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diff --git a/include/max25/packet-radio.md b/include/max25/packet-radio.md new file mode 100644 index 0000000..cc11708 --- /dev/null +++ b/include/max25/packet-radio.md @@ -0,0 +1,49 @@ +# Packet radio constants (MAX25) + +Compact reference for `max25d` / `max25-terminal`. Depth prose lives in the research vault (project docs), not shipped in this repo. + +## AX.25 + +| Symbol | Value | +|--------|-------| +| Call length | 1–6 chars, `A–Z` `0–9` | +| SSID | 0–15 (`-0` … `-15`) | +| Address field | 7 bytes encoded | +| Max digipeaters | 8 | +| UI control | `0x03` | +| UI PID | `0xF0` (no layer 3) | +| CRC | CCITT 0x1021, init 0xFFFF, LE on wire | +| Max frame | ~330 bytes | +| Max UI payload (host) | 256 bytes | +| Broadcast payload hint (1200 baud) | ≤ 48 chars | + +## KISS + +| Symbol | Value | +|--------|-------| +| FEND | `0xC0` | +| FESC | `0xDB` | +| TFEND | `0xDC` | +| TFESC | `0xDD` | +| CMD DATA | `0x00` | +| KISS DATA AX.25 | **without FCS** (TNC adds CRC) | + +## Serial / radio defaults + +| Item | Default | +|------|---------| +| Host pacing | 2400 baud equivalent | +| Terminal width | 80 columns | +| Input line | 80 chars | +| TNC2C line | 7E1, RTS/DTR on | +| AFSK on-air | 1200 baud | +| G3RUH FSK | 9600 baud | +| BayCom SER12 netdev | `bcsf0` | +| USB TNC device | `/dev/ttyUSB0` | + +## MAX25 IDs + +| Terminal | AX.25 | +|----------|-------| +| CALLERID | source / MYCALL | +| CALLID | destination | |