Taking the map where there is no signal
This post is for operators who take a radio somewhere the phone has no coverage: a SOTA summit, a long trail, a valley with no towers. It explains how APRS Connect keeps the map on screen with no signal, which part of that is free and which part needs APRS Connect Pro ($3.99 a month or $29.99 a year, with a 7-day trial through Google Play), and what the rest of the app does once the internet is gone.
The map keeps what you have looked at, in a cache that costs nothing. It can also hold whole regions that you download on purpose before you leave, which is a Pro feature. The two are easy to confuse, so most of this post is about the difference between them.
The tile cache is browsing history
Every tile the map draws is kept on the phone. Pan across your home county on Wi-Fi tonight, and those tiles redraw tomorrow with no connection. The cache is capped at a size you choose, up to 10 GB, under Settings → Map cache. The default keeps about a region's worth, and when the limit is reached the oldest areas you have not looked at again are dropped first.
The cache is history, not a download: somewhere the map has never shown you is not available offline, and an area you only scrolled past at a wide zoom has no street-level tiles to fall back on. To be certain a whole area is on the phone before a trip, download a region instead.
The tile cache works with or without Pro.
A region is a deliberate download
Settings → Offline maps lists the regions on the phone and lets you fetch more. A stored region is the complete map of its area, down to the detail level shown beside it, and it draws on its own with no signal at all. The tile cache is not involved. Each region shows its download size before you start and its date afterwards, with an Update action when newer map data is available. A download that fails keeps nothing, so there is no half-finished region to wonder about.
Regions are cut at state and province size. A whole US state at full detail runs to a few hundred megabytes (Kentucky is about 400 MB), and each region arrives as one file rather than tile by tile, so start the download on Wi-Fi and let it finish before you leave. You can keep any number of regions at once.
Once a region is stored there is nothing to switch on. It simply draws: inside its boundary the stored data is what you see, connected or not, and outside its boundary the map behaves exactly as before. The fonts and symbols the map needs are shipped with the app, so a phone that has never been online still gets a labelled map, not a bare outline.
Every tile the Map tab draws goes into the cache; a downloaded region covers the whole area whether or not you have looked at it.
Importing a map file
The Offline maps screen also has Add map file, which imports a map file you already have. That can be a region exported from another phone, or one you built yourself for an area the catalogue does not cover. An imported file is listed and drawn like any downloaded region, and it is visible while you are connected too, so you can check it before relying on it.
Cache and region, side by side
| Tile cache | Downloaded region | |
|---|---|---|
| How it gets there | By looking at the map | A download you choose on the Offline maps screen |
| What it covers | Places the map has shown you, at the zooms you used | The whole area, to the detail level listed beside it |
| Size | Capped at a size you choose, up to 10 GB | Shown before the download starts |
| Cost | Free | APRS Connect Pro |
| When Pro ends | Keeps working | Kept on the phone but not drawn |
What a radio still does with no signal
The app is local-first. Messages, packet history and the station list live in a database on the phone, so everything you heard on the way up is still there on the summit, and the map draws it from the cache or from a region. The traffic behind the picture depends on which connections you have.
With a radio channel connected (a KISS TNC over Bluetooth, Bluetooth LE or USB, or the app's audio modem over a cable), reception carries on without the internet. Stations heard over RF appear on the map with their real symbols, messages over RF arrive and can be answered, and your beacons keep going out. With Keep running in the background on, which is the default, all of that continues with the screen off; the Background & battery page explains the Android battery setting that can otherwise cut it.
What stops is everything that needs the internet:
- APRS-IS drops, so stations that only exist on the internet side stop updating, and anything you send goes out over RF alone.
- Weather radar is a live layer and has nothing to draw.
- Downloads and updates of regions wait until you are back in coverage.
A message sent over RF reaches the internet side only if a digipeater or igate within range carries it there, and the app cannot promise that from a hilltop. The delivery states tell you what actually happened: Digipeated means your packet was heard coming back through a repeater, and Delivered means the other station acknowledged it.
If Pro lapses
Nothing is deleted. Regions already on the phone are kept as they were, but they are not drawn while Pro is off, and the map goes back to its tile cache and the online basemap. The moment Pro returns, the regions draw again with no download needed. The tile cache never stops working either way.
Where to read more
- Map covers the tile cache, offline regions and every layer.
- Free and Pro lists exactly what the subscription switches on.
- Background & battery explains keeping reception alive with the screen off.
- Connect a radio helps you pick the link between radio and phone.
Downloading, importing and drawing regions need APRS Connect Pro; the tile cache does not.
