Operating RTTY

Operating RTTY

Everything on this page works in both builds and runs in the browser. Put the rig in RTTY (MODE › RTTY; press it again while in RTTY for RTTY-R) and the RTTY bar opens at the bottom of the scope, as the CW bar does. Leaving the mode closes it.

Decoder

The decoder is the DeepRTTY neural model (MIT) on ONNX Runtime Web, the runtime the CW decoder uses, for 45.45 Bd with a 170 Hz shift. It starts by itself when the bar opens, and DECODE switches it off and on. The model is about 6 MB, fetched once and kept in the browser.

It decodes a sliding window of the last 12 seconds each second: the newest characters are dim and may still correct themselves, and a character older than about two seconds is committed and never changes. A browser without WebAssembly SIMD, or too slow for the model, falls back to a classic FSK demodulator, and a CLASSIC tag on the strip says so.

CLR clears the text.

Tuning

The strip above the text is a waterfall of the received audio over the whole passband (300 to 3000 Hz), with the mark / space pair marked.

• Click a signal to move the dial so it lands on the pair. The step is 1 Hz in RTTY, as in CW.
• AUTOTUNE listens for a second and a half, finds the strongest pair of tones 170 Hz apart (a lone carrier does not count) and moves the dial onto it; with nothing on the band it leaves the dial alone.
• ZOOM narrows the strip to the pair, ±250 Hz; press again for the whole passband.
• REV swaps mark and space, for a station that comes out as garbage.
• The mark tone selector (2125, 1615 or 1275 Hz) must match where the rig puts the mark: in the rig's RTTY mode that is its RTTY MARK FREQUENCY setting (2125 on an Icom by default); with AFSK on a sideband it is the tone pair wfweb sends and listens on. Leave both at 2125 unless you have a reason.

Mark is the lower tone on LSB and in the rig's RTTY mode (Icom demodulates RTTY as LSB), the upper one on USB and RTTY-R; the bar follows the mode, and REV flips it on top of that.

The whole passband matters because in RTTY mode an Icom's dial is the mark frequency and the audio mark sits at the MARK FREQUENCY setting: a station a few hundred hertz off the dial is nowhere near the pair, and only the full strip shows it.

Transmitting: AFSK

The rig's own RTTY mode keys FSK from its key jack, which CI-V cannot drive. So wfweb sends RTTY as audio tones through the rig's data input, on LSB, with the standard 2125 / 2295 Hz pair (the mark tone selector moves it): AFSK. It is on by default: the bar switches the rig to LSB when it opens, and the top bar's mode tile reads RTTY - LSB while it runs. The AFSK button turns it off (the rig goes back to its RTTY mode, receive only) and that choice is remembered.

Closing the bar puts the rig back in the mode it was in before RTTY. Switching to another sideband by hand closes the bar without restoring anything.

wfweb sets the transmit audio level and switches the speech compressor off for the over, as for FT8; see Troubleshooting.

The keyboard

RTTY is an open channel: you key up and type.

• TX keys the transmitter. What you type goes out as you type it: the input box empties as the characters are queued, and while you think the bar sends idle diddles. Enter is a new line (CR LF), Backspace takes back a character that has not gone out yet, Escape stops. Press TX again (it reads END) to end the over once everything typed has gone out.
• SEND sends what is in the box as one over: key up, send, key down.
• STOP cuts at once and drops whatever had not gone out.

The TX line in the text area is the progress display: each character is shown pending, sending or sent, with a cursor.

Macros

Ten slots in two rows, laid out like the CW bar's. Slot 5 is EDIT / SET: in edit mode, a press on a slot opens its editor (SAVE, CLEAR, CANCEL). [CALL] (your callsign), [QSO] (the station you are working) and [RST] are filled in when sent, and each button shows its text filled in.

A macro pressed with the channel closed opens it, sends and ends the over. Pressed while the channel is open, it is appended and ends the over, unless it ends with [HOLD], which leaves the transmitter on so you can keep typing. The default slot 9, [QSO] DE [CALL] [HOLD], is the usual start of a reply; a held macro is drawn with a trailing ellipsis and a dashed border.

The macros are kept in the browser, in both builds.

Logging

The bar has CALL, QSO and RST (sent and received) fields. LOG QSO opens the entry pre-filled in RTTY; see Logbook. Hand-logged QSOs default to RTTY while the bar is open.

Things to know

• The video recording shows the strip and the contact as a conversation, your overs included.
• On a phone the RTTY bar gets the four soft keys without the PTT row: TX is in the bar. See Phones and Tablets.
• RTTY needs the rig's audio to reach the browser and the browser's TX audio to reach the rig's data input: the same setup as FT8. See Icom Menu Settings.