UVProTermBT

A desktop AX.25 packet messenger + terminal for the BTech UV-Pro / VGC VR-N76 (the "Benshi" radio family), talking to the radio's built-in KISS TNC over classic Bluetooth — no cable, no external TNC.

Five modes in one PyQt6 window (styled after OpenWave), light/dark themes:

• Chat — SMS-style APRS messaging (send/receive, auto-ack).
• APRS — live monitor of decoded traffic + a heard-stations list.
• BBS — a full AX.25 connected-mode terminal (connect to BPQ/nodes).
• Winlink — brings up the kernel AX.25 port and embeds PAT's web UI in-window.
• SSTV — send and receive images over the radio's Bluetooth audio channel (Robot36 and more). Reverse-engineered from HTCommander; see docs/GAIA_AUDIO_SSTV.md. (New in v0.9.5 — transmit + receive proven on air; needs pysstv + the SSTV decoder, see below.)

Why this exists: the usual Linux recipe for a Bluetooth KISS TNC (kissattach /dev/rfcomm0) does not work with this radio. Its KISS session is only served through BlueZ's SerialPort profile, reached via an SDP-negotiated connection — so UVProTermBT registers an org.bluez.Profile1 and reads the RFCOMM fd BlueZ hands back. See docs/UVPRO_N76_KISS_LINUX.md and docs/PROTOCOL.md for the full story.

Screenshots

Chat (APRS messaging)	BBS terminal

Winlink (PAT embedded in-window)	SSTV (received image, auto-decoded)

A Chat-tab APRS message transmitted by UVProTermBT, decoded by an independent direwolf monitor — end-to-end on-air proof:

Requirements

• Linux with BlueZ (developed on Kubuntu), Python 3.12+
• A BTech UV-Pro / VGC VR-N76 with KISS TNC firmware
• System BlueZ D-Bus bindings: python3-dbus, python3-gi (installed by install.sh)
• Winlink only: PAT installed separately, plus a PolicyKit agent (KDE/GNOME provide one). ax25-tools is installed for you. Run ./run.sh --check to verify everything Winlink needs is present.
• SSTV only: the SBC codec libsbc1 (system), pysstv (encode, installed by install.sh), and the decoder pip install git+https://github.com/colaclanth/sstv.git (numpy/scipy; needs libsndfile1). Without the decoder you can still transmit; receive needs it.

Install & run

git clone https://github.com/chengmania/UVProTermBT
cd UVProTermBT
./run.sh

That's it. ./run.sh installs everything it needs the first time (asks for your password once, for apt), then launches the app. Every run after that it just starts. After the first run there's also a "UVProTermBT" icon in your app menu you can use instead.

Prefer to do it by hand?

sudo apt install python3-dbus python3-gi
python3 -m venv --system-site-packages .venv
.venv/bin/pip install -r requirements.txt
.venv/bin/python -m uvprotermbt

First launch runs a setup wizard: enter your callsign, then pick your radio. On the radio, first enable KISS TNC (Settings → General Settings → KISS TNC → Enable KISS TNC) and pair it to this computer.

Using it

• Status bar shows your callsign, Bluetooth state (● green = connected), and the BBS session.
• Chat: /to CALL sets who messages go to, then type and press Enter.
• BBS: /connect KC3SMW-7 (direct) or /connect NODE via DIGI; type commands to the node; /ex and other node commands pass through; /bye to disconnect.
• Up/Down recalls previous input; double-click a heard station to set it as your chat target; Ctrl-T toggles the theme.
• SSTV: Transmit sub-tab — pick a mode, Load Image… (preview), Send. Receive sub-tab — leave it enabled; incoming images decode automatically (the mode is auto-detected, no selector). Images save to ~/.local/share/uvprotermbt/sstv/.

SSTV modes

Transmit uses pysstv; receive/auto-decode uses the colaclanth SSTV decoder. They don't cover exactly the same set, so which modes are available depends on the direction:

Direction	Modes
Transmit (17)	Robot36 · Martin M1/M2 · Scottie S1/S2/DX · PD90/120/160/180/240/290 · Pasokon P3/P5/P7 · Wraase SC2-120/SC2-180
Receive / decode (7)	Robot 36 · Robot 72 · Martin 1/2 · Scottie 1/2/DX (auto-detected from the VIS header)
Both send + receive in-app	Robot36 · Martin M1/M2 · Scottie S1/S2/DX

• Robot36 is the recommended default — fast, robust, universal, and works end-to-end within the app.
• You can transmit any of the 17 modes; the receiving station decodes with whatever SSTV software it runs (most decode all of these).
• PD / Pasokon / Wraase transmit fine but this app can't decode them if received. Robot72 is receive-only here (the decoder handles it; pysstv can't encode it).
• Neither library covers every historical SSTV mode — that's a limit of the SSTV libraries, not the radio link.

Troubleshooting

If pairing or connecting misbehaves, it's usually a stale Bluetooth bond — see the fix in docs/UVPRO_N76_KISS_LINUX.md. Connected-mode BBS work is happiest on a quiet frequency; keep the radio's own APRS beacon off while using it as a TNC.

License / credit

Copyright (C) 2026 Greg (KC3SMW).

UVProTermBT is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License v3.0 as published by the Free Software Foundation. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the LICENSE file for the full license text, or https://www.gnu.org/licenses/gpl-3.0.html.

Credits

With thanks to the projects that made this possible:

• HTCommander (Ylian Saint-Hilaire) — the SSTV feature (the radio's Bluetooth audio channel, the GAIA control protocol, and the SBC audio format) was reverse-engineered from it. Without HTCommander as a working reference, audio transmit wouldn't have been possible. See docs/GAIA_AUDIO_SSTV.md.
• PAT (Martin Hebnes Pedersen, LA5NTA) — the open-source Winlink client UVProTermBT embeds and hosts in-window. PAT does the Winlink B2F protocol; this app just brings up the AX.25 port and bridges the radio.
• pysstv and colaclanth/sstv — SSTV encode and decode, respectively.
• BlueZ — the Linux Bluetooth stack, and its libsbc SBC codec, used for the RFCOMM SerialPort transport and the audio channel.
• Built with PyQt6 and the kernel AX.25 stack / ax25-tools.