Introduction to the Massachusetts Rhode Island Digital NTS Net (MARIDN)

The Massachusetts Rhode Island Digital NTS Net (MARIDN) is a Section-Level net of the National Traffic System (NTS) of the ARRL. MARIDN meets weekly for the purpose of passing NTS messages within, into, and out of the sections of Eastern and Western MA and RI. MARIDN is supplemental to the Massachusetts Rhode Island Phone Net (MARIPN) and Massachusetts Rhode Island CW Net (MARICW). MARIDN uses digital modes rather than voice or CW, particularly the fldigi suite of software.

How to Participate in MARIDN

Participants in MARIDN use the fldigi software suite, particularly fldigi and flmsg. This introduction assumes the user has downloaded, installed and configured fldigi to run in their environment, and has a basic understanding of how to use the software, including the ability to receive and send using  fldigi, and send a message using flmsg. There are countless YouTube videos and other helpful documents to assist a new user with downloading and configuring fldigi; how to install and configure one’s fldigi setup is beyond the scope of this introduction.

MARIDN meets at 1800 local time every Tuesday. MARIDN may run additional sessions as needed, e.g., during declared emergencies and for ARES exercises.

To get started, set your system as follows:


3583 kHz, USB (or USB-Data); Squelch off; AGC fast; Noise Reduction off; Noise Blanker off; Audio (Speech) Processing off;

fldigi: Mode: THOR22; center-point 1500 Hz; AFC off; RsID on for receive and transmit;

flmsg: application running; open the “Received Messages” window (Utilities -> Received Messages) and position the window to be easily visible

The Net Control Station (NCS) will call the net, including instructions for checking in. All stations are encouraged to check in, whether or not they have traffic.

When a station sends a message, fldigi will decode the message and pass it to flmsg for display. Each received message will create a new row in the Received Messages window. Select (click on) a row, then click the View button to see that message in flmsg and also in a browser window.

Other Thoughts

MARIDN participants run a Zoom call simultaneous with the net, to help with coordination. We encourage stations to connect to the Zoom, especially the first few times they check in to the net. For more information about MARIDN, including the Zoom link, please contact Net Manager Jon N1ILZ at


MARIDN is an officially sanctioned net within the National Traffic System (NTS). Operators use the fldigi software suite to pass messages. In addition to traditional Radiograms, flmsg can natively send a wide variety of other forms, including ICS-213. We believe this can and will be an important part of NTS going forward. We encourage stations from all over Massachusetts and Rhode Island to join the fun!

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