Overview
A great number of exciting new digital operating modes have developed, largely because of the availability of personal computers, soundcards, and advanced software. But amateur digital communication began in earnest in the late 1940's (if you don't count Morse as a digital mode!) when hams worked out techniques of connecting mechanical Teletype keyboard/printers to amateur gear using FSK and AFSK modulation. There are too many different modes to list individually, but here are some of the major ones:
- Packet - One of the first "modern" digital modes, packet radio transmits data in groups or "packets" of 10s or 100s of bytes. This allows improved throughput and error control. The basic protocol for packet radio is AX.25. Transmission speeds typically range from 300 bps on the HF bands to 1200 and 9600 bps on VHF or UHF.
- PSK31 (or BPSK31, Binary Phase Shift Keying 31.25 Hz) Probably the most popular keyboard to keyboard digital mode today, PSK31 is normally generated and decoded using PC soundcards with one of many available software packages. PSK31 occupies very small bandwidths (approximately 100 Hz) and offers effective communication at low power.
- RTTY (radio teletype) is the original keyboard to keyboard mode, based on the 5-bit Baudot code, began with mechanical Teletypes as mentioned above. It is still a popular communications mode, but now uses PCs for coding and decoding, using 170 Hz frequency shift keying at a 45.45 baud rate -- 60 words per minute.
- Other Modes Many other data modes are available for experimentation, including Pactor and Clover that enhance packet operation, and MFSK, Olivia, Throb, DominoEX, MT63, and Thor which are other modes mainly for PC/soundcard operation. AMTOR is a special form of RTTY that provides error detection and correction.
Articles
General
- Getting Started in Digital Communications (series)
Introduction, QST March 1992, pp. 33-37
Packet, QST April 1992, pp. 44-49
RTTY, QST May 1992, pp. 41-47
AMTOR, QST June 1992. pp. 34-45
Feedback, QST October 1992, p. 66
- The HF Digital "Tower of Babel"
QST January 2001, pp. 50-53
A thumbnail of ten digital modes.
Packet
- TCP/IP: Pings, POPs and KISSes
If you're an active packeteer, sooner or later someone will bring up the subject of TCP/IP - Transmission Control Protocol/Internet Protocol.
- Packet Radio Frequency Recommendations of the Ad Hoc Committee on Amateur Radio Digital Communication
QST September 1987, p. 54 - Packet Radio Frequency Recommendations of the Committee on Amateur Radio Digital Communication
QST March 1988 p. 51 - "9600-Ready" Radios: Ready or Not?
QST May 1995, pp. 24-29
What the ARRL Lab says you should know before buying a VHF/UHF FM transceiver with 9600 baud capability. - An Inexpensive KISS-Mode TNC
QST November 2000, pp. 53-56
This little four IC TNC isn't full-featured, but one designed to operate in KISS mode including TCP/IP and APRS. - WinLink 2000: A Worldwide HF BBS
QST March 2000, p. 90
Software allows messages to pass between an amateur radio station and the Internet. - Introduction to Winlink 2000
QST June 2002, pp, 31-32
One integrated digital system links the VHF/UHF packet networks, ham-to-ham radio messages and Internet e-mail -- worldwide
PSK31
- The NJQRP Squirt
QST April 2001, pp. 40-43
A reduced-size 80-meter antenna designed for small lots, portable use, and the Warbler PSK31 Transceiver . - The Warbler--A Simple PSK31 Transceiver for 80 Meters
QST March, 2001. pp. 37-41 - Mobile Fun with PSK31!
QST January 2001, pp. 58-59
At last! A low power reliable mode of communication perfect for mobile and portable operation. Here is a sample installation
- PSK31 - Has RTTY's Replacement Arrived?
QST May 1999, pp. 41-44
There's a new HF digital mode in town and the gossip is flying! - PSK31: A New Radio-Teletype Mode
QEX July/Aug 1999, pp. 3-9
A look at the technical side of this new mode. - PSK31 2000
QST May 2000, pp. 42-45
In early 1999 hams throughout the world discovered a new way to communicate using a digital scheme known as PSK31. Where do we stand today? - A Panoramic Transceiving System for PSK31
QST June 2000, pp. 31-37
Combine an inexpensive transceiver, some free software and you're on PSK31 at a rock-bottom price! Add to that the fun and pride of building the transceiver and you've got an irresistible package! - The "New" HF Digital Modes-PSK31
QST April 1999, pp. 50-51
"I'll see you in Hell!" Insult, or technical challenge?
MFSK
- MFSK for the New Millennium
QST January 2001, pp. 33-36
Just like RTTY and PSK31...only different. A computer, a sound card and a free download and you're in!