
visual signal strength indicator
(useful for peaking antenna)
basic channel parameters from bulletin board Yes
good / bad frames counter Yes
user selectable colors for fore and background Yes

Group message decoding Yes
All encoding processing
(ITA2, ASCII, binary)

NCS file extension assignment based on file header analysis (third party app TrID by Marco Pontello) Yes
possibility to save decoded data to output file Yes
Sound device card input selector Yes
queued messages indicator EGC / LES respectively Yes
list of active LES frequencies sent on NCS Yes
automatically log RAW data messages for post processing Yes
LES file extension assignment based on file header analysis (third party app TrID by Marco Pontello) Yes

FleetNet & SafetyNet graphical map representation

LES channel message decoding! ~7 channels per satellite to explore Yes
LES channel all encoding processing Yes
Night mode Yes
Save sound card input Yes
Message counter Yes
Smart autoscroll for Terminal window Yes
Indicator of Ocean region serviced by satellite Yes
Sound notification upon EGC message v.1.5.0
Interactive tuner / spectrum analyzer v.1.5.0
Message persistency (SQLiteDB) between sessions v.1.5.0
Information spit in 3 tabbed pane v.1.5.0
Help section v.1.5.0
non-standard EGC area mapping (experimental) v1.5.1
mapping of oil-rigs (experimental) v1.5.1
The Enhanced Group Call (EGC) service is a message broadcast service with global coverage (except the poles) within the Inmarsat-C communications system. Two of the services provided are:
  • FleetNET
  • SafetyNET
FleetNET is used to send commercial messages to individuals or groups of subscribers (for example, individual companies communicating with their own Mobile Earth Stations (MES)). SafetyNET is used for broadcasting Maritime Safety Information (MSI) such as navigational warnings, meteorological warnings, meteorological forecasts and other safety related information (including Distress Alert Relays) from official sources.

Requirements if using communications radio:

  • Communications Receiver covering 1550 MHz in USB mode
  • Parabolic dish and preamplifier or patch antenna for 1550 MHz
  • Low noise amplifiier for 1550 MHz right after antenna.
  • Clear view to one of the satellites. For pointing a dish, a rough estimate is given by
  • Suitable audio cable between receiver and PC soundcard.
  • PC with soundcard
  • Java Runtime Engine: JRE v1.8 JDK

Requirements if using SDR

(may vary slightly depending on setup)
  • RTL-SDR USB stick covering 1550 Mhz
  • Parabolic dish and preamplifier or patch antenna for 1550 Mhz
  • Low noise amplifiier for 1550 MHz right after antenna.
  • Clear view to one of the satellites. For pointing a dish, a rough estimate is given by
  • USB extension cord
  • SDR#
  • Virtual Audio Cable
  • Java Runtime Engine: JRE v1.8 JDK

inmarsat setup

Mapping of "standard EGC" messages (circles / rectangles)

Tune your receiver to the NCS channel for your ocean region. That is ONE channel per Inmarsat C satellite - or per ocean region. You will receive navigational messages classified in Safety/Priority/Urgency/Distress. Its common to receive SAR (Search And Rescue) alerts or other messages addressed to a particular geographical area. The standardized messages can address areas shaped as a rectangles or a circles.
click on image for full size

Mapping of "non standard EGC" messages (polygons)

 Besides "circular" and "rectangular" areas, the latest pro release version analyzes the message content and attempts to decode area coordinates. The images below have been automatically generated by this process. This is an experimental feature.

Mapping of oil rigs

Another experimental feature is the attempt to plot the position of oil-rigs reported in EGC messages


The pro decoder enables you receive traffic from LES channels. You have so much more to explore! Select any active LES channel and start receiving messages. Some have more traffic than others, try them all out. Channel with ID 121 on AOR-E has some heavier traffic. Remember to respect the privacy of others!
Below: A table with a list of the currently available channels as sent by the satellite, (live example from AOR-E below).


Useful for getting a first rough estimate, where to point the satellite dish


For information on price / payment method contact me on:
admin @
LES+EGC version
Latest pay version: 11 Nov 2018


October 2008 - project start date
March 2017 - first pay version released

Testimonials (Pro version)

"I have to say that this software is a triumph." "I ran a wave audio file on a continuous loop for over 8 hours and your program is running flawlessly!" "Excellent results, and software works great"
"Many thanks for your time, it is greatly appreciated!"
"Just wanted to tell you I'm having a great time with your program!" "Just a thumbs up. The program works really good, and with the spectrum analyzer, I think it'll be excellent."