Connect a radio

APRS Connect speaks to real radios through several kinds of KISS TNC, and to the internet backbone with no radio at all. Every connection is a channel on the Radio screen (under More on the tab bar) — this page lists what's available and which guide to read next.

The six channel types

Tap Add channel on the Radio screen and pick what carries it:

• Bluetooth TNC — a paired Bluetooth Classic KISS TNC: a Kenwood TH-D74 or TH-D75 with its built-in TNC, or a Mobilinkd. Pair in Android first, then pick the radio from the paired list. → Bluetooth KISS TNCs
• Bluetooth LE TNC — a BLE KISS TNC such as a Mobilinkd TNC4 in LE mode or a B.B. Link. Nothing to pair: the app scans for the TNC advertising nearby. → BLE TNCs
• USB TNC — a KISS TNC on an OTG cable: a Mobilinkd TNC4, a TNC-X, a TNC-Pi, a machine running Direwolf, or a Kenwood data cable. → USB serial TNCs
• Audio modem — no TNC at all: an audio cable (or VOX) between the phone and the radio, with the app doing the AFSK 1200 modulation itself. → The AFSK audio modem
• Network TNC — KISS over TCP to Direwolf or any network TNC on your LAN. → KISS over TCP
• APRS-IS — the internet backbone over your phone's own connection. No radio required. → Connect to APRS-IS

Choosing a channel type

Channels: any combination, at once

A channel is one way onto the air, and you can run several: your handheld over Bluetooth, the shack Direwolf over the network, and APRS-IS, all at the same time. Each channel has its own name, its own switch, and its own row on the Radio screen showing its live state and traffic counters.

Two rules keep this honest:

• One live link per radio type. The phone has one Bluetooth Classic socket, one USB connection, one microphone — so switching on a second channel of one of those types turns the first off — and the app says so before you tap, naming the channel that will drop: one Bluetooth TNC link at a time. Network channels (APRS-IS, KISS over TCP) have no such limit and run concurrently.
• Beacons decide where they go. Each beacon has a Send via setting: EVERYWHERE — every connected channel, including ones you add later — or only the channels you name. A beacon pinned to channels that aren't connected does not go out and does not fall back to another. Messages are different: a message you send goes out over every connected link, and the packet log records which ones carried it. RF and internet status each show their own indicator on the messaging screens.

Channel status

The Radio screen distinguishes intent from reality. A switch that's on but a link that isn't working says so, in words, with the reason:

• Each channel row shows its state — CONNECTED, CONNECTING, RECONNECTING, ERROR — plus received and sent counters and when it last heard anything.
• A link that's up but has heard nothing for a while shows CONNECTED · QUIET with an explanation: a quiet channel is normal in low-traffic areas — or the radio's volume is down.
• A channel that can't come up says why the switch is disabled: "Set your callsign first", "No device paired", "No host set".
• A hardware TNC that connects but never hears anything gets the right first question on screen: check the radio is in KISS mode.
• Every row has its own RECONNECT button, and its own BEACON button that sends your enabled beacons over that channel alone.

Start here

A fresh install comes with a single APRS-IS channel, so the app works before you own any hardware — see Getting started. When you're ready for RF, add a channel for whatever TNC you have, then send your first beacon. For receiving with the screen off, read Background & battery.

Last updated 31 August 2026