ARRL

Digital Data Modes

Overview

fldigi_20100228.pngA 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.

Books and Publications

General

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

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.

PSK31

  • 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   Members Only
    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  Members Only
    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!

Web Links

General

Packet

PSK31

MFSK

  • MFSK16
    An MFSK DX Mode
  • Nino Porcino has a download the STREAM download for MFSK16, MFSK8 and other digital modes