Digital Modes

With digital modes you can work other amateur radio stations throughout the world with transmitter powers of 10 Watts or less using simple wire antennas - By Chris G3YTU

As the sunspot cycle progresses to a minimum, long distance HF propagation will be more difficult, but digital modes will benefit those of us who don’t have a beam and linear amplifier.

Weak Signal Propagation Reporter Network (WSPRnet) - Map illustrating 40m activity 23rd Feb 2016


You need an HF transceiver, antenna, computer and interface unit with suitable cables and software for your chosen mode(s).

If you have a transceiver with a computer control interface, you may be able to connect it to the computer so that you can read and control the frequency directly.

The interface unit serves to match the signal levels of the audio and isolate the Push to Talk (PTT) connection between the radio and the computer.

If the transceiver has the Voice-Operated Switch (VOX) feature you may be able to use this instead of the PTT in which case you only need to connect the transmit and receive audio to the computer.


Digital Modes RTTY & PSK31

The digital modes RTTY and PSK31 are the easiest to begin with and enable you to have a QSO in plain language at a reasonable speed.

RTTY has no error correction but PSK31 does, and can provide a good error free readout providing the signal is slightly above the noise level.

For RTTY start with the MMTTY software and check the AA5AU website which provides a lot of information on setting up the software.

For PSK31 you can try MMVARI or DIGIPAN software.

The Fldigi software by W1HKJ incorporates RTTY, PSK31 and many other digital modes, except for the WSJT weak signal modes, and enables you to switch between modes quickly.

This software is installed on the MSARS computer in the radio shack.




WSJT, WSJT-X and WSPR developed by Joe Taylor K1JT, are programs designed for weak-signal digital communications.

WSJT has digital protocols (JTMS, FSK441, ISCAT, JT6M, JT65 & JT4) optimized for Earth-Moon-Earth, Meteor Scatter, Ionospheric Scatter at VHF & UHF and also HF Skywave Propagation.


WSJT-X implements a new protocol JT9 optimized for the LF, MF and HF bands.

WSPR (Weak Signal Propagation Reporter) is designed for sending and receiving low power MF & HF signals to test propagation paths.

The results are displayed in real time at WSPRnet at:

The WSPR Version 2.11 also includes a package ‘FMT’ which enables you to make accurate frequency measurements such as those used by participants in the ARRL Frequency Measuring Tests ‘Challenge’ at:

JT65-HF is a development of the WSJT program specifically for HF by Joe Large W6CQZ.

You need to use software such as ‘Dimension 4’ to synchronise your computer with an accurate clock so that the software decodes the messages accurately.

For most of these modes you are able to exchange signal report and callsign, not really a conversation by any means, but still a contact!



There are even more digital modes to try such as Olivia and FSQ once you have conquered the simpler modes if you want a challenge.

There is also a software implementation of the HF digital voice algorithm called ‘FreeDV’. However, try the simpler modes first as they are more popular and you will find more stations on the air using them before experimenting with other more complex modes.



If you need help with getting started with any of the Digital Modes described in this article, please check the listed websites first to see if there is any information which provides you with a solution or contact me at: and I will try and help.




AA5AU Getting Started on RTTY at:

British Amateur Radio Teledata Group: (BARTG) at:




Essex Ham:

KB9UKD Digital Mode Audio Samples:






K7AGE PSK31 Videos:




WSJT Website Additional Reading:

NW7US Tomas David Hood Website:

and for JT65A link to:



RSGB RTTY/PSK31 for Radio Amateurs By Roger Cooke, G3LDI

ARRL Get on the Air with HF Digital By Steve Ford, WB8IMY

ARRL Work the World with JT65 and JT9 by Steve Ford, WB8IMY

RSGB Radio Amateur Operating Manual

RSGB Radio Communication Handbook