bateleur host interface

An application drives bateleur over two TCP ports on the station, set in the station file:

[protocols.bateleur]
enabled   = true
host      = "bateleur"
cmd_port  = 8310
data_port = 8311

This dialect is bateleur's own. MIL-STD-188-110 and STANAG 4285 define the waveform, not how an application talks to a modem, and this interface is not a copy of any other modem's. An application written for another 188-110 modem's TCP interface will not attach here unchanged.

One application at a time. A new connection on either port replaces the previous one, which is closed.

Host connections

Listeners bind to loopback by default. Clients send their normal protocol opening directly, including on data ports and the STANAG 5066 SIS port. There is no extra handshake or key file. A connection opening with an HTTP request line is closed before any command or data in its body is handled. The check preserves the first command's bytes and framing; binary openings are released as soon as they cannot be an HTTP method prefix.

Bateleur, ALE and selcall command lines are limited to 4096 bytes. Socket writers wait at 64 queued writes or 256 KiB; a slow reader stays connected. Modem callbacks and SIS indications hand off to a delivery thread for each connection, so socket backpressure never waits on reception or station ticks. Undelivered output remains in memory until the client reads it or closes. Explicit close drains output for up to 250 ms before shutting down.

Data port

• Bytes written are queued for transmission. They go out on SEND, or on their own after AUTOSEND milliseconds without new data.
• Bytes read are what the modem decoded off the air, delivered as soon as the decoder has committed to them. A long message arrives while it is still being sent. The receiver that produced the current RX START owns this stream until RX END; competing detections cannot insert bytes.

Command port

ASCII lines, terminated by CR, LF or both. Each command gets one answer line, OK ... or ERR <reason>. The modem also writes unsolicited event lines, so read the port as a stream of lines and match answers to commands in order.

Commands, including FRAMING, posted to the modem wait for completion, including any transmission already in progress. Audio buffering does not consume command queue space. A connection closing cancels its commands that have not started; a command already running finishes with its actual result.

The data buffer and posted transmit data each have a 65,536-byte limit. A refused SEND leaves the buffered bytes available. AUTOSEND stops and reports an error if posting fails.

Events

RX END retains the receiver's detail, such as signal lost before EOM, signal lost, signal ended, or receiver reset.

Receiving

• 188-110, 4539 and WBHF. The modem always listens for them, whatever MODE is set to. The preamble names the rate and interleave.
• 4285. Nothing on the air names the mode. The modem listens for 4285 only after MODE 4285 <mode>, and only in that mode.
• 16-tone. Like 4285, nothing on the air names the rate. The modem listens for it only after MODE 16 <rate>, and only at that rate. The last element is filled out with zero bits, so up to three NUL bytes may follow a message.
• 4529. As for 4285: the modem listens only after MODE 4529 <mode>, in that mode and on that sub-carrier.
• FSK. Nothing on the air names the mode either: the modem listens for it only after MODE FSK <mode>, and only in that mode.
• 39-tone. Always listened for; its preamble is its own but does not name the mode. After MODE 39 <mode> a transmission is decoded in that mode as soon as its timing is found. Otherwise the modem finds the mode from the data, which takes about eight seconds of it before RX START 39 <mode> and the first bytes. A synchronous 39-tone message has no end marker: it ends with RX END LOST when the signal goes.

Long messages

The station refuses any single transmission longer than [rig] max_key_s. A message too long for one key-up is sent as several complete transmissions, each with its own preamble and end marker, and each reported by its own TX START / TX END. A bateleur receiver hands their bytes on in order, so the far end's application reads one stream. Nothing re-sends a lost piece: these waveforms are one-way, and retransmission belongs to the layer above.