Digital Modes

Digital Modes

DIGITAL MODES

What Are "Digital Modes?"

The original digital mode is CW (Morse Code, Continuous Wave) Although more than 140 years old, bandwidth - efficient Morse code, originally developed by Samuel Morse and Alfred Vail in the 1840s, uses techniques that were not more fully understood until much later. Morse code is still used by amateur radio operators. Operators may either key the code manually using a telegraph key and decode by ear, or they may use computers to send and receive the code, and it still remains (in my opinion) one of the most reliable, simple, efficient modes, {better than phone (SSB) and other digital modes.} Think of Morse code as either on/off, or 1's and zeros.Broadly, Digital Modes fall into the categories listed below.: (This list is by no means inclusive.) Gone are the days of thinking amateur radio uses either a microphone or a key.

Digital Voice	D-STAR DMR System Fusion
Images	Amateur Television-Fast Scan (ATV)
Text and Data	FSK441 JT6M JT65 FT8/FT4 Olivia JS8 (aka JS8Call)
Beacon Modes	WSPR - Weak Signal Propagation Reporter FST41 CW

WSPR (pronounced "whisper") stands for "Weak Signal Propagation Reporter". It is a protocol, implemented in a computer program, used for weak-signal radio communication between amateur radio operators. The protocol was designed, and a program written initially, by Joe Taylor, amateur radio station K1JT. Software is now open source and is developed by a small team. The program is designed for sending and receiving low-power transmissions to test propagation paths on the HF bands. WSPR implements a protocol designed for probing potential propagation paths with low-power transmissions. Transmissions carry a station's call sign, Maidenhead grid locator, and transmitter power. The program can decode signals with S/N as low as −28 dB in a 2500 Hz bandwidth. Stations with internet access can automatically upload their reception reports to a central database called WSPRnet, which includes a mapping facility.

The protocol was designed to test propagation paths on the LF, MF and HF bands.. Also used experimentally at VHF and higher frequencies. Other applications include antenna testing, frequency stability and frequency accuracy checking. There are numerous software downloads available that are free that can make one's computer accurate to allow WSPR to function correctly. Use of WSPR sounds very complicated, but it is not. It is quite easy, and one can participate without an Amateur Radio License, but as a receive-only participant...known as a SWL (Short Wave Listener). More to come later...

The image posted below shows the stations that I've either heard, or the stations that have heard my station, K7UV during a 24 hour time period. This was on the 40 meter ham band (7.0386 MHz) and I limited my transmitter to just 2 watts output to a vertical antenna in my back yard. With coax (feed line) power losses, antenna radiated ~ 1.5 watts, yet my signal was heard on almost every continent, and I also heard stations many of whom were running even less power than my station, also from all continents. This image obviously shows how WSPR can decode signals, many of which are so weak that they can't be heard by the ear. The signals are literally "in the noise." I have not shown all of the North American stations because they are too numerous.

WSPR 24 Hr Map

FST41

{Extracted from the FST4 Quick Start Guide}

FST41 was introduced as part of WSJT-X in the summer of 2020. Version 2.3 of WSJT-X introduces a new family of digital modes we designate FST41 . These modes have a wide range of capabilities and potential applications. Their fundamental sensitivities are better than most older modes in WSJT-X and are close to the theoretical limits for the same information throughput rates. Particular target applications include ▪ WSPR-like, quasi-beacon transmissions on LF and MF bands ▪ QSOs with very weak signals on the LF and MF bands ▪ EME on VHF and UHF bands with T/R sequences both shorter and longer than 60 s ... but other uses will surely be found, as well. We expect that FST4 will serve some of its intended purposes better than older modes in WSJT-X, and without the strict time- and frequency-locking requirements of modes such as EbNaut.

Quick Start Guide
Download WSJT-X 2.5.4
WSJT-X Release Notes by Joe Taylor, K1JT

To receive or transmit using any of the digital modes requires an interface between the receiver or transceiver and your computer sound card. There are various levels of equipment from very basic to USB connected interfaces. (zero cost if you have a well-stocked junk box.) Basic kits available under $10 or commercial interfaces with rig-specific cables from $40 to $200.
This is a very basic isolation interface schematic.