Coverage log
The coverage log records Wi-Fi and mobile signal together with your position while you walk or drive. Afterwards you see the route colored by signal, on screen, in a PDF report or in Google Earth. Use it to find where your Wi-Fi gives out around a building or garden, or where mobile coverage drops along a road.
Record a walk or drive
- Open “Coverage log”. If you want, switch on “Wi-Fi and sensor positioning” first (see below).
- Tap “Start recording”. Allow notifications if asked: the recording runs with a notification, so it carries on with the screen off. “Stop” is on the notification too.
- Walk or drive. The screen shows the time, number of points and distance, the position accuracy, the serving mobile cell and the last Wi-Fi scan, and draws the track as you go.
- Tap “Stop recording” when done. The recording appears under “Recordings”.
A point is recorded at most every 2 seconds. Wi-Fi is scanned every 30 seconds, because Android allows apps only 4 scans per 2 minutes. So Wi-Fi readings are further apart than cellular ones, and a Wi-Fi reading is never repeated as if it had been measured again. Cellular readings need the phone-state permission, which the Cellular tool asks for.
Read the track
Choose “Cellular” or “Wi-Fi” above the map to color the track by that signal. The map is drawn north up.
| Color | Cellular (serving cell RSRP) | Wi-Fi (strongest access point) |
|---|---|---|
| Green, excellent | −90 dBm or better | −60 dBm or better |
| Light green, good | −91 to −100 dBm | −61 to −70 dBm |
| Orange, fair | −101 to −110 dBm | −71 to −80 dBm |
| Red, poor | below −110 dBm | below −80 dBm |
Gray means no reading at that point. On the Wi-Fi layer, only points where a scan came in are drawn.
Position quality and rings
GPS needs a moment to settle after it starts. The track therefore begins at the first position accurate to within 25 m, or after 30 seconds, whichever comes first. Until then the screen says “Waiting for a precise fix”.
Points with a position less certain than 25 m are still kept, because the signal reading there is real, but they're drawn as rings instead of dots: on screen, in the PDF report (which also counts them) and in Google Earth. Indoors and between tall buildings GPS is often 10 to 30 m off, so expect rings there.
Better positions indoors
“Wi-Fi and sensor positioning” is off by default; then only GPS is used. Switched on, the app uses Android's fused location, which combines GPS with Wi-Fi, mobile cells and the phone's motion sensors. It holds up better indoors, where GPS drifts. Choose it before you start recording. It's available on Android 12 and later.
Note: when Google Location Accuracy is on in your phone's settings, Android sends nearby Wi-Fi networks and cells to Google to work out the position. That is Android's processing, under your phone's settings.
Show the street map
Switch on “Map” to draw OpenStreetMap under the track, on screen and in PDF reports. It's off until you turn it on, because the map images are loaded from openstreetmap.org, which then sees the area shown. Without it, the track is drawn on a plain background.
Map images are kept on the phone so the same area isn't downloaded again. They're deleted when they haven't been shown for 7 days, and all of them when you turn Map off or delete a recording. If something on the map is wrong, “Map wrong? Report it to OpenStreetMap” under the map leads to OpenStreetMap's reporting page.
Reports and exports
Tap a saved recording to see its map. Its menu (“Export or delete”) offers:
| Choice | What you get |
|---|---|
| “Save report as PDF” / “Share report (PDF)…” | A report with a map for each layer (cellular and Wi-Fi), the spread of signal values, and tables of the cells and access points heard. |
| “Open in Google Earth” | Opens the track straight in Google Earth (or another app that opens KML files). |
| “Share as KML…” | A KML file through the share sheet, for example to import into Google My Maps. |
| “Save as KML” | The same KML file, saved where you choose. |
| “Save as CSV” | Every observation as a spreadsheet: time, position, accuracy and each cell and access point heard. |
| “Save for WiGLE (Wi-Fi CSV)” | The Wi-Fi readings in the CSV format WiGLE accepts for uploads. |
| “Delete” | Deletes the recording, after asking. This can't be undone. |
Google Earth isn't offered in the share sheet because it only opens KML files directly, so use “Open in Google Earth” for it.
Recordings are kept on this phone until you delete them, and they're left out of backups: a recording shows where you went. They only leave the phone when you export one.