Chapter 20
Android Auto
APRS on the car's display.
The app works on the car's display through Android Auto. Everything runs on the phone — the car screens are a view onto the same service, so APRS-IS, Bluetooth, BLE and USB TNCs, beaconing and messaging all carry on while you drive.
#Setting up
- Configure and test the app on the phone first (callsign, filter, beaconing, TNC).
- Install the app from the Play Store (see chapter 2): Android Auto then shows it without any extra settings.
- Connect to the car. The app appears in the Android Auto launcher as G7JJF APRS.
While the phone is projecting, the phone screen shows a Driving Mode — use the car display overlay; ← Back to Map dismisses it if a passenger wants to use the phone app.
#Home screen
The main car screen is a grid of tiles. The title shows APRS-IS · N stations, RF TNC · N stations or Not connected, and refreshes every two seconds.
| Tile | Function |
|---|---|
| Map | The drawn station map (needs a head unit with Car App API level 7 or later). |
| Stations | The 20 nearest stations to where you are now (the QTH when there is no GPS fix), with distance, direction and comment; updated as you drive. A–Z lists them by callsign, Nearest goes back to nearest first; the choice is kept (also on Weather, Repeaters and Objects). |
| Weather | The 20 nearest weather stations with temperature and wind. |
| Repeaters | Repeater objects heard on APRS. |
| Messages | Conversations, with the number of new messages — new since Messages was last opened in the car or on the phone. Open one to read the last 10 messages and Reply; new replies appear while it is open. A reply sent in several parts shows as one message; tap a message to read all of it. A dictated reply longer than one APRS message (67 characters) is sent as several, split between words. |
| Objects | Objects heard nearby, by their own names. Send Message on an object writes to its owner. |
| My Position | Car or phone GPS position, locator, speed, course and altitude; Show Me on Map. |
| Beacon Now | Shows what will be sent and sends a beacon. |
| Connect IS / Disconnect | Connect or disconnect APRS-IS using your saved settings. |
| Connect RF / Disconnect RF | Pick and connect a BLE TNC (live scan), a paired Bluetooth TNC (KISS or Text) or the USB TNC; or disconnect them. |
| About | Version, callsign, connection, server and session counts. |
Tapping a station in any list opens its details — comment, position, weather — with Navigate, Send Message and Map. Distances in the car lists are measured from where you are (car or phone GPS), or from your QTH when there is no fix.
#Messages in the car
- New messages show briefly on the car screen ("Message from JOKE: …") while the car app is open, and are counted on the Messages tile; open the conversation to read it in full and reply. With Spoken alerts on (Settings), the phone reads them out through the car speakers.
- Whole replies, once. Services such as JOKE and MPAD answer in several messages a few seconds apart. The app waits until the sender has been quiet for 10 seconds, then announces the whole answer as one — on the car screen, in the phone notification and in the app's own spoken alerts.
- Quick replies. Reply (and Send Message) opens a list of one-tap answers — OK, QSL 73, On my way, Running late, Driving will reply later — which work while moving, when many cars lock the keyboard. Type a message… opens the keyboard when the car allows it.
- Spoken or typed replies longer than one APRS message (67 characters) are sent as several, split between words.
#Navigate
Navigate on a station's details sends its position to the navigation app you use in Android Auto — Google Maps, Waze, TomTom GO or another — which starts a route to it. Android Auto chooses the app: the one you used most recently in the car.
#Alerts on the car screen
Android Auto shows notifications only from messaging, calling and navigation apps, so a station coming within your Proximity alert distance, or anyone sending an emergency, is notified on the phone, not the car screen. Emergencies are always spoken; with Spoken alerts on, nearby stations are spoken too, through the car speakers.
adb install -i com.android.vending, or turn on Unknown sources in Android Auto's developer settings.#The car map
On head units with Car App API level 7 or later the map is drawn directly on the car display with the same symbols, clustering and age fading as the phone map.
- On-screen buttons: + and − zoom (levels 4–18), ⊙ re-centres on your position and resumes following, TX sends a beacon, and the top button shows the map layer — Map, OSM, Sat or Topo, the same four as the phone map — and steps to the next each time you tap it. Drag (or use the Pan action) to move the map.
- Tap a station (generous 80-pixel target) for its details; tap a cluster to zoom in. Clusters are used below zoom 12 when more than eight stations are visible; labels appear from zoom 10.
- Your own position uses your beacon symbol while moving (the SSID symbol if Symbol from SSID is on, and a car if your beacon symbol is the house) and a house when parked, with a heading arrow and a trail of the last 120 points. Moving is taken from the GPS speed or, where the car's GPS gives none, from how far you travel between fixes; it changes back to a house a minute after you stop, so traffic lights don't make it flicker.
- A status strip shows the connection (IS, RF or both), the GPS source (car GPS, phone GPS or none), the number of stations shown at the current zoom, and your beacons — when the last went and when the next is due (TX 2m ago · next 1m; auto off when automatic beaconing is off). TX confirms on the car screen.
- Buttons and text are sized to the car screen's pixel density.
- Your position comes from the phone's GPS while it has a fix, and from the car's own GPS (where the head unit provides it) when it doesn't. The status bar shows which.
- Satellite imagery (Sat) is easier to see in bright sunlight. The layer is remembered. On Map the map turns dark when the car is in night mode, or the phone app is in night mode (☽) or the red theme; at those times OSM and Topo, which have no dark version, are shown at half brightness.
- Tiles are OpenStreetMap in the light theme and CARTO Voyager otherwise by day, and CARTO's dark map when the car is in night mode, so the screen isn't bright in the dark. They are cached on the phone (shared with the phone map, up to 200 MB).