Amateur RTTY on 20 metres, 14.083 MHz: 45.45 baud teletype and weekend contests

What you hear

A purring two-tone signal, the same family of sound as the weather teletype but slower in rhythm: 45.45 baud, the speed of a mechanical teleprinter, with the two tones 170 Hz apart. When nothing is typed the station sends a steady alternation of the two tones, the idle "diddle", and on the waterfall every signal is a pair of parallel lines 170 Hz apart. A contest station sounds like a machine gun of short bursts; a casual contact has long pauses while the operator reads.

Decoded, the text is all capitals, as the five-bit teleprinter code has no lower case. In a contest it is terse: a CQ with the callsign, the exchange of a 599 report and a serial number, TU, and on to the next one. Between contests the contacts are slower and friendlier, name, town, equipment, weather, with the odd RYRYRY test string from someone checking the link. The code has a letters shift and a figures shift, and a missed shift character turns a word into a run of digits until the next shift sets it right; the garbling is normal, not a fault.

Who transmits and why

Radio amateurs, since the years after the Second World War when surplus teleprinters became affordable. RTTY was the first digital mode of the hobby and it never left: it is still the mode of several of the year's big contests, 48-hour events in January, February, March and late September, and of many DX expeditions, which run RTTY alongside CW and voice because it is simple and robust. The standard on the amateur bands has not changed in seventy years: 45.45 baud, 170 Hz shift, five-bit ITA2 code, the higher tone being the mark. On 20 metres RTTY lives between 14.080 and 14.090 MHz, and 14.083 is a good place to drop in.

When and where to listen

The frequency is as busy as the calendar says. On a weekday there may be one or two contacts an hour, often DX stations working a short queue; at the weekend there is more; on a contest weekend the whole range from 14.080 upwards is wall to wall from Saturday morning until Sunday evening, and every pair of lines on the waterfall is a different station. The band hours are those of 20 metres: Europe around midday, North America in the European afternoon and evening, Asia in the morning. Any receiver with 20 metres works.

In ShackDeck

Station catalogue → Fax and digital signals → RTTY 20 m (14.083). The program picks a public receiver with 20 metres, tunes it to 14.083 MHz in USB and sets the RTTY mode with the amateur parameters, 45.45 baud and a 170 Hz shift; no receiver, antenna or account of your own is needed. The decoder finds the pair of tones in the passband and the AFC holds them; to read a different station, click its pair of lines on the waterfall. The text prints line by line in the text panel, and the callsigns in it are clickable: a click puts the callsign into the entry panel with its country, bearing and distance, and looks the station up.