Lanner: RTTY, SITOR-B and NAVTEX

Lanner implements the ITA2 alphabet and character framing, CCIR 476 seven-unit codewords, collective SITOR-B time-diversity FEC, and NAVTEX bulletin parsing. The code tables and primary sources describe the wire codes.

Operator entry points

Use the console for passive reception:

tools/console rtty monitor
tools/console sitor-b monitor
tools/console navtex monitor

These commands use the current dial and preserve the radio's sideband/filter. An optional --freq KHZ tunes once; subsequent manual radio retuning is allowed. Tone pairs can be acquired across receive audio up to 4 kHz. See the monitor guide for source selection and recording.

RTTY defaults to 45.45 Bd, 170 Hz shift and US-TTY figures, with unshift on space. --no-rtty-usos preserves figures across spaces. SITOR-B uses 100 Bd and 170 Hz shift. NAVTEX uses that receive path and extracts completed bulletins; no bulletin output can mean that reception has not reached a complete header and end marker. Broadcast assigned frequencies and USB dial frequencies differ: the SITOR default audio centre is 1700 Hz, so a 518 kHz assigned frequency corresponds to a 516.3 kHz USB dial.

Scope and evidence

The library includes waveform generation for RTTY and collective SITOR-B. This does not turn a passive monitor into a transmitter. SITOR-A ARQ, selective Mode-B addressing and a two-way console terminal are outside these entry points. NAVTEX parsing does not certify a bulletin's operational accuracy.

tests/lanner/ covers the character tables, modulation/demodulation, stream boundaries, tone/sample offsets, noise, time diversity and bulletin assembly. These are local software tests. No named independent on-air Lanner result is claimed in implementation evidence.