Build Coverage Map

Paint a colour-coded picture of signal strength as you walk or drive, then drape it over Google Earth.

Start, stop and run alongside the rest

Open Build Coverage Map and press START. CNA samples the serving-cell signal every few seconds and drops a colour-coded circle at your position; its radius grows with the distance you have moved, so faster stretches get larger circles. Press STOP to finish, or let the safeguard duration end it. MANAGE opens your saved maps.

The panel top-right shows the live sample: operator, cell id, current RSRP, network type and the running sample count.

Coverage mapping runs as its own background service, so you can lock the screen or switch apps and it keeps sampling; it can also run in parallel with route logging and a tower hunt at the same time.

Live coverage map being built, with START, STOP and MANAGE buttons — Building a map. Colour-coded circles trace your route; START, STOP and MANAGE sit along the bottom.

Three CNA notifications active at once: coverage map, logging and tower hunt — All three background tools active at once.

Three tools, in parallel

Because each tool is a separate foreground service, CNA can record a coverage map, a route log and a tower hunt simultaneously. Android shows one ongoing notification per active tool, each with an Open action. Stopping is always done from the tool's own screen.

Tap a circle

The coverage sample detail

Tap any circle, on the phone or in the exported KMZ, to open its full detail. The RSRP is shown large at the top, followed by the complete snapshot for that sample.

The popup gathers the fields explained on the Geographical and Spectrum pages into one place for that exact spot:

RSRP (shown large), the signal strength at this point.
Log time, and the connection state: Tech, Radio, Call, Data, Tx, Rx.
MCC, MNC, TAC and the cell id.
A frequency block: tech, band, ARFCN, DL freq, carrier BW, PCI, RSRP and RSRQ.

CNA labels the fields by radio state. When the radio is idle the panel reads Camped Cell and Camped frequency (you are camped, not actively transferring data), rather than "Primary" / serving. It is the same information, honestly labelled.

Signal-strength colours

Reading the circles

Circles are coloured on the same weak-to-strong ramp used throughout CNA.

≤ −110 dBm, very weak ≤ −100 dBm, weak ≤ −90 dBm, fair ≤ −80 dBm, good > −80 dBm, strong

List of stored coverage maps — Your stored coverage maps (up to 10).

Manage your saved maps

Every finished map is saved to a list (up to 10). Tap one to open its options:

Show, review the map again on screen.
Rename, give it a meaningful name.
Upload KMZ (RSRP), export coloured by signal strength for Google Earth.
Upload KMZ (RSRQ), export coloured by signal quality (see below).
Upload CSV, the raw samples for a spreadsheet.
Delete, remove a map you no longer need.

💡 Gmail is recommended when emailing exports, as some mail apps mishandle attachments.

RSRP vs RSRQ

Why also look at RSRQ?

RSRP (signal strength) tells you how much signal reaches your phone. But a cell can be strong and still perform poorly if it is congested or suffering interference from neighbouring cells. RSRQ (signal quality) captures that: it factors in interference and load, so it often reveals problems that a strong RSRP hides.

That is why CNA lets you export the very same coverage map two ways, coloured by RSRP and coloured by RSRQ. Comparing the two Google Earth overlays quickly shows spots where the signal looks strong but the quality, and therefore your real-world throughput, is not.

The CSV export

What the CSV contains

The CSV export is one row per sample, so you can filter, average and chart your coverage in a spreadsheet. It uses a semicolon as the delimiter (not a comma), so choose that delimiter when opening it. Every column is one of the parameters already explained above:

DateTime
Technology
RRC state
Call State
Data State
Tx / Rx data (B)
MCC (name + code)
MNC (name + code)
LAC
PCell id
UE latitude / longitude
Primary tech
Primary band
Primary ARFCN
Primary DL freq (MHz)
Primary carrier BW (MHz)
Primary PCI/PSC/BSIC
Primary signal (dBm)
Primary signal quality

A coverage map follows only the serving (primary) carrier, so there are no secondary-carrier columns; for the full multi-carrier layout see the Route Logging CSV.

Configuration

Applicable preferences

Preferences: Build Coverage Map settings — Preferences, Build Coverage Map.

Under Build Coverage Map related preferences you can set:

Map Type, Street or Satellite for the coverage view.
Max Duration, a safeguard that auto-stops the map after the chosen time, so it can never run indefinitely by accident.

Next: Route Logging

Where the coverage map paints signal strength, route logging records the full tower connection at each point, and links every position to the tower it was using.

📍 Open the Route Logging guide