Software
RTTYMailer
Windows • Free • ITTY submission client • W2TTY
RTTYMailer is the recommended way to submit articles to the ITTY AUTOSTART
channel. Originally written by Bill Bytheway K7TTY; currently maintained by
Paul Heller W2TTY. Handles all server configuration automatically —
no SMTP setup required. Write your article, select a channel, and click Send.
RTTYApp
Windows • SMTP listener • Queue manager • Modem driver • W2TTY
RTTYApp is the server-side software that manages the article queue for each
ITTY channel and drives the HAL ST8000 modem. It operates as an SMTP listener,
receiving submissions from RTTYMailer and feeding them to the teletype machine
in sequence. Originally written by Bill Bytheway K7TTY; currently maintained
by Paul Heller W2TTY. RTTYApp is used by channel operators, not end listeners.
RTTYArt
Windows • Free • RTTY art capture • by Bill Bytheway K7TTY
RTTYArt is Bill Bytheway K7TTY's program for capturing Baudot RTTY art from
paper tape to digital .pix format. It was the tool used to digitize the
collection now in the RTTY Art gallery. Includes a viewer for .pix files.
MMTTY
Windows • Free • RTTY decoder / encoder
MMTTY is the most widely used software RTTY decoder for Windows. It decodes
FSK audio to text and can encode text to audio for transmitting. Use it with
a virtual audio cable to decode the ITTY stream, or with a radio interface
for on-air RTTY.
fldigi
Windows / Mac / Linux • Free • Multi-mode decoder
fldigi is a cross-platform multi-mode digital decoder that includes RTTY.
It runs on Windows, Mac, and Linux, making it the best option for non-Windows
users who want to decode ITTY streams. Configure it for RTTY mode, 170 Hz
shift, and the appropriate baud rate for your chosen channel.
VB-Cable / BlackHole / Jack
Virtual audio routing • Required for stream decoding
To decode an ITTY stream, you need to route the audio from your media player
to your decoder software. These virtual audio cable utilities create a loopback
audio device that makes this possible without a physical cable connection.
RTTY Frequencies
The following are the standard amateur RTTY frequency segments as generally
observed in North America. RTTY uses lower sideband (LSB) with a 170 Hz
shift at the North American amateur standard. The mark tone is typically
placed at 2125 Hz in the audio passband, and the space tone at
1955 Hz (170 Hz below mark).
| Band |
Frequency Range |
Notes |
| 80m |
3.570 – 3.620 MHz |
US primary RTTY segment; 3.605 MHz is a common calling frequency |
| 40m |
7.080 – 7.125 MHz |
Active segment; watch for interference from voice stations |
| 20m |
14.070 – 14.112 MHz |
14.095 MHz is the most active RTTY frequency in the world |
| 15m |
21.070 – 21.110 MHz |
Good DX band when open; 21.090 MHz commonly used |
| 10m |
28.070 – 28.150 MHz |
Excellent DX when the band is open near solar maximum |
ITTY does not use radio frequencies — it is an internet audio stream.
The FSK signal in the stream uses standard 170 Hz shift at the appropriate
baud rate for each channel. See the ITTY
page for stream URLs and technical details.
Baudot Code Reference
The ITA2 (International Telegraph Alphabet No. 2) is the five-unit
Baudot code used by all ITTY channels. Each character is represented by five
binary elements — mark or space — plus a start element and a stop
element. Two shift states (LTRS and FIGS) double the available characters to
cover the full uppercase alphabet, digits, and punctuation.
The Code Card Corner
collects 21 pocket and wallet reference cards that teletype repairmen and
data communications professionals carried in the field — covering Baudot,
ASCII, EBCDIC, and modem parameters for machines from Model 28 to TermiNet 300.
For a complete ITA2 character table and introduction to the code, see
Introduction to Amateur Radio Teletype by Irv Hoff K8DKG,
featured on the home page.