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Your radio in the browser

This page shows you how to connect your own radio to APRScaching from a web browser, with no server and no software to install. You need a radio with a TNC, or only an audio cable; at the end the browser decodes what your radio hears, shows it live, and can pass it on to an instance.

What you need

  • A Chromium-based browser: Chrome, Edge, Brave or Opera, on a computer or an Android phone. Open the site over https://, or at http://localhost as on a Pocket phone. Brave ships Web Bluetooth switched off: enable Web Bluetooth API in brave://flags.
  • A signed-in account (Join).
  • One of these:
You have Button Notes
A USB KISS TNC, or a radio with a built-in KISS TNC on USB Connect USB radio Any TNC in KISS mode
A Bluetooth Low Energy KISS TNC, such as a Mobilinkd TNC3 or TNC4 Connect Bluetooth Finds TNCs that offer the BLE KISS service (Mobilinkd, many LoRa APRS trackers) or the Nordic UART service
Only an audio cable from the radio's speaker or data jack to the computer's soundcard Soundcard AFSK A software modem: decodes 1200-baud packet audio (AFSK, Bell 202), the modem APRS uses on 144.800 and 144.390 MHz, so no TNC is needed. Receive only
A Meshtastic node on USB Meshtastic node Reads positions of licensed nodes (licensed mode on, callsign as long name) and shows them under their callsign; licence-free nodes are ignored. Receive only

The page shows only the buttons your browser supports, and a line under them names the links it lacks. USB radios and Meshtastic nodes need Web Serial; Bluetooth TNCs need Web Bluetooth. Only Chromium-based browsers have them, so Firefox and Safari, and every browser on an iPhone or iPad, show Soundcard AFSK alone. For those, an ingest box feeds the instance instead.

Connect

  1. Open Settings → My radio (browser).
  2. Tune your radio to your APRS frequency: 144.800 MHz in Europe, 144.390 MHz in North America.
  3. Select the button for your hardware and pick the device in the browser's dialog.
  4. The status line shows ● live (USB radio) · N frames. Heard packets appear under Live RX.

The radio stays connected while you use the rest of the app: close Settings, open the map or Messages, and it keeps listening. While it is connected, a radio chip in the top bar shows the radio, the number of frames heard and the transmit state (TX on, RX only or TX locked until your callsign is verified). Select the chip to come back here; while your radio waits for transmit consent, selecting it asks for it instead.

The link ends when you select Disconnect, sign out, or close or reload the page. When the device goes away (unplugged, out of Bluetooth range), the app says Radio disconnected and why. For a station that runs around the clock, the instance's sysop runs an ingest box instead.

Work off-grid

Your radio and the browser are a station on their own. With no internet at all, the Field station panel lists Stations heard in the last hour and a Local inbox of the messages your radio heard. The panel keeps up to 500 heard frames for later.

Back online, turn on forwarding (next section) and select Sync N heard to replay those frames to the instance. Your own beacons stay out of the replay.

Send what you hear to an instance

  1. With a radio connected, or with frames held by the field station, switch on Forward to a gateway.
  2. Choose the Auth:
    • Signed (YOURCALL): for a public instance such as aprscaching.net. Your browser's key signs each batch, so no password is needed. The instance accepts only your own station's packets this way (any SSID of your callsign). Other stations your radio hears, and Meshtastic nodes, stay in your browser. That way no stranger can inject traffic in your name.
    • Secret (self-host): for your own instance. Enter the Gateway base URL and the Ingest secret that the instance's sysop set. With the secret, everything your radio hears is forwarded. The browser remembers the URL; it keeps the secret in memory for this session only, so you enter it again after a reload.

Packets your browser forwards never verify a find: at most a find is Logged (Tier C). Your own radio is not an independent witness of your own position: only a receiving station the instance trusts, hearing the frame on its own radio, can make a find Radio-verified. What your radio can verify, under the connect buttons, says the same. The packets still put stations on the map and messages in the log.

Transmit

Receiving is always allowed. Transmitting needs a verified callsign, a USB or Bluetooth TNC, and your consent for this tab; until your callsign is verified, the Transmit section says so.

Allow transmitting for this tab

When a USB or Bluetooth TNC connects under a verified callsign, the app asks once: Allow transmitting from YOURCALL-7 over your USB radio until you close this tab?

  • Allow lets this tab transmit from that callsign over that radio.
  • Receive only keeps the radio listening and sends nothing. Switch on Transmit in this tab, or select the radio chip in the top bar, to be asked again.

The consent lasts until you close the tab, and ends sooner when you switch Transmit in this tab off, disconnect the radio, lose the device, change the SSID, sign out or lose your callsign's verification. The app keeps it in the tab's memory only, so a reload or a new tab asks again. Nothing your radio sends goes out without it. Messages the instance sends for you (to APRS-IS, from the Mailbox, announcements) do not use your radio and follow their own settings.

Send a beacon

  1. Check the TX callsign: your callsign with the SSID you type, -7 by default.
  2. Under Beacon position, enter the latitude and longitude or select Use my location, and add an optional comment.
  3. Select Beacon, then Transmit in the confirmation.

A beacon and a message from this section ask you to confirm first. A message sent from Messages over the radio, and the ACK you send for a message heard for you, go out without a dialog: the tab's transmit consent covers them. Every one shows in the TX indicator and under Recent transmissions. To send a text message, see Send an APRS message. Read On-air etiquette and rules before you transmit.

See what you transmitted

For every frame your browser sends, the radio chip in the top bar lights TX, and a screen reader hears Transmitted to CALL at most once every few seconds. Recent transmissions, under the transmit section, lists the last 20 frames this tab sent: the time, the source callsign, the destination and path, a short summary (a message's text, a position, a status, a connect or disconnect) and the part of the app that sent it: My radio, Messages or Terminal. The list lives in this tab's memory only: the app never sends it to the instance and never stores it. Clear empties it, and signing out does too.

Troubleshooting

Problem What to check
No connect buttons The page is not on https://, or the browser has none of Web Serial, Web Bluetooth and Web Audio.
Only Soundcard AFSK shows The browser is not Chromium-based: use Chrome or Edge for a USB or Bluetooth TNC.
The radio is in use by the packet terminal One USB port opens in one place at a time. Close the TNC in the packet terminal first, or the other way round.
Connected, but 0 frames The TNC is not in KISS mode, or the radio is on the wrong frequency. With the soundcard, the input level is too low or too high: aim for the loudest level that does not clip.
Meshtastic node missing It needs Web Serial: use desktop Chrome or Edge.
The Bluetooth TNC is missing from the dialog Switch on the TNC's Bluetooth and pair it in the system settings first, if it asks for pairing. A TNC that offers only classic Bluetooth, not Bluetooth Low Energy, cannot connect.
Forwarding does nothing signed: sign in first. secret: the URL or the secret is wrong; the sysop can check the gateway log.
Sync N heard says to turn on forwarding Switch on Forward to a gateway and choose the Auth first.

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